Rozprawy doktorskie na temat „Water-ethanol mixture”

In this research project, adsorption is used in conjunction with carbon dioxide stripping to increase the efficiency of ethanol production by decreasing the effect of the product inhibition. The reduction in product inhibition is particularly important when ethanol is produced from the lignocellulosic biomass because genetically-modified microorganisms able to use all fermentable sugars are less tolerant to ethanol. Carbon dioxide removes some ethanol from the fermentation broth and reduces the level of ethanol toxicity, while adsorption is used to recover the entrained ethanol from the vapour phase. A series of adsorption screening experiments were performed to compare four activated carbon adsorbents and two hydrophobic ZSM-5 type zeolites. One activated carbon (WV-B 1500) exhibited the highest ethanol capacity. Adsorption isotherms for ethanol and water in the presence of carbon dioxide at different temperatures were determined. The temperature-dependent Toth isotherm model provided satisfactory fits for these isotherms. Ethanol adsorption experiments with and without the presence of water were conducted and showed similar ethanol adsorption capacities indicating that the presence of water has negligible effect for ethanol adsorption. A mathematical model was developed to predict the adsorption performance of activated carbon WV-B 1500 for ethanol vapour adsorption in the presence of carbon dioxide and water. The model takes into account changes in velocity due to adsorption, heat effects during adsorption, and heat losses to the surroundings. The model was validated with experimental data. Finally the model was used to predict the adsorption working capacities to assess the performance of the adsorption process in an industrial process. An economic analysis was performed by comparing a simulated base case ethanol production plant with a similar process coupled with carbon dioxide stripping and adsorption technology. The process was modeled using Aspen HYSYS to perform material and energy balances. The packed bed adsorption system, operating as a temperature-swing adsorption (TSA) or a vacuum-swing adsorption (VSA) system, was simulated to evaluate the performance of the adsorption system and to size and cost the associated equipment. Preliminary results showed that the grass roots cost for the ethanol production process coupled with carbon dioxide stripping and adsorption technology for three different TSA (purge gas at 80, 100, and 120°C) and VSA (adsorption pressure at 0.5, 0.2, and 0.1 atm) systems were more cost effective than the base case ethanol plant.

Ethanol is a renewable energy source that could decrease society's dependence on fossil fuels, while reducing greenhouse gas emissions. Producing ethanol on a small scale on South African farms could provide farmers with the capability of increasing their profits by reducing their input cost. Ethanol can be directly used as fuel and could supply alternative products to their market. This study evaluated the feasibility of using an ammonia/water hybrid heat pump in the ethanol production process. A model for the material and energy balance of a small scale ethanol plant was simulated, to obtain the requirements to which the hybrid heat pump had to adhere. A two stage hybrid heat pump (TSHHP) was then modelled. It is capable of operating at high temperatures and it has high temperature lift capabilities, which are suitable in the production of ethanol. The results from the model demonstrated that the TSHHP could operate at an average temperature lift of 106°C with a maximum temperature of heat delivery as high as 142°C and cooling as low as 9°C. Simultaneous heating and cooling demand in the ethanol production process can be met with the TSHHP. For the TSHHP model, 120 kW of heating and 65 kW of cooling is supplied while maintaining a COP of 2.1. The model accuracy was also verified against another simulation program. Implementation of the TSHHP into the ethanol plant was then discussed, as well as methods to optimize production by energy management. When compared to conventional heating and cooling systems, it was found that the TSHHP provides a more cost effective and energy efficient way of producing ethanol. The economic evaluation demonstrated that the installation cost of the TSHHP would only be 63% of the price of a conventional system. The main advantage is that the TSHHP uses only 38% of the energy used in a conventional system.
Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2009.

A di-2-piridil cetona benzoilhidrazona (DPKBH) é um reagente solúvel em uma série de solventes orgânicos mas pouco solúvel em água. Vem sendo utilizado para a determinação de metais, (principalmente do grupo de transição) como Fe(II), Fe(III), Ni(II), Cu(II), entre outros e como ligante de referência para estudar o comportamento dos íons Fe(II) e Fe(III) em presença de espécies orgânicos encontrados em águas naturais. Com o objetivo de entender melhor as propriedades do DPKBH em meio de etanol, foi necessário determinar as constantes de dissociaçãolionização em diferentes porcentagens desse solvente orgânico (10, 19, 29 e 48 %). Nestas porcentagens de etanol, através de medidas absolutas de pH determinaram-se os pKs do DPKBH utilizando-se a técnica potenciométrica e em 10 e 48 % de etanol através de medidas absolutas de pH associadas às absorbâncias das espécies presentes nos equilíbrios, utilizando-se a técnica espectrofotométrica. Nas devidas porcentagens de etanol, o comportamento do eletrodo foi previamente determinado. Os valores de pK1 3,210; 3,342; 3,398 e 3,360 e de pK2 10,834; 11,013; 11,793 e 11,382 foram obtidos respectivamente para 10, 19, 29 e 48 % de etanol, utilizando-se a técnica potenciométrica. Através da técnica espectrofotométrica os valores de pK1 foram 3,257 e 3,322 e pK2 10,880 e 11,820, em 10 e 48 % de etanol, respectivamente.
The di-2-pyridyl ketone benzoylhydrazone (DPKBH) is a soluble reagent in different organic solvents but slightly soluble in water. It has been used for metal determinations, (mainly transition metals) such as for Fe (II), Fe(III), Ni(II), Cu(II) and also like a reference ligand to study the behavior of Fe(II) and Fe(III) ions in the presence of organic species found in natural waters. So as to better understand the DPKBH properties In ethanol, it was necessary to determine the dissociation/ionization constant in different percentages of ethanol (l0, 19, 29 and 48%). In these ethanol percentages, through absolute pH measurements, pKs of DPKBH could be the found by using the potentiometric technique, and in 10 and 48% of ethanol the pKs of DPKBH were determined with pH measurements associated to absorbance of the species present in the equilibria by using the spectrophotometric technique. In appropiate percentage of ethanol the behavior of the glass electrode was previously determined. The pK1 values 3.210; 3.342; 3.398 and 3.362, and pK2 10.834; 11.013; 11.793 and 11.382 were found for 10,19,29,48 % of ethanol, by using the potentiometric technique. The spectrophotometric technique led to pK1 values 3.257 and 3.322, and the pK2 ones 10.880 and 11. 820 in 10 and 48 % of ethanol respectively.

Zeolite A membranes have great potential in pervaporation separation of ethanol/water mixtures with high flux and selectivity. Zeolite membranes usually synthesized from hydrogels in batch systems. In recent years, zeolite membranes are prepared in semicontinuous, continuous and recirculating flow systems to allow the synthesis of zeolite membranes with enlarged surface areas and to overcome the limitations of batch system at industrial level production. The purpose of this study is to develop a synthesis method for the preparation of good quality zeolite A membranes in a recirculated flow system from hydrogels and to test the separation performance of the synthesized membranes by pervaporation of ethanol/water mixture. In this context, three different experimental synthesis parameters were investigated with zeolite A membranes synthesized in batch system. These parameters were the composition of the starting synthesis hydrogel, silica source and the seeding technique. Syntheses were carried out using hydrogels at atmospheric pressure and at 95 °
C. The membranes were characterized by X-ray diffraction, scanning electron microscopy and pervaporation of 90 wt% ethanol-10 wt% water mixtures. v Pure zeolite A membranes were synthesized both in batch and flow systems. The membranes synthesized in batch system have fluxes around 0.2-0.3 kg/m2h and selectivities in the range of 10-100. Membranes with higher selectivities were obtained in batch system by using waterglass as silica source, seeding by dip-coating wiping method, and with a batch composition of 3.4Na2O:Al2O3:2SiO2:155H2O. The membranes prepared in flow system have higher pervaporation performances than the ones prepared in batch system in considering both flux and the selectivity. Fluxes were around 0.3-3.7 kg/m2h and selectivities were in the range of 102-104 for the membranes prepared in flow system which are comparable with the data reported in literature for batch and flow systems. A high quality zeolite A membrane was also synthesized from 3.4Na2O:Al2O3:2SiO2:200H2O hydrogel at 95 °
C for 17 hours in flow system. Pervaporation flux of this membrane was 1.2 kg/m2h with a selectivity >
25,000 at 50°
C. Although the synthesis method is resulted with high quality membrane, reproducibility of the synthesis method is poor and it should be improved.

Drug administration through the pulmonary route is an ancient technique that evolved from inhaling the smoke of certain leaves as a medicine. The optimum droplet diameter for the pulmonary system deposition has been identified to be in the range from 2 to 3.5 μm, with potential deposition rates of up to 80% of this size range. Currently, the most used aerosol generator methods are the pressurized metered dose inhalers. However, they generally exhibit low deposition efficiency with less than 20 % of the spray reaching the target area of the lungs as most of the drug deposited in the upper airways. This is for the most part due to the droplet size polydispersity that is inherent in these systems. The droplets of the biggest diameter will deposit in the upper airways, and then the deposited medicine will be swallowed and absorbed in the gastrointestinal tract. This can produce adverse medical side effects. Electrospray (ES) or electrohydrodynamic atomization (EHDA) is a promising atomization process due to its ability to produce a spray with monodisperse droplet size. The current study will investigate the feasibility of using electrospray in a pulmonary drug delivery system. Assessments, selection and characterization of suitable biocompatible solvents that can be used as a lung obstruction relief drug were carried out. Tests to identify the electrospray setup necessary to produce droplet sizes in the appropriate range for deposition in the lungs were carried out. The study found that both stable and pulsating cone jet modes can produce the required droplet size and the pulsating mode can produce at least four times higher flow than stable cone jet mode. A low-cost image analysis technique developed for this work gave satisfactory results that could be compared to droplet size scaling laws from the literature. However, it proved to be relatively time consuming and further automation of this technique would make it more suitable for large-scale studies. The image analysis results show a correlation between the cone length, cone angle and the applied voltage. The droplet scaling laws discrepancies such as the solution flow rate exponent and the constant that is used by some scaling laws may be attributed to the droplet evaporation time which is quite short for the water/ ethanol solutions. The emitter diameter and the conductivity effect on the I(Q) power law and the sensitivity of the onset voltage (Vonset) to the liquid flow rate (Q), were demonstrated for solutions of triethylene-glycol (TEG), and for an ethanol-water mixture solution.

Le développement actuel des piles à combustible SOFC fonctionnant à température intermédiaire suppose l'optimisation des méthodes de synthèse et de mise en forme pour les matériaux nouveaux développés au cours des dernières années. En effet, les propriétés électrochimiques de ces dispositifs sont étroitement liées aux caractéristiques des poudres de départ ainsi qu'à la microstructure des électrodes (ou de l'électrolyte) après leur mise en forme. Une amélioration significative des dites propriétés peut être obtenue par la nanostructuration des matériaux. Dans ce contexte, ce travail de thèse est consacré à l’élaboration du matériau de cathode Nd2NiO4+d ainsi que du matériau d'électrolyte Ce1-xAxO2-d. Les méthodes mises en œuvre sont la synthèse de nanopoudres en milieux éthanol/eau supercritiques et par voie pyrosol ainsi que le dépôt de couches minces en milieu CO2 supercritique. Les objets obtenus ont enfin été caractérisés par spectroscopie d'impédance électrochimique afin de quantifier leur performance pour l’application SOFC
The ongoing development of Intermediate Temperature Solid Oxide Fuel Cells implies the optimization of the synthesis and deposition methods for the new materials developed these past years. Indeed, electrochemical properties of these materials are closely linked to the initial powder characteristics as well as the electrode (or electrolyte) microstructure after deposition. Significant improvement of the aforementioned properties can be obtained via nanostructuration of the materials. Thus, this thesis is dedicated to the synthesis of the cathode material Nd2NiO4+d and the electrolyte material Ce1-xAxO2-d. Methods employed are namely nanopowder synthesis in water/ethanol supercritical mixtures and spray pyrolysis as well as thin film deposition in supercritical fluids. The obtained objects have finally been characterized by electrochemical impedance spectroscopy in order to assess their performance for the SOFC application

碩士
中原大學
化學工程研究所
91
Polyurethane (PU) membrane has a poor selectively for separating ethanol-water mixtures, but it has good mechanical properties and chemical resistance. Polyurethane membrane is suitable to be used as matrix. In order to improve the hydrophilic property of the PU membrane, utilize chemical initiation to graft hydrophilic monomers, 2-hydroxyethyl methacrylate (HEMA) and 4-hydroxybutyl acrylate (HBA), onto polyurethane membrane, respectively. The grafted membrane was applied in the pervaporation processes for ethanol-water separation. Changing degree of grafting onto polyurethane membrane with initial monomer concentration added was investigated. The effects of degree of grafting, feed concentration, feed temperature, and different kinds of hydrophilic monomer on the variation of separation factor and permeation rate were investigated. In this study, the factors of the initial monomer concentration, and monomer structure were affected the degree of grafting on the PU membrane. Higher and lower initial monomer concentration makes lower degree of grafting. The effects of degree of grafting, feed composition, operating temperature, and different kinds of hydrophilic monomer on the separation factor and permeation rate of ethanol-water pervaporation of grafted membranes were studied. From the experiment results, the separation factors of 99.07 and 387.12 and permeation rates of 6133 and 6196 g/m2hr for the PU-g-HEMA membrane with a degree of grafting, 17.79%, and the PU-g-HBA membrane with a degree of grafting, 38.11%, respectively, under the conditions of 90wt% ethanol feed concentration, and 25℃ operating temperature. Compared with PU membrane, which possess the separation factor of 15.56 and permeation rate of 4335 g/m2hr, the modified PU membranes show appreciable improvement in the performance.

The thesis presents detailed results of theoretical analyses based on extensive computer simulation studies with an aim to explore, quantify whenever possible, and understand structure and dynamics of polymers and proteins in several complex solvents. In order to make the Thesis coherent, we also study certain aspects of binary mixtures. Based on the phenomena studied, the thesis has been divided into four major parts: I. Dynamics of biological water: Distance dependent variation of dielectric constants in aqueous protein solutions II. Temperature dependent study of structural transformations in aqueous binary mixtures III. Conformation and dynamics of polymers in solution: Role of aqueous binary mixtures IV. Conformational change and unfolding dynamics of proteins: Role of sol-vent environment The above mentioned four parts have further been divided into thirteen chapters. In the following we provide a brief chapter-wise outline of the thesis. Part I consists of two chapters, where we focus on the study of dynamics of biological water and distance dependent variation of static and dynamic proper-ties (including dielectric constant) of water near different proteins. To start with, chapter 1 provides an introduction to the structure and dynamics of biological water. Here we discuss different experimental studies; including dielectric relaxation, NMR and salvation dynamics those explore the bimolecular hydration dynamics in great detail. We also discuss the wide range of computer simulation and theoretical studies that have been carried out to understand the dynamical behaviour of biological water. In chapter 2, we present our molecular dynamics simulation study to ex-plore the distance dependent static and dynamic behaviour of biological water near four different protein surfaces. Proteins are known to have large permanent dipole moments that can influence structure and dynamics of even distant water molecules. Therefore, distance dependence of polarization punctuation can provide important insight into the nature of biological water. We explore these aspects by studying aqueous solutions of four different proteins of different char-acteristics and varying sizes. We find that the calculated dielectric constants of the systems show a noticeable increment in all the cases compared to that of neat water. Total dipole moment auto time correlation function of water is found to be sensitive to the nature of the protein. We also define and calculate the effective dielectric constant of successive layers and find that the layer adjacent to protein always has significantly lower value (∼ 50). However, progressive layers exhibit successive increment of dielectric constant, finally reaching a value close to that of bulk 4–5 layers away. Theoretical analysis providing simple method for calculation of shellwise local dielectric constant and implication of these findings are elaborately discussed in this chapter. Part II deals with the temperature dependent study of aqueous DMSO and ethanol solutions and consists of three chapters. Chapter 3 provides a general introduction to the non-ideality (deviation from Raoult’s law) encountered in different binary mixtures. We discuss different theoretical models for treatment of binary mixtures. Finally we provide a systematic study about the non-ideality observed in aqueous binary mixtures. Here we discuss the anomalies observed in such systems and carry out a brief survey on the existing ideas of structural transformations associated with the solvation of a foreign molecule in water. In chapter 4, we discuss the results of temperature dependent study of struc-tural and dynamic properties of aqueous dimethyl sulfoxide (DMSO) mixture. It is now well-known that aqueous DMSO mixture exhibits signature of perco-lation driven structural aggregation at a mole fraction range xDMSO ≈ 0.15. We study the structural and dynamical change in this binary mixture below and above the percolation threshold along with decreasing temperature. Significant change in the molecular structure of DMSO as well as that of water is observed above the percolation threshold at a lower temperature, particularly at 200K. The structural arrangement of the DMSO molecules is found to be progressively more ordered with increasing DMSO concentration and decreasing temperature. On the other hand, water structure is found to be significantly deviated from tetrahedral arrangement in presence of DMSO clusters even at low temperature. The dynamics of water is also found to be considerably affected with increase of concentration and lowering of temperature. Similar phenomenon is observed for another amphiphilic molecule, ethanol, and has been discussed in chapter 5. Aqueous ethanol mixture is a widely studied solvent, both experimentally and using computer simulations. All the studies indicate several distinct salvation regimes. In recent molecular dynamics simulation studies, the reason for formation of micro-aggregates of ethanol is again attributed to percolation driven structural transformation. We carry out a temperature dependent study of water-ethanol binary mixture, particularly at low ethanol concentration to understand the molecular origin of such structural transformation. We find that the structural arrangement of ethanol as well as water molecules is similarly affected as that of DMSO with lowering of temperature. However, dynamics of water molecules in aqueous ethanol solution is found to be marginally affected, unlike the case of aqueous DMSO solution. We discuss the microscopic reason for such behaviour in a detailed manner. In Part III, we discuss the dynamics of linear polymer chains in different aqueous binary mixtures. Here we have three chapters. In chapter 6, we carry out a brief survey of the existing theories of polymers in solution. We discuss the quality of solvents depending on the preferred interactions between the polymer and the solvent or the polymer with its own. We also discuss the celebrated Flory-Huggins theory. We derive the expression of free energy of the Flory-Huggins theory in terms of the volume fraction of monomer and solvent molecules. In chapter 7, we discuss the results of our study of polymer dynamics in aqueous DMSO solution. We find that at a mole fraction 0.05 of DMSO (xDMSO ≈ 0.05) in aqueous solution, a linear polymer chain of intermediate length (n=30) adopts collapsed conformation as the most stable conformational state. The same chain exhibits an intermittent oscillation between the collapsed and the extended coiled conformations in neat water. Even when the mole fraction of DMSO in the bulk is 0.05, the concentration of the same in the first hydration layer around the polymer is found to be as large as 17 %. Formation of such hydrophobic environment around the hydrocarbon chain may be viewed as the reason for the collapsed conformation gaining additional stability. We find a second anomalous behaviour to emerge near xDMSO ≈ 0.15 that is attributed to the percolation driven structural aggregation of DMSO that lowers the relative concentration of the DMSO molecules in the hydration layer. In chapter 8, we carry out similar study of linear polymer chain in water– ethanol binary mixture. In this case also, we find a sudden collapse of the poly-merat xEtOH ≈ 0.05. Since ethanol molecules are known to form micro-aggregates in this concentration range, stability of collapsed state of polymer at this con-centration is anticipated to be correlated to this phenomenon. In fact, a purely hydrophobic polymer chain, in its collapsed form is anticipated to assist in the formation of spanning cluster comprised of hydrophobic ethyl groups at this concentration range thereby facilitating the percolation transition. We discuss these prospects in this chapter. Part IV deals with the solvent sensitivity to the conformational change and unfolding dynamics of protein. Part IV consists of five chapters. In chapter 9, we develop an understanding of protein folding and unfolding dynamics by discussing the fundamental theories developed in the last few decades. We also discuss the major role of solvents in stabilizing or destabilizing the native, ordered state. In chapter 10, we present a detailed study of unfolding of a small protein, chicken villin headpiece (HP36) in water-ethanol binary mixture, using molecular dynamics simulations. The prime objective of this work is to explore the sensitivity of protein dynamics towards increasing concentration of the cosolvent and unravel essential features of intermediates formed in the unfolding path-way. In water–ethanol binary mixtures, HP36 is found to unfold partially, under ambient conditions, that otherwise requires temperature as high as ∼ 600K to denature in pure aqueous solvent. The study unravels certain interesting aspects about the pathway of unfolding, guided by the formation of unique intermediates. Unfolding is initiated by the separation of hydrophoic core comprising three phenylalanine residues (Phe7, Phe11, Phe18). This separation initiates the melting of the helix2 of the protein. However, with an increase of cosolvent concentration different partially unfolded intermediates are found to be formed. We attribute the emergence of such partially unfolded states to the preferential solvation of hydrophobic residues by the ethyl groups of ethanol. We explore and subsequently quantify the detailed dynamics of unfolding in water-ethanol that appear to be more complex and sensitive to solvent composition. With an aim to develop a general understanding of the role of water–ethanol binary mixture in facilitating anomalous conformational dynamics of proteins, we carry out combined theoretical and experimental studies to explore detailed structural change of a larger protein, Myoglobin with increasing ethanol concentration. These studies are described in chapter 11. In agreement with our pre-vious observations, we identify in this case two well-defined structural regimes, one at xEtOH ≈ 0.05 and the other at xEtOH ≈ 0.25, characterized by formation of distinct partially folded conformations and separated by a unique partially unfolded intermediate state at xEtOH ≈ 0.15. We also find non-monotonic com-position dependence of (i) radius of gyration (ii) long range contact order (iii) residue specific solvent accessible surface area of tryptophan (iv) circular dichro-ism spectra and UV-absorption peaks. Multiple structural transformations, well-known in water-ethanol binary mixture, appear to have considerably stronger effects on the conformation and dynamics of protein Myoglobin. In chapter 12, we explore the free energy surface of unfolding pathway through umbrella sampling, for the small globular alpha-helical protein chicken-villin headpiece (HP36) in three different solvent conditions (water, xDMSO ≈ 0.15 and xDMSO ≈ 0.3). Recently established as a facilitator of helix melting, DMSO is found to be a good denaturant for HP36 and at a mole fraction of xDMSO ≈ 0.3, complete melting of the protein is ensured. The unfolding proceeds through initial separation or melting of the same aggregated hydrophobic core that com-prises three phenylalanine residues (Phe7, Phe11 and Phe18) accompanied by simultaneous melting of the helix2. Unfolding is found to be a multistage process involving crossing of three consecutive minima and two barriers at the initial stage. At a molecular level, Phe18 is observed to reorient itself towards other hy-drophobic grooves to stabilize the intermediate states. We identify the configuration of intermediates in all the solvent conditions which are found to be unique for the corresponding minima with similar structural arrangement. Consider-able softening of the barriers is observed with increasing DMSO concentration. Higher concentration of DMSO tunes the unfolding pathway by destabilizing the third minimum and stabilizing the second one, indicating the development of solvent modified, less rugged pathway. Chapter 13 provides a detailed microscopic mechanism of DMSO induced unfolding of HP36. We analyze the free energy contours of the protein HP36, obtained from molecular dynamics simulation in xDMSO ≈ 0.15 and xDMSO ≈ 0.3. The most probable intermediates obtained from the free energy contours are found to be similar to those obtained from umbrella sampling which again sup-ports the fact that the melting proceeds through formation of a series of unique intermediates. We characterize the preferential hydrophobic salvation of the hydrophobic core that drives the melting of secondary structure, by calculating time dependent radial distribution function and identifying the formation of strong orientation order between methyl groups of DMSO and phenyl alanine residues. Finally we employ Kramer’s rate equation to calculate the rate of bar-rier crossing that reveals significantly faster rate of unfolding with increasing DMSO concentration that is in agreement with simulation results. Whenever possible, we have discussed the scope of future work at the end of each chapter.

The thesis presents detailed results of theoretical analyses based on extensive computer simulation studies with an aim to explore, quantify whenever possible, and understand structure and dynamics of polymers and proteins in several complex solvents. In order to make the Thesis coherent, we also study certain aspects of binary mixtures. Based on the phenomena studied, the thesis has been divided into four major parts: I. Dynamics of biological water: Distance dependent variation of dielectric constants in aqueous protein solutions II. Temperature dependent study of structural transformations in aqueous binary mixtures III. Conformation and dynamics of polymers in solution: Role of aqueous binary mixtures IV. Conformational change and unfolding dynamics of proteins: Role of sol-vent environment The above mentioned four parts have further been divided into thirteen chapters. In the following we provide a brief chapter-wise outline of the thesis. Part I consists of two chapters, where we focus on the study of dynamics of biological water and distance dependent variation of static and dynamic proper-ties (including dielectric constant) of water near different proteins. To start with, chapter 1 provides an introduction to the structure and dynamics of biological water. Here we discuss different experimental studies; including dielectric relaxation, NMR and salvation dynamics those explore the bimolecular hydration dynamics in great detail. We also discuss the wide range of computer simulation and theoretical studies that have been carried out to understand the dynamical behaviour of biological water. In chapter 2, we present our molecular dynamics simulation study to ex-plore the distance dependent static and dynamic behaviour of biological water near four different protein surfaces. Proteins are known to have large permanent dipole moments that can influence structure and dynamics of even distant water molecules. Therefore, distance dependence of polarization punctuation can provide important insight into the nature of biological water. We explore these aspects by studying aqueous solutions of four different proteins of different char-acteristics and varying sizes. We find that the calculated dielectric constants of the systems show a noticeable increment in all the cases compared to that of neat water. Total dipole moment auto time correlation function of water is found to be sensitive to the nature of the protein. We also define and calculate the effective dielectric constant of successive layers and find that the layer adjacent to protein always has significantly lower value (∼ 50). However, progressive layers exhibit successive increment of dielectric constant, finally reaching a value close to that of bulk 4–5 layers away. Theoretical analysis providing simple method for calculation of shellwise local dielectric constant and implication of these findings are elaborately discussed in this chapter. Part II deals with the temperature dependent study of aqueous DMSO and ethanol solutions and consists of three chapters. Chapter 3 provides a general introduction to the non-ideality (deviation from Raoult’s law) encountered in different binary mixtures. We discuss different theoretical models for treatment of binary mixtures. Finally we provide a systematic study about the non-ideality observed in aqueous binary mixtures. Here we discuss the anomalies observed in such systems and carry out a brief survey on the existing ideas of structural transformations associated with the solvation of a foreign molecule in water. In chapter 4, we discuss the results of temperature dependent study of struc-tural and dynamic properties of aqueous dimethyl sulfoxide (DMSO) mixture. It is now well-known that aqueous DMSO mixture exhibits signature of perco-lation driven structural aggregation at a mole fraction range xDMSO ≈ 0.15. We study the structural and dynamical change in this binary mixture below and above the percolation threshold along with decreasing temperature. Significant change in the molecular structure of DMSO as well as that of water is observed above the percolation threshold at a lower temperature, particularly at 200K. The structural arrangement of the DMSO molecules is found to be progressively more ordered with increasing DMSO concentration and decreasing temperature. On the other hand, water structure is found to be significantly deviated from tetrahedral arrangement in presence of DMSO clusters even at low temperature. The dynamics of water is also found to be considerably affected with increase of concentration and lowering of temperature. Similar phenomenon is observed for another amphiphilic molecule, ethanol, and has been discussed in chapter 5. Aqueous ethanol mixture is a widely studied solvent, both experimentally and using computer simulations. All the studies indicate several distinct salvation regimes. In recent molecular dynamics simulation studies, the reason for formation of micro-aggregates of ethanol is again attributed to percolation driven structural transformation. We carry out a temperature dependent study of water-ethanol binary mixture, particularly at low ethanol concentration to understand the molecular origin of such structural transformation. We find that the structural arrangement of ethanol as well as water molecules is similarly affected as that of DMSO with lowering of temperature. However, dynamics of water molecules in aqueous ethanol solution is found to be marginally affected, unlike the case of aqueous DMSO solution. We discuss the microscopic reason for such behaviour in a detailed manner. In Part III, we discuss the dynamics of linear polymer chains in different aqueous binary mixtures. Here we have three chapters. In chapter 6, we carry out a brief survey of the existing theories of polymers in solution. We discuss the quality of solvents depending on the preferred interactions between the polymer and the solvent or the polymer with its own. We also discuss the celebrated Flory-Huggins theory. We derive the expression of free energy of the Flory-Huggins theory in terms of the volume fraction of monomer and solvent molecules. In chapter 7, we discuss the results of our study of polymer dynamics in aqueous DMSO solution. We find that at a mole fraction 0.05 of DMSO (xDMSO ≈ 0.05) in aqueous solution, a linear polymer chain of intermediate length (n=30) adopts collapsed conformation as the most stable conformational state. The same chain exhibits an intermittent oscillation between the collapsed and the extended coiled conformations in neat water. Even when the mole fraction of DMSO in the bulk is 0.05, the concentration of the same in the first hydration layer around the polymer is found to be as large as 17 %. Formation of such hydrophobic environment around the hydrocarbon chain may be viewed as the reason for the collapsed conformation gaining additional stability. We find a second anomalous behaviour to emerge near xDMSO ≈ 0.15 that is attributed to the percolation driven structural aggregation of DMSO that lowers the relative concentration of the DMSO molecules in the hydration layer. In chapter 8, we carry out similar study of linear polymer chain in water– ethanol binary mixture. In this case also, we find a sudden collapse of the poly-merat xEtOH ≈ 0.05. Since ethanol molecules are known to form micro-aggregates in this concentration range, stability of collapsed state of polymer at this con-centration is anticipated to be correlated to this phenomenon. In fact, a purely hydrophobic polymer chain, in its collapsed form is anticipated to assist in the formation of spanning cluster comprised of hydrophobic ethyl groups at this concentration range thereby facilitating the percolation transition. We discuss these prospects in this chapter. Part IV deals with the solvent sensitivity to the conformational change and unfolding dynamics of protein. Part IV consists of five chapters. In chapter 9, we develop an understanding of protein folding and unfolding dynamics by discussing the fundamental theories developed in the last few decades. We also discuss the major role of solvents in stabilizing or destabilizing the native, ordered state. In chapter 10, we present a detailed study of unfolding of a small protein, chicken villin headpiece (HP36) in water-ethanol binary mixture, using molecular dynamics simulations. The prime objective of this work is to explore the sensitivity of protein dynamics towards increasing concentration of the cosolvent and unravel essential features of intermediates formed in the unfolding path-way. In water–ethanol binary mixtures, HP36 is found to unfold partially, under ambient conditions, that otherwise requires temperature as high as ∼ 600K to denature in pure aqueous solvent. The study unravels certain interesting aspects about the pathway of unfolding, guided by the formation of unique intermediates. Unfolding is initiated by the separation of hydrophoic core comprising three phenylalanine residues (Phe7, Phe11, Phe18). This separation initiates the melting of the helix2 of the protein. However, with an increase of cosolvent concentration different partially unfolded intermediates are found to be formed. We attribute the emergence of such partially unfolded states to the preferential solvation of hydrophobic residues by the ethyl groups of ethanol. We explore and subsequently quantify the detailed dynamics of unfolding in water-ethanol that appear to be more complex and sensitive to solvent composition. With an aim to develop a general understanding of the role of water–ethanol binary mixture in facilitating anomalous conformational dynamics of proteins, we carry out combined theoretical and experimental studies to explore detailed structural change of a larger protein, Myoglobin with increasing ethanol concentration. These studies are described in chapter 11. In agreement with our pre-vious observations, we identify in this case two well-defined structural regimes, one at xEtOH ≈ 0.05 and the other at xEtOH ≈ 0.25, characterized by formation of distinct partially folded conformations and separated by a unique partially unfolded intermediate state at xEtOH ≈ 0.15. We also find non-monotonic com-position dependence of (i) radius of gyration (ii) long range contact order (iii) residue specific solvent accessible surface area of tryptophan (iv) circular dichro-ism spectra and UV-absorption peaks. Multiple structural transformations, well-known in water-ethanol binary mixture, appear to have considerably stronger effects on the conformation and dynamics of protein Myoglobin. In chapter 12, we explore the free energy surface of unfolding pathway through umbrella sampling, for the small globular alpha-helical protein chicken-villin headpiece (HP36) in three different solvent conditions (water, xDMSO ≈ 0.15 and xDMSO ≈ 0.3). Recently established as a facilitator of helix melting, DMSO is found to be a good denaturant for HP36 and at a mole fraction of xDMSO ≈ 0.3, complete melting of the protein is ensured. The unfolding proceeds through initial separation or melting of the same aggregated hydrophobic core that com-prises three phenylalanine residues (Phe7, Phe11 and Phe18) accompanied by simultaneous melting of the helix2. Unfolding is found to be a multistage process involving crossing of three consecutive minima and two barriers at the initial stage. At a molecular level, Phe18 is observed to reorient itself towards other hy-drophobic grooves to stabilize the intermediate states. We identify the configuration of intermediates in all the solvent conditions which are found to be unique for the corresponding minima with similar structural arrangement. Consider-able softening of the barriers is observed with increasing DMSO concentration. Higher concentration of DMSO tunes the unfolding pathway by destabilizing the third minimum and stabilizing the second one, indicating the development of solvent modified, less rugged pathway. Chapter 13 provides a detailed microscopic mechanism of DMSO induced unfolding of HP36. We analyze the free energy contours of the protein HP36, obtained from molecular dynamics simulation in xDMSO ≈ 0.15 and xDMSO ≈ 0.3. The most probable intermediates obtained from the free energy contours are found to be similar to those obtained from umbrella sampling which again sup-ports the fact that the melting proceeds through formation of a series of unique intermediates. We characterize the preferential hydrophobic salvation of the hydrophobic core that drives the melting of secondary structure, by calculating time dependent radial distribution function and identifying the formation of strong orientation order between methyl groups of DMSO and phenyl alanine residues. Finally we employ Kramer’s rate equation to calculate the rate of bar-rier crossing that reveals significantly faster rate of unfolding with increasing DMSO concentration that is in agreement with simulation results. Whenever possible, we have discussed the scope of future work at the end of each chapter.

碩士
嘉南藥理大學
環境工程與科學系
105
The purpose of this investigation is focused on the hydrophilic modification of polysulfone(PSF), poly ether imide(PEI), and polysulfone/ poly ether imide membranes on the improvement of separation performance of pervaporation process for dehydration of ethanol/water mixtures. The wet phase inversion method was used to prepare the modified membranes and posted coating poly ethylene imine for hydrophilic enhancement. The hydrophilic properties of modified membranes were tested by water contact angle measurement. The influent factors on the separation performance of modified membranes were included casting polymer concentration, poly ethylene imine concentration, ionization, feed ethanol concentration and operation temperature in pervaporation process. It was found that the increase in casting polymer concentration increased the skin layer thickness and improved the separation factors of membrane. The optimum prepared polysulfone membrane presented a 267 g/m2hr permeation flux and 334 separation factor. The best poly ethylene imine coating membrane showed a 200 g/m2hr permeation flux and 636 separation factor on pervaporation test. It is worth to noted that those modified membrane will be further increased the separation factor after using the chloride acid ionization. The permeation flux increased with increasing the operation temperature during the PV test due to the enhancement on polymer chain mobility of in the PV process. On the other hand, the feed ethanol concentration on the membrane swelling properties showed the significantly changed the permeation and separation behavior in the PV process. It is concluded that the modification of polyethylene imine coating and ionization exactly increased the hydrophilic of membranes and also improved the separation performance in this investigation.

碩士
國立中央大學
化學工程與材料工程研究所
98
This thesis contains two parts。The first part is a Design of Experiment(DOE) of a two-bed-eight-step PSA process of dehydration ethanol from previous work of our group. Feed pressure, production time, purge time, backfill time and feed temperature are the factors of full factorial design of experiment. The process of second part comes from previous work of our group but some operating conditions had changed. Besides adding one adsorption bed to the process, a storage tank is also added。Expecting recovery could be increased by removing purge step and at the same time some operating conditions are also altered to keep ethanol purity at 99.5wt% which fits the goal of dehydration ethanol。The PSA process is a three-bed-nine step process. Feed pressure, feed temperature, vent pressure, production time and backfill time are chosen to do full factorial design factors of experimental design。

碩士
國立臺灣科技大學
化學工程系
91
The purpose of this thesis is to investigate the two-step growth of MOCVD copper using thin films the mixture of ethanol alcohol and water as the additive. In the first step , we deposited Cu2O films with the mixture of ethanol alcohol and water as the additive at 275℃.In the second step, the Cu2O films were reduced to metallic copper by ethanol alcohol as the reducing agent at the same temperature. A highly dense, conformal, and continuous Cu thin film can be deposited for Cu seed layer application. The effect of temperature on Cu2O films was that the amount of Cu atoms increased with the temperature. The grain size of Cu thin film after reduction also increased with the temperature. The optimum temperature was 275℃ for the deposition of copper thin films for 3 min,and then the grain size was 350 Å .In addition, we observed that the grain size increased with time and the best resistivity is 3.99 µΩ-cm . To deposit highly dense、continuous and pure copper films, a muti-layer two- step growth method was performed on the TaN substrate at 250℃ .

abstract: While the solution diffusion model and pore flow model dominate pervaporation transport mechanism modeling, a new model combining the solution diffusion and viscous flow models is validated using membranes with large scale defects exceeding 2 nm in diameter. A range of membranes was characterized using scanning electron microscopy and x-ray diffraction (XRD) to determine quality and phase characteristics. MFI zeolite membranes of He/SF6 pure gas permeation ideal selectivities of 25, 15, and 3 for good, medium, and poor quality membranes were subjected to liquid pervaporations with a 5% ethanol in water feed, by weight. Feed pressure was increased from 1 to 5 atm, to validate existence of viscous flow in the defects. Component molar flux is modeled using the solution diffusion model and the viscous flow model, via J_i=F_i (γ_i x_i P_i^sat )+(ρ )/M_W ∅/μ_ij x_i P_h. A negative coefficient of thermal expansion is observed as permeances drop as a function of temperature in all three membranes, where ϕ=((ϵr_p^2)/τ∆x). Experimental parameter ϕ increased as a function of temperature, and increased with decreasing membrane quality. This further proves that zeolitic pores are shrinking in one direction, and pulling intercrystalline voids larger, increasing the (ϵ/τ) ratio. Permiabilities of the bad, medium, and good quality membrane also decreased over time for both ethanol and water, meaning that fundamental membrane characteristics changed as a function of temperature. To conclude, the model reasonably fits empirical data reasonably well.
Dissertation/Thesis
Masters Thesis Chemical Engineering 2016

I started writing this thesis not only to obtain a doctoral degree, but also to compile in a particular way all the work that I have done during this time. The articles published during these years can only give a short overview of my research task. I decided to give my own perspective of the things I have learned and the results I have obtained. Some sections are directly the published articles, but some other are not and contain a significant amount of unpublished data. Even in some cases the published plots have been modified / altered to provide more insight or to maintain consistency. Historical perspectives often provide a deep understanding of the problems and have been briefly discussed in some chapters. This thesis contains theoretical and computer simulation studies to under-stand effects of spatial correlation on dynamics in several complex systems. Based on the different phenomena studied, the thesis has been divided into three major parts: I. Pair hydrophobicity, composition-dependent anomalies and structural trans-formations in aqueous binary mixtures II. Microscopic analysis of hydrophobic force law in a two dimensional (2D) water-like model system III. Diffusion of a tagged particle on a rugged energy landscape with spatial correlations The three parts have been further divided into ten chapters. In the following we provide part-wise and chapter-wise outline of the thesis. Part I consists of six chapters, where we focus on several important aqueous binary mixtures of amphiphilic molecules. To start with, Chapter 1 provides an introduction to non-ideality often encountered in aqueous binary mixtures. Here we briefly discuss the existing ideas of structural transformations associated with solvation of a foreign molecule in water, with particular emphasis on the classic “iceberg” model. Over the last decade, several investigations, especially neutron scattering and diffraction experiments, have questioned the validity of existing theories and have given rise to an alternate molecular picture involving micro aggregation of amphiphilic co-solvents in their aqueous binary mixtures. Such microheterogeneity was also supported by other experiments and simulations. In Chapter 2, we present our calculation of the separation dependence of potential of mean force (PMF) between two methane molecules in water-dimethyl sulfoxide (DMSO) mixture, using constrained molecular dynamics simulation. It helps us to understand the composition-dependence of pair hydrophobicity in this binary solvent. We find that pair hydrophobicity in the medium is surprisingly enhanced at DMSO mole fraction xDMSO ≈ 0.15, which explains several anomalous properties of this binary mixture – including the age-old mystery of DMSO being a protein stabilizer at lower concentration and protein destabilizer at higher concentration. Chapter 3 starts with discussion of non-monotonic composition dependence of several other properties in water-DMSO binary mixture, like diffusion coefficient, local composition fluctuation and fluctuations in total dipole moment of the system. All these properties exhibit weak to strong anomalies at low solute concentration. We attempt to provide a physical interpretation of such anomalies. Previous analyses often suggested occurrence of a “structural transformation” (or, microheterogeneity) in aqueous binary mixtures of amphiphilic molecules. We show that this structural transformation can be characterized and better understood under the purview of percolation theory. We define the self-aggregates of DMSO as clusters. Analysis of fractal dimension and cluster size distribution with reference to corresponding “universal” scaling exponents, combined with calculation of weight-averaged fraction of largest cluster and cluster size weight average, reveal a percolation transition of the clusters of DMSO in the anomalous concentration range. The percolation threshold appears at xDMSO ≈ 0.15. The molecular picture suggests that DMSO molecules form segregated islands or micro-aggregates at concentrations below the percolation threshold. Close to the critical concentration, DMSO molecules start forming a spanning cluster which gives rise to a bi-continuous phase (of water-rich region and DMSO-rich region) beyond the threshold of xDMSO ≈ 0.15. This percolation transition might be responsible for composition-dependent anomalies of the binary mixture in this low concentration regime. Similar phenomenon is observed for another amphiphilic molecule – ethanol, as discussed in Chapter 4. We again find composition dependent anomalies in several thermophysical properties, such as local composition fluctuation, radial distribution function of ethyl groups and self-diffusion co-efficient of ethanol. Earlier experiments often suggested distinct structural regimes in water-ethanol mixture at different concentrations. Using the statistical mechanical techniques introduced in the previous chapter, we show that ethanol clusters undergo a percolation transition in the anomalous concentration range. Despite the lack of a precise determination of the percolation threshold, estimate lies in the ethanol mole fraction range xEtOH ≈ 0.075 - 0.10. This difficulty is probably due to transient nature of the clusters (as will be discussed in Chapter 6) and finite size of the system. The scaling of ethanol cluster size distribution and the fractal behavior of ethanol clusters, however, conclusively demonstrate their “spanning” nature. To develop a unified understanding, we further study the composition-dependent anomalies and structural transformations in another amphiphilic molecule, tertiary butyl alcohol (TBA) in Chapter 5. Similar to the above-mentioned aqueous binary mixtures of DMSO and ethanol, we demonstrate here that the anomalies occur due to local structural changes involving self-aggregation of TBA molecules and percolation transition of TBA clusters at xTBA ≈ 0.05. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of the largest water cluster. This second transition gives rise to another set of anomalies around. We conclude this part of the thesis with Chapter 6, where we introduce a novel method for understanding the stability of fluctuating clusters of DMSO, ethanol and TBA in their respective aqueous binary mixtures. We find that TBA clusters are the most stable, whereas ethanol clusters are the most transient among the three representative amphiphilic co-solvents. This correlates well with the amplitude of anomalies observed in these three binary mixtures. Part II deals with the topic of hydrophobic force law in water. In the introductory Chapter 7 of this part, we briefly discuss the concept of hydrophobicity which is believed to be of importance in understanding / explaining the initial processes involved in protein folding. We also discuss the experimental observations of Israelachvili (on the force between hydrophobic plates) and the empirical hydrophobic force law. We briefly touch upon the theoretical back-ground, including Lum-Chandler-Weeks theory. We conclude this chapter with a brief account of relevant and important in silico studies so far. In Chapter 8, we present our studies on Mercedes-Benz (MB) model – a two dimensional model system where circular disks interact with an anisotropic potential. This model was introduced by Ben-Naim and was later parametrized by Dill and co-workers to reproduce many of the anomalous properties of water. Using molecular dynamics simulation, we show that hydrophobic force law is indeed observed in MB model, with a correlation length of ξ=3.79. The simplicity of the model enables us to unravel the underlying physics that leads to this long range force between hydrophobic plates. In accordance with Lum-Chandler-Weeks theory, density fluctuation of MB particles (leading to cavitation) between the hydrophobic rods is clearly distinguishable – but it is not sufficiently long ranged, with density correlation extending only up to ζ=2.45. We find that relative orientation of MB molecules plays an important role in the origin of the hydrophobic force in long range. We define appropriate order parameters to capture the role of orientation, and briefly discuss a plausible approach of an orientation-dependent theory to explain this phenomenon. Part III consists of two chapters and focuses on the diffusion of a Brownian particle on a Gaussian random energy landscape. We articulate the rich history of the problem in the introductory Chapter 9. Despite broad applicability and historical importance of the problem, we have little knowledge about the effect of ruggedness on diffusion at a quantitative level. Every study seems to use the expression of Zwanzig [Proc. Natl. Acad. U.S.A, 85, 2029 (1988)] who derived the effective diffusion coefficient, Deff =D0 exp (-β2ε2 )for a Gaussian random surface with variance ε, but validity of the same has never been tested rigorously. In Chapter 10, we introduce two models of Gaussian random energy surface – a discrete lattice and a continuous field. Using computer simulation and theoretical analyses, we explore many different aspects of the diffusion process. We show that the elegant expression of Zwanzig can be reproduced ex-actly by Rosenfeld diffusion-entropy scaling relationship. Our simulations show that Zwanzig’s expression overestimates diffusion in the uncorrelated Gaussian random lattice – differing even by more than an order of magnitude at moderately high ruggedness (ε>3.0). The disparity originates from the presence of “three-site traps” (TST) on the landscape – which are formed by deep minima flanked by high barriers on either side. Using mean first passage time (MFPT) formalism, we derive an expression for the effective diffusion coefficient, Deff =D0 exp ( -β2ε2)[1 +erf (βε/2)]−1 in the presence of TSTs. This modified expression reproduces the simulation results accurately. Further, in presence of spatial correlation we derive a general expression, which reduces to Zwanzig’s form in the limit of infinite spatial correlation and to the above-mentioned equation in absence of correlation. The Gaussian random field has an inherent spatial correlation. Diffusion coefficient obtained from the Gaussian field – both by simulations and analytical methods – establish the effect of spatial correlation on random walk. We make special note of the fact that presence of TSTs at large ruggedness gives rise to an apparent breakdown of ergodicity of the type often encountered in glassy liquids. We characterize the same using non-Gaussian order parameter, and show that this “breakdown” scales with ruggedness following an asymptotic power law. We have discussed the scope of future work at the end of each chapter when-ever appropriate.

I started writing this thesis not only to obtain a doctoral degree, but also to compile in a particular way all the work that I have done during this time. The articles published during these years can only give a short overview of my research task. I decided to give my own perspective of the things I have learned and the results I have obtained. Some sections are directly the published articles, but some other are not and contain a significant amount of unpublished data. Even in some cases the published plots have been modified / altered to provide more insight or to maintain consistency. Historical perspectives often provide a deep understanding of the problems and have been briefly discussed in some chapters. This thesis contains theoretical and computer simulation studies to under-stand effects of spatial correlation on dynamics in several complex systems. Based on the different phenomena studied, the thesis has been divided into three major parts: I. Pair hydrophobicity, composition-dependent anomalies and structural trans-formations in aqueous binary mixtures II. Microscopic analysis of hydrophobic force law in a two dimensional (2D) water-like model system III. Diffusion of a tagged particle on a rugged energy landscape with spatial correlations The three parts have been further divided into ten chapters. In the following we provide part-wise and chapter-wise outline of the thesis. Part I consists of six chapters, where we focus on several important aqueous binary mixtures of amphiphilic molecules. To start with, Chapter 1 provides an introduction to non-ideality often encountered in aqueous binary mixtures. Here we briefly discuss the existing ideas of structural transformations associated with solvation of a foreign molecule in water, with particular emphasis on the classic “iceberg” model. Over the last decade, several investigations, especially neutron scattering and diffraction experiments, have questioned the validity of existing theories and have given rise to an alternate molecular picture involving micro aggregation of amphiphilic co-solvents in their aqueous binary mixtures. Such microheterogeneity was also supported by other experiments and simulations. In Chapter 2, we present our calculation of the separation dependence of potential of mean force (PMF) between two methane molecules in water-dimethyl sulfoxide (DMSO) mixture, using constrained molecular dynamics simulation. It helps us to understand the composition-dependence of pair hydrophobicity in this binary solvent. We find that pair hydrophobicity in the medium is surprisingly enhanced at DMSO mole fraction xDMSO ≈ 0.15, which explains several anomalous properties of this binary mixture – including the age-old mystery of DMSO being a protein stabilizer at lower concentration and protein destabilizer at higher concentration. Chapter 3 starts with discussion of non-monotonic composition dependence of several other properties in water-DMSO binary mixture, like diffusion coefficient, local composition fluctuation and fluctuations in total dipole moment of the system. All these properties exhibit weak to strong anomalies at low solute concentration. We attempt to provide a physical interpretation of such anomalies. Previous analyses often suggested occurrence of a “structural transformation” (or, microheterogeneity) in aqueous binary mixtures of amphiphilic molecules. We show that this structural transformation can be characterized and better understood under the purview of percolation theory. We define the self-aggregates of DMSO as clusters. Analysis of fractal dimension and cluster size distribution with reference to corresponding “universal” scaling exponents, combined with calculation of weight-averaged fraction of largest cluster and cluster size weight average, reveal a percolation transition of the clusters of DMSO in the anomalous concentration range. The percolation threshold appears at xDMSO ≈ 0.15. The molecular picture suggests that DMSO molecules form segregated islands or micro-aggregates at concentrations below the percolation threshold. Close to the critical concentration, DMSO molecules start forming a spanning cluster which gives rise to a bi-continuous phase (of water-rich region and DMSO-rich region) beyond the threshold of xDMSO ≈ 0.15. This percolation transition might be responsible for composition-dependent anomalies of the binary mixture in this low concentration regime. Similar phenomenon is observed for another amphiphilic molecule – ethanol, as discussed in Chapter 4. We again find composition dependent anomalies in several thermophysical properties, such as local composition fluctuation, radial distribution function of ethyl groups and self-diffusion co-efficient of ethanol. Earlier experiments often suggested distinct structural regimes in water-ethanol mixture at different concentrations. Using the statistical mechanical techniques introduced in the previous chapter, we show that ethanol clusters undergo a percolation transition in the anomalous concentration range. Despite the lack of a precise determination of the percolation threshold, estimate lies in the ethanol mole fraction range xEtOH ≈ 0.075 - 0.10. This difficulty is probably due to transient nature of the clusters (as will be discussed in Chapter 6) and finite size of the system. The scaling of ethanol cluster size distribution and the fractal behavior of ethanol clusters, however, conclusively demonstrate their “spanning” nature. To develop a unified understanding, we further study the composition-dependent anomalies and structural transformations in another amphiphilic molecule, tertiary butyl alcohol (TBA) in Chapter 5. Similar to the above-mentioned aqueous binary mixtures of DMSO and ethanol, we demonstrate here that the anomalies occur due to local structural changes involving self-aggregation of TBA molecules and percolation transition of TBA clusters at xTBA ≈ 0.05. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of the largest water cluster. This second transition gives rise to another set of anomalies around. We conclude this part of the thesis with Chapter 6, where we introduce a novel method for understanding the stability of fluctuating clusters of DMSO, ethanol and TBA in their respective aqueous binary mixtures. We find that TBA clusters are the most stable, whereas ethanol clusters are the most transient among the three representative amphiphilic co-solvents. This correlates well with the amplitude of anomalies observed in these three binary mixtures. Part II deals with the topic of hydrophobic force law in water. In the introductory Chapter 7 of this part, we briefly discuss the concept of hydrophobicity which is believed to be of importance in understanding / explaining the initial processes involved in protein folding. We also discuss the experimental observations of Israelachvili (on the force between hydrophobic plates) and the empirical hydrophobic force law. We briefly touch upon the theoretical back-ground, including Lum-Chandler-Weeks theory. We conclude this chapter with a brief account of relevant and important in silico studies so far. In Chapter 8, we present our studies on Mercedes-Benz (MB) model – a two dimensional model system where circular disks interact with an anisotropic potential. This model was introduced by Ben-Naim and was later parametrized by Dill and co-workers to reproduce many of the anomalous properties of water. Using molecular dynamics simulation, we show that hydrophobic force law is indeed observed in MB model, with a correlation length of ξ=3.79. The simplicity of the model enables us to unravel the underlying physics that leads to this long range force between hydrophobic plates. In accordance with Lum-Chandler-Weeks theory, density fluctuation of MB particles (leading to cavitation) between the hydrophobic rods is clearly distinguishable – but it is not sufficiently long ranged, with density correlation extending only up to ζ=2.45. We find that relative orientation of MB molecules plays an important role in the origin of the hydrophobic force in long range. We define appropriate order parameters to capture the role of orientation, and briefly discuss a plausible approach of an orientation-dependent theory to explain this phenomenon. Part III consists of two chapters and focuses on the diffusion of a Brownian particle on a Gaussian random energy landscape. We articulate the rich history of the problem in the introductory Chapter 9. Despite broad applicability and historical importance of the problem, we have little knowledge about the effect of ruggedness on diffusion at a quantitative level. Every study seems to use the expression of Zwanzig [Proc. Natl. Acad. U.S.A, 85, 2029 (1988)] who derived the effective diffusion coefficient, Deff =D0 exp (-β2ε2 )for a Gaussian random surface with variance ε, but validity of the same has never been tested rigorously. In Chapter 10, we introduce two models of Gaussian random energy surface – a discrete lattice and a continuous field. Using computer simulation and theoretical analyses, we explore many different aspects of the diffusion process. We show that the elegant expression of Zwanzig can be reproduced ex-actly by Rosenfeld diffusion-entropy scaling relationship. Our simulations show that Zwanzig’s expression overestimates diffusion in the uncorrelated Gaussian random lattice – differing even by more than an order of magnitude at moderately high ruggedness (ε>3.0). The disparity originates from the presence of “three-site traps” (TST) on the landscape – which are formed by deep minima flanked by high barriers on either side. Using mean first passage time (MFPT) formalism, we derive an expression for the effective diffusion coefficient, Deff =D0 exp ( -β2ε2)[1 +erf (βε/2)]−1 in the presence of TSTs. This modified expression reproduces the simulation results accurately. Further, in presence of spatial correlation we derive a general expression, which reduces to Zwanzig’s form in the limit of infinite spatial correlation and to the above-mentioned equation in absence of correlation. The Gaussian random field has an inherent spatial correlation. Diffusion coefficient obtained from the Gaussian field – both by simulations and analytical methods – establish the effect of spatial correlation on random walk. We make special note of the fact that presence of TSTs at large ruggedness gives rise to an apparent breakdown of ergodicity of the type often encountered in glassy liquids. We characterize the same using non-Gaussian order parameter, and show that this “breakdown” scales with ruggedness following an asymptotic power law. We have discussed the scope of future work at the end of each chapter when-ever appropriate.

This thesis explores the structural and dynamical aspects of small, charged and neutral, solute molecules in both pure water and in aqueous binary mixtures, with emphasis on water-ethanol binary mixture. We employ both extensive computer simulations and sophisticated theoretical analyses. Throughout the thesis, the focus has been on a microscopic level understanding of many of the unique features that these systems exhibit. Based on the system of interest, we divide the thesis into three major parts. In the first part, we deal with the dynamics of two linear neutral diatomic molecules, namely carbon monoxide (CO) and nitric oxide (NO), in water. We find a significant result that the translational motion of these small diatomics is strongly coupled to their rotational motion, which in turn are coupled to the complex motions of the surrounding water. We examine the validity of the hydrodynamic predictions by modeling these solutes as prolate ellipsoids. For the translational diffusion, the predicted values agree well with the hydrodynamic boundary value predictions. In rotational diffusion, the slip boundary values are found to be in good agreement with the simulation results. We also develop a mode-coupling theory to understand the complexity of translation-rotation coupling. We devote part two to understand the structure and dynamics of ions in water. We find that the charged linear diatomic cyanide (CN-) ion exhibits certain differences, while the neutral diatomic CO and NO show similar features. We observe that the water molecules around CN- are more structured than those around the neutral solutes. Thus, the translational diffusion of the ion becomes slow compared to that of neutral molecules. We also find that the rotational motion of the ion is slower than the neutral solutes. In the third part, we study the same solutes in aqueous binary mixtures. We explore the translational and rotational dynamics of three probes, CO, NO, and CN- at different compositions of water-ethanol binary mixture. We find multiple anomalous results such as (i) faster rotational motion of CO and NO than CN- in the binary mixture. However, for CO and NO, the fastest rotation is in pure ethanol; for CN-, the rotation is slowest in pure ethanol. (ii) The larger translational diffusion of the neutral molecule in pure ethanol than in water but the reverse for the ion. (iii) A pronounced anomaly in the composition dependence of translational-rotational dynamics at low ethanol composition, and (iv) a reentrant type behavior in the viscosity dependence of orientational relaxation. For the first time, we implement a calculation of the rotational binary friction following the sophisticated kinetic theory scheme of Evans and co-workers. We develop a detailed mode-coupling theory and suggest that such an approach if completely implemented, can provide a more reliable description than the hydrodynamic predictions. In another work, we study the rigid monovalent cations Li+, Na+, K+, and Cs+ at various compositions of water-ethanol mixtures. For the first time, we report the diffusion constants of these cations at various compositions of the water-ethanol mixture. Though the diffusion of cations becomes slow with the increasing composition, at a particular composition, the diffusivity of ions increases with the increase in its size. We also observe that the coordination number of water in the first solvation shell of all the four cations decreases with the increase in ethanol composition, with the highest being in pure water and the coordination number of ethanol increases with the increase in ethanol compositions with a maximum in pure ethanol. We could establish a novel finding of ion-induced segregation in the mixture. The ions are found to induce a microheterogeneity where water molecules preferentially solvate them while the ethyl groups of ethanol occupy the intervening space. The last part of the thesis includes the future directions and research prospects derived from this thesis. We also discuss a preliminary study on zinc and lithium ions in water, considering their application to the organic framework of batteries.

博士
國立中山大學
機械與機電工程學系研究所
100
In this dissertation, the molecular behaviors of water/ethanol mixtures of different weight fractions inside Au nanotubes of different radii at steady state were investigated by molecular dynamics simulation. Five weight fractions of water/ethanol (0/100, 100/0, 25/75, 50/50, and 75/25) and three radii of Au nanotubes (13, 22, and 31.1 Å) were considered in order to understand the effects of Au nanotube size and water/ethanol fraction on the structural and dynamical behaviors of the water and ethanol molecules. The density profiles show two shell-like formations inside the Au nanotubes because water molecules prefer to adsorb on the wall of Au nanotube. According to the density distribution, the space inside Au nanotubes can be divided into three regions, those of contact, transition, and bulk regions, in order from the interior wall surface to the nanotube center. The bulk region has a lower local weight fraction compared to the system water/ethanol weight fraction. In addition, the local water/ethanol weight fraction in the contact region is higher than that of the system. When the system water/ethanol weight fraction becomes higher, the local water/ethanol weight fraction also becomes higher. In 25/75, 50/50, and 75/25 weight fraction mixtures, the number of H-bonds per water and per ethanol are different from those of pure 100% water and 100% ethanol in the Au nanotube due to the nanoconfinement effect. Moreover, the distribution of number of H-bonds in regions where there is only one material will be similar to the distribution in the corresponding region of the pure material, whether 100% water or ethanol. In all regions, the probability to form different H-bonds is affected significantly by the local weight fraction of water/ethanol. Three radii of Au nanotubes (13, 22, and 31.1 Å) were considered in order to understand the effects of Au nanotube size and water/ethanol fraction on the structural and dynamical behaviors of the water and ethanol molecules. In the transition and bulk regions, diffusion coefficients for water and ethanol molecules become higher due to the weak interaction with Au atoms. The values of diffusion coefficients for water molecules in the contact regions are much lower than for those in other regions and are similar for different water/ethanol weight fractions due to the strong interaction with Au atoms. When the radius of the Au nanotube becomes larger, the values of local weight fraction inside the larger radius Au nanotube become higher than those inside small radius Au nanotubes because the ratio of water number to the nanotube inner surface area becomes higher. In addition, water inside a larger radius Au nanotube has a shorter water-water hydrogen bond lifetime (H-bond) in the contact region because the smaller curvature causes weaker interaction with Au atoms.

This thesis is mainly concerned with some important properties of complex fluids, and how these properties are influenced by structures in the nano/mesoscopic scale. Short-range assembly of the constituent molecules results in an amazing variety of phase behavior in these systems. Liquid-liquid phase transitions, or transitions from a homogeneous(mixed) phase to an immiscible phase (two-phase coexistence), are the outcome of a competition between entropy and short-ranged attractive forces, and form an important part of this thesis. A rich phase behavior is uncovered by a detailed study of liquid-liquid phase transitions in a mixture of ethanol(E) and water(W), induced by the addition of ammonium sulfate(AS) ions (E and W are otherwise completely soluble in each other). This is the main motivation for choosing this system. Furthermore, experimental evidence of the presence of supramolecular association in alcohol-water mixtures [J.-H. Guo et al., Phys. Rev Lett, 91, 15401(2003)] enhances our interest to study the phase behavior in more detail. The presence of a critical point, at which there is a second order phase transition, is quite common in complex fluids. An issue which has been the subject of extensive scientific research in recent years is the influence of nano/mesoscopic structure on the critical behavior of these fluids corresponds to the Ising universality class. However, the approach to the asymptotic regime is governed by a competition between the correlation length of critical concentration fluctuations and the additional length scale arising due to structuring., which results in a crossover from the universal Ising behavior to the mean-field behavior, sometimes within the critical domain. This phenomenon of crossover criticality is presently explored in the E + W + AS system. A significant portion of the thesis presents explorations on the critical behavior in the vicinity of special critical points (SCP), which are formed by the coalescence of two or more critical points. Recentrant liquid-liquid phase transitions observed in the E + W + AS system, furnishes an unique opportunity for the realization of three SCPs – the double critical point(DCP) and the critical double point(CDP) formed by the merger of two critical points , and a critical inflection point(CIP), formed by the merger of three critical points. A CIP had not been experimentally realized prior to the studies presented in this thesis. Apart from the above studies investigations are also carried out on the conformational changes of a technologically important conducting polymer, polyethylene dioxythiophene doped with polystyrene suflonate (PEDOT-PSS), in various solvents. The electrical and optical properties of the polymer films get enhanced when solution processed with specific solvents. The experiments presented in this thesis are directed at unraveling the role of conformational modifications in the electrical and optical properties of these systems. The experimental techniques that were employed in the present studies are: Laser light scattering, small-angle X-ray scattering(SAXS) measurements and visual observations. The eoexistence surface of the system E + W + AS was determined by visual observations. Laser light scattering measurements were conducted to study the critical behavior of osmotic susceptibility (xr) of E + W + As, whereas SAXS studies were conducted to ascertain the existence, and quantify the spatial extent of the additional length scale in the two systems investigated. The main objectives of this research were: (i) to study the phase behavior of the ternary mixture E + W + AS at atmospheric pressure; (ii) to check the existence of crossover from 3-D Ising to mean-field critical behavior while moving away from Tc in this system; (iii) to determine the nature (monotonic or nonmonotonic) of crossover; (iv) to provide some insight into the origin of this crossover behavior in terms of an additional length scale characteristic of the system; (v) to understand the evolution of the critical behavior in the proximity of CDP, and DCP; (vi) to experimentally realize the CIP; and (vii) to investigate the presence of solvent-induced conformational changes in conducting polymer.

This thesis is mainly concerned with some important properties of complex fluids, and how these properties are influenced by structures in the nano/mesoscopic scale. Short-range assembly of the constituent molecules results in an amazing variety of phase behavior in these systems. Liquid-liquid phase transitions, or transitions from a homogeneous(mixed) phase to an immiscible phase (two-phase coexistence), are the outcome of a competition between entropy and short-ranged attractive forces, and form an important part of this thesis. A rich phase behavior is uncovered by a detailed study of liquid-liquid phase transitions in a mixture of ethanol(E) and water(W), induced by the addition of ammonium sulfate(AS) ions (E and W are otherwise completely soluble in each other). This is the main motivation for choosing this system. Furthermore, experimental evidence of the presence of supramolecular association in alcohol-water mixtures [J.-H. Guo et al., Phys. Rev Lett, 91, 15401(2003)] enhances our interest to study the phase behavior in more detail. The presence of a critical point, at which there is a second order phase transition, is quite common in complex fluids. An issue which has been the subject of extensive scientific research in recent years is the influence of nano/mesoscopic structure on the critical behavior of these fluids corresponds to the Ising universality class. However, the approach to the asymptotic regime is governed by a competition between the correlation length of critical concentration fluctuations and the additional length scale arising due to structuring., which results in a crossover from the universal Ising behavior to the mean-field behavior, sometimes within the critical domain. This phenomenon of crossover criticality is presently explored in the E + W + AS system. A significant portion of the thesis presents explorations on the critical behavior in the vicinity of special critical points (SCP), which are formed by the coalescence of two or more critical points. Recentrant liquid-liquid phase transitions observed in the E + W + AS system, furnishes an unique opportunity for the realization of three SCPs – the double critical point(DCP) and the critical double point(CDP) formed by the merger of two critical points , and a critical inflection point(CIP), formed by the merger of three critical points. A CIP had not been experimentally realized prior to the studies presented in this thesis. Apart from the above studies investigations are also carried out on the conformational changes of a technologically important conducting polymer, polyethylene dioxythiophene doped with polystyrene suflonate (PEDOT-PSS), in various solvents. The electrical and optical properties of the polymer films get enhanced when solution processed with specific solvents. The experiments presented in this thesis are directed at unraveling the role of conformational modifications in the electrical and optical properties of these systems. The experimental techniques that were employed in the present studies are: Laser light scattering, small-angle X-ray scattering(SAXS) measurements and visual observations. The eoexistence surface of the system E + W + AS was determined by visual observations. Laser light scattering measurements were conducted to study the critical behavior of osmotic susceptibility (xr) of E + W + As, whereas SAXS studies were conducted to ascertain the existence, and quantify the spatial extent of the additional length scale in the two systems investigated. The main objectives of this research were: (i) to study the phase behavior of the ternary mixture E + W + AS at atmospheric pressure; (ii) to check the existence of crossover from 3-D Ising to mean-field critical behavior while moving away from Tc in this system; (iii) to determine the nature (monotonic or nonmonotonic) of crossover; (iv) to provide some insight into the origin of this crossover behavior in terms of an additional length scale characteristic of the system; (v) to understand the evolution of the critical behavior in the proximity of CDP, and DCP; (vi) to experimentally realize the CIP; and (vii) to investigate the presence of solvent-induced conformational changes in conducting polymer.

碩士
國立臺灣科技大學
化學工程系
89
This study was to investigate the adsorption behavior of ethanol /water mixtures over ion-exchange resins (Amberlyst 15, Amberlyst 35, and Amberlyst 39). The experiments included three parts：dynamic uptake behavior, adsorption equilibria, and breakthrough curves. The operation temperatures were 293.15 K, 303.15 K, and 318.15 K. The results of dynamic uptake behavior showed that the adsorption ability of the resins for water was in the order of Amberlyst 39＞Amberlyst 15＞ Amberlyst 35. The selectivity coefficient (K) between water and ethanol was determined by fitting the equilibrium isotherm to a simple model assuming that K was a constant over the entire composition range. It was indicated that the selectivity decreased with increasing temperature. The breakthrough curves of the studied systems were fairly correlated with the model of Weber and Chakravorti (1974). External film mass transfer coefficient and effective diffusivity were determined from the data correlation. The mass transfer coefficient of water in the resins were in the order of Amberlyst 39＞Amberlyst 15＞ Amberlyst 35. In addition, the breakthrough curves were fitted to a breakthrough function and thus the shape factor, β, of each run was obtained. The lower of β, the more favorable adsorption isotherm was expected. The results of this study showed that Amberlyst 39 is the most flavorable adsorbent for separation of ethanol / water solutions.

abstract: ABSTRACT Among the major applications of pervaporation membrane processes, organic separation from organic/water mixtures is becoming increasingly important. The polydimethylsiloxane (PDMS) is among the most interesting and promising membranes and has been extensively investigated. PDMS is an "organicelastomeric material, often referred to as "silicone rubber", exhibiting excellent film-forming ability, thermal stability, chemical and physiological inertness. In this thesis incorporation of nanosilicalite-1 particles into a PDMS matrix and effect of particle loading and temperature variation on membrane performance was studied. A strong influence of zeolite was found on the pervaporation of alcohol/water mixtures using filled PDMS membranes. The mixed matrix membrane showed high separation factor at higher zeolite loading and high flux at higher temperature.
Dissertation/Thesis
M.S. Chemical Engineering 2012

碩士
淡江大學
化學工程與材料工程學系碩士班
99
The mass transport of ethanol solvent dehydration process by using pervaporation (PV) modules has been investigated theoretically. Pervaporation modules were employed instead of the traditional ethanol-solution distillation process which was known as a high energy consuming process. Two operation systems were studied in the present study such as batch and continuous systems. The solution-diffusion model was used to describe the mass transfer behavior in dense membrane layer. Accordingly, the overall mass-transfer resistance from the feed stream to the permeate side was thus calculated with the aid of resistance-in-series model. A mathematical treatment in two-dimensional partial differential equations (PDEs) has been developed by making the differential mass balance in the continuous PV system. The partial differential equations can be transformed into an ordinary differential equations (ODEs) system using finite difference technique and then solved by using the fourth-order Runge-Kutta method. The activity coefficient on ethanol/water mixture were estimated by UNIversal Functional Activity Coefficient (UNIFAC) method to obtain the partial pressure of non-ideal binary mixture for predicting the permeate flux across membrane. The influences of feed solution concentration, feed volumetric flow rate, and membrane material under fixed feed temperature on the mass flux across the membrane were obtained and the concentration polarization phenomena in the feed stream were also discussed.

碩士
中原大學
化學工程研究所
98
Ethanol gasoline is a mixture of anhydrous ethanol and diesel, which may replace gasoline contain lead, and serve as bio-fuel. If the water content of ethanol is less than 0.5 wt %, and it may be blended into gasoline used in engine. Otherwise, the engine should be redesigned. Zeolite 3A is a widely used adsorbent in industry for ethanol dehydration. However, it has a low efficiency with adsorption selectivity and regeneration. Recently, some investigators have tried to use biomass based materials as a replacement to Zeolite 3A, such as starch. However, starch powder was recovered after adsorption with water vapor, and significant decrease of its adsorption ability was observed. In the present study, starch was immobilized into silica gel using sol-gel method for solving these problems. Results of energy-dispersive x-ray analysis showed that the starch particles are successfully immobilized into silica gel. The selectivity of the new material was found to be 2.4 times than that of Zeolite 3A. The adsorption ability of the new material increased by about 36.3% compared to that of raw starch. Furthermore, data using isotherm models and R-square values analysis suggested that Langmuir model is the most suitable model for this adsorbent material. Based on the above results, the immobilized starch was proven to be superior in terms of adsorption selectivity and regeneration ability over other adsorbents. Thus, this adsorbent material might be a potential adsorbent for application in ethanol dehydration systems.

no
Experimental solubilities of budesonide, hydrocortisone, and prednisolone in ethanol + water mixtures at 298.2 K are reported. The solubility of drugs was increased with the addition of ethanol and reached the maximum values of the volume fractions of 90 %, 80 %, and 80 % of ethanol. The Jouyban-Acree model was used to fit the experimental data, and the solubilities were reproduced using previously trained versions of the Jouyban-Acree model and the solubility data in monosolvents in which the overall mean relative deviations (OMRDs) of the models were 5.1 %, 6.4 %, 37.7 %, and 35.9 %, respectively, for the fitted model, the trained version for ethanol + water mixtures, and generally trained versions for various organic solvents + water mixtures. Solubilities were also predicted by a previously established log-linear model of Yalkowsky with the OMRD of 53.8 %.

碩士
靜宜大學
應用化學系
99
The chemicals used in this study include ethanol、water and 1,3-propanediol, because the applications of these solvents are very wide, and they are also fed in with green solvents with very low toxicity. Ethanol is a good solvent and can dissolve a lot of organic medicines. It can be applied extensively not only in pharmacy, but also in cosmetics. Water can be used widespreadly. We can find its values in lots of areas, like pharmacy, cosmetics, and food industries. 1,3-propanediol can be applied in pharmacy and cosmetics as a excipient or a humectant. In this work, we obtained reliable density, viscosity, refractive index, and surface tension at the temperatures of 298.15 K, 308.15 K, 318.15 K, and 328.15 K for the three binary systems of ethanol + water, ethanol + 1,3-propanediol, and water + 1,3-propanediol, and the ternary system of ethanol + water + 1,3-propanediol at the temperature of 298.15 K under atmospheric pressure. The excess molar volumes (VE), deviations in the viscosity (Δη), deviations in the surface tension (Δσ), mole fraction deviations in the refractive index (ΔxnD), and volume-fraction deviations in the refractive index (ΔφnD) for the mixtures were derived from these experimental data. The binary data of VE, Δη, Δσ and ΔnD were correlated as a function of the mole fraction using the Redlich-Kister equation. The ternary excess data were correlated with the equations of Jasiński and Malanowski, Cibulka, Singh et al., Pintos et al., Calvo et al., and Mascato et al. The ternary data were also predicted using the equation of Scatchard et al., Tsao and Smith, Toop, Kohler, Colinet, and Jacob and Fitzner. The result is reasonally closed to the experimental result.

博士
中原大學
化學工程研究所
101
In this study, microporous ZIF-7 (zeolitic imidazolate framework-7) and meso-micro PB (Prussian Blue) particles were successfully incorporated into chitosan (CS) membranes to form mixed-matrix membranes (MMMs). The as-prepared MMMs were used to separate mixtures of water/ethanol at 25oC in the pervaporation process. In the first, the separation efficiency of MMMs with 5 wt % ZIF-7 incorporation showed 19 times higher than that of the pristine CS membranes, because of the rigidified polymer chain of the MMMs. The other nano-scale ZIF-7 particles with particle size of 50 nm were successfully synthesized at room temperature and used to incorporate into CS membranes for separation of mixtures of water/ethanol. It was showed that the loading content with 20 wt% has the optimum value. Furthermore, the MMMs were utilized one step method to directly synthesize the ZIF-7 in the CS membrane. It was also displayed that higher separation factor like MMMs incorporation of micro-scale ZIF-7 particles. From the point view of PSI value, the 20 wt% n-ZIF/CS MMM showed 2.5 times higher than the dir-ZIF/CS-2 MMM. Regardless of which methods, the ZIF-7 crystal particles exhibited good interfaces with the CS polymer because of the nature of their organic linkers and hydrogen bonding. From the other MMMs incorporation of PB particles, it was clearly showed higher flux due to the large pore size of PB particles. The separation factor and the flux of the as-prepared membranes clearly exceed the upper limit of the previously reported CS based membranes and MMMs. The present work demonstrates better pervaporation performance of the ZIF-7 particles incorporated CS membrane for the separation of water and ethanol and the feasibility of using this system for pervaporation.

碩士
長庚大學
化工與材料工程學系
99
The sorption, diffusion and pervaporation (PV) behaviors of ethanol aqueous solutions in polydimethylsiloxane (PDMS) and PDMS-zeolite membranes at 298 K are investigated in this study. The morphologies and the characteristics of zeolite, PDMS and PDMS-zeolite membranes were determined by using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and Fourier-transform infrared spectroscopy (FTIR). The zeolite powders showed typical mordenite framework inverted (MFI) zeolite characteristics according to XPS, XRD and FTIR analyses. A dense PDMS film was observed, and the SEM images showed that the zeolite particles were well dispersed within the PDMS matrix without forming obvious defects in the PDMS-zeolite membranes. The sorption isotherms of ethanol and water binary mixtures were determined using the gravimetric method. The PDMS-zeolite membranes showed higher solvent sorption levels and selectivities (ethanol over water) than the pristine PDMS membrane. The Flory-Huggins equation and the universal quasi chemical (UNIQUAC) model were utilized to predict the individual sorption levels at various ethanol/water compositions. The concentration-dependence Flory-Huggins interaction parameter (χ12 and χiM) and UNIQUAC-HB theory (the UNIQUAC model accounting for the hydrogen bond effect) were employed to examine the improved efficiency on the prediction power. The Flory-Huggins model using variable χiM values and the UNIQUAC-HB theory gave better sorption prediction. The permeant diffusivities were determined by conducting transient sorption data and utilizing the Fick’s second law. Both permeants exhibited similar diffusivity from the mixture in the PDMS film. The PDMS-zeolite membrane demonstrated higher diffusion selectivity than the pristine PDMS membrane. The diffusivities from the ethanol aqueous solutions strongly depended on the ethanol sorption levels in membranes. In contrast, ethanol and water diffusivities from the mixtures in the PDMS-zeolite membrane were dependent on their individual concentrations in the membrane. The PDMS-zeolite membrane demonstrated higher sorption and diffusion selectivities than the pristine PDMS membrane. These results showed that the PV performance could be improved by blending MFI zeolites into a PDMS membrane. The liquids sorption levels, diffusivities and the Fick’s law were utilized to predict the PV flux for PDMS and PDMS-zeolite membranes. The predicted flux of the components was in agreement with the experimental data for ethanol/water mixtures in the PDMS membrane. However, for PDMS-zeolite membrane, the predicted component flux was lower than experimental data. The factors that caused the PV separation factor of PDMS-zeolite membrane to be reduced were still unclear and needed further study.

碩士
靜宜大學
應用化學系
100
In the separation processes of traditional distillation, the hardest process to deal with is the mixtures with azeotropes. In this study, the purpose is to add an entrainer to the azeotropic mixture to change its relative volatility, and thus achieve the removal of its azeotropic point. The advantage of this method is the entrainer is easily recovered without any change in operating pressure. Therefore, it can save the investment capital and energy. In this study 1,2-propanediol, 1,3-propandiol, and polyethylene glycol 200 (PEG-200) are used as the extrainers for the ethanol + water azeotropic mixture. The vapor-liquid equilibria (VLE) at 101.3 kPa were consucted for the seven binary systems, including ethanol + water, ethanol + 1,2-propanediol, ethanol + 1,3-propanediol, ethanol + PEG-200, water + 1,2-propanediol, water + 1,3-propanediol, and water + PEG-200, and three ternary systems, including ethanol + water + 1,2-propanediol, ethanol + water + 1,3-propanediol, and ethanol + water + PEG-200. The liquid phase activity coefficients were calculated according to the equation including the fugacity coefficients of vapor phase and the equation of the modified Raoult's law. Calculations of the fugacity coefficients of vapor phase were made with Soave-Redlich-Kwong (SRK) equation of state. In the binary systems, only the ethanol + water system appears a minimum azeotrpe. Thermodynamic consistency tests were performed for the VLE data of ethanol + water system using the Kojima method and the direct test of Van Ness. The consistency test of McDermott-Ellis as modified by Wisniak and Tamir was performed for the ternary systems of ethanol + water + 1,2-propanediol. The VLE data of the binary and ternary mixtures were correlated using the three-suffix Margules, Wilson, NRTL, and UNIQUAC activity-coefficient models. The models with their best-fitted interaction parameters of the binary systems were also used to predict the ternary vapor-liquid equilibrium. In this study, the ethanol-water azeotropic system in the presence of 1,2-propandiol, 1,3-propandiol, or PEG-200 at concentrations of 10 wt%, 30 wt%, and 50 wt%, which is added attemptedly to removal of the azeotropic point of the azeotropic mixture, were discussed. This study showed that adding the entrainer with an adequate amount, the azeotropic point can be removed effectively. The results showed that the removal of the ethanol-water azeotropic point only needs 30 wt% of 1,2-propandiol, 1,3-propandiol, or PEG-200 entrainer. These three entrainers are all green solvents and 1,2-propandiol is considered to be the best based on the separartion efficiency and the material cost.

碩士
中原大學
化學工程研究所
103
In this study, different morphology of the ZIF-7（zeolitic imidazolate framework-7） materials were prepared by hydrothermal method, such as plate, sphere and nano-particles. Then, discuss to the growing of ZIF-7 seeds were effected by hydrothermal conditions.The as-synthesised ZIF-7 materials were successfully incorporated into the chitosan(CS) solution to form the mixed matrix membranes ( MMMs）. The as-prepared MMMs were used to separate mixtures of water/ethanol at 25oC in the pervaporation process. The separation efficiency of MMMs with ZIF-7 materials showed good the flux and separation factor higher than that of pure CS membranes. However, doping too much ZIF-7 hydrophobic particles into the CS solution caused to ZIF-7 materials become agglomeration in the membranes.As a result, the flux and separation factor were decreased. In pervaporation performance, the MMMs with 0.5 wt% ZIF-7 nano-particles doping into the CS solution had higher flux (742g/m2h), separation factor (1582) and pervaporation separation index(PSI, 1174 Kg/m2h). At the same operational conditions, such as 90 wt% ethanol solution and at 25oC operational environment, the separation factor and the flux of the as-prepared membranes clearly exceed the upper limit of the previously reported CS based membranes and MMMs. The present work demonstrates better pervaporation performance of the ZIF-7 particles incorporated CS membrane for the separation of water and ethanol and the feasibility of using this system for pervaporation.

碩士
嘉南藥理科技大學
環境工程與科學系暨研究所
98
ABSTRACT The purpose of this investigation is to prepare a semi-IPN poly glycidyl methacrylate/polysulfone composite membrane for dehydration of water/ethanol solution by pervaporation. Utilizing semi-IPN technology with suitable dosage of cross linking agent, monomer concentration, radiated dosage, and initiator, the composite membranes were prepared and characterized the physical and chemical properties and their influences on the performance of pervaporation. In the first part of this investigation, the dry method was used to prepare the semi-IPN poly glycidyl methacrylate/polysulfone composite membrane. The effect of the PGMA content in the membranes on the morphology and hydrophilicity were investigated and the influences of the properties changes on the dehydration performance were also concerned by characteristics analysis. It was found that the radiated dosage and monomer concentration significantly dominated the content of PGMA in semi-IPN membranes and the increase in PGMA content also enhanced the water selectivity and swelling properties of composited membranes. Due to the IPN structure in polymer matrix, the selectivity of membranes increased and declined the permeation rate of permeate with increasing the degree of IPN. Thought the increase in monomer concentration enhanced the degree of IPN in the membrane, but the excessive monomer induced a homo-polymerization and lead to a decrease in the PGMA content in composite membranes. This homo-polymer induced the phase separation in the casting solution and further formed the micro-phase separation in the membrane formation. It is concluded that the optimum radiated dosage and monomer concentration in the semi-IPN solution are the key factors to prepare the homogeneous composite membranes. The second part of this investigation is to utilize the ring opening reaction with sulfuric acid to grafting the sulfuric group on the semi-IPN polymer. The sulfuric acid opened the epoxy group of PGMA to form the sulfonated PGMA. It was expected that the sulfuric group significantly enhanced the hydrophilic properties. The increase in the sulfuric group content in the composited membranes preferred the water selective property during the pervaporation and declined the water contact angle on the membrane surface. It is indicated that the hydrophilic properties of the polymer further increased by the sulfonation. The separation performance of pervaporation also showed the significantly improvement for dehydration by the semi-IPN modification on the polysulfone membranes. The third part of this study is to prepare the asymmetric membranes. It was found that the micro phase separation in the casting solution strongly declined the selectivity of IPN membranes. Base on the morphology observations and separation performance analysis, they were indicated that the polymer phase separation could not form a defect free skin layer and this factor dominated the decline of selectivity of composited membranes in the separation process.

碩士
國立臺灣大學
化學工程學研究所
103
To overcome the problems of phase separation between polymer and fillers and low separation performance of a membrane at high filler loading, we have synthesized a novel and efficient mixed matrix membrane (MMM) by incorporating water-based synthesis of ZIF-8 nanoparticles into polyvinyl alcohol (PVA) membranes. The ZIF-8 nanoparticles without drying is preferred for the fabrication of PVA/ZFI-8 MMMs. The incorporation of ZIF-8 nanoparticles does increase both of the flux and separation factor of a PVA membrane. However, both of the pervaporation performances of PVA/ZIF-8 MMMs could be further improved by crosslinking with glutaraldehyde (GA). The result shows that PVA/ZIF-8 MMMs with GA have superb performances on pervaporation separation of ethanol dehydration. The best flux and separation factor of PVA/ZIF-8 MMMs with GA are 0.486 kg/m2h and 4725 respectively when the doped amount of ZIF-8 nanoparticles is 39.0 wt%. The permeability is three times as much as that of pristine PVA with GA crosslinked and the separation factor is nearly 9 times as much as that of the pristine PVA with GA crosslinked.