Dissertations / Theses on the topic 'Seperation'
To see the other types of publications on this topic, follow the link: Seperation.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Seperation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Vold, Truls Chr. "Droplet breakup and coalescence in compact wellstream seperation." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2323.
Full text
2
Ertekin, Betul, Mahmut Kus, Aysenur Erdogan, Sumeyra Buyukcelebi, and Mustafa Ersoz. "Microphase Seperation Depending on Different Parameters for Nanopatterned Devices." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35202.
Full textAbstract:
We report a comparative study on microphase separation of a serial of block copolymers (BCPs) de-pending on some parameters such as solvent, annealing time. Toluene-Chlorobenzene mixtures show the best phase separation in comparison with other pristine or mixture of solvents. The results were optimized for large area studies.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35202
3
Derafshi, Ziba. "A numerical study of incompressible unsteady internal flow with seperation." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/17245.
Full text
4
Evans, Huw. "Theories of cloud curve phase seperation in nonionic micellar systems." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382178.
Full text
5
Robinson, Alex. "Linking child care to infant attachment : what lies in-between?" Thesis, Open University, 2000. http://oro.open.ac.uk/54411/.
Full textAbstract:
Objectives: To investigate the relationship between maternal separation anxiety, hours in non-maternal child care and security of motherinfant attachment in early infancy. Design: Prospective. Methods: The participants for this study were 67 mothers and their infants enrolled in a large scale prospective study. The first 100 women were sent a letter outlining the current study and requested to 'opt in'. Those mothers who agreed to participate completed the Maternal Separation Anxiety Scale (MSAS) when the infant was ten and seventeen months. The mother-infant attachment relationship was assessed according to the standardised Strange Situation Procedure when the infant was aged seventeen months (+/- two weeks). All other data were collected in the main study. Results: Maternal Separation Anxiety was not predictive (alone or in combination with other variables) of attachment status. Significant differences in levels of separation anxiety were found between mothers who were and mothers who were not employed outside the home. Separation anxiety was also related to a number of variables, including the age of the infant when the mother planned to use non-maternal child care, the total hours of non-maternal child care, infant temperament and maternal sensitivity. Conclusions: The non-significant results in the main analysis mean that no firm conclusions regarding a relationship between levels of maternal separation anxiety, hours in non-maternal child care and security of mother-infant attachment in infancy can be drawn. Future research (with a larger and more diverse sample) should continue to explore the concept of maternal separation anxiety in relation to a number of other variables, including maternal role preference and quality of child care, as it may hold important implications for social policy and preventative clinical work.
6
Mudoch, James D. "Competition and Niche Seperation between Corsac and Red foxes in Mongolia." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504440.
Full text
7
Seehara, Panpailin. "Mixed-conducting LSC/CGO and Ag/CGO composites for passive seperation membranes." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517682.
Full textAbstract:
Dense ceramic oxygen separation membranes can pass oxygen perm-selectively at elevated temperature and have potential for improving the performance and reducing the cost of several industrial processes: such as the conversion of natural gas to syngas, or to separate oxygen from air for oxy-fuel combustion in electricity generation (to reduce NOx emissions and facilitate CO2 sequestration). These pressure-driven solid state membranes are based on fast oxygen-ion conducting ceramics, but also need a compensating flow of electrons. Dual-phase composites are attractive since they provide an extra degree of freedom, compared with single phase membranes, for optimising the overall membrane performance. In this study, composites containing gadolinia doped ceria (CGO, Ce0.9Gd0.1O2- ) and either strontium-doped lanthanum cobaltite (LSC, La0.9Sr0.1CoO3- or La0.6Sr0.4CoO3- ) or silver (Ag) were investigated for possible application as oxygen separation membranes in oxy-fuel combustion system. These should combine the high oxygen ion conductivity of CGO with the high electronic conductivity and fast oxygen surface exchange of LSC or silver. Dense mixed-conducting composite materials of LSC/CGO (prepared by powder mixing and sintering) and Ag/CGO composites (prepared by silver plus copper oxide infiltration method) showed high relative density (above 95%), low background gas leakage and also good electrical conduction. The percolation threshold of the electronic conducting component was determined to be approximately 20 vol.% for both LSC compositions and 14 vol.% for Ag. Isotopic exchange and depth profiling by secondary ion mass spectrometry was used to investigated the oxygen tracer diffusion (D*) and surface exchange coefficient (k*) of the composites. Composites just above the electronic percolation threshold exhibited high solid state oxygen diffusivity, fast surface exchange activity moderate thermal expansion and sufficient mechanical strength thus combining the benefits of their constituent materials. The preliminary work on oxygen permeation measurement showed that the reasonable magnitude of oxygen fluxes is possible to be achieved. This indicates that the composites of LSC/CGO and Ag/CGO are promising for further development as passive oxygen separation membranes.
8
Kunapareddy, Naveen. "A Proof-of-Concept Test for Seperation Efficiency of an Electro-Cyclone." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1237569168.
Full text
9
Kruger, Theunis Johannes. "A generic framework for continuous energy management at cryogenic air seperation plants." Diss., University of Pretoria, 2003. http://hdl.handle.net/2263/25037.
Full textAbstract:
Please read the abstract in the section 00front of this documentDissertation (MSc (Electrical Engineering))--University of Pretoria, 2003.
Electrical, Electronic and Computer Engineering
unrestricted
10
Lapp, Anthony. "Seasonal Variability of Groundwater Contribution to Watershed Discharge in Discontinuous Permafrost in the North Klondike River Valley, Yukon." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32298.
Full textAbstract:
The objectives of this thesis were: (1) to quantify seasonal groundwater contribution to total stream discharge and (2) further our understanding of sub-arctic carbon sources and pathways within a sub-arctic discontinuous permafrost river catchment. Twenty-two samples were taken from the North Klondike River, 14 samples from 5 of its tributaries, and 46 rain and snowmelt samples from the Dawson City Airport, Yukon, Canada,. During the winter months, groundwater is responsible for greater than 95% of total river discharge. Spring freshet and summer flow bring snowmelt and precipitation, contributing anywhere from 30% to greater than 60% of total river discharge. Groundwater is characterised by high concentrations of geogenic solutes from weathering during recharge, dissolved inorganic carbon, and carbon-14 activities of 0.61 pMC. Tritium activities indicate a fast moving system, with groundwater ages measuring less than 10 years. The most significant discharge of organic carbon from the system is during spring freshet (434,192 kg carbon). Primary productivity within the system is estimated to be 10.2 grams of carbon per metre squared, with approximately 96% of carbon being sequestered or emitted as carbon dioxide.
11
Bhattacharjee, G. "Role of additives in enhancing the kinetics of gas hydrate formation and dissociation: application in gas separation and storage." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2017. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4524.
Full text
12
Ikeuchi, Masashi, Ryosuke Tane, Muneaki Fukuoka, and Koji Ikuta. "Nanofibrous Surface Patterning using Nano-Meshed Microcapsules Induced by Phase Seperation Assisted Electrospray." IEEE, 2009. http://hdl.handle.net/2237/13928.
Full text
13
Chaudhuri, Julian Brajendra. "Kinetic studies on the emulsion liquid membrane extraction of lactic acid." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253779.
Full text
14
Cornelius, Chris James. "Physical and Gas Permeation Properties of a Series of Novel Hybrid Inorganic-Organic Composites Based on a Synthesized Fluorinated Polyimide." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28230.
Full textAbstract:
A series of hybrid inorganic-organic composites were fabricated from a functionalized fluorinated polyimide and tetraethoxysilane (TEOS), tetramethoxysilane, methyltrimethoxysilane (MTMOS), and phenyltrimethoxy-silane (PTMOS) employing the sol-gel process. Polyimides were synthesized from 4,4'-hexafluoroisopropylidene dianiline (6FpDA) and 4,4'-hexafluoroisopropyl-idenediphthalic anhydride (6FDA) utilizing a solution imidization technique. The hybrid materials were synthesized by in-situ sol-gel processing of the aforementioned alkoxides and a fully imidized polyimide that was functionalized with 3-aminopropyltriethoxysilane. The gas permeability, diffusivity, and selectivity were evaluated for He, O2, N2, CH4, and CO2, while the physical properties of these hybrid materials were evaluated using several analytical techniques. The results from this study revealed that gas transport and physical properties were dependent on the type of alkoxide employed in the hybrid inorganic-organic material. Gas permeability was observed to increase with increasing gas penetrant size for MTMOS and PTMOS based hybrids, while TEOS based hybrids decreased gas permeability at all compositions. In general, MTMOS based hybrid materials had the largest increases in permeability, which was attributed to an increase in free volume. The TEOS based hybrid materials had the largest decreases in permeability, while PTMOS based hybrid materials had performance in between these alkoxides. Decreased permeability for the TEOS based hybrids was attributed to the formation of lower permeable material at a particle interface and coupled with increasing tortuosity. Results of PALS studies suggested that there was an increase in free volume and pore size for MTMOS based hybrids, while both TEOS and PTMOS based hybrids had decreases in both average pore size and free volume. The temperature dependence of permeation, diffusivity, and sorption were evaluated from 35oC to 125oC. These results suggested that there was a decrease in solubility for all hybrids employed in this study. Furthermore, increases in permeability for the MTMOS based hybrids were created by increased penetrant diffusion. Physical property studies revealed that the type of inorganic material incorporated into the hybrid influences the degree of swelling, bulk density, Tg, and thermal stability. Hybrid materials were also created employing 3,5-diaminobenzoic acid (DABA) in the synthesis of modified 6FDA-6FpDA polyimides in order to evaluate how improvements in inorganic and polymer compatibility influenced the gas transport properties. From this separate study, it was found that increases in both permeability and selectivity were possible. The mechanism attributed to this simultaneous increase in permeability and selectivity was the formation of a more permeable and selective interphase at the interface of an inorganic particle and the polymer matrix. In addition to these studies, 6FDA-6FpDA polyimide molecular weights were changed from 19.3K to 35.3K to probe its role on gas transport and physical properties. These studies revealed that permeability, diffusivity, and solubility increased with increasing molecular weight, while density decreased with increasing molecular weight. These results suggest that there is an increase in free volume with increasing 6FDA-6FpDA polyimide molecular weight.Ph. D.
15
Chelgren, Kimberly DeHate. "Death Anxiety in Young Adults: The Predictive Role of Gender and Psychological Seperation From Parents." UNF Digital Commons, 2000. http://digitalcommons.unf.edu/etd/179.
Full textAbstract:
This study examined the predictive role of gender and psychological separation in the death anxiety of young adults. A total death anxiety score and eight psychological dependency scores, four for mom and four for dad, were obtained from male and female participants between the ages of 17 and 26 years old. Females were found to have significantly higher total death anxiety than were males. Females also had significantly higher emotional dependency on mom than did males. Regression analysis revealed that gender and emotional dependency on mom account for 14% of the variance in total death anxiety. Additional results with males and females data separated revealed significant correlations between total death anxiety and conflictual dependency/dad and conflictual dependency/mom for females and emotional dependency/dad, emotional dependency/mom, and functional dependency/mom for males. An explanation for the differences in dependencies found between the males and females is given.
16
YOUNG, Coral. "WOMEN AND MARRIAGE: THE HOUSING CONSEQUENCES OF OPTING OUT." Thesis, The University of Sydney, 1993. http://hdl.handle.net/2123/398.
Full textAbstract:
This thesis reviews the housing-related implications of separation and divorce for women. It arges that the housing circumstances must be placed within a broader perspective of the social and economic consequences and ideological environment surrounding divorce. In the same way, operation of the housing system must be placed within a wider context, particularly in relation to the degree of change in its operational environment within the last 20 years. The thesis finds that the circumstances surrounding leaving a marriage are personally traumatic, and lead to a period of economic, housing and personal crisis. Over time, although the tendency is for establishment of re-equlibrium, considerable disadvantages prevail for women. The quickest method of establishing re-equilibrium for women is to repartner.
17
YOUNG, Coral. "WOMEN AND MARRIAGE: THE HOUSING CONSEQUENCES OF OPTING OUT." University of Sydney, Urban and Regional Planning, 1993. http://hdl.handle.net/2123/398.
Full textAbstract:
This thesis reviews the housing-related implications of separation and divorce for women. It arges that the housing circumstances must be placed within a broader perspective of the social and economic consequences and ideological environment surrounding divorce. In the same way, operation of the housing system must be placed within a wider context, particularly in relation to the degree of change in its operational environment within the last 20 years. The thesis finds that the circumstances surrounding leaving a marriage are personally traumatic, and lead to a period of economic, housing and personal crisis. Over time, although the tendency is for establishment of re-equlibrium, considerable disadvantages prevail for women. The quickest method of establishing re-equilibrium for women is to repartner.
18
Fernando, Samantha. "Monoclonal antibody (mAb) purification by counter current chromatography (CCC)." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/6522.
Full textAbstract:
Counter current chromatography (CCC) is a form of liquid liquid chromatography, which the Brunel Institute for Bioengineering (BIB) team have developed to process scale. In this thesis, its application has been successfully extended to the rapid, scalable purification of monoclonal antibodies (mAb) from mammalian cell culture, using aqueous two-phase systems (ATPS) of inorganic salts and polymer. A polyethylene glycol (PEG) and sodium citrate system was found to be the most appropriate by robotic phase system selection. The search for an economical alternative to protein A HPLC is a substantial bioprocessing concern; in this work CCC has been investigated. Initial studies showed that unpredictably, despite separation from impurities being achieved, some loss in the IgG‘s ability to bind to Protein A was seen, as confirmed by Protein A BiaCore analysis. CCC machines were seen to adversely affect IgG functionality. This led to a systematic investigation of the effect of CCC phase mixing on IgG functionality in a number of different CCC instruments, allowing direct comparisons of modes of CCC (hydrodynamic and hydrostatic CCC) and their associated mixing (wave-like and cascade, respectively). The varying g forces produced within the CCC column were determined using a recently developed model to calculate g force range. The effect of interfacial tension was also studied using a custom built 'g' shaker. The optimum CCC mode was identified to be the non synchronous CCC, operated in a hydrodynamic mode but allowing bobbin to rotor speed (Pr ratio) to be controlled independently. In a normal synchronous J type centrifuge a Pr of 1 is fixed, this is where the bobbin and rotor speed are identical I.e. one bobbin rotation (where mixing occurs) to one rotor revolution (where settling occurs). Constraints were seen with this 1:1 ratio and the separation of mAb using ATPS. This work has shown with the use of the non synchronous CCC at a Pr of 0.33, mixing is reduced and rotor rotations increased. Consequently the associated g force range is decreased. Furthermore, by the extension of settling time, the clear separation of the mAb from impurities has been achieved with retention of biological activity. This thesis demonstrates the importance of settling time for ATPS in phase separation and documents the fundamental requirements for the successful separation of biologics. Purified non synchronous CCC samples have additionally undergone rigorous quality control testing at Lonza Biologics by their purification scientists. This work has ultimately showed that with optimisation, the non synchronous CCC can be used to produce biological samples that are of industry standard.
19
Wallace, Jamie Stuart. "Development of a Carbon Dioxide Continuous Scrubber (CDOCS) System for Alkaline Fuel Cells." Thesis, University of Canterbury. Mechanical Engineering, 2006. http://hdl.handle.net/10092/1077.
Full textAbstract:
Alkaline fuel cells (AFC's) using renewable fuels are a developing technology capable of meeting market niches in standby, standalone and distributed power generation. AFC's generate electricity, heat and water using hydrogen and oxygen as fuels. While AFC's have been known and the principles demonstrated for over sixty years, their use has been restricted primarily to space applications. Recent technological developments have seen the cost of AFC stacks fall considerably; this together with several other advantages over competing fuel cell technology, has rekindled interest in commercial systems. The main deterrent to wide spread commercialisation of AFC systems is susceptibility to carbon dioxide (CO2) in atmospheric air used as the oxygen supply. AFC's require a low cost, low energy, continuous scrubbing device to reduce CO2 in air from approximately 380 parts per million (ppm) atmospheric concentration to below 50 ppm. Current technology to overcome this problem, a solid expendable absorbent called soda lime, is not viable for commercial systems. The project scope included concept generation of a device to remove CO2 from air, the development of a CO2 measurement technique, investigation of chemistry and flow phenomena to determine design relations, and product design and embodiment. The scrubber system conceived specifically for AFC systems uses the temperature swing chemistry of a liquid chemical absorbent, monoethanolamine, and a packed bubble column apparatus to provide intimate gas-liquid interaction. Prototype development proved the Carbon Dioxide Continuous Scrubber (CDOCS) concept and a Patent Cooperation Treaty (PCT) patent was granted, followed by a full American patent. A gas chromatographic measurement technique was developed to measure low ppm concentration CO2 in air, enabling regular monitoring of scrubbed gas. Carbon dioxide was separated from a small sample of scrubbed air by chromatographic columns, and the gases analysed with a thermal conductivity detector. The GC system was capable of measuring to 10 ppm with good resolution and accuracy. Experimental studies were carried out to characterise the flow dynamics and absorption phenomena in the packed bubble column absorber. The relationship between absorption performance and gas-liquid contact time, an important operating parameter for use with AFC's, was theoretically determined and later confirmed by experiment. The regeneration process was studied and the optimal regenerator design determined to be second, smaller packed bubble column. Experiments were conducted to establish design relations for regeneration temperature, flush gas flow rate and the effect of multiple regeneration cycles. A prototype CDOCS system was built to enable experimental characterisation of scrubbing performance as a function of primary design and operating parameters including liquid depth, regenerator operating temperature and solution composition. This resulted in a good understanding of the system, and an optimised experimental run was performed for cost and performance comparison to existing scrubbing technology. The CDOCS was capable of reducing CO2 in air from 380 to 80 ppm for thirty days, providing low cost, low maintenance scrubbing compared to soda lime. The capital cost of the CDOCS is considerably more than for soda lime scrubbers, and the penalty for extended operation is parasitic power consumption by the CDOCS system totalling less than 7% of fuel cell output. It is suggested that a combination of the two technologies be used initially to provide effective, low cost scrubbing for AFC and CDOCS co-development. Future work on the CDOCS project should include reduction of chemical vapour carry over to the fuel cell, followed by integration with an AFC system. This would allow further development, refinement and design for production to reduce capital cost.
20
Brits, Leanne. "Vapour-liquid-liquid equilibria measurements for the dehydration of low molecular weight alcohols via heterogeneous azeotropic distillation." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96850.
Full textAbstract:
Thesis (MEng)--Stellenbosch University, 2015.ENGLISH ABSTRACT: The operation and optimisation of a distillation train directly effects the total energy consumption of a typical processing plant. With this in mind, the efficient separation of low molecular weight alcohol azeotropes, using heterogeneous azeotropic distillation, is of great economic and environmental importance. Heterogeneous azeotropic distillation involves the addition of an extraneous component, known as an entrainer, to the mixture to facilitate separation. Benzene has long been replaced as the entrainer of choice, due to its carcinogenic nature, and research into finding a more suitable entrainer has commenced. To determine if an entrainer is suitable for a particular separation, detailed phase behaviour information of the ternary alcohol/entrainer/water system is required; vapour-liquid (VLE), vapour-liquid-liquid (VLLE) equilibria data and the composition of all azeotropes present. This is complicated by the fact that thermodynamic models (like the nonrandom two-liquid (NRTL), universal functional (UNIFAC) and universal quasichemical (UNIQUAC) activity coefficient models) often fail to predict the phase equilibria of ternary systems. The lack of available experimental phase equilibria data, and the inability of thermodynamic models to predict phase equilibria data, has fueled the need for the experimental determination of accurate, repeatable isobaric VLE, VLLE and azeotropic data. With this in mind, this research is focused on the experimental determination of VLE, VLLE and azeotropic data for three low molecular weight alcohol/entrainer/water systems at 101.3 kPa. Following an extensive literature study on azeotropes, applicable separation techniques and available VLE and VLLE data in literature, the ethanol/2-butanone/water, n-propanol/2-butanone/water and iso-propanol/2-butanone/water systems were chosen for experimental investigation. The experimental determination was carried out in a Gillespie type still, equipped with an ultrasonic homogenizer. The temperature and pressure accuracies of the equipment were found to be 0.03°C and 2mbar respectively. The chosen experimental methodology was verified, and its repeatability tested, through the measurement of isobaric VLE and VLLE data of ethanol/isooctane, ethanol/n-butanol/water and n-propanol/isooctane/water systems at 101.3 kPa and subsequent comparison of the measured data with literature data. The compositional error reported, taking into account experimental and analysis effects, is ±0.014 mole fraction. All experimentally determined data sets, verification and new data, were tested for thermodynamic consistency by using the Wisniak modification of the Herrington test, the L/W consistency test, as well as the McDermott-Ellis consistency test, and found to be consistent. The Othmer-Tobias correlation was used to ensure the measured LLE data followed a steady trend, with all R-values larger than 0.910. For all three of the new systems chosen, the absence of ternary heterogeneous azeotropes was noted. The presence of a ternary homogeneous azeotrope was found for both the ethanol/2-butanone/water and iso-propanol/2-butanone/water systems. No ternary azeotropes are present for the n-propanol/2-butanone/water system. Suitable entrainers were compared to 2-butanone (MEK) by plotting measured data and literature information of five similar alcohol/entrainer/water systems on a ternary phase diagram. It was found that MEK could not be considered as a suitable entrainer for heterogeneous azeotropic distillation of ethanol, n-propanol and IPA. This is due to the absence of a ternary heterogeneous azeotrope for the aforementioned alcohol/MEK/water systems. Finally, the ability of thermodynamic models (NRTL, UNIFAC and UNIQUAC) to predict experimental data was determined both visually and through descriptive statistics. This entailed the inspection of ternary phase diagrams and the calculation and evaluation of average absolute deviation (AAD) and and average absolute relative deviation (AARD%) values. The measured data were modelled in Aspen Plus®. It was found that none of the models could predict the ternary systems with acceptable accuracy and the data were regressed. In general, the regressed parameters for the NRTL, UNIFAC and UNIQAC models improved the model predictions when compared to the built-in Aspen parameters. The UNIFAC model predicted the ethanol/MEK/water and n-propanol/MEK/water systems most accurately while none of the models could predict the IPA/MEK/water systems with acceptable accuracy.
AFRIKAANSE OPSOMMING: Die ontwerp en optimering van 'n distillasietrein het ‘n duidelike effek op die totale energieverbruik van ‘n tipiese prosesaanleg. Met dit in gedagte, is ‘n meer doeltreffende skeiding van lae molekulêre massa alkohol aseotrope, met behulp van heterogene aseotropiese distillasie, voordelig vir die ekonomie en die omgewing. Heterogene aseotropiese distillasie behels die toevoeging van 'n eksterne komponent, wat bekend staan as 'n skeidingsagent, om uiteindelik die skeiding te fasiliteer deur die komponente se dampdrukke te verander. Benseen was in die verlede ‘n gewilde skeidingsagent, maar dit is a.g.v. sy karsenogeniese eienskappe nie meer aanvaarbaar om te gebruik nie. Nuwe navorsing in hierdie veld fokus dus onder andere op die identifisering van meer geskikte skeidingsagente. Om te bepaal of 'n skeidingsagent geskik is, word indiepte fasegedrag inligting benodig, i.e. damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata en die samestelling van alle aseotrope teenwoordig. Ongelukkig kan termodinamiese modelle dikwels nie die fasegedrag van ternêre stelsels voorspel nie. Dit, sowel as die beperkte beskikbaarheid van eksperimentele ewewigsdata in die literatuur, het dus hierdie navorsing aangevuur. Die projek het gefokus op die experimentele bepaling van damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata en aseotropiese data vir drie alkohol/skeidingsagent/water-stelsels by 101.3 kPa. Na ‘n indiepte literatuurstudie van aseotrope, gepaste skeidingstegnieke en beskikbare damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata, is 2-butanone (MEK) gekies as ‘n moontlike skeidingsagent en die etanol/MEK/water-, n-propanol/MEK/water- en iso-propanol/MEK/water-stelsels gekies vir eksperimentele ondersoek. Die data is met ‘n dinamiese Gillespie eenheid gemeet, toegerus met ‘n ultrasoniese homogeniseerder om vloeistof-vloeistof skeiding te voorkom. Die akkuraatheidsbande van temperatuur- en druk meetinstrumente was 0,03°C en 2 mbar, onderskeidelik. Die eksperimentele metode en die herhaalbaarheid van metings is bevesting, deur die isobariese damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata van etanol/iso-oktaan, etanol/n-butanol/water en n-propanol/iso-oktaan/water te vergelyk met onafhanklike stelle ooreenstemmende data uit die literatuur. Die gesamentlike eksperimentele en analitiese fout wat gemaak kon word tydens bepaling van molfraksie samestellings was ±0.014 molfraksie. Alle gemete eksperimentele data is getoets vir termodinamiese samehang deur middel van beide die L/W en McDermott-Ellis konsekwentheidstoetse. Die Othmer-Tobias korrelasie is gebruik om seker te maak dat die gemete LLE data ‘n konstante tendens volg, met alle R-waardes groter as 0.910. Vir al drie van die nuwe stelsels wat gekies is, was ‘n drieledige heterogene aseotroop afwesig. Die teenwoordigheid van drieledige homogene aseotrope is egter waargeneem vir die etanol/MEK/water- en IPA/MEK/water-stelsels. Geen drieledige aseotrope is vir die n-propanol/MEK/water-sisteem gevind nie. Alle gemete data, asook literatuur inligting van vyf soortgelyke alkohol/skeidingsagent/water sisteme, is op ‘n drieledige fase diagram voorgestel om die skeidingsagente met mekaar te vergelyk. Hiervolgens word dit getoon dat MEK nie as ‘n gepaste skeidingsagent vir heterogene aseotropiese distillase beskou kan word nie a.g.v. die afwesigheid van ‘n drieledige heterogene aseotroop in die voorgenoemde alkohol/MEK/waterstelsels. Die vermoë van die termodinamiese modelle (NRTL, UNIFAC en UNIQUAC) om die eksperimentele data te voorspel is visueel (per grafiek) sowel as deur beskrywende statistiek bepaal. Dit behels die inspeksie van drieledige fasediagrame en die berekening en evaluasie van die gemiddelde absolute afwyking en gemiddelde absolute relatiewe afwykingswaardes. Hierdie teoretiese data is met Aspen Plus® bepaal. Nie een van die modelle kon die drieledige stelsels se fasegedrag met aanvaarbare akkuraatheid voorspel nie. Die parameters vir die NRTL-,UNIFAC- en UNIQUAC-modelle kan verbeter word deur middel van regressie, in vergelyking met die ingeboude Aspen parameters. Dit is bevind dat die UNIFAC model die etanol/MEK/water- en n-propanol/MEK/water-stelsel die beste kan voorspel. Nie een van die bogenoemde modelle kon egter die fasegedrag van die IPA/MEK/water-stelsel voorspel nie.
21
Tripathi, Nagendra. "Formation of oxide-inclusions by ladle glaze and a preliminary examination on the possibility of inclusion seperation by bubble floatation." Licentiate thesis, KTH, Materials Science and Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1669.
Full textAbstract:
The present work was to study the role of ladle glaze as apotential supplier of inclusions to the steel melt during theladle refining process. In this study, the total number ofinclusions at the beginning and at the end of the ladletreatment process was found to be increasing with ladle age,which is the number of heats, the ladle being used. Asubstantial increase in inclusion population was noticed aftera certain ladle age.
Totally four types of inclusions named as; type-1 (MgO),type-2 (spinel), type-3 (an oxide solution) and type-4 (spinelin the center surrounded by the oxide solution of type-3) wereobserved in the beginning of the ladle refining process.Thermodynamic calculation revealed that the type-3 and type-4inclusions were generated by the reactions between EAF slag andladle glaze. Even a part of inclusions of type-2 (spinel phase)could be formed by these reactions. Three types of inclusionswere found before casting, viz. type-5 (oxide solution with lowcontents of MgO and SiO2), type-6 (small MgO islands embeddedin an oxide solution) and type-7 (spinel in the centersurrounded by the oxide solution of type-5). Inclusions of bothtype-5 and type-7 were the products of the reaction betweeninclusions of type-2 and the liquid metal. On the other hand,the occurrence of pieces of MgO having sharp edges in the oxidesolution suggested that the type-6 inclusions were generated bythe ladle glaze.
A preliminary examination on the possibility of inclusionseparation by bubble floatation, experiments using cold modelswere also carried out. De-ionised water and silicon oil wereused as the bulk phase. Charcoal particles of different sizeranges were employed as the dispersed phase. The examination ofcharcoal-water-gas system indicated that the positivefloatation coefficient is not a sufficient condition for theinclusion separation. The experimental results were found to bein contradiction with the prediction of a typical model thatconsiders interfacial energies. The omitting of the drag forcewas believed to be the reason causing the failure of the modelprediction in the charcoal-water-gas system. The failure of themodel prediction suggested a need of a new model taking intoaccount interfacial energies, drag force, buoyancy force andgravity force.
Key words:oxide inclusions, ladle metallurgy, ladleglaze, inclusion population, ladle age, interfacial tension,inclusion separation
22
Craig, Gregory (Gregory Lorne) Carleton University Dissertation Psychology. "The effect of unattended digits upon identification of an attended letter; the influence of letter-digit seperation and physical similarity." Ottawa, 1992.
Find full text
23
Loudermilk, Elaine, Renice Obure, Julie Obenauer, Megan Quinn, and Jill D. Stinson. "The Role of Adverse Childhood Experiences in Adult Divorce and Separation." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/7952.
Full textAbstract:
Background: Healthy marriage promotes better health outcomes compared to negative marital experiences. Previous research has shown that exposure to trauma prior to age 18, or Adverse Childhood Experiences (ACEs), increases the likelihood of poor health in adults. These negative experiences impact future relationships and contribute to increased risk for depression, substance abuse, and lowered immune system. This study used ACE scores by category to investigate the effect of ACEs on the risk of divorce or separation and explored the hypothesis that children who have experienced ACEs are more likely to report being divorced or separated in later life. Methods: ACEs examined individually included those considered as abuse (swearing, physical abuse, forced to touch, and sex) and those categorized as household dysfunction (parent/guardian depression, alcohol, or substance use, incarceration, family abuse, and parental divorce). Descriptive statistics were completed in SAS with the 2011 and 2012 Behavioral Risk Factor Surveillance System (BRFSS) data. All ACE categories were found to be significant using chisquare (p<0.05). Final analysis using Stata (N=69,793) compared adults who were divorced or separated to those who were married or widowed. Simple and multiple logistic regressions were completed for ACEs, controlling for income, race, age, education level and gender. Results: Those who experienced ACEs of forced sex or had a parent in prison had double the odds of experiencing divorce or separation (OR=2.46, p<0.001 and OR=2.03 p<0.001 respectively). Exposure to parent/guardian alcohol use in the home was shown to have a less dramatic effect on divorce/ separation, although this was still significant (OR=1.57, p<0.001). Forced touch was found to almost double the odds of divorce/separation (OR= 1.96, p<0.001). Higher income was shown to have a protective effect on marital status (OR=0.60 p<0.001). While age, males, and education level were statistically significant, the variables did not have a meaningful effect on reducing chances of divorce/separated (ORs between 0.87 and 0.96, p<0.001). Conclusion: Those who experienced ACEs as a child were at more risk of being currently divorced/separated. The current study found that adults who were forced to have sex or forced to touch as a child were at increased risk of divorce/separation. Individuals with a parent in prison were twice as likely to experience divorce/separation. Studying the effect ACEs have on marriage could contribute to further understanding ways in which to prevent unhealthy relationships. This in turn could reduce the risk for divorce and adverse health problems in adults who have experienced ACEs. More studies need to be done to fully understand the consequent effects on ACEs and divorce/separation.
24
Jain, Manish. "Separation of sulfur compounds from FCC gasoline by pervaporation." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7081.
Full text
25
Petersen, Jacques R. "A geochemical investigation of ground water and soils affected by evaporation pond seepage, at the Namakwa Sands Mineral Seperation Plant(MSP)." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/4218.
Full textAbstract:
Bibliography: leaves 78-81.Evaporation ponds are used for treating wastewaters in arid regions worldwide. Namakwa Sands an Anglo American plc operation, mines heavy minerals along the semi arid West Coast of South Africa. An acid effluent is generated during treatment of these heavy minerals. The effluent is neutralized and disposed of into unlined evaporation ponds. Seepage from the ponds affects the surrounding environment as well as the subsurface waters. The main objective of this study was to investigate the effects of the seepage on the groundwater resources and potential implications for contaminant migration in the subsurface environment.
26
Kull, Kenneth. "Synthesis and Characterization of Novel Polyurethanes and Polyimides." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6530.
Full textAbstract:
Four novel high performance soft thermoplastic polyurethane elastomers utilizing methylene bis(4-cyclohexylisocyanate) as a hard segment, 1,4 butanediol as a chain extender and modified low crystallinity carbonate copolymer as a soft segment were synthesized. The samples were characterized by infrared spectroscopy (FTIR), tensile, elongation, hardness, abrasion resistance and atomic force microscopy (AFM). SAXS data shows evidence of an interdomain "center-to-center" distance of 45Å. DSC traces show evidence of one glass transition temperature and a weak melting region. DMA analysis reveals a low temperature secondary relaxation and the glass to rubber transition followed by a rubbery plateau. All samples demonstrated the ability to maintain excellent physical and mechanical properties in hardness below 70 Shore A. Thermoplastic polyurethanes in this study do not possess surface tackiness usually observed in soft polyurethanes. Biocompatability testing showed no toxicity of these samples as indicated by USP Class VI, MEM Elution Cytotoxicity and Hemolysis toxicology reports. This novel type of polyurethane material targets growing markets of biocompatible polymers and can be utilized as peristaltic pump tubing, balloon catheters, enteral feeding tubes and medical equipment gaskets and seals.
Polyimides are a family of engineering polymers with temperature stability, high polarity and solvent resistance. These high-performance materials are used in aerospace applications, in the production of semi-dry battery binders, and in a host of other high temperature demanding situations. However, their glass transition and melt temperatures are characteristically very high and close to one another, making them difficult to melt process and limiting them to thin film formulations from their polyamic acid precursors. Here, a new series of thermoplastic polyether-polyimides (PE-PIs) are synthesized by incorporating a polyetherdiamine monomer to reduce rigidity and break up an otherwise fully aromatic backbone as seen with most conventional polyimides. It will be shown that control of the stoichiometric ratio between the aromatic 4,4'-methylenebis(2,6-dimethylaniline) and aliphatic polyetherdiamines relative to PMDA (pyromellitic dianhydride), along with the molecular weight of the polyetheramine, can be used to tune the Tg to best balance between temperature performance and processability.
27
Ravindra, B. K. "Seperation between state and religion." Thesis, 2000. http://hdl.handle.net/2009/1470.
Full text
28
曾秀冬. "Seperation of Caseinophosphopeptides by Electrodialysis." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/04209248798449397639.
Full textAbstract:
碩士國立臺灣大學
化學工程研究所
85
The tryptic hydrolysis of Ca-caseinate to produce caseinophosphopeptides(CPP) was investigated. CPP can enhance the absorption of calcium in small intestine. To obtain a high purity CPP, the electrodialysis was employed according to the highly negative charged property of CPP. At first, the operation conditions such as electric field strength, current density, temperature, ionic strength and pH were investigated. The optimum conditions were as follows: electric field strength 4.29V/cm, current density 3.70mA/cm2 temperature 17 ℃, ionic strength 3.71mM and pH 4.2. Under these conditions, the highest CPP purity was obtained owing to the negative charge of CPP was most suitable to the separation by electrodialysis. In addition, the membrane material also affects the peptides transported and CPP purity, and the hydrophilic membrane was better than hydropbobic one TbJOUgh the experiments with different MWCO membranes, i.e., PVDF 5K. PES 10K, PVDF 10K, PVDF 1OOK, PVDF 500K, PVDF O.1μm and PVDF 3μm, the PVDF 1OOK membrane exhibited the highest performance, the purity of CPP attamed was 27.70%.
29
Tsai, Jia-Wen, and 蔡嘉文. "The Improvement of Seperation Theory in Membrane Ultrafiltration." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/58946996463851631771.
Full textAbstract:
碩士淡江大學
化學工程學系
85
The resistance-in-series model and boundary layer model applied to analyze the permeate flux of membrane ultrafiltration, have been further discussed in present study. Ultrafiltration of a carboxymethyl cellulose (CMC) aqueous solution has been carried out in a tubular membrane module made of ceramic. The simplified equation of resistance-in-series model for the prediction of permeate flux has been derived with the consideration of slight declination of transmembrane pressure along the tube axis. The prediction of permeate flux by correlation equation confirms quite well with the experimental results. The boundary-layer theory coupled with the concentration-polarization theory has been also applied to analyze the permeate flux of membrane ultrafiltration, in which a more reasonable model of permeate-flux equation has been introduced to correct the previous work. Two numerical examples have been illustrated and the results show that the theoretical prediction of present study is more close to that in the previous work.
30
Cheng, Yu-Lun, and 鄭又綸. "Development of Seperation Technique of Compound Noise Sources." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/85728580548317532259.
Full textAbstract:
碩士國立臺灣海洋大學
系統工程暨造船學系
99
Most nowadays city has high density population living in confined space. Inevitably, diverse kinds of noise exit in our living environment. Among which, the compound noise generated from complicated complex ground transportation system has seriously affected the quality of living environment and working performance. The aim of this thesis is mainly to develop the separation technique of the compound noise sources from the two more ground transportation systems. At the first step in the study, various sound collectors or accumulators are used to collect directionally the sound from various transportation system at a receiving rite, then the compound sound separation method is developed on the basis of the energy ratios amongst the directionally collected sounds each other. By the sound focussing effect consideration, a high performance sound collector has developed. This sound collector can exaggerate the directional sound level more than 10dB(A), comparing with the sound level measured by the collector deviated the sound source direction by an amount of no less than . Also, the collected sound field in the designed high performance sound collector has simulated by using the software package Raynoise. To validate the correctness of the established sound separation technique and to compare the sound collection effects with respect to the steel sound collection disk, the steel sound barrel, the plastic sound barrel and the high performance sound collector, the experimental measurement are carried out in an anechoic chamber and outdoors respectively. It shows that the accuracy of the compound noise separation by working the high performance sound collectors in the test with an error range between 0.2dB~0.8dB, the collected sound level can exaggerate 13dB~18dB, the available angle of collectors need for noise separation is .
31
Datta, Nivedita. "High temperature seperation of sugar by reverse osmosis." Thesis, 1992. http://localhost:8080/xmlui/handle/12345678/3314.
Full text
32
Akhtar, Faheem. "Water Vapor Separation: Development of Polymeric and Mixed-Matrix Membranes." Diss., 2019. http://hdl.handle.net/10754/631897.
Full textAbstract:
Removal of water vapor from humid streams is an energy-intensive process used widely in industry.
Effective dehumidification has the potential to significantly reduce energy consumption and the overall cost of a process stream. Membrane-based separations, particularly dehumidification, are an emerging technology that can change the landscape of global energy usage because they have a small footprint, they are easy to scale up, to implement and to operate. The focus of this thesis is to evaluate new directions for the development and use of materials for membrane-based dehumidification processes. It will show advances in the synthesis of new copolymers, a surprising boost in performance with the addition of 2-D materials, propose the use of polybenzimidazole for challenging dehumidification applications, and show how by tuning the nanostructure of a commercially available block copolymer (BCP) it is possible to increase the performance.
The design of novel amphiphilic ternary copolymers comprising P(AN-r-PEGMA-r-DMAEMA) allowed selective removal of water vapors from gaseous streams; the effect of varying PEGMA chain length on membrane performance was studied. The membranes showed an excellent performance when the content of the PEGMA segment was 2.9 mol% with a chain length of 950Da.
In the mixed-matrix approach, the inclusion of graphene oxide (GO) nanosheets in a different copolymer enhanced the membrane performance by creating selective tortuous pathways for inert gases. The well-distributed GO nanosheets in the defect-free composite membranes resulted in an 8 fold increase in water vapor/N2 selectivity compared to neat membranes.
Thirdly, dense polybenzimidazole membranes showed good water vapor permeability, and the addition of TiO2-based fillers with varying chemistry and geometry enhanced the performance of PBI membranes.
Lastly, the effect of tuning the morphology of commercially available BCP on dehumidification was demonstrated successfully. The self-assembled morphology formed with cylindrical hydrophobic cores, and the hydrophilic coronas, formed ion-rich highways for fast water vapor transport. Water vapor permeability improved up to 6-fold with the nanostructure modulation more than any membrane reported in the literature.
In summary, the work reported in this dissertation has the potential to lay a framework towards tailor-made next-generation membranes aimed for water vapor removal in various dehumidification applications.
33
Lin, Cheng-Yun, and 林政雲. "A Feasibility Study of Chitooligosaccharides Seperation in Countercurrent Chromatography." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/94773080605775010716.
Full textAbstract:
碩士國立交通大學
應用化學系
90
Two methods which are used to separate chitooligosaccharides are HPLC and CE, but they cannot handle great sample volume either. In this study, we try to separate and collect chitooligosaccharides in either of aqueous two phase solvent system and organic/aqueous solvent system in countercurrent chromatography. Experimental factors are composition of solvent, sample concentration and pH value. As the result, in aqueous two phase solvent system, chitooligosaccharides with low molecular weight and high polarity are hardly separated while they almost stay in the upper layer, PEG(polyethylene glycol) - rich phase. Even though we increase the molecular weight or concentration of PEG, add different kinds of salts including phosphate and citrate, change the concentration of salt, or lower the pH value in solvent system, chitooligosaccharides cannot be eluted out. It is suggested that a good affinity exists between chitooligosaccharides and PEG. In organic/aqueous solvent system, however, no matter how greatly we try to increase the polarity or the pH value of our solvent systems, the partition coefficient of chitooligosaccharides between the two phase cannot be increased, so they remain in the aqueous phase.
34
Li, Tian Si, and 黎天賜. "Seperation of bilirubin from pig bile by affinity chromatography." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/34855714907034280804.
Full textAbstract:
碩士國立臺灣大學
食品科技研究所
84
More than ten millions pigs are slaughtered annually in Taiwan, and the gallbladders are treated as wastes. In this experiment, bilirubin in pig biles was separated by using entrapping type affinity gel beads, which were prepared with agarose, alginate or chitosan as carrier, and bovine serum albumin (BSA) as affinity matrix.Continous flow operation and batch type operation were the two major divisions.In continous flow operation,affinity gel beads,packed in column(2.0x20 cm),were treated with diluted biles and then washed previously with buffers,deionized water and finally eluated with 50%ethanol/water.In batch type operation,gel beads were treated almost in the same way except the beads were floated in the flask.Ethanol elution solutions from both operat- ions were collected and absorbance at 450nm were detected.Further purification was conducted through column chromatography on Sephadex G-25,and the recovery and purity of final bilirubin products were analyzed by HPLC method.Result showed that the optimum BSA content in gel beads and BSA-bilirubin absorption time was 1.5-2.0% and 5min,respectively,based on the absorption amount of bilirubin on BSA in beads.Among the carriers, alginate was tested to be the most suitable in this experiment for the convenience of gel beads preparation and the strong absorption of bilirubin on BSA in it. Compared with the batch type operation, continous flow operation showed more convenience and higher bilirubin product concentration,and was found to be suitable for the primary isolation.In the durability test, the efficiency of the alginate beads repeatedly used for 8 cycles in continous flow and batch type operation was 54.2 and 19.4%, respectively.By HPLC method,the recovery and purity of final bilirubin products was estimated to be 30 and 36%, respectively.
35
Giri, Goutam. "Fixed Bed Column Study for Removal of Chromium (VI) from Aqueous Solution by Using Saw Dust(GMELINA ARBOREA)." Thesis, 2009. http://ethesis.nitrkl.ac.in/988/1/10500011_-_FINAL_THESIS.pdf.
Full textAbstract:
The study on performance of low-cost adsorbent such as saw dust of Gmelina arborea (Ghambhari tree) in the removal of Chromium (VI) ion from aqueous solution is performed. The
adsorbent material adopted was found to be an efficient media for removal of Chromium (VI)ion in continuous mode using fixed bed column. A comparative study has also been done on the adsorption capacity of saw dust of different mesh sizes. The column studies were conducted with
a fixed column of diameter 7cms and a bed height of 50cms. The flow rate of solution passing through the adsorbent bed was maintained at a fixed value of 1litre/min. It was found that the metal uptake capacity (amount of removal) of Chromium (VI) ion decreased but the adsorption
capacity (percentage of removal) increased with the decrease in the concentration of chromium (VI) in the initial sample solution. It was also observed that the order of metal uptake capacity & adsorption capacity of saw dust of different ISS mesh size for removal of Chromium (VI) removal was as follows: (-30 +10) > (-50 +30) > (-70 +50) .
36
Mondal, T. K. "Phase Equilibrium Modeling in Gas Purification System." Thesis, 2009. http://ethesis.nitrkl.ac.in/1517/1/Mtech-thesis-Tarun.pdf.
Full textAbstract:
A thermodynamic model based on activity is proposed to correlate and predict the vapour-liquid equilibria of the aforesaid systems. The activity based models render an insight in to the molecular physics of the system; hence accurate speciation of the equilibriated liquid phase becomes a reality besides its prediction ability of solubility of the acid gases over alkanolamine solutions. The activity based model has been developed using extended Debye-Hückel theory of electrolytic solution with short range, non-electrostatic interactions. The vapor phase non-ideality has been taken care of in terms of fugacity coefficient calculated using Virial Equation of State. The equilibrium constants are taken from literature as functions of temperature only. The neutral and ionic species present in the equilibrated liquid phase have been estimated with zero interaction model and incorporated here. The interaction parameters in the activity models are estimated by minimizing the objective function, which is the summation of relative deviation between the experimental and model predicted CO2 partial pressures over a wide range.
The parameter estimation for the phase equilibrium models have been formulated here as a multivariable optimization (minimization) problem with variable bounds. The MATLAB 7.6 optimization toolbox has been used extensively for the present work. ‘fmincon’ function, which is a constrained optimization function uses quasi-Newton and Sequential Quadratic Programming (SQP) methods, has been used here for minimization of the proposed objective functions with variable bounds for both approximate and rigorous modeling. There remains a necessity of refinement of the developed rigorous thermodynamic model in terms of the accurate speciation, i.e., exact determination of the species concentration in the equilibrated liquid phase and use of better optimization algorithm, may be non-traditional one, which will ensure global minima.
37
Patel, Sourav. "Preparation and characterization of porous adsorbent for chromium(VI) removal." Thesis, 2010. http://ethesis.nitrkl.ac.in/1772/1/(10600030)cr_removal_2.pdf.
Full textAbstract:
Chromium (VI) compounds are widely used in industry such as electroplating, meal finishing, leather tanning, pigments, etc. In recent years ground water is the main source of domestic water supply. Chromate poisoning cause severe skin disorders allergic dermatitis, liver and kidney damage. Thus chromium causes great public concern. A wide range of separation process has been investigated for the removal of Chromium (VI) from water. Adsorption using activated carbons posed to be the efficient method for removal of Chromium ions from water.
To use carbon as an adsorbent requires activation or surface modification of carbon. Methods like thermal and chemical methods of activation are common, but some problems are associated with them. Electrochemical method as one of the method of surface modification of commercially available activated carbon can be applied. The result is better adsorption of Chromium (VI) ions. The present thesis includes various adsorption techniques. A literature review of adsorption characteristics has been included. Our project work include fabrication of an experimental setup, surface modification (oxidation at anode) in 0.5 M KCl solution at various intensity of currents, and latter comparisons of BET surface area, porosity, FTIR analysis ( for identification of changes in bonds after electrochemical oxidation) and adsorption in spectrophotometer.
Surface area, pore volume and pore size all decrease with increase in current intensity. A significant loss in porosity and decrease in pore diameter were observed and is due to blockage of pores by formation of functional groups (carboxylic acidic groups, hydroxyl groups, lactonic grops, phenolic group) and aggregation of humic substances. As the intensity of oxidation is increased by increasing the intensity of source current the amount of adsorption also increases. Also it is observed that if the intensity of current is increased from 0.1 Amp to 2.1 Amp, the amount of adsorption increases. But as the current approaches to 2.1 Amp the adsorption amount doesn’t change significantly. Sample oxidized at 2.1 ampere was analyzed in FTIR. In the FTIR spectra it is revealed that in some ranges dip in transmittance was observed. Suitable reasons were found out. This process of activation can be suitably applied for activation of carbon.
38
Agarwal, Vinay Kumar. "Stability Study of Important Metal Organic Frameworks (MOFs) and a Review on their Gas Adsorption Properties." Thesis, 2012. http://ethesis.nitrkl.ac.in/3167/1/eThesis_Vinay_Agarwal_108CH008.pdf.
Full textAbstract:
Metal Organic Frameworks (or, MOFs) have shown tremendous potential in adsorptive separation applications and gas storage owing to some of their extraordinary features in terms of specific surface area, pore volume, low to moderate heat of adsorption and fairly uniform pore size distribution. But, the success or failure of any adsorbent material largely depends on their stability in varying experimental conditions. In this work, we have highlighted the synthesis of 3 most versatile MOFs reported till date viz. Cu-BTC (or, HKUST-1), Cr-BDC (or, MIL-101) and Zn-BDC (or, MOF-5). Each of these MOFs after their successful synthesis and characterization were exposed to a regulated environmental conditionto study the effect of moisture sensitivity. Such a study is particularly important since any real time experiment with MOF is bound to come to terms with varying degree of moisture or water vapor, especially when exposed for longer duration. After detailed experimentation we concluded that a controlled exposure to ambient conditions didn’t have a severe effect on MOF’s thermal stability. Cr-BDC was found to be taking up more moisture during the course of time as compared to Cu-BTC and Zn-BDC. The degree of crystallinity appeared to be reduced over the time interval and surface morphology too gets affected.
Moreover, we have carried out a comprehensive review of 3 very important industrially and environmentally important gases viz. H2, CO and CO2 on these three MOF matrices. The reason behind choosing theses gases stems out from the fact that H2 is projected as a future fuel which may very well replace the conventional fossil fuels, both CO2 and CO are the most important green house gases and their emission needs to be effectivelyarrested, mixture of these gases are emitted from various sources e.g. steam reforming of naphtha, partial oxidation of hydrocarbons, metallurgical plants etc. Apart from these facts, physical properties of each of them are quite different. H2 is a non-polar gas whereas CO has a permanent dipole moment and CO2 has a quadrupole moment. Studying the effects of these physical properties could be interesting from a fundamental point of view to understand the adsorption phenomenon. The retrieved experimental data from literature was model fit using standard isotherm models viz. Langmuir, Freundlich, Freundlich-Langmuir, Dual Site Langmuir (DSL) and Virial models. Additionally, a comparative study between simulation data (available in literature) and experimental data (at same conditions)was carried out for a proper validation. CO was selected on the basis of its polarity and CH4 was chosen since it is non-polar. The adsorbent for the study was Cu-BTC.
Our findings are summarized as:
(I) All the isotherm models are not equally efficient in predicting the adsorption behavior in low and high pressure regime. Freundlich-Langmuir model is seen to be the best in explaining the adsorption behavior irrespective of the type of probe or adsorbent surface.
(II) The experimental H2 adsorption data as reported by various researchers varied considerably from lab to lab and H2 adsorption on none of the adsorbents studied in this work satisfies the Department of Energy (DoE) target of 6.5 wt%.
(III) Cr-BDC (or, MIL-101) showed the highest affinity for CO2. This uptake of CO2 is the highest reported till date.
(IV) Although experimental data on CO adsorption on any MOF material is scarce, but still within our review, we have found Cr-BDC to have the highest loading of CO. The higher loading can be attributed to very high surface area (ca. 3000 m2 g-1) for Cr-BDC amongst the studied MOFs.
(V) The comparison of simulation with experimental data of CO and CH4 on Cu-BTC has shown that for polar molecule e.g. CO, simulation data under predicts the experimental data whereas in the higher loading region simulation data over predicts. This is less marked for non-polar gas like CH4. It is worth mentioning that even though there are variations in simulation result predictions with experimental data but still Grand Canonical Monte Carlo (GCMC) simulation is a strong method in predicting experimental excess adsorption data particularly when total pore volume information and single crystal XRD data is available.
39
Garg, Deepak. "Adsorptive removal of dyes from aqueous solution using Cu-BTC and Commercial Activated Carbon." Thesis, 2012. http://ethesis.nitrkl.ac.in/3168/1/eThesis_Deepak_Garg_(108CH010).pdf.
Full textAbstract:
This thesis is dedicated to the liquid phase adsorption of dyes, namely Rhodamine B and Erioglaucine, where they represent the class of a basic and an acid dye respectively. The adsorbents used are Metal Organic Framework (Cu-BTC) and Activated Carbon. The characterization was done for each of the adsorbent. On the one hand, the experimental data did not envisage Cu-BTC as an effective adsorbent for liquid phase adsorption while on the other hand, Activated Carbon showed some encouraging results on the batch experiments conducted on various parameters like effects of adsorbent dose, initial pH and contact time.
40
Ranjan, Debesh Kumar. "Preparation of Ceramic Membranes for Effluent Treatment." Thesis, 2013. http://ethesis.nitrkl.ac.in/5373/1/109CH0542.pdf.
Full textAbstract:
This work highlights the fabrication of ceramic microfiltration membranes using drill mud as the raw material. The raw material was pre-processed and paste casting method was used for fabrication. Three different membranes were successfully fabricated (keeping a standard stoichiometric composition of raw materials and binders) at three different sintering temperatures e.g. 500, 800 and 900oC. Comprehensive characterization techniques viz. scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), BET surface area and Mercury porosimetry were followed to ascertain the nature of the membrane fabrication. The membrane sintered at 900oC, having an average pore size of 18ìm was found best suited for oil-water emulsion studies. A rejection of ca. 38% was observed for this membrane. Another variant of ceramic membrane was fabricated at 900oC with an addition of 25% kaolin. A better rejection of ca. 49% was found for this case which can be attributed to better structural properties of the membrane surface and uniformity in pore size distribution. All the membranes were studied for their regeneration and reusability. A detailed cost analysis was also performed and it was seen that the membranes fabricated were much cheaper than the similar products reported in literature.
41
Selsa, H. "Screening of solvents for carbon dioxide absorption in ionic liquids using cosmotherm." Thesis, 2014. http://ethesis.nitrkl.ac.in/5991/1/E-158.pdf.
Full textAbstract:
Recently room temperature ionic liquids (ILs); called green solvents are emerging as promising candidates to capture due to their wide liquid range, low melting point, negligible vapor pressure, high solubility and reasonable thermal stability. However, these solvents, suffer from a major disadvantage of high viscosities in their unreacted state, which makes them very difficult to handle and transport in an industrial scenario. To make up for this, combining RTILs with conventional solvents like alkanolamines have been proposed.Again, owing to the huge number of possible combinations between cations and anions and blends of the resulted ILS/RTILs with alkanolamines, a solvent screening procedure became essential in narrowing down the solvents/blended solvents with the desired properties. In view of this, various thermophysical and physicochemical properties intended for CO2 absorption were predicted for the ionic liquids as well as their alkanolamine blends using the computational chemistry software “cosmotherm”.Various properties like density, heat capacities, viscosities, conductivity, melting point etc were studied by changing the substituent cation or anion of ILS/RTILs and their combinations with alkanolamines as well.On comparison of the predicted properties, it has been noticed that the anions TF2N and PF6 exhibits the most desirable properties in combination with the solvents MEA, DEA and PE.The screened solvents in this study might be proving their worth on experimental verification.
42
Verma, T. "Reactive extraction of acetic acid." Thesis, 2014. http://ethesis.nitrkl.ac.in/6068/1/E-191.pdf.
Full textAbstract:
Acetic acid is an important carboxylic acid widely used in chemical, pharmaceutical, food and other industries. The growing importance of biological production (fermentation) expressed with new routes and increasing production rates, leads to look for technologies of downstream processing for product separation. The reactive extraction can be used for the recovery of an acetic acid from aqueous solution.The reactive extraction with specific extractant and a proper combination of extractant and diluents provides the higher capacity and selectivity of an acetic acid. The recovery of acetic acid by reactive extraction is studied using an organic solvent such as toluene, petroleum ether and n-hexane. The feed concentration of acetic acid in the aqueous solution ranges in between 0.1 to 0.4 gmol/l. The extraction of acetic acid from aqueous solution (feed concentration 0.4 gmol/lit) with organic solvent gives the distribution coefficient (KD) in toluene, petroleum ether and N-Hexane solvents equal to 1.29, 0.79 and 0.6 respectively. Further, the reactive extraction is carried out with the mixtures of extractant–diluents. The tri-iso-octylamine is used as an extractant. The extraction of acetic acid with 40% of tri-iso-octylamine in an organic solvent shows the highest distribution coefficient for toluene, petroleum ether and n-hexane. These are 3.65, 2.70 and 2.63 respectively. By comparing results, it can be concluded that using the mixtures of extractant–diluents, the extraction is significantly improved.
43
Kumar, Balasa Satis. "Fabrication and characterization of kaolin based membrane for catalyst recovery." Thesis, 2014. http://ethesis.nitrkl.ac.in/6432/1/212CH1346-6.pdf.
Full textAbstract:
In this project work, Kaolin was the primary raw material for membrane fabrication. Various additives/binders were also used based on their suitability and effectiveness in imparting special properties e.g. mechanical strength and dispersion properties for homogeneity to the final or finished membrane. During membrane preparation with various stoichiometric compositions of ingredients, it was observed that higher percentages of kaolin didn’t result into membranes with good flexural strength whereas increasing the % of red-mud enhanced the mechanical strength quite considerably e.g. 10.11 MPa (membrane F), 18.93 MPa (membrane G) and 12.04 MPa (membrane H) respectively. Methanol permeation studies showed that the average steady state flux was highest for membrane G (ca. 4.23×10-4 m3 m-2 sec-1). The fabricated membranes were undergone catalyst recovery study in a batch membrane module. In this work, Cu-BTC (or, HKUST-1 or, MOF-199), a well-known Metal Organic Framework (MOF) was selected as the potential catalyst. Several cycles (or batches) were carried out inside the membrane module and it was observed that membrane G performed better than the rest and a recovery percentage of ca. 61% was noted after 3 cycles before the membrane pores were completely choked. Membrane de-fouling and regeneration studies were carried out in detail using back-washing treatment inside the module itself and ultra-sonication techniques for preparing the membranes for next round of operations.
44
Palai, Ashis. "Analysis of Essential Oil Content Obtained from Plant Materials Using Steam Distillation." Thesis, 2015. http://ethesis.nitrkl.ac.in/6793/1/2015_BT_Ashis_111CH0081.pdf.
Full textAbstract:
An expansive number of materials contain Essential Oils with broad bioactvities. Recognizing the significance of plant and its restorative quality, Essential Oil was extracted utilizing Steam Distillation technique. In this venture Steam Distillation was utilized to concentrate oil from distinctive plant materials like eucalyptus leaf, curry leaf, hibiscus leaf, marigold blossoms, rose blooms, orange peels and so forth. Examination has affirmed hundreds of years of down to earth utilization of vital oils, and we now realize that the 'fragrant drug store' contain mixes with an amazingly expansive scope of biochemical effects. Fundamental oils are accepted to speak to the very substance of odour and flavour. The recuperation of Essential Oil from the crude organic beginning material is essential since the nature of the oil is enormously impacted amid this step. There is a mixed bag of strategies for acquiring unstable oil from plant. Steam distillation technique was discovered for systems of the extraction of key oil from plants as legitimate distiller will protect the first characteristics of the plant. The distillation was led in Clevenger apparatus where bubbling, gathering and decantation was finished. Examination of Essential oil had been done utilizing Gas Chromatography-Mass Spectrometer, which gives evaluates Essential Oil subjectively and quantetatively. Volume of Oil acquired had been changed with respect to temperature and heating
45
Raman, R. Shashank V. "Preparation and Characterization of Activated Carbon from Waste Food Packaging Polymers." Thesis, 2015. http://ethesis.nitrkl.ac.in/6865/1/PREPARATION_Raman_2015.pdf.
Full textAbstract:
The two of the major challenges which we are facing in the modern era are the management of the waste plastics and the waste water from the industries. Water pollution is one of the major challenges faced by the environmental engineers today due to toxic metal releases from various industries. Among various technologies, adsorptive removal of these toxins by the usage of activated carbon as the adsorbent is more promising and economical as it is known for its high adsorption capacity. The preparation of activated carbon from waste food packaging polymers, which is about 35% of the total plastic waste accumulated, would not only reduce the voluminous quantities of plastic but also help in water treatment. A relatively new technique, Hydrothermal Carbonization (HTC), was used for the carbonization of the raw material instead of the traditional carbonization process. A pressure vessel was fabricated for HTC and the temperature set at 235 degrees celcius and the holding time was 15 hours. After processing the „hydrochar? with benzene to remove ash, dirt and iron rust (if there) it was activated with 1 M KOH for a period of 10 hours and subsequent drying for 5 days under the temperature 70 degrees celsius. Proximate analysis, Field Emission Scanning Electron Microscope (FESEM), Iodine Number, Fourier Transform Infrared Spectroscopy (FTIR), and Methylene Blue Number were the characterization techniques implemented. It was observed that the methylene blue number was high indicating the presence of high percentage of mesopores content.
46
Mallick, Sabyasachi. "Reactive Extraction of Butyric Acid Using Tri-Octyl Amine in Decanol." Thesis, 2015. http://ethesis.nitrkl.ac.in/6940/1/Reactive_Mallick_2015.pdf.
Full textAbstract:
The application of reactive extraction for the separation of butyric acid from its aqueous solution is a relatively new technique. It has many uses in different industries, and currently there is a great interest in using it as a precursor to biofuels. Research works are available on equilibrium study of the reactive extraction of butyric acid where aliquat-336 and tri-butyl phosphate were used as the reactive extractant. But no one has used TOA as the extractant, and nowhere study on the kinetic behaviour of reactive extraction of butyric acid has been done. Also the detailed study on the effect of temperature on the Butyric acid-TOA- Decanol system is unavailable. The present research work has focused on the reactive extraction of butyric acid from its aqueous solution using Tri-Octyl-Amine (TOA) in the active diluent decanol. Equilibrium and kinetic studies was performed at very low concentrations of butyric acid in water viz. 0.05M to 0.3M at 250C, 300C, 350C and 400C. The effect of temperature on the extraction equilibrium and kinetics was considered. In the equilibrium study, the complexation constant (KE(1:1) ) was evaluated and the type of complex formed was also determined. The distribution coefficient (KD) and extraction efficiency (E%), were determined. In the kinetic study, the order of the reaction (n), the rate constant (k) and the mass transfer coefficient (KL) were found from the experimental data. Extraction efficiency (E%) of 98% and distribution coefficient (KD) of 49 has been achieved at 400C. The order of the reaction (n) has been found to be 1. The mass transfer coefficient (KL) has been found to be 10.77×10-3 cm/min.
47
Biswas, Snehasis. "Separation of Chromium (VI) By Bulk Liquid Membrane Technique." Thesis, 2015. http://ethesis.nitrkl.ac.in/7033/1/Separation_Biswas_2015.pdf.
Full textAbstract:
In this work an attempt has been made for faster extraction and separation of Cr (VI) from its model solution with minimal use of carrier. Studying the effects of various process parameters viz. source and stripping phase concentration and pH on the overall performance of this bulk liquid membrane technique have been a key objective along with the membrane reusability. Aqueous solution of potassium dichromate (K2Cr2O7) was used as the source phase or model contaminant for Cr (VI) ions. 1, 2-dichloroethane was the preferred solvent used as the liquid membrane phase in this work. Aqueous solution of NaOH was found to be the effective stripping phase. Performances of several carriers had been investigated and tri-n-octylamine (TOA) was found to be the most suitable in facilitating the transport mechanism. A comprehensive kinetic study was carried out and the effect of various parameters viz. carrier concentration, feed and stripping phase concentrations and pH were studied. A key objective of this work was to achieve maximum separation of Cr (VI) with minimal carrier concentration and this work successfully reports a removal percentage of ca. 98% of Cr (VI) ions with 0.25 vol. % of TOA within a span of 2 hrs. The transport mechanism was observed to be more effective in the acidic pH range w.r.t the feed phase (ca. pH 1) whereas the optimum stripping phase concentration of NaOH was 0.3 N. Membrane reproducibility study showed that the performance of the liquid membrane remained largely unaffected even after fourfold use.
48
Das, Chitra. "Liquid-Liquid Equilibrium Studies on Extraction of Commercially Significant Carboxylic Acids." Thesis, 2015. http://ethesis.nitrkl.ac.in/7990/1/2015_Liquid_Das.pdf.
Full textAbstract:
Carboxylic acids are commercially very important organic acids and their extraction from fermentation broth can be one of the sources of recycling back these important organic acids.Here, we have worked on two systems: experimental tie-line results and solubility (binodal) curves were obtained for the ternary systems of water + acetic acid + hexanol and water + caproic acid + methyl isobutyl ketone at temperature of 308K and at atmospheric pressure. The concentrations of the components in the equilibrium phases were measured using gas chromatography for hexanol and methyl isobutyl ketone and acid concentration in each phase was determined by titration against NaOH solution. The water concentration was determined using mass balance. Using the equilibrium tie line phase compositions graph was plotted for the ternary systems. Solubility or binodal curves were obtained by joining these tie line phase compositions. The two phase and the one phase region were then determined for the ternary systems. Distribution coefficients and separation factors were calculated for the ternary systems to determine whether the solvents used were suitable for extraction of those specific organic acids from their aqueous phases.
49
Negi, Deepika. "Reactive Extraction of Butyric Acid using Tri-Octyl Amine in Decanol." Thesis, 2016. http://ethesis.nitrkl.ac.in/8561/1/2016_MT_214CH1102_Deepika_Negi.pdf.
Full textAbstract:
Reactive extraction is a separation technique using the reaction between extractant and the material to be extracted. The extractant present in the organic phase reacts with the material present in the aqueous phase and the reaction complexes thus formed are solubilized in the organic phase. The application of reactive extraction for separating Butyric Acid (BA) from its aqueous solution is a new technique. Butyric acid (BA, CH3CH2CH2CO2H) also known as butanoic acid, abbreviated as BTA, is a short chain carboxylic acid. It has many important applications in various industries. It can be used as an energy source by converting into butanol by biological conversions. It is anti carcinogenic, as it induces morphological and biochemical differentiation in a range of cells, which leads to concomitant suppression of neoplastic properties and presently it is being used as a precursor to biofuels. It is a promising chemical as it has the potential for future energy needs by converting into butanol through biological transformation. Study of effect of pH on reactive extraction process is essential because pH varies as the process of reactive extraction proceeds. Normally pH of solution containing acid is below pKa values of the respective acid but as the extraction proceeds, due the removal of the acid, pH approaches near 7.0. Thus for reactive extraction process an extractant-diluent combination is required which could recover the acid efficiently at all pHs . Fermentation process usually operates in the temperature range of 305 to 313 K. Thus an extractant is effective only if it operates efficiently in this temperature range. In addition to this, the climate variation, feed and bioreactor conditions makes the study of temperature effect even more important.
50
Kella, Tatinaidu. "Synthesis of Zeolite-X from Coal Fly Ash and Its Application in Removal of Methylene Blue Dye." Thesis, 2016. http://ethesis.nitrkl.ac.in/9277/1/2016_MT_TKella.pdf.
Full textAbstract:
Fly ash is an industrial by product which is generated by combustion of coal. During the combustion minerals partially melt to form fly ash particles which is heavy burden on the land because of dumping. The present concern over fly ash is to convert value added products such as zeolite type of materials on proper treatment. Fly ash is having silica, alumina in core and glass phase is on the surface which is more soluble in the alkaline phase to form aluminosilicate gel, so that fly ash having the potential to form zeolite type of material. In the present study, synthesized zeolite X type of material from coal based fly ash. Synthesized zeolite X was characterized by various techniques such as X-ray diffraction (XRD) analyzer, scanning electron microscope (SEM) and BET analysis. Surface area of the zeolite, pore volume, pore radius of the synthesized zeolite was measured and it has been found that synthesized zeolite having mesoporous pores. The synthesized zeolite using as adsorbent in the removal of methylene blue dye from the aqueous solution. The wastewater containing dyes, generated by the textile, printing and papermaking industries, pose major hazard to the environment and the public health. The influences of five dominant parameters of pH, temperature, time, initial dyes concentration, and adsorbent mass on dyes adsorption were investigated for synthesized zeolite X (from fly ash), Commercial zeolite (13X) and Raw fly ash. The percentage of dye removal was mathematically described as a function of experimental parameters and was modeled through central composite design (CCD). According to the predicted experiments, optimum conditions of 10, 32.7°C, 47.87 min, 50 ppm, and 0.25 g, for pH, temperature, time, initial dyes concentration, and adsorbent mass were resulted, respectively for synthesized zeolite X as adsorbent and the maximum dye removal percentage obtained 82. Optimum conditions of 10, 27.08 °C, 54.13 min, 50 ppm, and 0.66 g, for pH, temperature, time, initial dyes concentration, and adsorbent mass were resulted for raw fly ash as adsorbent and the maximum dye removal percentage obtained 42.66. Optimum conditions of 10, 46.96 °C, 32.61 min, 50 ppm, and 0.25 g, for pH, temperature, time, initial dyes concentration, and adsorbent mass were resulted for commercial zeolite (13X) as adsorbent and the maximum dye removal percentage obtained 64.02. Among these three adsorbents, synthesized zeolite gave the maximum percentage of dye removal.