Добірка наукової літератури з теми "Doped activated carbon"

Nowadays one of the biggest challenges for carbon materials is their use in CO2 capture and their use as electrocatalysts in the oxygen reduction reaction (ORR). In both cases, it is necessary to dope the carbon with nitrogen species. Conventional methods to prepare nitrogen doped carbons such as melamine carbonization or NH3 treatment generate nitrogen doped carbons with insufficient nitrogen content. In the present research, a series of activated carbons derived from MOFs (ZIF-8, ZIF-67) are presented. Activated carbons have been prepared in a single step, by pyrolysis of the MOF in an inert atmosphere, between 600 and 1000 °C. The carbons have a nitrogen content up to 20 at.% and a surface area up to 1000 m2/g. The presence of this nitrogen as pyridine or pyrrolic groups, and as quaternary nitrogen are responsible for the great adsorption capacity of CO2, especially the first two. The presence of Zn and Co generates very different carbonaceous structures. Zn generates a greater porosity development, which makes the doped carbons ideal for CO2 capture. Co generates more graphitized doped carbons, which make them suitable for their use in electrochemistry.

The goal of this research was to synthesize activated nitrogen-doped nanocarbons with high specific surface area and adjustable pore size distribution using wood charcoal as a raw material. The resulting carbon materials were tested for possible application as oxygen reduction reaction catalysts in alkaline media. Activated carbons were obtained using a thermochemical activation method with NaOH. Nitrogen was introduced into activated carbons using dicyandiamide solution. It was demonstrated that the content of introduced nitrogen depends on oxygen content in the structure of the activated carbon. The oxygen reduction reaction activity of the activated and nitrogen-doped carbon material was comparable with a commercial 20% Pt/C catalyst. Electrocatalytic properties of the synthesized N-doped wood-derived carbon catalysts may be associated with the highly developed surface area, specific ratio of micro- and mesopores, as well as the high percentage of pyridinic nitrogen.

Nitrogen-dopped activated carbon was synthesized to see its effect on the characterization of the nitrogen surface functional groups, crystal size, and morphology of the resulting sample. Synthesis of nitrogen-doped activated carbon was carried out by varying the addition of Urea as a nitrogen doping source. Activated carbon compared its characteristics with variations in the concentration of added Urea to activated carbon, at 1:3 and 1:5. The FTIR results obtained were the presence of functional groups indicating the presence of nitrogen bonds in each sample. The crystallinity results showed that the samples were classified as crystalline and nitrogen doping influenced the size of the crystallinity of each sample. The morphology of nitrogen-doped activated carbon shows differences in the grain size of nitrogen-doped activated carbon. Crystallinity and morphology have been shown to affect battery anode performance. The more crystalline of anode material, the electrochemical properties are better. The smaller the grain size of the sample morphology, the stability of the battery cycle is to be great.

Nitrogen-doped activated carbon/reduced graphene oxide composites are prepared by pre-carbonization of the precursors (mixture of graphene oxide and nitrogen-doped activated carbons) and KOH activation of the pyrolysis products.

Carbon compounds with large surface area can be used as electrocatalytic cathodes for fuel cells. Nitrogen atoms largely determine the properties of doped activated carbon, such as hardness, wear resistance, electrical resistance etc., and therefore there is a need for new scientific information on the properties and structure of modified carbon matrix. Wood char and activated carbons based on wood char, cellulose, black liquor, and fine cellulose sludge were obtained in different activation conditions and doped with dicyandiamide. The obtained N-doped carbon materials porous structures were compared taking into account preparation conditions and raw material.

Its relatively low cost and high surface area makes activated carbon an ideal adsorbent candidate for H2S removal. However, physical adsorption of H2S is not very effective; therefore, methods to facilitate reactive H2S oxidation on carbons are of interest. The performance of H2S removal of non-impregnated, impregnated, and doped activated carbon in low-temperature syngas was evaluated in fixed-bed breakthrough tests. The importance of oxygen content and relative humidity was established for reactive H2S removal. Impregnates especially improved the adsorption rate compared to non-impregnated carbons. Non-impregnated carbons could however retain a high capture capacity with sufficient contact time. In a relative performance test, the best performance was achieved by doped activated carbon, 320 mg g−1. Ammonia in syngas was found to significantly improve the adsorption rate of non-impregnated activated carbon. A small quantity of ammonia was consumed by the carbon bed, suggesting that ammonia is a reactant. Finally, to validate ammonia-enhanced desulfurization, bench-scale experiments were performed in biomass-based gasification syngas. The results show that when the ammonia concentration in syngas was in the tens of ppm range, 40–160 ppm H2S oxidation proceeded rapidly. Ammonia-enhanced oxidation allows utilization of cheaper non-impregnated activated carbons by in situ improvement of the adsorption kinetics. Ammonia enhancement is therefore established as a viable method for achieving high-capacity H2S removal with unmodified activated carbons.

In this paper, we present the results of the gamma irradiation method to obtain N-doped mesoporous activated carbons. Nitrogen-enriched mesoporous carbons were prepared from three chosen commercial activated carbons such as Carbon Black OMCARB C-140, KETJENBLACK EC-600JD and PK 1-3 Norit. HRTEM, SEM, Raman spectra, elemental analysis, XPS studies and widely approved N2 adsorption–desorption measurements allowed us to evaluate the effectiveness of N atom insertion and its influence on the BET surface area and the pore structure of modified carbons. The obtained materials have an exceptionally high N content of up to 3.2 wt.%. Additionally, selected N-doped activated carbons were fully characterized to evaluate their applicability as carbon electrode materials with particular emphasis on Oxygen Reduction Reaction (ORR). The proposed method is a relatively facile, efficient and universal option that can be added to the already known methods of introducing heteroatoms to different carbons.

The aim of this study was to determine the adsorption performance of a petroleum pitch-based activated carbon (PPAC1:3) before and after a post-treatment with H2S. In the first step, a microporous activated carbon (PPAC1:3) with a highly developed porous structure was produced through a chemical activation route with KOH. Afterward, the synthesized activated carbon was thermally treated yielding two different series of functionalized activated carbons: (i) a series of carbons were treated directly with H2S at elevated temperatures (600 °C and 800 °C), and (ii) a series of carbons were generated by combining an oxidation treatment with plasma followed by H2S treatment at elevated temperatures (600 °C and 800 °C). The chemical and structural characteristics of the S-doped and S-/O-co-doped porous carbons were investigated by means of different experimental techniques, such as XRD, RAMAN, FESEM, XPS, TPD, N2, and CO2 adsorption, and finally tested in CO2 and CH4 adsorption at atmospheric and high pressure. The functionalized porous carbons possessed specific surface areas of 2420–2690 m2/g, total pore volume of 1.05–1.18 cm3/g, and sulfur content up to 2.55 atom % (the sulfur content of the original carbon was 0.19%). After a careful analysis of the carbon dioxide and methane uptake at atmospheric (0.1 MPa) and high pressure (4 MPa), adsorption results confirm that the microporous structure is the main structural parameter defining the adsorption performance and, to a lower extent, the surface chemistry. Overall, a significant improvement in the total uptake can be appreciated after the H2S treatment.

Porous carbon electrode materials are utilized in supercapacitors with very fast charge/discharge and high stability upon cycling thanks to their electrostatic charge storage mechanism. Further enhancement of the performance of such materials can be achieved by doping them with heteroatoms which alter the kinetics of charge/discharge of the adsorbed species and result in pseudocapacitance phenomena. Here, microporous N-doped activated carbons were synthesized by thermochemical activation process. The structure and composition of the final material were adjusted by tuning the synthesis conditions and the choice of precursor molecules. In particular, N-doped activated carbons with a controlled specific surface area in the range of 270–1380 m2/g have been prepared by KOH-activation of sucrose/ammonium citrate mixture. By adjusting the composition of precursors, N-doping was varied from ca. 1.5 to 7.3 at%. The role of the components and synthesis conditions on the composition and structure of final products has been evaluated. The N-doped activated carbon with optimized structure and composition has demonstrated an outstanding performance as electrode material for aqueous electrolyte supercapacitors. The specific capacitance measured in a 3-electrode cell with 0.75 mg/cm2 loading of optimized activated carbon in 1M H2SO4 changed from 359 F/g at 0.5 A/g charging rate to 243 F/g at 20 A/g. Less than 0.01% of capacitance loss has been detected after 1000 charging/discharging cycles.

Homogenous spherical nanoporous carbon beads (NCB) were made from pure polymeric precursors and successfully synthesised under varying conditions to improve the adsorption kinetics of gold onto the surface. The aim of this project was to optimize the surface structure and chemistry of NCB for the sequestration of gold. The nanopore structure and surface chemistry of the NCB were tailored through the presence of sulphur-doped heteroatoms, impregnation with toluene solution containing a ferrocene/melamine mixture and the variation of activation time. The carbon samples were examined using low temperature nitrogen adsorption, scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). The experimental results from this work have shown that the synthesised NCB exhibit a homogenous, sponge-like surface and improved adsorption kinetics through increased adsorbance speed in comparison to the benchmark industrial carbon. The NCB samples have narrow pores with a diameter of <~2 nm which are distributed between a size fraction of micro and mesopores. Sample MU-4 developed the greatest surface area (1971 m2/g), pore volume (1.113 cm3/g) and kinetic rate constant 0.077 min-1.

Photocatalysis is an advanced oxidation process for the purification and remediation of contaminated waters and wastewaters, and is advantageous over conventional treatment technologies due to its ability to degrade emerging and recalcitrant pollutants. In addition, photocatalytic disinfection is less chemical-intensive than other methods such as chlorination, and can inactivate even highly resistant microorganisms with good efficacy. Process sustainability and cost-effectiveness may be improved by utilizing solar irradiation as the source of necessary photons for photocatalyst excitation. However, solar-induced activity of the traditionally-used titania is poor due to its inefficient visible light absorption, and recombination of photo-excited species is problematic. Additionally, mass transfer limitations and difficulties separating the catalyst from the post-treatment slurry hinder conversions and efficiencies obtainable in practice. In this research, various strategies were explored to address these issues using novel visible light active photocatalysts. Two classes of carbon-enhanced photocatalytic materials were studied: activated carbon adsorbent photocatalyst composites, and carbon-doped TiO2. Adsorbent photocatalyst composites based on activated carbon and plasmonic silver/silver chloride structures were synthesized, characterized, and experimentally investigated for their photocatalytic activity towards the degradation of model organic pollutants (methyl orange dye, phenol) and the inactivation of a model microorganism (Escherichia coli K-12) under visible light. The adsorptive behaviour of the composites towards methyl orange dye was also studied and described according to appropriate models. Photocatalytic bacterial inactivation induced by the prepared composites was investigated, and the inactivation mechanisms and roles of incorporated antimicrobial silver on disinfection were probed and discussed. These composites were extended towards magnetic removal strategies for post-use separation through the incorporation of magnetic nanoparticles to prepare Ag/AgCl-magnetic activated carbon composites, and the effect of nanoparticles addition on the properties and photoactivities of the resulting materials was explored. Another silver/silver halide adsorbent photocatalyst composite based on activated carbon and Ag/AgBr exhibiting visible light absorption due to both localized surface plasmon resonance and optical band gap absorption was synthesized and its photocatalytic activity towards organics degradation and microbial inactivation was studied. Carbon-doped mixed-phase titania was also prepared and experimentally investigated.

Cette thèse développe quatre modèles pour simuler le procédé d’adsorption de l’ammoniac sur du charbon actif dopé au sulfate de zinc. Ils sont décrits par des équations de bilans de matière, de la thermodynamique, de l’hydrodynamique et de la cinétique d’adsorption. Puisqu’il est nécessaire de connaitre les valeurs de certains paramètres pour simuler les modèles, le charbon actif est d’abord caractérisé. Des mesures expérimentales des isothermes d’adsorption de l’ammoniac sur le charbon actif dopé ont d’abord été réalisées. Une méthode basée sur l’analyse de sensibilité des paramètres a ensuite été utilisée pour évaluer l’estimabilité des paramètres inconnus impliqués dans l’équation de l’isotherme d’adsorption de Sips et de Toth. Les paramètres estimables ont ensuite été identités en utilisant des données expérimentales trois températures différentes 288, 303 et 313K. Cette thèse développe quatre modèles pour simuler le procédé d'adsorption de l'ammoniac sur du charbon actif dopé au sulfate de zinc. Ils sont décrits par des équations de bilans de matière, de la thermodynamique, de l'hydrodynamique et de la cinétique d'adsorption. Puisqu'il est nécessaire de connaître les valeurs de certains paramètres pour simuler les modèles, le charbon actif est d'abord caractérisé. Des mesures expérimentales des isothermes d'adsorption de l'ammoniac sur le charbon actif dopé ont d'abord été réalisées. Une méthode basée sur l'analyse de sensibilité des paramètres a ensuite été utilisée pour évaluer l'estimabilité des paramètres inconnus impliqués dans l'équation de l'isotherme d'adsorption de Sips et de Toth. Les paramètres estimables ont ensuite été identifiés en utilisant des données expérimentales à trois températures différentes 288, 303 et 313 K. Des fronts de percée expérimentaux à différentes concentrations d'ammoniac et à différents débits de gaz ont ensuite été mesurés et utilisés pour déterminer le coefficient de transfert de matière global (kLDF), le coefficient de dispersion axiale (Dax), le coefficient de diffusion effectif (De) et le coefficient de diffusion intracristalline (Dµ) mis en jeu dans les équations du modèle, implémentées et résolues dans le logiciel Comsol Multiphysics®. Il a été démontré que les étapes limitantes du procédé d'adsorption sont la diffusion et l'adsorption de l'ammoniac sur le cristal de sulfate de zinc. Les modèles ont ensuite été validés en utilisant quatre fronts de percée supplémentaires différents de ceux utilisés pour identifier les paramètres. Les prédictions du modèle et les mesures expérimentales montrent un bon accord, quantifié par les indices de performance et validés par le test d'hypothèse de Kolmogorov-Smirnov. Enfin, la simulation CFD de l'écoulement gazeux dans un caisson de purification d'air a été réalisée en développant un modèle dynamique qui prend en compte la géométrie et l'hydrodynamique. Les modèles développés ont permis de mieux comprendre les phénomènes d'adsorption et peuvent être utilisés comme un outil prédictif pour la conception et le fonctionnement optimal du procédé d'adsorption de l'ammoniac pour les caissons d'épuration de l'air équipant les cabines pressurisées à air épuré (CPAE) des engins mécanisés
This thesis deals with the development of four models to simulate an industrial adsorption process of ammonia on zinc sulphate-doped activated carbon. It is described by mass balance, thermodynamic, hydrodynamics and adsorption kinetics equations. Since the values of parameters are needed to implement the model, the activated carbon is first characterised. Experimental measurements of ammonia adsorption isotherms on doped activated carbon were first carried out. Then a method based on the sensitivity analysis of parameters was used to evaluate the estimability of the unknown parameters involved in the Sips and Toth adsorption isotherm equations. The most estimable parameters were then identified using experimental data measured at three different temperatures, i.e. 288, 303 and 313 K. Experimental breakthrough fronts at different ammonia concentrations and gas flow rates were then measured and used to determine the overall mass transfer coefficient (kLDF), the axial dispersion coefficient (Dax), the effective diffusion coefficient (De) and the intracrystalline diffusion coefficient (Dµ) involved in the model equations, implemented and solved within Comsol Multiphysics® software. It was demonstrated that the adsorption process are limited by the diffusion and adsorption of ammonia on the zinc sulphate crystal. The identified models were then validated by means of four additional breakthrough fronts that were different from those used to identify the parameters. The model predictions and the experimental measurements showed a very agreement which is quantified by means of performance indices and confirmed by a Kolmogorov-Smirnov test. Finally, the CFD simulation of the gas flow in an air purification box was carried out by developing a dynamic model that takes into account the geometry and hydrodynamics. These models have improved the understanding of the adsorption process and can be used as a predictive tool for the design and optimization of air purification boxes used to equip cabins with pressurization and air-conditioning of mechanical devices

碩士
國立屏東科技大學
環境工程與科學系所
101
Volatile organic compounds and formaldehyde are common in building materials, paint and adhesive agent, which can cause formaldehyde to emit 0.11~2.11 ppm which is higher than the WHO indoor control standard (0.8 ppm), used for making building materials and fixing up a building. Although as time goes on formaldehyde will slowly decrease, the risk at causing cancer is 100~1000 times higher than the acceptable risk (10-6). Moreover, since its releasing period lasts for 3 to 15 years, it becomes invisible killer of indoor air pollution. Taiwan is a hot and humid place. There may be the problem of desorption when using adsorbents. However, the use of titanium dioxide as a catalyst can degrade harmful organics into harmless substances and purify air. Therefore, this study focuses on preparing zinc and iron co-doped titanium dioxide and sol-gel titanium coating coconut shell activated carbon, coal activated carbon and natural zeolite etc, in order to extend the life cycle of the adsorptive materials and improve indoor air quality. The properties of materials, specific surface area and porosity, surface structure image and element composition with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), X-ray diffraction, the water isotherms and kinetics, kinetics of formaldehyde, adsorption and photolysis of formaldehyde airbag experiments. To explore zinc and iron co-doped titanium dioxide coated activated carbon and zeolite on the removal of formaldehyde. The result shows that with the SEM, titanium dioxide whose block surface contains sheets has obvious characteristic peaks of anatase (25.28o) and rutile (27.42o). Otherwise, zinc and iron co-doped titanium dioxide whose block surface contains random pieces has very weak peaks. But the formaldehyde adsorption of removal for them is close and is 0.086 and 0.084 g kg-1 respectively. Under the irradiation of mosquito and fluorescent lamp for 2 hours, the removal of formaldehyde for titanium dioxide is 0.104 and 0.111 g kg-1 respectively. Besides, under the irradiation of them for 4 and 24 hours, the removal for zinc and iron co-doped titanium dioxide is 0.113 and 0.091 g kg-1 respectively. It demonstrates that adding zinc and iron to titanium dioxide destroys the phenomenon of titanium dioxide forming anatase and rutile crystal structure, which reduces the effect and rate of photolytic degradation for formaldehyde. The organic matter for layer-by-layer and filamentous coconut shell activated carbon is 98.2%. And it with coal activated carbon of layered- groove accounts for 56.7%. With EDS analysis, the superficial carbon atoms is 94.2% and 90.7% respectively. The isotherms of water on activated carbon are classified as the V-type in IUPAC. The adsorption amount of water in low humidity is low, and adsorption amount increased significantly when raising the humidity. What’s more it has hysteresis at 45% ~ 75% RH, which means it belongs to micro-porous or meso-porous adsorbent. Zeolites are similar typeⅡ in IUPAC classification multilayer adsorption occurs with increasing humidity after monolayer adsorption. And their H4 type has narrow slit-like pores, which is consistent with the SEM image. In 10% RH airbag experiments, the remove of adsorption on coconut shell activated carbon and coal activated carbon is 0.097 g kg-1 and that of natural zeolite is 0.025 g kg-1. And for these materials in 75% RH, the remove is 0.417 g kg-1, 0.419 g kg-1 and 0.166 g kg-1 respectively. It shows raising humidity enhance the adsorption of formaldehyde for these materials. The difference of adsorption among these materials may come from the difference of their BET-specific surface area. The BET-specific surface area of coconut shell activated carbon is 684 m2 g-1 (83% porous); coal activated carbon is 761m2 g-1 (58% porous), and zeolite has minimum of 34.9 m2 g-1. Activated carbon processes larger non-polar surfaces, especially coconut shell activated carbon, it has more micro-porous surface. Coating titanium dioxide can easily lead to the loss of material micro-porous and coating zinc and iron co-doped titanium dioxide cause it to jam in the material pores and give rise to the reduction of meso-pores, macro-pores and micro-pores, which can result in BET-specific surface area decreasing more obviously. For example, the BET-specific surface area of coconut shell activated carbon coated titanium dioxide and zinc and iron co-doped titanium dioxide is 664 and 398 m2 g-1 respectively, and the adsorption of formaldehyde for them reduces to 0.366 and 0.361g kg-1 respectively, coal activated carbon is 584 and 512 m2 g-1 respectively, and the adsorption of formaldehyde for them is 0.351 and 0.339 g kg-1 respectively. Zeolite is 38 and 22 m2 g-1 respectively, and the adsorption of formaldehyde for them is 0.186 and 0.187 g kg-1 respectively. They display that coating results in not only reduction of material BET-specific surface area but also reduction of formaldehyde adsorption. In the XRD analysis, titanium dioxide coated coal activated carbon and coconut shell activated carbon both process anatase crystalline, but zinc and iron co-doped titanium dioxide coated doesn’t, zeolite has characteristic peaks of 25.76° and 27.86°. By the SEM image, with thick coating titanium dioxide, the Ti/C of coal activated carbon surface is 1.86; that of coconut shell activated carbon is 0.19 and Ti/SiO2 of zeolite is 0.10. With coating zinc and iron co-doped titanium dioxide, the Ti/C of coconut shell activated carbon is 0.02, coal activated carbon is 0.01 and the Ti/SiO2 of zeolite is 0.02. The addition of zinc and iron reduces the coating effects of titanium dioxide. Under the irradiation of fluorescent (24hr) and mosquito lamp (6hr), the photolytic amount of formaldehyde for titanium dioxide coated coal activated carbon (0.073 and 0.112 g kg-1), coconut shell activated carbon (0.033 and 0.067 g kg-1) and zeolite (0.101 and 0.203 g kg-1 ) are all higher than that for zinc and iron co-doped titanium oxide coated coal activated carbon (0.042 and 0.091 g kg-1), coconut shell activated carbon (0.039 and 0.052 g kg-1) and zeolite (0.093 and 0.119 g kg-1). Furthermore, the effect under the irradiation of mosquito lamp is better than that under the irradiation of fluorescent. Because titanium dioxide coated zeolite is in sufficient amount of formaldehyde, it continues its photolytic degradation as time goes on. Consequently, the photolytic amount for it is the most among these materials, which indicates that the photolysis continuity of titanium dioxide can be expected. The concentration of carbon dioxide (50-360 ppm) in each airbag increases after photolysis. The addition of concentration of carbon dioxide under the irradiation of mosquito lamp (180-360) is more than under the irradiation of fluorescent lamp (50-150 ppm).

博士
國立中興大學
材料工程學研究所
92
Diamond-like Carbon (DLC) films containing various metal doping were synthesized by using a cathodic-arc activated deposition (CAAD) process. Metal plasma with intensive ion energies catalyzes the decomposition of hydrocarbon gases (C2H2), and induces the formation of hydrogenated amorphous carbon films with a mixture of sp2 and sp3 carbon bonds. The composite film structure consists of a metal- doped amorphous carbon film on top of a graded metal nitride interlayer, which provides enhanced mechanical and tribological properties. In this study, the plasma characteristics of the CAAD process for the deposition of metal-doped a-C:H was investigated by Langmuir probe measurement and optical emission spectroscopy. The catalysis effect of three common transition metal plasmas, including Cr, Ti, and Zr was investigated. This experiment depicts the advantage of the catalysis effect of Cr plasma in synthesizing DLC films with a higher sp3 carbon bond ratio comparing with that of Ti and Zr plasma. The wear properties were correlated with the metal doping determined by atomic size and electronic configuration. A catalytic ability ranking of transition metals for the deposition of metal-doped amorphous carbon films was suggested. Nitrogen was also introduced to form nitrogen-containing Cr-C:H/N films, which contained a mixture of sp2 and sp3 carbon bonds. The mechanical properties were correlated with the nitrogen doping. When nitrogen atoms occupy the substitutional sites to a large percentage, a donor energy level would be created and induces an increasing electrical conductivity.

碩士
國立屏東科技大學
環境工程與科學系所
101
People spend about 90% of their time on indoor activites every day, and about 30% of global new or renovated buildings have hazardous indoor air pollutants such as volatile organic compounds (VOCs). For example, toluene is common in decorating materials and consumed products, and indoor emitted toluene will cause harm to human health in the long term. Charcoal products are common adsorptive materials, but the adsorptive ability is limited. Titanium dioxide possesses the function of photocatalysis for volatile organic compounds, but it can have terrific activity under the condition of wavelength being smaller than 387.5 nm. In the study, we choose two kinds of charcoal materials (Longan charcoal and Makino bamboo charcoal) as activative materials, and use three kinds of concentration of sodium hydroxide solution as activators. To screen better photocatalyst under fluorescent lamp irradiation, we modify titanium dioxide with nitrogen, iron, zinc and citric acid co-doped, and household mosquito lamps and fluorescent lamps are taken as light sources, respectively. Then we select activated charcoal materials as supports to coat photocatalys, and toluene as a pollutant. The properties of materials, specific surface area and porosity, surface structure image and element composition with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), x-ray diffraction, photocatalytic activity of toluene and methylene blue experiment, sorption kinetics of toluene experiment, adsorption and photocatalysis of toluene experiments is analyzed. To discuss the effects of activation for charcoal materials, the characteristics of doped titanium dioxide, and the properties and removals of toluene for photocatalyst coated granular activated charcoal. The charcoal materials were activated with sodium hydroxide solution in chemical activation. With the increasing concentration of sodium hydroxide, the content of organic matter raise. The charcoal materials are mainly C (≒ 90) and O. We observe that parenchyma cells appear rift, etch, and even the collapsed surface of tube walls with the SEM. With the number of pores increasing and the pores widening, the materials are able to become easier to shatter. Also, the granular completeness can be destroyed, which causes the yield (78~52%) of granules decrease. Since bulk density is reduced, and particle density is increased, porosity raises. Moreover, it significantly boosts the BET-specific surface area and the total pore volume, which the micropores account for 80.8~88.1% and the average pore diameter is 21.5 Å. The BET-specific surface area of 5M LC and 5M MBC is 566 and 333 m2 g-1, respectively. Which benefits adsorption kinetics of 0.015P/P0 toluene (10% RH), and the toluene adsorption for 5M charcoal materials is 16.5~29.1 times the amount of Longan charcoal and Makino bamboo charcoal. The adsorption of 5M LC reaches a balance more difficult than that of 5M MBC does and they still remain 80% of toluene adsorption at constant temperature after six-hour desorption. Under the situation of 346 ppm toluene, the removal of 5M charcoal materials is 4 to 5 times the amount of original materials, and its rate of removal is over 90% in 2 hours. Therefore, we can conclude that the activation of 5M sodium hydroxide solution can obviously improve the amount and rate of adsorption for charcoal materials to toluene. We observe the surface of photocatalysts with the SEM, and find that the blocks of titanium dioxide are the largest and most. Co-doping with nitrogen, iron, zinc and citric acid can lower the ability of turning into block of TiO2 and increase the tiny particles. The blocks of NFeTiO2 are the smallest and least, but its tiny particles are the most. The tiny particles contain is more titanium than the blocks. The ratio, O/Ti, of NFeZnCATiO2 and NFeZnTiO2 is 2.05 and 2.87, respectively, and Fe (0.1~0.13%) and Zn (0.02~0.11%) can be measured, but N can't. In X-ray diffraction, the characteristic peak positions of photocatalysts are consistent with anatase, and the crystal form of photocatalysts could be identified as anatase. There are the removals of methylene blue by photocatalysts under mosquito lamp irradiation for 6 hours: the removal of TiO2 is the greatest (6.34 g kg-1). However, the removals of co-doped TiO2 reduce to 3.87~4.79 g kg-1. Nevertheless, both of two situation mentioned above can be photolyzed completely under mosquito lamp irradiation for 24 hours. Under fluorescent lamp irradiation for 24 hours, the removals of co-doped TiO2 are 5.18~5.50 g kg-1, while the TiO2 is only 3.10 g kg-1. The adsorption of NFeZnCATiO2 to toluene (57.5 ppm, 10%RH) is the highest (1.05 g kg-1) for 24 hours, but that of TiO2 (0.34 g kg-1) is the lowest. Under mosquito lamp irradiation, the removal of photocatalysts is NFeTiO2 (6.58 g kg-1) > NFeZnTiO2≒NFeZnCATiO2 > TiO2 (4.72 g kg-1). As for under fluorescent lamp irradiation, the removal is NFeTiO2 (2.33 g kg-1) > TiO2 > NFeZnTiO2 ≒ NFeZnCATiO2 (0.83 g kg-1). Under 75%RH, the adsorption of NFeTiO2 is 2.01 g kg-1 and that of TiO2 is 1.60 g kg-1. Under mosquito lamp irradiation, the final removal of the control group is 1.30 g kg-1, which shows that photochemical reaction of toluene will be inhibited in high-humid environment. The TiO2 (7.24 g kg-1) is better than NFeTiO2 (4.89 g kg-1) for 6 hours. Under fluorescent lamp irradiation, the removal of NFeTiO2 (4.16 g kg-1) is slightly higher than that of TiO2 (2.97 g kg-1). It demonstrates that though the N, Fe co-doped TiO2 which has tiny particle and higher Ti content has slightly less removal for organic compound than TiO2 does under mosquito lamp irradiation. Furthermore, no matter the organic compound is in liquid or gas, the removal of NFeTiO2 for organic compound is better than TiO2 under fluorescent lamp irradiation. The particle density of NFeTiO2 coated 5M charcoal increases, and that of TiO2 coated 5M charcoal remain. Photocatalyst coated 5M charcoal causes the increase of pH value and the decrease of organic matter. In the surface observation of the SEM, TiO2-coated charcoal materials have ablation phenomenon, but probably because the capability of turning into blocks decline, the structural destruction of NFeTiO2 coated 5M charcoal is not obvious. Both coatings are heterogeneous and have blocks on them. As the frequency of NFeTiO2 coating increases, the contents of Ti and O increase whereas the content of carbon decreases, and 5M bamboo charcoal has better effect of coating. The weak anatase charateristic peaks of TiO2 and NFeTiO2 coated 5M charcoal appear only at 25.28° in the X-ray diffraction. As the frequency of NFeTiO2 coating increases, the characteristic peaks become more obvious. When 5M MBC is used as a support, brookite peaks (30.8°) appear. Photocatalyst-coated charcoal causes micropore surface area and pore volume to decrease, which has more obvious effect with TiO2 coating and only the pore volume of NFeTiO2 coated 5M LC and 5M MBC which is coated twice (0.2204 and 0.1377 cm3 g-1) slightly lowers than that of the 5M charcoal (0.2595 and 0.1519 cm3 g-1). The ratio of toluene uptake adsorption (114.0~125.8 and 31.4~34.9 g kg-1) for NFeTiO2/5M LC and NFeTiO2/5M MBC is similar to that of BET surface area (426 and 142 m2 g-1). The ratio of desorption to adsorption of NFeTiO2/5M LC and NFeTiO2/5M MBC is respectively 0.18 and 0.35 which is corresponding with their BJH/BET surface area (0.194 and 0.28 respectively). The residual of toluene in NFeTiO2/5M LC and NFeTiO2/5M MBC constantly increase, and the range is 90.3~100.1 and 19.3~22.7, respectively. We speculate toluene is still filling in micropore. The adsorption of Makino bamboo charcoal and NFeTiO2/5M MBC (75.1 and 257.6) for 75%RH water vapor, is more excellent than that of Longan charcoal and NFeTiO2/5M LC (58.9 and 174.2), and water can be desorbed completely. The toluene (346.4 ppm, 10%RH) adsorption mainly occurs for two hours, and the removal of 5M LC is highest. Additionally, the removal of NFeTiO2/5M MBC is lower than that of 5M MBC. During the 12th~36th hour, the removals of 5M MBC and NFeTiO2/5M MBC below a mosquito lamp and fluorescent lamp are 1.8, 1.3 and 6.6, 4.9, respectively. The removals of 5M MBC, TiO2- and NFeTiO2- coated 5M charcoal for toluene (808.3 ppm, 75%RH) adsorption are 36.2~38.3, 28.0~29.3 and 20.5~21.9 g kg-1, respectively, and when a mosquito lamp is added, the removals are 5.9, 7.9, 8.5, respectively. When a fluorescent lamp is added, the removals are 6.6, 2.3 and 6.4 g kg-1, respectively. Which shows that removal effect of adsorption is better than that of photoysis, N, Fe co-doped TiO2 not only improves the photolysis of toluene under a fluorescent lamp irradiation (which is triple the effect of TiO2), but also excels TiO2 under a mosquito lamp irradiation.

碩士
國立中興大學
環境工程學系所
105
Advanced Oxidation Processes (AOPs) mainly removes contaminants by free radical oxidation which is produced from oxidants. In this study, Potassium peroxymonosulfate (PMS) was used as the oxidant to produce sulfate radicals (SO4-•) which had stronger redox potential than hydroxyl radical (OH•). However, it shows slow response for PMS producing sulfate radicals. A transition metal catalyst to enhance activate degradation speed is needed. In order to reduce the cost and environmental impact of the metal catalyst, non-metallic catalysts will be seen as a future trend. In this work, one-step preperation for sulfur-doped carbon nitride (CNS) was used as a non-metallic and easily prepared catalyst to activate PMS to degrade target contaminants Rhodamine B (RhB) and Bisphenol A (BPA). CNS was analyzed by FE-SEM, TEM, BET, XRD, XPS and other instruments. Since the prepared CNS exhibits a higher surface area and catalytic activity than the undoped sulfur-based carbonitride (CN). Contaminants degradation by CNS activated PMS exhibits a much higher efficiency than CN activated PMS. Therefore we speculate that the synergistic effect of sulfur and nitrogen co-doping in CNS may lead CNS exhibit higher catalytic and photocatalytic properties. From RhB and BPA degradation test, temperature, pH, co-existing ion simulation of the target contaminants may occur in the environment. It is more conducive for CNS catalyzed PMS to degrade contaminants in high temperature and neutral conditions. When high concentrated NaCl as co-existing ions was added into contaminated water, the effect of CNS catalyzed PMS degradation was not affected. The free radical scavenger test proved that sulfate radicals are the main free radicals in this experiment. Finally, five times CNS recyclability recveals almost the same result to CNS catalyzed PMS degradation batch experiment. These characteristics indicate that CNS is a convenient preparation and effective nonmetallic photocatalyst and is suitable for catalyzing PMS degradation of RhB and BPA.

碩士
國立臺灣科技大學
化學工程系
106
In this study, a low-cost chemical phenylphenol has been implemented as the precursor of activated carbon for electrochemical capacitor applications. The energy storage capability of this activated carbon is further enhanced by doping of B and N. In undoped activated carbon, the specific surface area of the activated carbon can be increased by raising the pyrolysis temperature and the amount of the pore-forming potassium agents, and the pore size also become larger and more. The molar ratio of phenylphenol to potassium increased from 1:1.5 to 1:20, specific surface area increased from 948 m2 g-1 to 2528 m2 g-1, when para-phenylphenol is used as a precursor at 900C; specific surface area increased from 1323 m2 g-1 to 1740 m2 g-1, when ortho-phenylphenol is used as a precursor. The specific capacitance can be greater than 200 F g-1, using a high specific surface area undoped activated carbon at scan rate of 0.5 mV s-1 in 0.5 M H2SO4(aq). The specific capacitance exceeds 400 F g-1 at scan rate of 1 mV s-1 in 1 M TEABF4 in ACN. Also it displays good cycle stability. Boron-doped activated carbon obtained after incorporation of 5% boric acid, regardless of the molar ratio of phenylphenol to potassium is 1:12 or 1:20, both achieve a larger specific surface area than undoped activated carbon, the specific surface area can be up to 2609 m2 g-1, and the pore also tends to increase in size. The specific capacitance of the boron-doped activated carbon is 316.6 F g-1 at scan rate of 0.5 mV s-1 in 0.5 M H2SO4(aq). The specific capacitance is 509.7 F g-1 at a scan rate of 1 mV s-1 in 1 M TEABF4 in ACN. The specific surface area is up to 2659 m2 g-1, when the amount of boric acid is increased to 10%, the specific surface area and pores are more enhanced than 5% boron. The specific capacitance of the boron-doped activated carbon is 344.7 F g-1 at scan rate of 0.5 mV s-1 in 0.5 M H2SO4(aq). The specific capacitance is 521.3 F g-1 at a scan rate of 1 mV s-1 in 1 M TEABF4 in CAN, regardless of whether the doping amount of boron is 5% or 10%, and it shows good cycle stability. After doping with nitrogen, the activated carbon obtained through pyrolysis at 900C, the specific surface area reaches 3000 m2 g-1 or more, and the amount of mesoporous pores is raised as well. Nitrogen-doped activated carbon is measured with specific capacitance more than 500 F g-1 at scan rate of 0.5 mV s-1 in 0.5 M H2SO4(aq). Specific capacitance more than 550 F g-1 can be obtained at a scan rate of 1 mV s-1 in 1 M TEABF4 in ACN, and the cycle stability is also excellent, but the yield is less than 20%. Finally, two different electrolytes (TEABF4 and TBABF4) and five different pore size distributions of activated carbon were used to study the connections between different pore sizes on different ion sizes. We also find TBA+ hardly enter pores which the size is smaller than 1.5 nm, when comparing the difference in cyclic voltammetry curves measured from different electrolytes and the pore size distribution pattern.

碩士
國立中正大學
化學工程研究所
107
Activated carbon (AC) is regarded as one of the most promising active materials for high performance supercapacitor (SC) owning to its high specific surface area and theoretical specific capacity. In this study, oil palm empty fruit bunch (EFB) which is the agricultural residue was employed as precursor to produce ACs which were fabricated by a series of cleaning, carbonization and chemical activation processes. The as-produced AC possesses a specific surface area of 2774 m2/g, which is very high among the AC produced from biomass materials. In order to enhance the performance of SC, the AC was modified by nitrogen doping treatment. The specific capacity of AC and nitrogen-doped AC were 182 to 215 F/g, respectively, at a current density of 0.5 A/g in 6M KOH aqueous electrolyte. We demonstrated that the agriculture waste can be processed to become activated carbon with a high specific surface area for SC application.

Studies have shown that high-efficiency micro- and mesoporous activated carbon with high added value can be obtained on the basis of lignocellulose biomass in a three-stage thermochemical process. A methodology has been developed for the synthesis of nitrogen-doped activated carbon by synthesis with dicyandiamide in dimethylformamide suspension as a raw material using wood, its processing residues and wood char.

AbstractCarbon quantum dots (CQDs) are relatively new carbon allotrope. It triggered an investigation of new CQD research of synthesis, properties CQDs, and applications. CQDs are quasispherical carbon particles with a size less than 10 nm with crystalline sp2 cores of graphite and quantum effects. A subclass of CQDs are graphene quantum dots (GQDs), and they have a structure of one or several graphene layers with diameter < 10 nm with higher crystallinity than CQDs. CQDs also play an important role in medicine. CQDs are used in intracellular ion detection, toxin detection, pathogen, vitamin, enzyme, protein, nucleic acid, and biological pH value determination. Despite the broad range of biomedical applications, we would like to focus on antibacterial properties of pure CQDs and their polymer composites. The antibacterial effect of CQDs is based on noninvasive photodynamic therapy (PDT). PDT can cause a specific biological response on the cellular or subcellular level, such as apoptosis, programmed death, or necrosis, a nonprogrammed pathway. CQDs are a very promising new antibacterial nanoparticles.

Hantzsch dihydropyridines represent an important source of hydrogen to be transfered to other un-saturated organic molecules, leading the formation of pyridine aromatic ring as driving force. The hydrogen transfer process was evaluated using 1,4-dyhydropyridines and heterogeneous cobalt cat-alyst supported over N-doped activated carbon. The 4-position of the dihydropyridine ring was sub-stituted with H (4a), Me (4b) and Ph (4c) groups, showing that only 1 reacted to yield the correspond-ing pyridine compound indicating that the presence of steric hindrance took place on the reaction. Additionally; three solvents –tetrahydrofuran (THF), acetone, and acetonitrile– were tested, showing reactivity only with unsaturated ones, but not with THF. This observation indicates that dihydro-pyridine works as hydrogen donor and solvent as hydrogen aacceptor in the hydrogen transfer pro-cess. Keywords: Hantzsch dihyropyridine; Heterogeneous cobalt oxide catalyst; Hydrogen transfer; Unsaturated solvents

With the aim of improving the ethanol oxidation in fuel cells, researchers have developed numerous catalysts to break up the C-C bond. Most of the tests have been carried out at low temperature, using Nafion membrane as electrolyte. The cell performance of the Direct Ethanol Fuel Cells (DEFCs) at low temperature is still far from its industrial application. To improve the DEFC power density, high temperature operation (150–200 °C) has been suggested to promote the complete oxidation of ethanol. Thus, three different catalysts (Pt-Ru (1:1), Pt-Sn (1:1) and Pt-Sn-Ru (1:1:0.3), all of them supported on both non-activated and activated carbon were tested in H3PO4 doped PBI-based fuel cell, using vapour fed ethanol, operating in the range of 150–200 °C, and high ethanol concentration 6.7 M. The catalyst were synthesized using NaBH4 as reducing agent and were characterized by XRD, ICP-AES and TPR analyses. The best performance was reached at the highest temperature and with the catalyst based on Pt-Ru. The best results for the Ru-based catalyst can be explained by the higher level of alloying reached for the Ru than for Sn, which modifies the crystalline structure of Pt and enhances the activity oxidation of ethanol and of intermediates that are generated during the oxidation of ethanol.