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Catalytic wet air oxidation of phenol in a trickle bed reactor: kinteics and reactor modelling.Eftaxias, Athanasios 14 February 2003 (has links)
Wastewater treatment and re-use of industrial process water is a critical issue for the suitable development of human activities. The need for effective water recycling has reinforced the research on tailored low cost pollution abatement since the existing solutions are not longer universal. In particular, the emerging Catalytic Wet Air Oxidation (CWAO) process is one of the most promising technologies for the remediation of moderately concentrated and/or biotoxic water pollutants, when a stable and active catalyst can be provided. To this purpose, the catalytic activity and stability of active carbon was tested in the CWAO of the target compound, phenol, at mild conditions of temperature and pressure. The active carbon, which is a relatively inexpensive catalytic material is shown to be stable and to yield higher phenol destruction and less toxic partial mineralisation products, compared to a widely used copper oxide catalyst. During the CWAO of phenol, numerous partial oxidation products appeared and the knowledge of the kinetics that control their oxidation process is fundamental for the design, modelling and scale up of CWAO pilot plant or industrial units. Complex kinetic modelling was undertaken using both the classical gradient based method and a stochastic algorithm termed Simulated Annealing (SA). SA was shown to perform better in the identification of multiparameter kinetic reaction schemes, allowing to improve the kinetic modelling of CWAO beyond the actual state of art in this field. Detailed kinetic analysis of CWAO is scarce in the literature and the same situation holds for engineering studies. There is a clear need for the simultaneous development of process chemistry and engineering aspects. Consequently, we parallely focused on the state of art modelling of a Trickle Bed Reactor (TBR), being the priority candidate of best performing CWAO reactor. First, the ability of TBR in CWAO was affirmed by appropriate experimental comparison of batch slurry reactor and continuous fixed bed reactors operating either in the cocurrent downflow mode (TBR), or upflow mode (FBR) of the gas and liquid flow. A phenomenological transport-reaction model of the TBR was then developed and programmed. The TBR model implements the previously obtained oxidation kinetics and emphasis on important aspects of TBR, namely catalyst wetting, and mass transfer between the phases. Non-isothermal operation is also accounted for to face the need for autothermal operation, lowering the global process costs. The validation of the model was successfully done with the available experimental data from the laboratory TBR and thus provided a reliable tool for the scale up study of the CWAO process. The outcomings of this model aided scale up, allow to give recommendation on the design and operation of industrial units, thereby making more reliable the implementation of CWAO units on an industrial level. / El tratamiento y el reciclaje de afluentes acuosos son de máximo interés para conseguir un desarrollo sostenible de las actividades humanas. La necesidad de aprovechar en un futuro cercano las aguas residuales de procesos industriales de un modo eficaz ha reforzado la investigación sobre métodos de bajo coste para su recuperación, dado que las tecnologías existentes ya no son universalmente aplicables. La oxidación catalítica por vía húmeda (CWAO) es uno de los procesos emergentes más prometedores particularmente para el tratamiento de aguas contaminadas con materia orgánica, en concentraciones medio altas, y/o biotóxica. Sin embargo, la implementación del método es adecuada siempre que se use un catalizador activo y estable. Con este propósito, la actividad catalítica y la estabilidad del carbón activo se ha comprobado en la CWAO usando como compuesto modelo el fenol. En condiciones de temperatura y presión moderadas el carbón activo ha demostrado ser un material catalítico barato, que a la vez, es estable, mas activo en la conversión de fenol, además produciendo menor cantidad de productos de oxidación parcial tóxicos que los catalizadores soportados convencionales. Durante la CWAO del fenol, numerosos productos intermedios se forman, por lo que el conocimiento de la cinética de su oxidación es fundamental para el diseño, modelización y escalado fiable del proceso a escala de planta piloto o incluso industrial. Debido a la insuficiencia de los clásicos métodos de optimización para llevar acabo la estimación de parámetros en modelos de alta complejidad, el uso de algoritmos estocásticos se ha probado con éxito, permitiendo el desarrollo de modelos cinéticos más avanzados que los que se implementan actualmente en el campo de la CWAO. El desarrollo de modelos cinéticos complejos es escaso en la literatura actual, así como los estudios que tratan los aspectos químicos y de ingeniería del proceso de la CWAO. Sin embargo, hay una necesidad clara para el desarrollo simultaneo de los aspectos químicos y de ingeniería de la tecnología. Consecuentemente, en paralelo se ha enfocado en la modelización de un reactor de goteo (TBR), según el estado de arte actual en el campo de estos reactores. Es demostrado que estos reactores son más adecuados que los reactores agitados con catalizador en suspención para la CWAO de compuestos orgánicos que tienden a reacciones de polimerización en fase liquida. Además se han probado dos distintos modos de operación, con flujo de gas y liquido cocorriente descendiente o ascendiente, y se ha demostrado que la primera forma de operación es la mas adecuada para este sistema. A continuación un modelo fenomenológico para el TBR ha sido desarrollado y programado. El modelo implementa la cinética previamente obtenida, y además se ha puesto énfasis en la incorporación de los efectos de mojado, y de transferencia de materia. La operación no isotérmica se ha estudiado también para investigar la posibilidad de operar de modo autotérmico, disminuyendo así los costes de operación del proceso. La validación del modelo fenomenológico con los datos experimentales obtenidos en el TBR del laboratorio ha sido favorable. Posteriormente, este modelo ha sido utilizado como una herramienta fiable para el escalado del proceso. Los resultados obtenidos de la modelización del escalado permiten la extracción de recomendaciones sobre el diseño y la operación de unidades industriales, haciendo más fiable la aplicación del método a escala industrial.
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Sintese de materiais carbonosos ativados a partir de coque de petroleo / Synthesis of activaded carbon materials from petroleum cokeMéndez, Manoel Orlando Alvarez, 1977- 28 March 2005 (has links)
Orientador: Antonio Carlos Luz Lisboa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T17:26:02Z (GMT). No. of bitstreams: 1
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Previous issue date: 2005 / Resumo: Materiais Carbonosos Ativados (MCA), tais como Carvões Ativados (CA) e Peneiras Moleculares de Carbono (PMC), são caracterizados por apresentar elevada área superficial específica e um grande volume de poros em sua matriz carbonosa, sendo sua principal propriedade a de adsorver moléculas tanto na fase líquida quanto na gasosa. O Brasil importa em sua totalidade peneiras moleculares produzidas a partir de precursores carbonosos, empregando-os nas mais diversas áreas de ciência e tecnologia e em vários segmentos industriais. O coque de petróleo é um resíduo com alto teor de carbono fixo e baixo teor de cinzas, e em decorrência de sua estrutura praticamente amorfa, é um material de pouco valor comercial, sendo considerado um resíduo problemático, tanto em termos ambientais quanto comerciais. Desta forma, a utilização de coque de petróleo para a produção de CAs e de PMCs torna-se atrativa para a utilização deste resíduo. O presente trabalho teve como objetivo estudar a síntese de carvões ativados através das ativações física e química de coque de petróleo proveniente da unidade de coqueamento retardado da REPLAN - PETROBRÁS, buscando avaliar as influências dos parâmetros de processo na qualidade dos CAs, tais como: concentração de agente ativante, tempo de ativação, temperatura de ativação e granulometria do coque de petróleo. A ativação física apresentou resultados insatisfatórios devido a baixa reatividade do coque de petróleo com o dióxido de carbono. Contudo, o coque de petróleo apresentou uma maior reatividade com hidróxido de potássio, permitindo desenvolver uma metodologia adequada para a ativação química do coque de petróleo com KOH, de modo a obter carvões ativados de elevada área superficial. Os resultados obtidos indicam a possibilidade de produção de carvões ativados de elevada área superficial, superiores a 2000 m2.g-1 a partir do coque de petróleo / Abstract: Activated Carbon MateriaIs (ACM), such as Activated Carbons (AC) and Carbon Molecular Sieves (CMS), are characterized by a high specific surface area em high pore volume in their carbon matrix, being their principal property to adsorb molecules in liquid and gas phase. Brazil imports all its molecular sieves, using them in several areas of science and technology and industrial segments. Petroleum coke is a high carbon content residue with low ash content, and due to its amorphous structure have low comercial value, being considered an environmental and comercial problem. In this sense, the utilization of petroleum coke to produce AC and CMS becomes an atractive utilization of this residue. The objective of the present work was to study the synthesis of activated carbon by physical and chemical processes using as raw material the petroleum coke originated from the delayed coking unit from REPLAN PETROBRAS, evaluating the infiuence of process parameters, such as activating agent concentration, activation time, activation temperature and average particle size on the AC quality. The results of physical activation of petroleum coke was not satisfactory due to the low reactivity of the petroleum coke with the carbon dioxide. However, the petroleum coke presented higher reactivity with potassium hidroxide, given the possibility to develop an adequate methodology to chemically activate petroleum coke with KOH, in order to obtain activated carbon with high specific surface area. The results indicated the possibility to produce activated carbon materiaIs from petroleum coke with surface area higher than 2000 m2 .g-l / Mestrado / Engenharia de Processos / Mestre em Engenharia Química
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Možnosti odstranění mikropolutantů vodárenskými procesy / Options removal of micropollutants with water treatment processesZdražilová, Alena January 2016 (has links)
This diploma thesis is engaged in problems of micropollutants removal by water treatment process. The first part aims to define single micropollutants, possibilities of their removal in laboratory and micropollutants removal on water treatment plant. In the second part, there is data evaluation of water analyses on factual water treatment plant. Also there is description and evaluation of experiment, which aims to pesticide removal from river by using filtration across granulated active carbon.
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Procena remedijacionog potencijala sedimenta zagađenog prioritetnim organskim zagađujućim materijama / Investigation of remediation potential of sediment polluted with priority organic pollutantsGrgić Marko 16 August 2019 (has links)
<p>Predmet istraživanja ove doktorske disertacije je procena potencijalno biodostupne frakcije odabranih prioritetnih organskih polutanata (pentahlorbenzena, heksahlorbenzena, lindana, trifluralina, 4-oktilfenola i 4-nonilfenola) u sedimentu, ispitivanje biodegradacionog potencijala ovih jedinjenja u sedimentu u različitim uslovima, kao i procena potencijala stabilizacije<br />sedimenta dodatkom ugljeničnih sorpcionih agenasa. U cilju razvoja metoda za određivanje biodostupnosti odabranih organskih polutanata ispitivane su i optimizovane metode višestepene i jednostepene parcijalne ekstrakcije primenom sledećih hemijskih agenasa: Tenaks smole, XAD-4 smole i rastvora ciklodekstrina (2-hidroksipropil-β-ciklodekstrina, β-ciklodekstrina i metil-β-ciklodekstrina). Optimalni agens za procenu biodostupne frakcije odabranih organskih zagađujućih materija sa sedimenta XAD-4 smola, a optimalno vreme ekstrakcije primenom jednostepenih ekstrakcija je oko 8 h. Procena biodegradacionog potencijala odabranih prioritetnih organskih zagađujućih materija u sedimentu ispitana je u različitim aerobnim i anaerobnim uslovima uz optimizaciju uslova putem biostimulacije i bioaugmentacije. Pokazano je da svih šest odabranih jedinjenja poseduju značajan potencijal biodegradacije u anaerobnoj sredini pri čemu u slučaju lindana i trifluralina dolazi do potpunog uklanjanja biodostupne količine jedinjenja primenom sva četiri ispitana inokuluma. Aerobni potencijal u ispitanim uslovima pokazali su samo alkil fenoli, gde je takođe uklonjena skoro celokupna količinabiodostupne frakcije jedinjenja u sedimentu (78-85%). Potencijal remedijacije sedimenta dodatkom ugljeničnih materijala ispitan je sa aspekta odabira ugljeničnih sorpcionih agenasa (aktivni ugalj, biougalj i humus); određivanja optimalne količine materijala; isptivanja dugoročnih i kratkoročnih efekata dodatka ovih agenasa na biodostupnost organskih zagađujućih materija kako bi se ispitao efekat starenja i toksičnosti dobijenih smeša. Rezultati stabilizacije zagađujućih supstanci u sedimentu pokazuju da: (1) povećanje doze sva tri sorpciona agensa dovodi do povećanja efikasnosti imobilizacije i smanjenja biodostupne frakcije odabranih organskih jedinjenja; (2) starenjem smeša sedimenta i sorbenata u toku prvih 90 dana dolazi do daljeg smanjenja biodostupne frakcije svih jedinjenja, nakon čega se biodostupna koncentracija ispitivanih jedinjenja primenom aktivnog uglja ne menja, dok primenom biouglja i humusa dolazi do porasta biodostupne frakcije jedinjenja. Testovi fitotoksičnosti su pokazali da je <em>Zea mays </em>akumulirao značajno veće količine ispitivanih jedinjenja iz netretiranog sedimenta u poređenju sa <em>Cucurbita pepo</em> i <em> Lactuca sativa. </em>Toksičnost smeša sedimenta sa aktivnim ugljom i humusom procenjena na osnovu inhibicije luminiscencije na <em>Vibrio fischeri</em> kao i ispitivanjem <em>Zea mays </em>germinacije i produkcije biomase je pokazala značajno smanjenje u odnosu na netretirani sediment. Akumulacija ispitivanih jedinjenja u biomasi <em>Zea mays </em>u netretiranom sedimentu je bila značajno veća u odnosu na sve smeše sedimenta i aktivnog uglja i humusa. Sva tri sorbenta pokazala su veliki remedijacioni potencijal za sediment zagađen organskim zagađujućim supstancama, ali je aktivni ugalj pokazao najbolje performance.</p> / <p>The aim of the research in this PhD dissertation is the assessment of the potentially biodegradable fraction of selected organic pollutants (pentachlorbenzene, hexachlorobenzene, lindane, trifluraline, 4-octylphenol and 4-nonylphenol) in the sediment, estimation of the biodegradation potential of these compounds in sediment in different conditions, as well as the assessment of the stabilization potential sediment by the sediment amendment with of carbon rich sorption agents. In order to develop and optimise methods for the bioavailability assessment of the selected organic pollutants, methods of multistage and single-step non exhaustive extraction were studied using the following chemical agents: Tenax resin, XAD -4 resin and a cyclodextrin solution (2-hydroxypropyl- β-cyclodextrin, β-cyclodextrin and methyl-β-cyclodextrin). Results showed that optimal agent for estimating the bioavailable fraction of selected organic pollutants from the sediment is XAD-4 resins, and that the optimum extraction time using single-step extraction is about 8 h. The assessment of the biodegradation potential of selected priority organic pollutants in the sediment was examined in various aerobic and anaerobic conditions, with the optimization of conditions through biostimulation and bioaugmentation. It has been shown that all six selected compounds possess significant biodegradation potential in the anaerobic environment, where in the case of lindane and trifluraline there is complete removal of the bioavailable amount of the compound using all four inoculum tested. Aerobic potential under the applied conditions has been showen only for alkyl phenols, where almost all of the bioavailable fraction of the compound in the sediment was removed (78-85%). The potential of sediment remediation with the amendment of sediment withcarbon rich materials was examined from the aspect of selecting carbon sorption agents (activated carbon, biochar and humus); estimation the optimal material doses; the long -term and short-term effects of the addition of these agents on the bioavailability of organic pollutants in order to examine the effect of aging and the toxicity of the resulting mixtures. The results of the stabilization of pollutants in the sediment show that: (1) increasing the dose of all three sorption agents leads to an increase in the immobilization efficiency and reduction of the bioavailable fraction of the selected organic compounds; (2) aging of the amended sediment during the first 90 days results in a further reduction of the biodegradable fraction of all compounds, after which the biodegradable concentration of the selected compounds remain the same in the case of activated carbon amendment, while the bioavailable fraction of the compound increases with the use of biohar and humus. Phytotoxicity tests showed that <em>Zea mays </em> accumulated significantly higher amount of selected organic pollutants from unamended sediment, comparing to <em>Cucurbita pepo </em> and <em>Lactuca sativa</em>. Toxicity of activated carbon and humus amended sediment assessed by <em>Vibrio fischeri </em> luminescence inhibition test and by measuring <em>Zea mays </em>germination and biomass yield was significantly reduced in the amended sediment samples. Accumulation of the selected organic pollutants in the <em>Zea mays</em> biomass in the unamended sediment were a significantly higher than in the humus and activated carbon amended sediment. Both sorbents show potential to be used as remediation agents for organically contaminated sediment, but activated carbon exhibited the better performance.</p>
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Desulphurization of diesel fuel using carbon-based metal oxide nanocompositesCherubala, Rusumba Bienvenu 04 1900 (has links)
M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / This thesis presents a slight on desulphurization process of the commercial diesel fuel
using the carbon-based metal oxide nanocomposites such as graphene oxide, ZnO, rGO
as a nano-adsorbent, activated carbon (PAC and AC) and charcoal Granular active
carbon (GAC) to produce a fuel of less than 10 ppm sulphur content. Due to the high
percentage of sulphur compounds in the fuel causing air pollution, acid rain and other
problems related to combustion process. The synthesised of sorbents were achieved
using incipient impregnation, microwaved-assisted and chemical exfoliation methods.
The materials were characterized using Thermogrametric Analyzer (TGA), Fourier
transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD), Brunauer,
Emmett and Teller (BET). The examination effect of operating conditions on the
adsorption capacity with DBT and Sulphur compounds adsorption, the isotherms and the
adsorption kinetic models were evaluated.
The experimental data for PAC and AC were well suited to Freundlich isotherm and
pseudo second-order kinetic models. The results shown that the sulphur feed
concentration, the space velocity and the functional groups of the adsorbents have a
considerable effect on the adsorption. In addition, it was observed that the temperature
in the range of 30 to 80oC has a significant effect on the adsorption of Sulphur compounds from diesel fuel using 20 wt.% of sorbents. The rGO substrate which contained abundant oxygen functional groups was confirmed to promote the dispersion metal oxide and increased the adsorption efficiency of sulphur compounds (H2S and SO2) by providing oxygen ions weakly bound to the sulphur molecules. For the desulfurization process by adsorption, PAC and AC exhibited a better affinity for 80% removal of sulphur compared to the GAC and GO. The effects of metal species such as zinc oxide (ZnO) and reduced graphite oxide (rGO) composite on the adsorption capacity of hydrogen sulphide (H2S) were investigated. It was found that depending on the copper load, the adsorption
capacity of H2S increased up to 20 times compared to pure ZnO. To study the oxidation
changes on copper and zinc oxides, crystallite analysis by XRD and chemical state
analysis by XPS were performed.
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Sustainable water treatment processes : Scenarios for a better environment in Håbo municipality / Hållbar vattenreningsprocess : Scenarion för en bättre omgivning i Håbo kommunTrozell, Oskar, Wiman, Daniel, Wiggins, Elis, Stigenberg, Elin, Bergström, Alva, Andersson, Emilia January 2021 (has links)
Clean drinking water is a vital part of our society and a basic human right. With an ever growing population and a decreasing quality of raw water, new methods need to be introduced to keep up with the demand for clean, biostable, and sustainable production of drinking water. The aim of this study is to evaluate Håbo municipality’s increasing usage of chemicals in their water treatment process and to investigate current and future possible technologies for water treatment for Håbo to make their process more sustainable. In this study four scenarios of different cost and change of today’s water treatment plants are presented, while our overall recommendation is to build a new facility. A new plant with new treatment methods such as ultrafiltration is most in line with Håbo municipality’s vision of decreasing chemical usage and sustainability, all while maintaining the water quality. Due to Håbo’s growing population and today’s water plants running close to maximum capacity, a new facility with a larger capacity should be considered.
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