In industrial wastewater, there are usually many kinds of organics and heavy metals and can cause damage on human health and environment without well treatment. Printed Circuit Board (PCB) industrial wastewater is a typical example due to the complicated manufacture processes and the use of specific chemicals. In this study, the PCB industrial wastewater is collected and then treated by the combination of Fenton method and Ferrite Process (or called Fenton-Ferrite Process, FFP). Moreover, the recycling possibility of sludge generated from FFP is also studied. Through this study, the treatment procedure of wastewater containing organics heavy metals is established and the direction of sludge reuse is also provided. To realize the characteristic of PCB industrial wastewater, the wastewater from some PCB factory in southern Taiwan was firstly collected and analyzed to identify the pollution concentrations and then treated by FFP. The experimental results showed that the optimum parameters of Fenton method in FFP were pH = 2, [Fe2+]= 500 mg/L, [H2O2]= 3000 mg/L, reaction time= 60 min and batch dosing, and the residual COD and TOC were 84.9 mg/L and 58.3 mg/L under the COD regulation standard 120 mg/L. Meanwhile, the proper conditions of Ferrite Process in FFP were pH= 10, reaction temperature= 80¢J, reaction time= 40 min, aeration rate= 3 L/min/L wastewater, Fe/Cu molar ratio= 10 and three-stage reaction. Under that circumstance, the residual [Cu2+] in wastewater was 0.18 mg/L and the Toxicity Characteristic Leaching Procedure (TCLP) test of sludge from FFP was 4.58 far below the effluent standard 3 mg/L and TCLP standard 15 mg/L. The properties of sludge were further investigated by X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and Superconducting Quantum Interference Device (SQUID). The pattern of XRD indicated that the major structures were Fe3O4 and CuFe2O4; the figure of SEM showed that the surface of sludge was composed of many round particles and the distribution of particle size was from 50 nm-100 nm; the magnetic property analyzed by SQUID showed that the saturation moment was 62.85 emu/g. In the research of sludge applied in catalytic incineration, the o-xylene conversion was 97 % by sludge but only 31 % by quartz sand at 400 ¢J. Moreover, in the 72 hr-decay test of catalyst, the results clearly indicated that the performance did not obviously decline and there were no any byproducts but CO2. Therefore, the investigation revealed that the sludge had great potential in catalytic reaction. The catalytic performance of various ferrospinels generated from different manufactured conditions was also studied. Through the screening of catalysts, the order of various ferrospinels activity was Cu-ferrite > Mn-ferrite > ferrite ¡Ü Zn-ferrite and the most effective Cu-ferrite was manufactured at pH= 9 and T= 90 ¢J. After 72 hr test, the decay of catalyst was not also found. In the examination of Cu-ferrite physical property, the XRD pattern showed that the structure was CuFe2O4; the figure of SEM illustrated that there was no difference between the surface of fresh and used catalyst; the magnetic property measured by SQUID showed that the saturation moment was 30.89 emu/g.

The synthetic approach was developed for the preparation of N-bridged diiron phthalocyanines substituted by different electron-withdrawing alkylsulfonyl substituents. Six novel phthalocyanines bearing small (methylsulfonyl, ethylsulfonyl and hexylsulfonyl) and bulky (t-butylsulfonyl, adamantylsulfonyl and cyclohexylsulfonyl) substituents have been prepared and characterized by electrospray ionization mass spectrometry (ESI-MS), UV-Vis, FT-IR and EPR. Two complexes (with hexylsulfonyl and t-butylsulfonyl substituents) were characterized in addition by Mössbauer techniques, X-ray photoelectron spectroscopy (XPS) and Fe K-edge X-ray absorption spectroscopy (XANES, EXAFS, high resolution Kβ emission spectroscopy). It has been evidenced that the electronic state of iron in these complexes depends on the size of the substituents. While N-bridged diiron phthalocyanines having methylsulfonyl, ethylsulfonyl and hexylsulfonyl substituents are cationic (PcFeIVNFeIVPc)+N3- complexes, N-bridged diiron phthalocyanines with bulkier t-butylsulfonyl, adamantylsulfonyl and cyclohexylsulfonyl substituents are formally neutral PcFeIIINFeIVPc species. The catalytic properties of six N-bridged diiron phthalocyanines have been studied, using tert-butyl hydroperoxide (tBuOOH) as the oxidant in the oxidation of toluene, p-xylene as well as in the oxidation of various alcohols. This thesis demonstrates the efficiency of N-bridged diiron phthalocyanines substituted by electron-withdrawing alkylsulfonyl groups as oxidation catalysts, in conditions required by environmental and industrial preoccupations

Submitted by WENDER MESSIATTO DA SILVA (wendermessiatto@yahoo.com.br) on 2018-06-08T16:36:25Z No. of bitstreams: 1 silva_wm_me_Ilha.pdf: 2741794 bytes, checksum: 942a41a5e8d98fe17b8da88fec150d33 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-06-11T14:05:34Z (GMT) No. of bitstreams: 1 silva_wm_me_ilha.pdf: 2741794 bytes, checksum: 942a41a5e8d98fe17b8da88fec150d33 (MD5) / Made available in DSpace on 2018-06-11T14:05:34Z (GMT). No. of bitstreams: 1 silva_wm_me_ilha.pdf: 2741794 bytes, checksum: 942a41a5e8d98fe17b8da88fec150d33 (MD5) Previous issue date: 2018-04-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os impactos ambientais decorrentes de vazamentos em postos de combustíveis têm sido preocupantes para órgãos ambientais ao redor do mundo, sobretudo por deteriorarem a qualidade das águas subterrâneas utilizadas como fonte de abastecimento, sendo os compostos benzeno, tolueno e xilenos (BTX) os de maior preocupação à saúde pública. A biorremediação é uma técnica viável do ponto de vista econômico e ecológico quando se utiliza consórcio microbiano de bactérias e fungos aliado a solução de nutrientes. Este trabalho verificou os efeitos da biorremediação sobre microambientes formados em erlenmenyers contendo solo arenoso fino de textura arenosa fina, bastante comum no noroeste paulista, contaminado por soluções sintéticas de BTX por intermédio de consórcio de microrganismos (bactérias ácido láticas, leveduras, bactérias fototróficas e actinomicetes). O desempenho de um consórcio de microrganismos foi verificado por meio de alterações de pH, teor de umidade, teor de carbono e pela de remoção de BTX do microambiente constituído de solo arenoso fino contaminado por solução sintética de BTX mediante a bioestimulação comparando-se os efeitos do ácido esteárico como surfactante. O uso de ácido esteárico como surfactante prejudicou o processo de biorremediação nos microambientes, com isso a remoção de BTX foi menor do que nos microambientes que não possuíam ácido esteárico. De acordo com resultados deste trabalho, um valor adequado para a aplicação da solução de microrganismos em campo é o de 0,02 mL de solução de microrganismos por cm³ de solo arenoso fino, pois ao se utilizar 6,25 mL de solução de microrganismos para 300 cm³ de solo arenoso fino no período de 7, 30 e 58 dias de experimento foi constatado resultados econômicos e relativamente eficientes no curto prazo. / The environmental impacts resulting to leaks at fuel stations has been worrying for environmental agencies around the world mainly for deteriorating the quality of the groundwater used as a water supply whereby the BTX compounds (benzene, toluene and xylene) the most worrisome public health. Bioremediation is a viable technique because the use of bacterial, fungal and yeast microbial consortia is economic and ecological associated with nutrient solutions. The effects of bioremediation verified through a consortium of microrganisms (lactic acid bacteria, yeasts, phototrophic bacteria and actinomycetes) on microenvironment in enlermeyers containing fine sandy texture lateritic soil, very common in São Paulo northwest region, contaminated by synthetic solutions of BTX. The performance of a consortium of microorganisms verified by pH changes, moisture content and organic carbon content of the microenvironments and the rate of BTX removal in fine sandy soil contaminated with BTX synthetics solutions by bioestimulation, comparing the effects of stearic acid as surfactant. The use of stearic acid as a surfactant impaired the bioremediation process in the microenvironments, thus the removal of BTX was lower than in microenvironments that did not possess stearic acid. According to the results of this work, a value of microorganisms per cm³ of microorganisms solution to the soil is 0.02 mL of microorganisms solution 300 cm³ of fine sandy soil in the period of 7, 30 and 58 days of experiment was confirmed and is useful in the short term.

Orientador: William Deodato Isique / Resumo: Os impactos ambientais decorrentes de vazamentos em postos de combustíveis têm sido preocupantes para órgãos ambientais ao redor do mundo, sobretudo por deteriorarem a qualidade das águas subterrâneas utilizadas como fonte de abastecimento, sendo os compostos benzeno, tolueno e xilenos (BTX) os de maior preocupação à saúde pública. A biorremediação é uma técnica viável do ponto de vista econômico e ecológico quando se utiliza consórcio microbiano de bactérias e fungos aliado a solução de nutrientes. Este trabalho verificou os efeitos da biorremediação sobre microambientes formados em erlenmenyers contendo solo arenoso fino de textura arenosa fina, bastante comum no noroeste paulista, contaminado por soluções sintéticas de BTX por intermédio de consórcio de microrganismos (bactérias ácido láticas, leveduras, bactérias fototróficas e actinomicetes). O desempenho de um consórcio de microrganismos foi verificado por meio de alterações de pH, teor de umidade, teor de carbono e pela de remoção de BTX do microambiente constituído de solo arenoso fino contaminado por solução sintética de BTX mediante a bioestimulação comparando-se os efeitos do ácido esteárico como surfactante. O uso de ácido esteárico como surfactante prejudicou o processo de biorremediação nos microambientes, com isso a remoção de BTX foi menor do que nos microambientes que não possuíam ácido esteárico. De acordo com resultados deste trabalho, um valor adequado para a aplicação da solução de microrganismos em campo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The environmental impacts resulting to leaks at fuel stations has been worrying for environmental agencies around the world mainly for deteriorating the quality of the groundwater used as a water supply whereby the BTX compounds (benzene, toluene and xylene) the most worrisome public health. Bioremediation is a viable technique because the use of bacterial, fungal and yeast microbial consortia is economic and ecological associated with nutrient solutions. The effects of bioremediation verified through a consortium of microrganisms (lactic acid bacteria, yeasts, phototrophic bacteria and actinomycetes) on microenvironment in enlermeyers containing fine sandy texture lateritic soil, very common in São Paulo northwest region, contaminated by synthetic solutions of BTX. The performance of a consortium of microorganisms verified by pH changes, moisture content and organic carbon content of the microenvironments and the rate of BTX removal in fine sandy soil contaminated with BTX synthetics solutions by bioestimulation, comparing the effects of stearic acid as surfactant. The use of stearic acid as a surfactant impaired the bioremediation process in the microenvironments, thus the removal of BTX was lower than in microenvironments that did not possess stearic acid. According to the results of this work, a value of microorganisms per cm³ of microorganisms solution to the soil is 0.02 mL of microorganisms solution 300 cm³ of fine sandy soil in the period of 7, 30 and 58 days of exper... (Complete abstract click electronic access below) / Mestre

Orientador: Melissa Gurgel Adeodato Vieira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-24T22:58:23Z (GMT). No. of bitstreams: 1 Stofela_SaraKarolineFigueiredo_M.pdf: 3437110 bytes, checksum: 75c3b9d81bd674bc6b2d46a4347ba152 (MD5) Previous issue date: 2014 / Resumo: Resíduos contaminados com compostos orgânicos, sendo grande parte formados por hidrocarbonetos aromáticos, como o benzeno, tolueno e xileno, vem sendo gerados em grandes quantidades nas indústrias e em derramamentos de postos de estocagem de combustíveis. Sendo assim, surge espaço para novas pesquisas de tratamento desses efluentes, como a adsorção em argilas organofílicas. Portanto, o objetivo deste trabalho é avaliar o potencial da argila organofílica Spectrogel na adsorção dos compostos BTX. Para este estudo foram realizados teste de hidratação e expansão em meio orgânico, estudo do efeito do pH, avaliação do potencial de remoção e estudo cinético, por meio de ensaios cinéticos de adsorção monocomposto, bicompostos e tricompostos, estudo de equilíbrio, atráves de ensaios de equilíbrio monocomposto, bicompostos e tricompostos, nas temperaturas de 15, 25 e 35 oC, estudo termodinâmico, caracterização do material adsorvente antes e após os ensaios de adsorção, estudo de regeneração do adsorvente, e análise estatística do processo de adsorção. A argila apresentou uma eficiência de remoção de 95%, 89% e 96% para o benzeno, tolueno e xileno, respectivamente e mostrou que o processo é rápido com no máximo 120 min para atingir o equilíbrio. No estudo cinético, tanto o modelo pseudoprimeira-ordem, quanto o pseudossegunda ordem apresentaram boas correlações. O modelo de difusão intrapartícula e modelo de Boyd indicaram que a adsorção é controlada tanto pela difusão intrapartícula, como pela difusão externa. O estudo de equilíbrio indicou que o xileno é o contaminante com maior afinidade pelo meios adsorvente. Entre os modelos de isotermas utilizados nos ajustes dos dados experimentais, o modelo de Dubinin-Radushkevitch foi o que apresentou melhor correlação para todas as isotermas monocomposto. Para as isotermas bicompostos, o modelo de Freundlich foi o que melhor se ajustou. Os parâmetros termodinâmicos mostraram que o processo de adsorção de BTX em argila Spectrogel é espontâneo e endotérmico. A caracterização do adsorvente após a adsorção dos BTX mostrou que o mesmo é pouco poroso e possui a superfície heterogênea, evidenciando a presença dos compostos BTX e algumas mudanças estruturais no material adsorvente. Por fim, os ensaios de regeneração indicaram a regeneração do adsorvente por meio do eluente etanol / Abstract: Contaminated waste with organic compounds, being largely composed of aromatic hydrocarbons such as benzene, toluene and xylene, has being generated in large quantities in industries and spills fuel storage stations. Thus, it arises space for further research about treatment of these effluents, such as adsorption on organoclay. Therefore, the aim of this study is to evaluate the adsorption of BTX compounds into organoclay Spectrogel. For this study tests of hydration and expansion in organic media and tests of the effect of pH were conducted. Equilibrium study was also performed by tests of mono-component, bi-component and multicomponent solutions at temperatures of 15, 25 and 35 oC. The adsorbent was characterized before and after the adsorption experiments. Finally, the regeneration of the adsorbent through eluents and a statistical study of the adsorption process were also performed. The evaluation of the potential removal provided a removal efficiency of 95%, 89% and 96% for benzene, toluene and xylene, respectively and showed that the process is fast taking a maximum of 120 min to reach equilibrium. In the kinetic study, both the pseudo first order model, as well as pseudo second order model showed a good correlation. The intraparticle diffusion model and Boyd model indicated that adsorption is controlled by both intraparticle diffusion and external diffusion. The equilibrium study indicated that xylene is the most competitive contaminant by active adsorption site. Among the isotherm models used, only the Dubinin-Radushkevitch showed a good correlation for all mono-component isotherms. For bi-component isotherms, the Freundlich model showed the best fit. The thermodynamic parameters indicated that the adsorption process of BTX into clay is spontaneous and endothermic. The characterization of the study showed that the this adsorbent is porous and presents a heterogeneous surface after adsorption and the presence of BTX compounds and structural changes were observed in the adsorbent material after process. The dessorption tests indicated a possible regeneration of the adsorbent using ethanol as eluent.z / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

A series of bench-scale experiments was carried out to determine the rate and efficiency with which benzene and p-xylene, components of gasoline, could be removed from an unsaturated soil by air stripping. Glass columns, 30 cm in length, were packed with soil and wetted to volumetric moisture contents of 10 and 18 percent. Air saturated with one of the volatile organic compounds (VOCs) was used to load the column. Clean air was used to strip the contaminant from the soil. Benzene and p-xylene concentrations in the soil water and air were reduced four orders of magnitude after a few hours (2-8) of stripping. Benzene was removed faster than p-xylene. Air flow was the rate-limiting step early in the stripping, however slow desorption from the soil became rate-limiting as the stripping progressed. As moisture content increased the rate of removal of both contaminants decreased.

Submitted by Adriana Martinez (amartinez@unoeste.br) on 2018-05-21T16:53:33Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Kátia.pdf: 1082341 bytes, checksum: bf243e25171e37a60f802300dab1ff02 (MD5) / Made available in DSpace on 2018-05-21T16:53:33Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Kátia.pdf: 1082341 bytes, checksum: bf243e25171e37a60f802300dab1ff02 (MD5) Previous issue date: 2018-03-21 / Leaks at gas stations cause major problems for the environment, especially with regard to contamination of groundwater and soils. The major problems of oil derivative contamination are attributed to monoaromatic hydrocarbons (BTEX - benzene, toluene and xylene), which are the most soluble and mobile constituents of the gasoline fraction, being the first to reach the water table. In the most recent survey carried out by the State Company of Environmental Sanitation Technology of the State of São Paulo (CETESB), it was identified that more than 85% of the contamination cases in the region of West Paulista are related to waste from fuel stations. The present study evaluated the toxicological potential of exposure of adult male rats to the commercial gasoline / ethanol blend (75/25 by volume), with emphasis on the possible impacts on reproductive morphophysiology. Adult male Wistar rats were allocated into 4 experimental groups (n = 8 / group). The animals received commercial gasoline diluted in corn oil via gavage at doses of 0 (control group- C), 16 (group A - GA), 160 (group B - GB) or 800 mg / kg / day (group C - GC). The reproductive organs were collected and weighed. The sperm parameters evaluated were motility, plasma membrane integrity and acrosomal, mitochondrial activity and morphology. In addition, the epididymis and right testis were collected for sperm counts. Histopathological analysis of the testis and epididymis, spermatogenesis and cell counts. For the machine learning test, different pattern recognition algorithms were used: Artificial Neural Network (ANN), Bayes Classifier (BAY), K-Nearest Neighbors (KNN), Support Vector Machine (SVM) and Optimum Path Forest OPF). The results were compared by ANOVA with Tukey's posterior test, and the Kruskall-Wallis test with Dunn's a posteriori, considering p <0.05. The sperm parameters were reduced in a dose-dependent manner. Mitochondrial activity and acrosomal integrity were decreased in the GC and GB groups in relation to the control group. There was an increase of isolated heads in the GC and GB groups in relation to the control group. Plasma membrane integrity was reduced in GC in relation to the control group. A decrease in the number of mobile spermatozoa with progressive trajectory was observed in the GC and GB groups, in relation to the control group. The daily sperm production was reduced in GC and GB in relation to the control group. In addition, this parameter was lower in GC than in GB. There was a significant delay in transit time in the tail of the epididymis in the GC and GB groups in relation to the control group. The number of Sertoli cells decreased in the GB and GC groups when compared to the CG and GB groups. Histopathological analysis, spermatogenesis and germ cell counts showed no significant difference between the groups. There was presence of pattern with the subdivision of two classes (control group and exposed groups), with better classification with the SVM test and 90% accuracy for control group. Thus, it was concluded that the exposure of rats to different doses of the commercial gasoline / ethanol mixture can alter spermatogenesis and sperm quality, with a recognizable classification pattern of machine learning algorithms. / Vazamentos em postos de combustíveis provocam grandes problemas ao meio ambiente, principalmente no que diz respeito à contaminação de águas subterrâneas e solos. Os maiores problemas da contaminação por derivados de petróleo são atribuídos aos hidrocarbonetos monoaromáticos (BTEX - benzeno, tolueno e xileno), que são os constituintes mais solúveis e mais móveis da fração da gasolina, sendo os primeiros a atingir o lençol freático. No mais recente levantamento realizado pela Companhia Estadual de Tecnologia de Saneamento Ambiental do Estado de São Paulo (CETESB), identificou-se que mais de 85% dos casos de contaminação na região do Oeste Paulista estão relacionados a resíduos de postos de combustíveis. O presente estudo avaliou o potencial toxicológico da exposição de ratos machos adultos à mistura comercial de gasolina/etanol (75/25 em volume), com ênfase nos possíveis impactos sobre a morfofisiologia reprodutiva. Ratos machos Wistar adultos foram alocados em 4 grupos experimentais (n=8/grupo). Os animais receberam gasolina comercial diluída em óleo de milho, via gavagem, nas doses de 0 (grupo controle - C), 16 (grupo A - GA), 160 (grupo B - GB) ou 800 mg/kg/dia (grupo C - GC). Os órgãos reprodutivos foram coletados e pesados. Os parâmetros espermáticos avaliados foram motilidade, integridade da membrana plasmática e acrossomal, atividade mitocondrial e morfologia. Além disso, o epidídimo e testículo direito foram coletados para contagens espermáticas. Também foram realizadas análise histopatológica do testículo e epidídimo, contagens dos estágios da espermatogênese e de células. Para o teste de aprendizado de máquina foram utilizados diferentes algoritmos de reconhecimento de padrões: Artificial Neural Network (ANN), Bayes Classifier (BAY), K-Nearest Neighbors (K-NN), Support Vector Machine (SVM) e Optimum Path Forest (OPF). Os resultados foram comparados por ANOVA com o teste “a posteriori” de Tukey, e o teste de Kruskall-Wallis, com “a posteriori” de Dunn, considerando p<0,05. Os parâmetros espermáticos foram reduzidos de maneira dose-dependente. A atividade mitocondrial e integridade acrossomal foram diminuídas nos grupos GC e GB em relação ao grupo controle. Houve um aumento de cabeças isoladas nos grupos GC e GB em relação ao grupo controle. A integridade de membrana plasmática foi reduzida em GC em relação ao grupo controle. Foi observada uma redução no número de espermatozoides móveis com trajetória progressiva nos grupos GC e GB, em relação ao grupo controle. A produção diária espermática foi reduzida em GC e GB em relação ao grupo controle. Além disso, este parâmetro foi menor em GC em relação a GB. Houve um atraso significativo no tempo de trânsito na cauda do epidídimo nos grupos GC e GB em relação ao grupo controle. O número de células de Sertoli sofreu redução nos grupos GC e GB quando comparado aos grupos controle e GA. A análise histopatológica, contagem dos estágios da espermatogênese e de celulas germinativas não apresentaram diferença significativa entre os grupos. Houve presença de padrão com a subdivisão de duas classes (grupo controle e grupos expostos), com melhor classificação com o teste SVM e 90% de acurácia para o grupo controle. Assim, concluiu-se que a exposição de ratos a diferentes doses da mistura comercial de gasolina/etanol pode alterar a espermatogênese e a qualidade espermática, com reconhecível padrão de classificação de algoritmos de aprendizado de máquina.

The increased use of alcohols as gasoline additives, and possible substitutes, has prompted the investigation of the fate of gasoline/alcohol mixtures in the environment. In situ bioremediation is one technique that can successfully be applied to remove ground water contaminants particularly in situations where the adsorptive capacity of the soil plays a major role. Frequently, enhanced in situ bioremediation techniques rely on indigenous microorganisms to degrade ground water contaminants; this technique may sometimes include the addition of acclimated bacteria. In this study, soil microcosms were constructed in order to simulate the conditions found in a saturated aerobic aquifer. The biodegradation potential of methanol, benzene, and m-xylene was investigated. Uncontaminated soil from the surface, 12, 16.5, and 18 foot depths was utilized to observe the differences in microbial responses throughout the soil profile. The biodegradation potential of the indigenous microbiota was determined and compared to that of benzene acclimated bacteria, for all the compounds in the mixture. To observe the impact that chemical and physical soil characteristics may have on microbial responses, soils from each depth were classified on the basis of their particle size, moisture content and pH. Substantial methanol, benzene, and m-xylene biodegradation by the indigenous microorganisms occurred in all subsurface soils. While methanol was readily biodegradable over concentrations ranging from about 80 mg/L to about 200 mg/L, benzene inhibited methanol biodegradation at about 125 mg/L in all soil depths. The addition of benzene acclimated bacteria considerably increased the biodegradation rates of all compounds in the mixture. Such increases in biodegradation rates may be attributed to the activities of both groups, the indigenous microorganisms and the benzene acclimated bacteria. The results obtained by this study suggest that biodegradation of methanol, benzene, and m-xylene can readily occur in a saturated aerobic subsurface environment. The physical and chemical properties of a ground water aquifer seem to have a marked effect on microbial responses, and consequently on the biodegradation potential of water contaminants. / Master of Science

Thesis (M. Tech.) - Central University of Technology, Free State, 2006 / Electron microscopy plays an important role in diagnostic histopathology. When this investigation is anticipated, extra tissue is submitted directly for electron microscopy. However, often it is decided only later in a problematic case to perform this investigation and then the only tissue available is embedded in the routine laboratory’s paraffin block. This tissue has to be retrieved from the wax and this entails using a clearing agent before the rest of the electron microscopy method can be implemented. Traditionally xylene is the agent that is used but has the disadvantage of being extremely toxic. This study compared the morphological effects of a relatively new and non toxic clearing agent, Tissueclear®, with that of xylene. Exposure of tissue to clearing agents for 30 minutes and overnight was performed to assess whether Tissueclear® gave better results in the long term than xylene, in the hope that the laboratory turn around time could be improved and the amount of toxic reagents used in the EM laboratory will be reduced. A second part of the study involved a questionnaire submitted to laboratory staff to assess their knowledge of xylene toxicity. Of the 325 cases submitted for electron microscopy at Universitas Hospital between January 2004 and July 2005, 140 of these had to be retrieved from paraffin wax. Four specimens were prepared from each case. Two were processed in xylene for 30 minutes and overnight and two in Tissueclear® for 30 minutes and overnight. The specimens were evaluated for consistency and resin compaction as well as ultrastructural preservation of the cell membrane, cytoplasmic content and extracellular material. The results showed that Tissueclear® and xylene gave comparable results after 30 minutes and that Tissueclear® was superior after overnight processing. This meant that a specimen submitted for electron microscopy would be processed immediately without waiting for the following morning as was the case with xylene and that the processing time for such a specimen had been shortened from 3 to 2 days. It also meant that the laboratory staff was exposed to one less toxic reagent. The results on the questionnaire showed that there were large areas of ignorance regarding toxicity as well as appropriate safety procedures that need to be followed in the laboratory. It is hoped that this study will improve awareness in this regard and encourage the use of other newer less toxic reagents.

A small-scale model of a CVD reactor was built. Axial and radial of major species concentrations and temperature profiles were obtained with a micro gas chromatograph and a fine thermocouple. Those temperature and species concentrations revealed detailed thermal and chemical structures of the CVD reactor. The concentrations of argon plus hydrogen, methane, and C2Hx (C2H2 + C2H4 + C2H6) resulting from xylene decomposition were measured along the CVD at different temperatures. Ferrocene was added to xylene to investigate the effect of a catalyst on composition profiles. The results with ferrocene indicated an increase in CH4 and C2Hx concentrations. At 1000 C and above, the increase of C2Hx concentration is higher than that for CH4. The effect of ferrocene was very minor on the concentration of the gases. Finally composition and temperature profiles were measured and plotted for the radial direction at X=75 cm and T=1200 C. The overall rate constant for the gas-phase reaction was calculated based on the measured species concentration data using the Benson and Shaw reaction mechanism. Our study showed that the Benson and Shaw mechanism could be used in the temperature range lower than 800 C. Also the effect of hydrogen in the syntheses of CNTs, in the CVD reactor using xylene and ferrocene, was studied. Both single-step and two-step methods were applied. In the single-step method, the ferrocene was dissolved in the xylene. In the two step-method the catalyst preparation step was performed first; ferrocene powder was placed in the preheater for a certain period of time and carried by a mixture of argon and hydrogen at fixed concentration to get catalyst nanoparticles deposited on the reactor wall. Xylene then was injected to the reactor. To study the effect of hydrogen, the synthesized materials were observed by SEM and TEM. The results showed that the presence of hydrogen is essential for CNTs to be synthesized by the CVD method, and also the concentration of hydrogen in the reactor has a great effect on the quality of CNTs. The yield of CNTs in the two-step method was slightly higher than that in the one-step method.