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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Influência do suporte em catalisadores de Ni aplicados à reforma a vapor do ácido acético / Influence of support on Ni catalysts applied to acetic acid steam reforming

Cordeiro, Luciano 18 July 2016 (has links)
O hidrogênio é considerado uma das principais alternativas aos combustíveis fósseis. Dentre os processos para sua produção, a reforma a vapor do bio-óleo é uma das mais promissoras. Sendo o ácido acético um dos componentes majoritários do bio-óleo, ele vem sendo usado como molécula modelo na reforma a vapor. Porém, problemas como baixo desempenho catalítico e formação de coque ainda precisam ser contornados. Nesse sentido, o suporte utilizado tem um papel importante. No entanto, ainda não foi esclarecido quais propriedades do suporte contribuem mais para a eficiência catalítica. Neste trabalho, a reforma a vapor do ácido acético foi avaliada sobre catalisadores de níquel. Foram utilizados catalisadores constituídos de Ni0 ancorado em suportes com diferentes propriedades (MgO, ZrO2, TiO2 e Al2O3). A área superficial do suporte e a forte interação Ni-suporte foram fundamentais para a dispersão metálica dos catalisadores. A dispersão metálica e capacidade do suporte ativar a molécula de H2O foram as propriedades que aparentemente mais influenciaram no desempenho catalítico. Para as reações realizadas a 500 °C, a conversão do ácido acético, seletividade para H2 e formação de coque foram basicamente influenciadas pela dispersão metálica. Nas reações realizadas a 600 °C, a formação de coque foi menor para os catalisadores com maior dispersão metálica. A conversão do ácido acético e seletividade para H2 a 600 °C foram influenciadas pela dispersão metálica dos catalisadores, mas aparentemente a capacidade do suporte ativar a molécula de H2O foi o que mais contribui. O catalisador 10Ni/Al2O3 apresentou a maior dispersão metálica e em reações a 500 °C isso levou a uma alta conversão e alta seletividade para H2 com baixa formação de coque. O catalisador 10Ni/MgO apresentou desempenho regular em ambas as temperaturas. Já o catalisador 10Ni/TiO2 teve o pior desempenho independente da temperatura, devido à baixa dispersão metálica. Apesar da alta formação de coque devido à dispersão metálica relativamente baixa, o catalisador 10Ni/ZrO2 exibiu alta conversão e foi o mais seletivo para H2 a 600 °C, provavelmente pela capacidade do ZrO2 ativar a molécula de H2O. / Hydrogen (H2) is considered one of major alternatives to fossil fuels. Among the processes for H2 production, steam reforming of bio-oil is one of the most promising. As acetic acid is present in large amounts in bio-oil, it is used as model molecule in steam reforming reactions. However, problems such as low catalytic performance and coke formation yet need to be solved. In this sense, supports used display important role. However, it is not clear what support characteristics contribute more to catalytic properties. Here, acetic acid steam reforming was carried out over Ni catalysts. It were used catalysts consisting by Ni0 anchored in supports with different properties (MgO, ZrO2, TiO2 and Al2O3). Surface area of support and strong Ni-support interaction were key to metal dispersion of catalysts. Metal dispersion and the capacity of support to activate H2O molecule were apparently the properties that more influence the catalytic performance. For reactions carried out at 500 °C acetic acid conversion, H2 selectivity and coke formation were primarily influenced by metal dispersion. In reactions performed at 600 °C coke formation was lower for catalysts with higher metal dispersion. Acetic acid conversion and H2 selectivity at 600 °C were influenced by metal dispersion of catalysts, but apparently the ability of support to activate H2O molecule was the most important. 10Ni/Al2O3 showed higher metal dispersion and at 500 °C this led to a high conversion and high selectivity for H2 with low coke formation. 10Ni/MgO catalyst showed intermediate performance at both temperatures. Already 10Ni/TiO2 catalyst had the worst performance independent of temperature due to low metal dispersion. Despite the high coke formation, due to the relatively low metal dispersion, 10Ni/ZrO2 catalyst exhibited high conversion and was the most selective to H2 at 600 °C, probably due to the ability of ZrO2 to activate H2O molecules.
82

Avaliação de agentes bióticos e abióticos aplicados em pós-colheita na proteção de uva Itália contra Botrytis cinerea /

Camili, Elisangela Clarete, 1977- January 2004 (has links)
Resumo: Perdas significativas ocorrem durante o armazenamento e a comercialização de uvas de mesa devido, principalmente, à ocorrência do mofo cinzento (Botrytis cinerea Pers.:Fr.) e, visando o controle de patógenos emprega-se, geralmente, o dióxido de enxofre (SO2). Diante da restrição crescente ao uso de produtos químicos em pós-colheita, tem ocorrido considerável interesse em métodos alternativos de controle. Este trabalho teve como principal objetivo avaliar os efeitos dos agentes bióticos (Lentinula edodes (Berk.) Pegler e Agaricus blazei (Murril) ss. Heinem) e abióticos (quitosana, ácido acético e irradiação UV-C), possíveis indutores de resistência, na proteção de uva Itália pós-colheita contra B. cinerea. In vivo, avaliou-se o efeito direto e indireto dos agentes de controle através do tratamento dos cachos de uva, antes e após a inoculação com o patógeno. Utilizaram-se extratos aquosos dos cogumelos A. blazei (linhagem ABL 29) e L. edodes (linhagem LED 17) nas concentrações de 0,0; 2,5; 5,0; 10,0; 20,0 ou 40,0 % (v/v); quitosana nas concentrações de 0,00; 0,25; 0,50; 1,00; 1,50 e 2,00 % (v/v); vapor de ácido acético a 0,0; 2,6; 5,2; 10,5 ou 21,0 mg.L-1 e; irradiação UV-C (254 nm) nas doses de 0,00; 0,84; 1,30; 2,40; 3,60; 4,80 e 7,50 kJ.m-2. Para inoculação, em cada cacho foram feridas 10 bagas, fazendo-se um furo por baga de 2 mm de profundidade, procedendo-se em seguida, a aspersão da suspensão de conídios ( 105 conídios.mL-1) de B. cinerea. Após os tratamentos, os cachos foram mantidos a 25 1 C / 80-90 % UR; quando avaliações de incidência e severidade foram realizadas diariamente, além de análises físicas e físico-químicas da uva. Avaliações in vitro do efeito dos agentes de controle sobre o patógeno também foram realizadas analisando-se o crescimento micelial e a germinação dos conídios de B. cinerea... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Significant losses of table grapes occur during storage and commercialization due mainly to the occurrence of gray mold (Botrytis cinerea Pers.:Fr.), and sulfur dioxide (SO2) is frequently used to control such pathogens. Due to increasing restrictions on the postharvest use of chemical products, considerable interest in alternative control measures has arisen. The main objective of this study was to evaluate the effects of biotic (Lentinula edodes (Berk.) Pegler and Agaricus blazei (Murril) ss. Heinem) and abiotic (chitosan, acetic acid and UV-C irradiation) agents as possible resistance inducers in 'Itália' grapes, aimed at post-harvest protection against B. cinerea. The direct and indirect effects of these control agents were evaluated in vivo by treating bunches of grapes before and after inoculation with the pathogen. Aqueous extracts of the mushrooms A. blazei (strain ABL 29) and L. edodes (strain LED 17) were used in the concentrations of 0.0; 2.5; 5.0; 10.0; 20.0 and 40.0 % (v/v); chitosan at 0.00; 0.25; 0.50; 1.00; 1.50 and 2.00 % (v/v); acetic acid vapor at 0.0; 2.6; 5.2; 10.5 and 21.0 mg.L-1 and UV-C (254 nm) irradiation at doses of 0.00; 0.84; 1.30; 2.40; 3.60; 4.80 and 7.50 kJ.m-2. For inoculation, 10 grapes in each bunch were injured by piercing the grape to a depth of 2 mm, followed by spraying with the inoculum of B. cinerea conidia ( 105 conidia.mL-1). After the treatments, the bunches were kept at 25 1 C / 80-90 % RH, carrying out daily evaluations of disease incidence and severity, as well as physical and physical-chemical analyses of the grapes. In vitro evaluations of the effect of the control agents were also carried out based upon mycelial growth and germination of B. cinerea conidia. The results showed that the extracts of A. blazei and L. edodes failed to control deterioration by B. cinerea in 'Itália' grapes when applied after inoculation. However, the A. blazei... (Complete abstract, click electronic access below) / Orientador: Eliane Aparecida Rodrigues da Silva / Coorientador: Sérgio Florentino Pascholati / Banca: Nilton Luiz de Souza / Banca: José Maria Monteiro Sigrist / Mestre
83

"Avaliação da atividade antimicrobiana e citotóxica in vitro do vinagre a ácido acético: perspectiva na terapêutica de feridas" / In vitro evaluation of antimicrobial and cytotoxicity activities of vinegar and acetic acid: perspectives for wound therapeutics Ribeirão Preto.

Iwa Keiko Aida Utyama 29 September 2003 (has links)
O uso correto de produtos químicos com ação antimicrobiana na terapêutica de feridas tem sido uma das preocupações dos profissionais da saúde. A temática em questão representa uma séria problemática agravada, principalmente, pela diversidade de opções, o que traz a insegurança sobre qual é a mais indicada, bem como, pelo uso indiscriminado o que pode resultar na seleção de cepas resistentes. Diante do exposto, foi estabelecido como objetivos: avaliar in vitro a atividade antimicrobiana do ácido acético e do vinagre por meio da Técnica de Difusão de Poço sobre as cepas de Pseudomonas aeruginosa, E. coli e Staphylococcus aureus; determinar a Concentração Inibitória Mínima (CIM); e revelar a citotoxicidade dos referidos produtos sobre Artemia salina Leach. Para análise estatística foi usado o teste de variância ANOVA – ONEWAY seguida do teste de comparações múltiplas; com nível de significância &#61537; = 5%. Assim sendo, pelo método de difusão de poço o vinagre branco, tinto (30,0 e 25,0%) e o ácido acético a 1,0 são mais eficazes que o ácido acético a 0,7%, vinagre branco e tinto a 10,0% (p<0.05) sobre as cepas de Pseudomonas aeruginosa e Escherichia coli. Vale considerar que os produtos analisados não apresentaram ação antimicrobiana sobre Staphylococcus aureus. A Concentração Inibitória Mínima (CIM) do ácido acético nas cepas avaliadas foi a 0,25%, e do vinagre branco a 2,0% para Pseudomonas aeruginosa e Escherichia coli sendo que para Staphylococcus aureus a 3,0%. As cepas de P. aeruginosa e E. coli foram todas inibidas pelo vinagre tinto a 1,5%, e sobre as de Staphylococcus aureus a 3,0%. Ainda, com relação a CIM dos produtos químicos testados, não se verificou diferença entre cepas de Staphylococcus aureus hospitalar e comunidade. O ácido acético foi citotóxica em todas as concentrações estudadas. Já, o vinagre branco e tinto em 0,25% e 0,125% não apresentaram citotoxicidade. Ainda que, não tenha sido a preocupação nesse momento de buscar correlação entre os dados desse estudo com o uso in vivo é importante atentar que tais produtos têm sido amplamente utilizados como agente antimicrobiano no tratamento de feridas, e muitas vezes em concentrações elevadas que podem causar danos aos tecidos dificultando, assim, o processo de cicatrização. A nosso ver é premente despertar nos profissionais da saúde a consciência crítica-reflexiva em relação à utilização das evidências científicas de maneira que possam analisar e aplicar com critério os resultados das pesquisas em prol da qualidade da assistência à saúde. / One of the concerns of health professionals has been the correct use of chemical products with antimicrobial action on wound therapeutics. This issue represents a serious problem, which is made even worse due to the facts that there is a diversity of options of products, which builds insecurity in regards to which product is more appropriate, and there is an uncontrolled use that may result in the selection of resistant species. In this sense, we set the following goals for this study: perform an in vitro assessment of the antimicrobial activity of acetic acid and vinegar using the Technique of Diffusion of Well on strains of Pseudomonas aeruginosa, E. coli, and Staphylococcus aureus; determine the Minimal Inhibitory Concentration (MIC); and reveal the cytoxicity of the referred products over Artemia salina Leach. ANOVA – ONEWAY test was used for statistic analysis, followed by the multiple comparison test; with a significance level &#61537; = 5%. By the well diffusion technique, the white vinegar, red vinegar (30 and 25%), and the acetic acid at 1.0 % are more effective than the acetic acid at 0.7%, white and red vinegar at 10% (p<0,05) over the strains of Pseudomonas aeruginosa and Escherichia coli. The analyzed products did not present antimicrobial actions over Staphylococcus aureus. The Minimal Inhibitory Concentration for the acetic acid on the species was 0.25%. For white vinegar on Pseudomonas aeruginosa and Escherichia coli was 2.0%, and 3.0% on Staphylococcus aureus. All P. aeruginosa and E. coli were inhibited by red vinegar at 1.5%, and at 3.0% for Staphylococcus aureus. In regard to the MIC of the tested chemical products, no difference was found between the hospital and community Staphylococcus aureus. Acetic acid was cytotoxic in all studied concentrations, while white and red vinegar in 0.25% and 0.125% did not show any cytoxicity. Although this study was not concerned with finding a relation among the study’s data with the in vivo use, it is important to observe that such products have been largely used as antimicrobial agents for wound treatment, at concentrations often so high that human tissue might suffer damage; thus hindering the healing process. It is, therefore, essential to stimulate health professionals a critical-reflexive consciousness regarding the use of scientific evidence in a way to analyze and apply the research outcomes in favor of a quality health care.
84

Efeito do pH e do ácido acético sobre a produção de bioinseticida por Bacillus thuringiensis a partir de glicerol proveniente da fabricação de biodiesel / Effect of pH and acetic acid on bioinsetice production by Bacillus thuringiensis using glycerol from biodiesel synthesis

Marta Heloisa dos Reis Chagas 05 October 2012 (has links)
Bacillus thuringiensis é uma bactéria do solo, gram-positiva, que se destaca pela capacidade de sintetizar um cristal protéico, adjacente ao esporo, responsável pela ação tóxica contra diversas espécies de dípteros, como a larva do mosquito Aedes aegypti, o qual é o principal vetor da dengue. A dengue hoje é uma das doenças de maior preocupação para as agências de saúde brasileiras, uma vez que o Brasil possui temperatura e condições socio-econômicas que favorecem proliferação do mosquito transmissor. O Brasil se destaca por desenvolver combustíveis alternativos aos combustíveis de origem petrolífera, como etanol e biodiesel. Porém, durante a reação de transesterificação de óleos/gorduras para a produção de biodiesel é gerado também glicerina e, por não haver uma demanda deste sub-produto no mercado mundial, seu destino se tornou um problema e um desafio para as indústrias de biodiesel. Logo, desenvolver um bioinseticida para o combate da dengue empregando a glicerina como fonte de carbono é uma forma de encontrar novas aplicações para a glicerina e contribuir para o controle de uma doença de impacto nacional. Estudos realizados comprovaram que o ácido acético é um composto produzido e consumido pelas células de Bacillus thuringiensis durante seu crescimento. Além disso, apresenta papel fundamental para a produção de um composto chamado poli-?-hidroxibutirato (PHB), que é fundamental no fornecimento de energia para a síntese da toxina. No presente trabalho estudou-se o efeito do ácido acético sobre o crescimento de Bacillus thuringiensis e sobre a atividade larvicida do meio fermentado contra larvas de Aedes aegypti. Foram avaliadas as concentrações de 1 g/L, 3 g/L e 5 g/L de ácido acético nas seguintes fases: (i) início da fermentação, (ii) ponto de valor mínimo de pH e (iii) ponto de desaceleração do aumento do pH. Os ensaios foram realizados em frascos Erlenmeyer de 1000 mL em incubadora de movimento recíproco. Os resultados obtidos demonstraram que a adição de ácido acético no início e no tempo igual a 10 horas de fermentação favorece o crescimento celular e a produção de toxinas. O resultado mais expressivo de produção de toxinas foi obtido com adição de 5 g/L de ácido no início da fermentação. Neste ensaio o resultado de porcentagem de morte de larvas foi 8 superior ao resultado encontrado no ensaio sem adição de ácido (ensaio controle). Já no ensaio com adição de ácido com 20 horas de fermentação foi observada a maior concentração celular máxima, porém, obteve-se uma menor atividade larvicida do meio fermentado, comparado com o ensaio controle. / Bacillus thuringiensis is a gram-positive soil bacterium that is distinguished by the ability of synthesizing a protein crystal adjacent to the spore. This protein is responsible for the toxic action against several species of Diptera, as the larvae of the Aedes aegypti mosquito, which is the main vector of dengue. As Brazil possesses temperature and socioeconomic conditions that favors proliferation of the dengue transmitting mosquito, it is one of the major concerns to health agencies in Brazil. Brazil stands out for developing alternative fuel sources to petroleum fuels such as ethanol and biodiesel. However, during the transesterification reaction of oils/fats for the production of biodiesel glycerin is also generated. As there is no demand for this sub-product in the global market, its fate has become a problem and a challenge for the biodiesel industry. Therefore the development of an insecticide for fighting dengue using glycerol as the carbon source is a way to find new applications for glycerin and to contribute to the control of a disease with nationwide impact, considered a public health problem. Studies have shown that acetic acid is a compound produced and consumed by Bacillus thuringiensis\' cells during their growth. Moreover, it presents a major role in the production of a compound called poly-?-hydroxybutyrate (PHB), which is critical for providing energy for the toxin synthesis. In the present study, it was studied the effect of acetic acid on the growth of Bacillus thuringiensis and on the larvicidal activity of the fermented broth on the larvae of Aedes aegypti. The concentrations tested were 1 g/L, 3 g/L and 5 g/L of acetic acid, added in the following stages: (i) beginning of the fermentation, (ii) time of minimum pH value and (iii) time of deceleration of the increasing pH value. The assays were performed in 1000 mL Erlenmeyer flasks in a reciprocating motion shaker. The results showed that the addition of acetic acid at the beginning and at 10 hours of fermentation improves cell growth and toxin production. The most significant result regarding toxin production was achieved with the addition of 5 g/L of acid at the beginning of the fermentation. In this assay the net percentage of killing of the larvae was eight times higher than the results found in the test without the addition of acid (control test). For the test in which acetic acid was added at 20 hours of fermentation it was observed a higher cellular concentration, however, there was a lower larvicidal activity of the fermented broth, compared to the control test.
85

Reduction of Visceral Fat in Response to Consumption of Red Wine Vinegar

January 2019 (has links)
abstract: Objectives: To investigate the potential of vinegar supplementation as a means for reducing visceral fat in healthy overweight and obese adults, and to evaluate its effects on fasting blood glucose and fasting insulin. Subjects and Methods: Forty-five sedentary overweight and obese adult participants with a waist circumference greater than 32 inches for women and 37 inches for men were randomly assigned to one of two groups, the vinegar group (VIN, n=21) or the control group (CON, n=24), and instructed to consume either two tablespoons of liquid red wine vinegar (3.6g acetic acid) or a control pill (0.0225g acetic acid) twice daily at the beginning of a meal for 8 weeks. Participants were also instructed to maintain normal diet and physical activity levels. Anthropometric measures, dual-energy x-ray absorptiometry (DXA) scans, blood samples, and 24-hour dietary recalls were collected at baseline and at end of trial. A compliance calendar was provided for daily tracking of vinegar supplementation. Results: Compliance to vinegar supplementation averaged 92.7 ±13.3% among the VIN group and 89.1 ±18.9% among the CON group. There were no statistically significant differences in anthropometric measurements between baseline and week 8: weight (P=0.694), BMI (P=0.879), and waist circumference (P=0.871). Similarly, DXA scan data did not show significant changes in visceral fat (P=0.339) or total fat (P=0.294) between baseline and week 8. The VIN group had significant reductions in fasting glucose (P=0.003), fasting insulin (P <0.001), and homeostatic model assessment of insulin resistance scores (P <0.001) after treatment. Conclusions: These data do not support the findings from previous studies that indicated a link between vinegar supplementation and increased fat metabolism, specifically visceral fat reduction. / Dissertation/Thesis / Masters Thesis Nutrition 2019
86

Synthesis of Novel Cysteine Peptide Nucleic Acid (CPNA)

Ajmera, Mehul J 03 December 2007 (has links)
Many diseases are caused due to abnormalities in production of specific protein. Across this protein the conventional lock and key mechanism shows binding at the specific cites of protein. However use of antisense technology can prevent formation of protein. It does so by binding to mRNA and prevents transcription. The structural modifications lead to synthetic molecules with 18-mer units which show significant improvement in binding properties, this gives birth to a new class of oligomers called Peptide Nucleic Acid (PNA). We herein report cysteine based PNA called CPNA.
87

A Molecular view of inital Atmospheric Corrosion : In situ surface studies of zinc based on vibrational spectroscopy

Hedberg, Jonas January 2009 (has links)
Atmospheric corrosion takes place on most metals as they interact with thesurrounding environment. A degradation of the metal is the common result,which often leads to a shortened lifespan of the material. Hence, knowledge onthe fundamental interaction between a gas containing corrosive constituentsand a metal surface, which is the starting point of atmospheric corrosion, isimportant in many contexts. As the nature of atmospheric corrosion is inherentlycomplex, it imposes demands on the analytical studies that are neededin order to understand the fundamentals on a molecular level. Consequently,in-situ vibrational techniques, providing molecular information, have beenutilized in this work to study atmospheric corrosion by targeting the initialstages of the interaction between corrosive air and a metal surface. The initialstages (from minutes until days of exposure) were studied as these havea large influence on the atmospheric corrosion for prolonged exposure times. More specifically, the interaction between humidified air to which organicacids were added, and zinc was targeted in order to address a situation inindoor atmospheric corrosion, where organic acids are of importance. Zinc isa constituent in e.g. brass, which is an alloy used in many indoor applications. A systematic investigation utilizing complementary acting vibrational techniquesthus enabled detailed information on the mechanisms of the onsetof atmospheric corrosion of zinc induced by acetic and formic acid. Corrosionproducts of both two dimensional and three dimensional character couldbe separately studied by combining VSFS (interface sensitive), IRAS (nearsurfacesensitive), and CRM (bulk sensitive). The Zn surface was found to be heterogeneous with different hydroxylgroups present on the surface. As this surface was exposed to formic or aceticacid, the OH groups on the surface were rapidly displaced in a ligand exchangewith formate or acetate. These ligands, organised in two dimensionalstructures, promoted corrosion by weakening the bonds of the Zn atoms totheir surrounding matrix. The subsequent growth of three dimensional corrosion products, Zn hydroxyacetate and formate, observed within short exposure times of Zn exposedto acetic and formic acid, was found to be electrochemical in nature.Cathodic areas consisting of more crystalline ZnO were observed. The potentialdifference between these more noble areas on the surface and those of lessnoble character created an electrochemical cell, initiating release of Zn ionsinto the aqueous adlayer in the anodic reactions. These Zn ions precipitatedas localised corrosion products. The cathodic areas increased the local pHon the surface, thereby promoting precipitation in their vicinity. The resultson initial stages of this type of corrosion were found to have similarities withprevious field studies of Zn exposed to real indoor environments. One way to decrease the corrosion rate of zinc is by adsorbing a corrosioninhibitor to the metal surface in order to protect it. As a model for sucha corrosion inhibitor, octadecanethiol (CH3(CH2)17SH) was seen to provideincreased corrosion protection of both reduced and oxidised Zn substrates byforming an adsorbed surface layer with an ordered structure. / QC 20100719
88

A Study on Photocatalytic Treatment of Acetic Acid Wastewater by Nanostructured Film of TiO2

Tsai, Ming-hsiu 07 September 2004 (has links)
In the work, photocatalytical treatment of acetic acid wastewater by nanostructured film of TiO2 under ultra-violet ¡]UV¡^ light illumination was studied. Nanosized TiO2 suspension was prepared by the sol-gel process. Then it was dip-coated on indium tin-oxide¡]ITO¡^glass, which could be used as the anode if applicable. Effects the UV light intensity, UV light wavelength, reactive area of TiO2 film, solution pH, and applied bias voltage on photocatalysis efficiency of acetic acid in term of COD removal were studied in this work. Experimental results have shown that a pseudo first-order kinetics was obeyed in all tests. In this study UV light of 312nm outperformed that of 365nm ¡]15.3¢H vs. 11.0¢H¡^. UV light intensity of 20W was also found to be superior to 10W with COD removal of 11.0¢H against 6.7¢H. COD removal at pH¡×3.18 was about 3.6 times greater as compared with that of at pH=9.98. When the reactive area of TiO2 film was increased to three times, the COD removal was almost doubled. An applied external voltage was found to enhance the removal of COD. When an external voltage of 15V was applied, the COD removal was increased to 84.6¢H. It is ascribed to an external voltage would prevent or lower the extent of electron-hole recombination. In this work, the pseudo first-order reaction rate equation K¡¬=1.7679(COD)-0.7547 was obtained for various concentrations of acetic acid tested.
89

Organic Acids Production From Cheese-whey

Turkmenoglu, Secil 01 June 2006 (has links) (PDF)
In this study, production of organic acids from cheese-whey was studied. Optimization of organic acids production was performed in semi-batch and batch reactors. Two sets of experiments were performed. First set of experiments were performed in semi-batch reactors for the optimization of organic loading rate (OLR) and hydraulic retention time (HRT). As a result of Set 1 experiments optimum OLR was found to be 15 g COD l-1. Second set of experiments were performed in batch reactors by using the optimum OLR found in Set 1 experiments. Set 2 experiments were conducted to study the effect of using different seed cultures and Basal Media (BM) on Volatile fatty avid (VFA) production. Main acidogenesis products were acetic acid (Hac), butyric acid (Buty) and propionic acid (HPr) with smaller quantities of i-butyric acid (i-Buty), valeric acid (Val) and caproic acid (Cap). It was seen that BM had a suppressive effect on ethanol (EtOH) production while it stimulated the VFA production. Higher VFA productions and variety of VFA types were observed in Test Reactors seeded with acidogenic culture (R3 and R6).
90

Fate Of Nonylphenol Compounds In Aerobic Batch Reactors

Omeroglu, Secil 01 May 2012 (has links) (PDF)
Today, numerous studies indicate the presence of synthetic organics such as nonylphenol (NP) compounds in wastewater. NP compounds are a group of chemicals including nonylphenol, nonylphenol polyethoxylates (NPnEO) and nonylphenoxy polyethoxy acetic acids (NPnEC). Since NP compounds have significant industrial, commercial and domestic use, they enter environmental systems and reach human beings from various pathways. Their presence is of concern because they are toxic, carcinogenic and endocrine disrupting due to their ability to mimic oestrogen hormone. The information available on the degradation of NPnEOs, is such that degradation starts with the reduction of ethylene oxide units, resulting in the formation of nonylphenol, nonylphenol mono- or diethoxylate (NP1EO and NP2EO) and nonylphenoxy acetic acid (NP1EC). Although their fate during wastewater treatment was investigated in the past, not many research investigating their fate in sludge treatment can be found. Therefore, the objective of this study is first to come up with reliable extraction and measurement methods for NP compounds and then to investigate the fate of NP2EO in aerobic digesters. After the development of techniques for the extraction and measurement of NP compounds, aerobic reactors spiked with NP2EO were operated. The samples were analyzed for solids content, COD, pH and NP compounds. The results showed that NP2EO degrades rapidly under aerobic conditions. As time proceeded, NP1EC formation was observed with the degradation of NP2EO, and NP1EC became the dominant specie. The solids concentration measurements showed that concentration of NP compounds did not affect the efficiency of aerobic digesters.

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