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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

Comportamento de sistemas pós-filtros adsorvedores na remoção de compostos orgânicos precursores e subprodutos da desinfecção. / Behavior of post-filter adsorbers in the removal of organic precursors and disinfection byproducts.

Pereira, Claudia Mota Santos 14 August 2009 (has links)
O presente trabalho teve como objetivo avaliar a eficiência de pós-filtros adsorvedores constituídos de Carvão Ativado Granular (CAG) na remoção de compostos orgânicos precursores e na formação de subprodutos da desinfecção, em particular dos trialometanos (THM) na Estação de Tratamento de Água Alto da Boa Vista (ETA ABV), abastecida por reservatórios de água bruta com elevado grau de eutrofização. Os ensaios foram conduzidos em ETA Piloto composta por tanque de reservação de água filtrada, ozonizador, tanque de reservação de água ozonizada e 4 pós-filtros adsorvedores, sendo duas unidades dotadas de CAG de origem mineral e duas unidades dotadas de CAG de origem vegetal. Os filtros foram operados em paralelo, sendo que duas colunas foram alimentadas com água filtrada da ETA ABV (Filtro F3 CAG de origem mineral e Filtro F4 CAG de origem vegetal) e as outras duas alimentadas com água filtrada e ozonizada (Filtro F1 CAG de origem mineral e Filtro F2 CAG de origem vegetal). A avaliação da remoção de compostos orgânicos precursores e formação de subprodutos da desinfecção foi feita através de análises de carbono orgânico total (COT), UV-254 nm e formação de THM. A análise dos resultados gerados de julho de 2007 a dezembro de 2008 permitiu concluir que 93% do THM é formado nas primeiras 24 horas de contato da amostra com o cloro, simulando a pós cloração e pós alcalinização da ETA ABV. O processo de oxidação por ozônio não foi efetivo na remoção de THM instantâneo, visto que a média dos 38 valores de THM instantâneo para a água filtrada (17,8 ± 5,6 g/L) foi igual a média obtida para o THM instantâneo na água ozonizada. A remoção de THM pelos filtros de CAG foi mais significativa nos primeiros três meses de operação do sistema, apresentando remoção de 80% para os filtros com CAG de origem mineral e 70% para os filtros com CAG de origem vegetal, a partir do quarto mês de operação do sistema a remoção de THM caiu para um valor médio de 34%, o que mostra uma iminente saturação do leito adsorvedor. Os pós-filtros adsorvedores constituídos de CAG de origem mineral apresentaram melhor comportamento com respeito a remoção de THM e COT quando comparado com os pós-filtros dotados de CAG de origem vegetal. / The main purpose of this work was to evaluate the performance of a Granular Activated Carbon (GAC) post-filter adsorbers in the removal of organic precursors and in the formation of disinfection byproducts, especially trihalomethanes (THM) in Alto da Boa Vista Water Treatment Plant (ABV WTP), which takes raw water from a highly eutrophized reservoirs. The tests was conducted on a Pilot WTP composed of filtered water tank, ozonator, ozonized water tank, and four post-filter adsorbers: two units with mineral GAC media and two units with vegetal GAC media. The filters were operated in parallel, with two columns fed with filtered water from ABV WTP (F3 Filter mineral GAC and F4 Filter vegetal GAC) and the other fed with ozonized water (F1 Filter mineral GAC and F2 Filter vegetal GAC). The evaluation of the removal of organic precursors and the formation of disinfection byproducts was made through analysis of Total Organic Carbon (TOC), UV-254 nm and THM formation. The results generated from July 2007 to December 2008 showed that 93% of THM is formed in the first 24 hours of contact with the chlorine in the sample, simulating the post chlorination and post alkalinization of ABV WTP in samples of filtered water, ozonized water, and post-filter adsorbers effluent. Ozone oxidation process was not effective in removing THM. Was found the same instantaneous THM values in the filtered water (17.8 g/L± 5.6 g/L) and in the ozonized water. During the first three months of post-filter adsorber operation, THM removal efficiencies were around 80% for F1 and F3 (mineral GAC media) and around 70% for F2 and F4 (vegetal GAC media). After four months of operation, THM removal efficiencies decreased to 34% average value, thus indicative of GAC saturation. Regarding THM and TOC removal efficacy, the mineral GAC performed better than the vegetal GAC.
82

Ozonização: uma alternativa para clarificação do caldo de cana-de-açúcar. / Ozonation: an alternative for clarification of sugarcane.

Christiane Reis Fonseca 16 February 2017 (has links)
A agroindústria canavieira no Brasil é um setor de destaque por exercer papel fundamental na economia, sendo responsável pela geração de empregos, renda e produtos e subprodutos de interesse como, açúcar, etanol e energia. A clarificação do caldo de cana é um dos processos unitários mais críticos das usinas açucareiras. Atualmente, o açúcar brasileiro é clarificado utilizando-se o processo de contato com dióxido de enxofre, conhecido como sulfitação. Existe, porém, uma tendência mundial na redução do uso de compostos à base de enxofre nos alimentos, devido a possíveis efeitos nocivos à saúde. Além disso, a queima de enxofre elementar nas usinas é fonte de emissões de gases sulforosos, desconforto no ambiente de trabalho das fábricas e corrosão de metais nas instalações industriais. Dessa forma, alternativas à sulfitação têm sido avaliadas, entre as quais a ozonização, processo que carece de estudos fundamentais. No presente trabalho foram avaliados parâmetros de transferência de massa do ozônio, tanto em água como em solução modelo contendo sacarose e compostos fenólicos presentes no caldo de cana (ácidos ácido p-cumárico, cafeico, siríngico e clorogênico, além do flavonoide quercetina). A partir destes experimentos foi verificado que a ozonização da mistura de fenólicos é caracterizada por uma reação lenta devido à presença de ozônio dissolvido no meio. Observou-se que não houve degradação da sacarose e os principais intermediários identificados foram ácidos orgânicos, não ocorrendo, porém, mineralização completa dos compostos fenólicos. Após este estudo foram realizados experimentos de ozonização com caldo de cana seguindo um projeto experimental com o objetivo de verificar a remoção de cor ICUMSA e também de compostos fenólicos. Verificou-se importante remoção de cor (80%) após duas horas de ozonização a 40 oC, empregando-se 30 mg L-1 de ozônio no gás alimentado à vazão de 0,5 L min-1. Por outro lado, obtiveram-se 50% de remoção de compostos fenólicos para concentração de O3 no gás de 20 mg L-1, vazão de gás de 0,5 L min-1 e temperatura de 60 °C. Realizou-se por fim uma análise econômica preliminar para fins de comparação entre o processo de sulfitação e ozonização. O processo de ozonização demanda um investimento inicial maior que a sulfitação e à peroxidação. Quando os custos operacionais são comparados verifica-se que o custo operacional para a ozonização é 29% menor que a sulfitação e 43% menor que a peroxidação. Os resultados sugerem a possível aplicação da ozonização como tecnologia alternativa à utilização de enxofre no processo de clarificação. / The sugarcane agroindustry in Brazil currently stands out because it plays a major role in the economy, being responsible for generating jobs, income and products and by-products of interest, such as sugar, ethanol and power. The clarification of sugarcane juice is one of the most critical unit processes in sugar mills. Brazilian sugar is clarified using the sulphitation process. There is a worldwide trend in reducing the use of sulfur compounds in food because of its possible harmful effects on the consumer. In addition, burning elemental sulfur causes serious environmental problems, such as emissions of sulfurous gases, causing acid rain, discommodity in the working environment of plants and corrosion of metals in industrial facilities. Alternative treatments of sugarcane juice, replacing sulfur dioxide have been considered, among them ozonation. The main limitation of ozonation processes is gas-liquid mass transfer. In the present work, ozone mass transfer parameters were evaluated both in water and in model solutions of sucrose containing phenolic compounds present in the sugarcane juice. The main degradation products formed during the process were identified. From these experiments, ozonation of phenolic compounds in solution is characterized by a slow reaction due to the presence of dissolved ozone in the medium. The main intermediates identified were organic acids demonstrating that complete mineralization of the phenolic compounds does not occur. Ozonation experiments with sugarcane juice were carried out following an experimental design aiming at studying color and phenolic compounds removals. After two-hour experiments 80% color removal was achieved ozone concentration of 30 mg L-1, 0.5 L min-1 flow rate and 40 ° C. Moreover, 50% removal of phenolic compounds was achieved for 20 mg L-1 ozone concentration, 0.5 L min-1 flow rate and 60 ° C. The results confirm the efficiency of color removal, main target of the sugar industry. Finally, a preliminary economic analysis was carried out the purpose of comparing the sulphitation and ozonation process, and it was verified that ozonation requires an initial investment greater than sulphitation. Ozonation process requires an initial investment greater than sulphitation and peroxidation. On the other hand, operating costs were compared, the operating cost for ozonation is 29% lower than sulphitation and 43% lower than peroxidation. Results suggest the possible application of ozonation as an alternative technology to the use of sulfur in the clarification process.
83

Comportamento de sistemas pós-filtros adsorvedores na remoção de compostos orgânicos precursores e subprodutos da desinfecção. / Behavior of post-filter adsorbers in the removal of organic precursors and disinfection byproducts.

Claudia Mota Santos Pereira 14 August 2009 (has links)
O presente trabalho teve como objetivo avaliar a eficiência de pós-filtros adsorvedores constituídos de Carvão Ativado Granular (CAG) na remoção de compostos orgânicos precursores e na formação de subprodutos da desinfecção, em particular dos trialometanos (THM) na Estação de Tratamento de Água Alto da Boa Vista (ETA ABV), abastecida por reservatórios de água bruta com elevado grau de eutrofização. Os ensaios foram conduzidos em ETA Piloto composta por tanque de reservação de água filtrada, ozonizador, tanque de reservação de água ozonizada e 4 pós-filtros adsorvedores, sendo duas unidades dotadas de CAG de origem mineral e duas unidades dotadas de CAG de origem vegetal. Os filtros foram operados em paralelo, sendo que duas colunas foram alimentadas com água filtrada da ETA ABV (Filtro F3 CAG de origem mineral e Filtro F4 CAG de origem vegetal) e as outras duas alimentadas com água filtrada e ozonizada (Filtro F1 CAG de origem mineral e Filtro F2 CAG de origem vegetal). A avaliação da remoção de compostos orgânicos precursores e formação de subprodutos da desinfecção foi feita através de análises de carbono orgânico total (COT), UV-254 nm e formação de THM. A análise dos resultados gerados de julho de 2007 a dezembro de 2008 permitiu concluir que 93% do THM é formado nas primeiras 24 horas de contato da amostra com o cloro, simulando a pós cloração e pós alcalinização da ETA ABV. O processo de oxidação por ozônio não foi efetivo na remoção de THM instantâneo, visto que a média dos 38 valores de THM instantâneo para a água filtrada (17,8 ± 5,6 g/L) foi igual a média obtida para o THM instantâneo na água ozonizada. A remoção de THM pelos filtros de CAG foi mais significativa nos primeiros três meses de operação do sistema, apresentando remoção de 80% para os filtros com CAG de origem mineral e 70% para os filtros com CAG de origem vegetal, a partir do quarto mês de operação do sistema a remoção de THM caiu para um valor médio de 34%, o que mostra uma iminente saturação do leito adsorvedor. Os pós-filtros adsorvedores constituídos de CAG de origem mineral apresentaram melhor comportamento com respeito a remoção de THM e COT quando comparado com os pós-filtros dotados de CAG de origem vegetal. / The main purpose of this work was to evaluate the performance of a Granular Activated Carbon (GAC) post-filter adsorbers in the removal of organic precursors and in the formation of disinfection byproducts, especially trihalomethanes (THM) in Alto da Boa Vista Water Treatment Plant (ABV WTP), which takes raw water from a highly eutrophized reservoirs. The tests was conducted on a Pilot WTP composed of filtered water tank, ozonator, ozonized water tank, and four post-filter adsorbers: two units with mineral GAC media and two units with vegetal GAC media. The filters were operated in parallel, with two columns fed with filtered water from ABV WTP (F3 Filter mineral GAC and F4 Filter vegetal GAC) and the other fed with ozonized water (F1 Filter mineral GAC and F2 Filter vegetal GAC). The evaluation of the removal of organic precursors and the formation of disinfection byproducts was made through analysis of Total Organic Carbon (TOC), UV-254 nm and THM formation. The results generated from July 2007 to December 2008 showed that 93% of THM is formed in the first 24 hours of contact with the chlorine in the sample, simulating the post chlorination and post alkalinization of ABV WTP in samples of filtered water, ozonized water, and post-filter adsorbers effluent. Ozone oxidation process was not effective in removing THM. Was found the same instantaneous THM values in the filtered water (17.8 g/L± 5.6 g/L) and in the ozonized water. During the first three months of post-filter adsorber operation, THM removal efficiencies were around 80% for F1 and F3 (mineral GAC media) and around 70% for F2 and F4 (vegetal GAC media). After four months of operation, THM removal efficiencies decreased to 34% average value, thus indicative of GAC saturation. Regarding THM and TOC removal efficacy, the mineral GAC performed better than the vegetal GAC.
84

Ozonização catalítica do chorume proveniente do aterro sanitário de Cachoeira Paulista-SP na presença de ferro em sistema contínuo / Catalytic ozonation of the leachate from the Landfill Cachoeira Paulista- SP in the presence of iron in a continuous system

Renata Alves de Brito 13 October 2014 (has links)
O chorume é um líquido produzido na decomposição dos resíduos sólidos e apresenta riscos ambientais, devido à variedade de substancias poluentes presentes na matriz. O chorume in natura utilizado neste trabalho foi proveniente do aterro sanitário de Cachoeira Paulista - SP, sendo caracterizado com elevadas concentrações de COT (1233,33 mgL-1), DQO (3565,0 mgL-1) e DBO5/DQO = 0,099. Diante da baixa biodegradabilidade do chorume (DBO5/DQO < 0,2), utilizou-se a ozonização catalítica, em presença de ferro, em sistema contínuo, como uma alternativa para viabilizar o tratamento deste efluente. Diversas configurações de reatores foram avaliadas, sendo utilizados, inicialmente, reatores contínuos rudimentares (PVC). As avaliações reacionais e operacionais dos protótipos possibilitaram a elaboração de um reator construído com bases conceituais de engenharia, confeccionado em vidro borosilicato, e em dois módulos: o corpo do reator com duas entradas, sendo uma de alimentação, localizada acima, e a outra de introdução de ozônio, que foi feita por meio de um difusor de vidro sinterizado na base do reator. O segundo módulo foi feito para garantir que a espuma formada durante a reação fosse eliminada pela quebra da tensão através de ar comprimido, retornando-a, sob a forma líquida, ao sistema. As avaliações iniciais da ozonização catalítica do chorume in natura, para a verificação da potencialidade deste tratamento, foram realizadas sem o uso de um planejamento experimental, sendo o melhor resultado obtido na ordem de 72,64 % para a redução de COT. Após a seleção do reator de ozonização para o processo contínuo e a escolha do íon ferroso como catalisador, foi elaborado um planejamento fatorial fracionado (24-1) para avaliação das variáveis (potência, vazão de saída do reator, concentração de Fe2+, pH), no qual, o melhor resultado para a redução de COT foi de 59,38%. Este desempenho inferior para a redução de COT pode ser atribuído à substituição do gás de oxigênio puro por ar comprimido, reduzindo a vazão mássica de ozônio disponível para o tratamento. Entretanto, este processo pode ser viabilizado no tratamento prévio do chorume, pois a ozonização proporcionou uma elevada redução de DQO na ordem de 82,3 % e um aumento de 74,4% na biodegradabilidade (DBO5/DQO = 0,389) do chorume, podendo torná-lo potencialmente tratável por processos convencionais. / Leachate is a liquid produced in the decomposition of solid waste and presents environmental risks due to the variety of polluting substances existing in the matrix. The in natura leachate used in this work was from the landfill of the city Cachoeira Paulista in the state of São Paulo, which was characterized with high concentrations of TOC (1233.33 mgL-1) COD (3565.0 mg.L-1) and BOD5/COD = 0.099. Due to the low biodegradability of leachate (BOD5/COD < 0.2), the catalytic ozonation in the presence of iron in a continuous system was used as a viable alternative for the treatment of this effluent. Several configurations of reactors were evaluated, and, initially, rudimentary continuous reactors (PVC) were used. The reactional and operational evaluations of the prototypes enabled the creation of a reactor built on conceptual foundations of engineering, that was made of borosilicate glass, and in two modules: the body of the reactor with two entries, one for feeding, located above, and the other one for ozone introduction, made through a sintered glass diffuser at the bottom of the reactor. The second module was made to ensure that the foam formed during the reaction is eliminated by breaking the tension via compressed air, returning it, in liquid form, to the system. Initial assessments of the catalytic ozonation of the in natura leachate, to verify the potential of this treatment, were performed without the use of an experimental design, and the best result obtained was to reduce TOC on about 72.64 %. After selecting the ozonation reactor for continuous process and choosing ferrous ion as catalyst, a fractional factorial design (24-1) was prepared to evaluation the selected variables (potency, output flow of reactor, Fe2+ concentration, pH) in which the best result for the TOC reduction was 59.38%. This inferior performance for the TOC reduction can be associated to the replacement of pure oxygen gas by compressed air, reducing the ozone mass flow available to the treatment. However, this process can be made possible in the pretreatment of leachate, because the ozonation provided a high reduction of COD on about 82.3% and an increase of 74.4% on the biodegradability (BOD5/COD = 0.389) of leachate, and that can make it potentially treatable by conventional methods.
85

Ozonização catalítica do chorume proveniente do aterro sanitário de Cachoeira Paulista-SP na presença de ferro em sistema contínuo / Catalytic ozonation of the leachate from the Landfill Cachoeira Paulista- SP in the presence of iron in a continuous system

Brito, Renata Alves de 13 October 2014 (has links)
O chorume é um líquido produzido na decomposição dos resíduos sólidos e apresenta riscos ambientais, devido à variedade de substancias poluentes presentes na matriz. O chorume in natura utilizado neste trabalho foi proveniente do aterro sanitário de Cachoeira Paulista - SP, sendo caracterizado com elevadas concentrações de COT (1233,33 mgL-1), DQO (3565,0 mgL-1) e DBO5/DQO = 0,099. Diante da baixa biodegradabilidade do chorume (DBO5/DQO < 0,2), utilizou-se a ozonização catalítica, em presença de ferro, em sistema contínuo, como uma alternativa para viabilizar o tratamento deste efluente. Diversas configurações de reatores foram avaliadas, sendo utilizados, inicialmente, reatores contínuos rudimentares (PVC). As avaliações reacionais e operacionais dos protótipos possibilitaram a elaboração de um reator construído com bases conceituais de engenharia, confeccionado em vidro borosilicato, e em dois módulos: o corpo do reator com duas entradas, sendo uma de alimentação, localizada acima, e a outra de introdução de ozônio, que foi feita por meio de um difusor de vidro sinterizado na base do reator. O segundo módulo foi feito para garantir que a espuma formada durante a reação fosse eliminada pela quebra da tensão através de ar comprimido, retornando-a, sob a forma líquida, ao sistema. As avaliações iniciais da ozonização catalítica do chorume in natura, para a verificação da potencialidade deste tratamento, foram realizadas sem o uso de um planejamento experimental, sendo o melhor resultado obtido na ordem de 72,64 % para a redução de COT. Após a seleção do reator de ozonização para o processo contínuo e a escolha do íon ferroso como catalisador, foi elaborado um planejamento fatorial fracionado (24-1) para avaliação das variáveis (potência, vazão de saída do reator, concentração de Fe2+, pH), no qual, o melhor resultado para a redução de COT foi de 59,38%. Este desempenho inferior para a redução de COT pode ser atribuído à substituição do gás de oxigênio puro por ar comprimido, reduzindo a vazão mássica de ozônio disponível para o tratamento. Entretanto, este processo pode ser viabilizado no tratamento prévio do chorume, pois a ozonização proporcionou uma elevada redução de DQO na ordem de 82,3 % e um aumento de 74,4% na biodegradabilidade (DBO5/DQO = 0,389) do chorume, podendo torná-lo potencialmente tratável por processos convencionais. / Leachate is a liquid produced in the decomposition of solid waste and presents environmental risks due to the variety of polluting substances existing in the matrix. The in natura leachate used in this work was from the landfill of the city Cachoeira Paulista in the state of São Paulo, which was characterized with high concentrations of TOC (1233.33 mgL-1) COD (3565.0 mg.L-1) and BOD5/COD = 0.099. Due to the low biodegradability of leachate (BOD5/COD < 0.2), the catalytic ozonation in the presence of iron in a continuous system was used as a viable alternative for the treatment of this effluent. Several configurations of reactors were evaluated, and, initially, rudimentary continuous reactors (PVC) were used. The reactional and operational evaluations of the prototypes enabled the creation of a reactor built on conceptual foundations of engineering, that was made of borosilicate glass, and in two modules: the body of the reactor with two entries, one for feeding, located above, and the other one for ozone introduction, made through a sintered glass diffuser at the bottom of the reactor. The second module was made to ensure that the foam formed during the reaction is eliminated by breaking the tension via compressed air, returning it, in liquid form, to the system. Initial assessments of the catalytic ozonation of the in natura leachate, to verify the potential of this treatment, were performed without the use of an experimental design, and the best result obtained was to reduce TOC on about 72.64 %. After selecting the ozonation reactor for continuous process and choosing ferrous ion as catalyst, a fractional factorial design (24-1) was prepared to evaluation the selected variables (potency, output flow of reactor, Fe2+ concentration, pH) in which the best result for the TOC reduction was 59.38%. This inferior performance for the TOC reduction can be associated to the replacement of pure oxygen gas by compressed air, reducing the ozone mass flow available to the treatment. However, this process can be made possible in the pretreatment of leachate, because the ozonation provided a high reduction of COD on about 82.3% and an increase of 74.4% on the biodegradability (BOD5/COD = 0.389) of leachate, and that can make it potentially treatable by conventional methods.
86

Cellulose degradation in pulp fibers studied as changes in molar mass distributions

Berggren, Rickard January 2003 (has links)
In this thesis, size-exclusion chromatography (SEC) of woodpolymers dissolved in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) has been used to characterize the molar massdistributions (MMD) of wood polymers in pulp fibers afterchemical degradation. Characterization of birch kraft pulps subjected to ozonedegradation and acid hydrolysis, respectively, rendereddifferent changes in the MMD. Ozone degradation resulted inlarge redistributions of the original MMD, observed as thedevelopment of a distinct fraction of cellulose withintermediate molar mass. Acid hydrolysis resulted in minorchanges of the original MMD compared to ozonation. Fiberssubjected to acid hydrolysis were considerably weaker thanozonated fibers. These results indicated that there aredifferences in how the two chemicals degrade the fiber. The solubility of softwood kraft pulp fibers was enhanced byderivatization of the fiber polymers with ethyl-isocyanateduring simultaneous dissolution in LiCl/DMAc. Thederivatization made it possible to achieve reliable estimationsof the MMD, and hence molar masses, of softwood kraft pulps.The derivatization procedure made it possible to dissolve 90 %of softwood kraft pulps with kappa numbers over 50. Severe alkaline degradation of birch and Norway spruce woodchips was studied both by varying the pulping time and byvarying the initial alkali concentration. Differences werefound in the MMD of the two fiber types, and the alkalinedegradation was found to affect polymers in the entire MMD. Multi-angular laser light scattering (MALLS) was used as adetection technique with SEC on cellulosic samples. The MMD andaverage molar masses obtained through directstandardcalibration with commercial standards were compared with MMDand molar masses as obtained by MALLS-detection. Largediscrepancies were found, and two methods of correcting forthese discrepancies were developed. Theoretical simulations of polymer degradation wereperformed. Random, or homogeneous degradation was used as amodel for alkaline cellulose chain scission, and a resemblancewith experimental data was observed. End-wise depolymerizationof cellulose was also simulated and the results are discussedin the light of experimentally observed MMD. <b>Keywords:</b>cellulose, kraft pulp, birch, spruce,ozonation, acid hydrolysis, degradation, MMD, sizeexclusionchromatography, light scattering, molar mass, chainscission
87

Source Characterization and Pretreatment Evaluation of Pharmaceuticals and Personal Care Products in Healthcare Facility Wastewater

Nagarnaik, Pranav Mukund 2011 May 1900 (has links)
Healthcare facility wastewaters are a potentially important and under characterized source of pharmaceuticals and personal care products to the environment. In this study the composition and magnitude of pharmaceuticals and personal care products (PPCPs) released into a single municipality’s wastewater system from a hospital, a nursing care facility, an assisted living facility and an independent living facility are presented for 54 pharmaceuticals, 8 hormones and 31 Alkylphenol ethoxylates (APEOs). Chemical oxidation using molecular ozone and advanced oxidation processes (AOPs) (UV-hydrogen peroxide, Fenton’s Reagent, and Photo – Fenton’s Reagent) were screened and evaluated as potential treatment technologies for removal of APEOs in water and wastewater. In this research, APEOs were found to be dominant PPCP class out of 94 individual analytes measured, accounting for more than 65% of the total mass loading observed leaving the healthcare facility wastewater. Seventy one out of the total measured PPCPs were detected in wastewater from at least one of the facilities. Healthcare facility wastewater are the source of PPCPs to the environment; however, their contribution to the total magnitude of PPCPs in municipal wastewater and the surrounding environment will be determined by the relative flow contribution of wastewater released from the facility to the municipal sewer network. Molecular ozone and advanced oxidation processes were observed to remove APEOs from analyzed water matrices; however, understanding the product formation during the oxidation process is important before concluding a suitable treatment process. Molecular ozone reacted selectively with the double bond in the APEO while AOPs reaction was non selective oxidation. During the AOPs, OH· formation rate and scavenging rate constant of wastewater was found to be the factors governing the oxidation process. Thus, the research carried out informs a risk management decisions concerning the prevalence of PPCPs in the wastewater and use of oxidation systems as a treatment technologies for removal of PPCPs.
88

Kinetic Study on Degradation of Gas-phase 1, 3-Butadiene and Propylene Glycol Monomethyl Ether Acetate (PGMEA) by UV/O3

Huang, Bo-Jen 24 October 2005 (has links)
This study investigates the rate kinetics for BD and PGMEA oxidation by UV/O3 process. The reactor constructs of a 100 cm x 20 cm x 85 cm (L x W x H) stainless steel chamber, in which four vertical steel plates (20 cm x 65 cm, W x H) were inserted to establish a plug flow path for the flowing gas. The reactor has a total effective volume of 170 L. Each of the five compartments of the reactor is equipped with an individual UV irradiation system with a 3.0-cm x 15-cm (ID x L) quartz sheath that housed an UV lamp, and two electric UV power inputs of 0.147 or 0.294 W/L were obtained. The gas flows perpendicularly to the UV lamps in the reactor. The influent tested VOC concentration was adjusted to about 50 ppm, and the gas flows were controlled at the individual flow rate of 60 and 120 L/min. The effects of moisture content (relative humidity, RH), ozone dosage (initial molar ratio of ozone to the tested VOC, m) and UV volumetric electric power input on the removal of the tested VOCs are investigated in the study. Also, kinetic models of the tested VOCs by photolysis, ozonation and UV/O3 have been developed and confirmed with reference to the experimental data. According to the kinetic models, both photolysis rate and oxidation rate by UV/O3 are following the first order behavior with respect to the tested VOC concentrations which are low. The result reveals the absorbance for the reactions is weak absorbance under UV irradiation. The reaction rates are proportional to the UV electric power inputs in UV-initiated reactions. And the parameter, £i, which represents the ratio of OH radical consumption rate by the tested VOC to the total OH radical consumption rate, can be obtained by simulating the performance of experimental data of OH reactions. The experimental results reveal that for BD oxidation with a gas space time of 85 sec and RH = 40 ¡V 99%, BD photolysis did not occur at wavelength of 185 nm with UV electric power inputs of 0.147 and 0.294 W/L. The ozonation efficiency of BD reached 90% at m = 3.5, and RH had no influence on the removal efficiency of BD. The removal efficiencies by UV/O3 process reached 90% with m = 2.2 and 1.6 for UV power inputs of 0.147 and 0.294 W/L, respectively. The addition of ozone apparently encouraged BD removal efficiency by UV/O3 process. And the enhancement of ozone dosage (m = 0.5 ¡V 4.4) would promote the decomposition of BD more effectively than the enhancements of UV power input (from 0.147 to 0.294 W L-1) and RH (from 40 to 99%). For PGMEA photolysis in a batch reactor with volume of 1.188 L, the photolysis occurred at wavelength of 185 nm under UV irradiation. And the photolysis rate follows the first order behavior with respect to the concentration of PGMEA. But PGMEA photolysis did not occurred at UV wavelength of 254 nm. PGMEA ozonation was performed in the same batch reactor; and the removal efficiency of only 50% at m = 3.96 would take 35 min. So, PGMEA ozonation in the plug flow reactor did not be observed at the conditions of the gas space time of 85 sec and RH = 15 ¡V 99%. Besides, the photolysis of PGMEA was carried out at the above conditions. The removal efficiency of PGMEA by UV/O3 could reach 90% at the conditions of the gas space time of 170 sec, UV volumetric electric power input of 0.294 W/L and m = 2.9. And the enhancement of UV power input (from 0.147 to 0.294 W L-1) would promote the decomposition of PGMEA more effectively than the addition of ozone dosage (m = 1.05 ¡V 15.63) and RH = 15 ¡V 99%.
89

Oxidation characteristics of fluorine-, nitrogen-, and sulfur-containing organic compounds by UV/O3

Chang, Ken-Lin 10 September 2007 (has links)
DMSO (dimethyl sulfoxide) is a liquid with a high boiling point (189 oC) that has been extensively utilized in various industries owing to its ability to dissolve various organic and inorganic compounds. DMSO is increasingly being adopted as a detergent or a photo-resistant stripping solvent in manufacturing semiconductors and liquid crystal displays (LCD). Therefore, DMSO is now a major component of wastewater. The biological treatment of DMSO-containing wastewater generates noxious DMS (dimethyl sulfide) and other compounds that may cause odor problems. Also having a high water solubility and a moderate boiling point (110 oC), tetrafluoro propanol (TFP) has been extensively applied in the manufacture of CD-R and DVD-R, due to its ability to dissolve organic dyes. The spin coating process produces a large amount of wastewater containing TFP. No reports have been written on the biodegradability of TFP to the authors¡¦ knowledge. Additionally, HMDS (hexamethyldisilazane) has been extensively used in life science microscopy and material science. For instance, the semiconductor industry employs HMDS to promote the adhesion of photo-resistant material to oxide(s). HMDS is classified as a carcinogen, and has an ammonia odor. Condensing incinerators have been found to be unsuitable for treating HMDS-containing waste gases, because of the formation of silicon dioxide, which blocks porous adsorbents. Biological treatment also appears to be unpromising due to its low water solubility and limited biodegradability. This investigation evaluates the feasibility, effectiveness and oxidation characteristics of aqueous DMSO, TFP and gaseous HMDS (hexamethyldisilazane) by UV/O3 processes. A reactor made entirely of acrylic plastic with an effective volume of 10 L was employed for the reactions. The tested VOCs concentrations were adjusted to 400¡V890mg/L and 772¡V887 mg/L for DMSO and TFP, respectively, and the gas (ozone-enriched air) flow rate was controlled at 3L/min. The effects of various solution pH values (acidic, alkaline, uncontrolled), solution temperatures (26 oC, 37 oC, 48 oC and 60 oC), and UV wavelengths (254 nm and 185+254 nm) on the removal of tested VOCs were studied . Additionally, the operation costs of treating DMSO and TFP by UV/O3 were estimated. Experimental results demonstrate that acidic conditions (pH = 3.6) favored the degradation of DMSO, and that the removal efficiency could reach 95% at a volumetric UV intensity P/V of 2.25 W/L and a reaction time of 120 min. However, alkaline conditions (pH = 9.5) favored the decomposition of TFP, with the removal efficiency reaching 95% at P/V = 2.5 W/L and a reaction time of 60 min. Both DMSO and TFP exhibited zero-order degradation kinetics when sufficient ozone was supplied. Raising the oxidation temperature did not increase the UV/O3 oxidation of TFP in the tested concentration and temperature ranges. Operation costs of the UV/O3 per unit volume of wastewater with DMSO or TFP are comparable to those of the methods described in the literature. For the gaseous HMDS oxidation, two batch reactors with effective volumes of 1.2 and 5.8 L were used employed with the decomposition occurred under UV (185+254 nm) irradiation and UV (254 nm)/O3 processes. Tests were performed with initial HMDS concentrations of 32¡V41mg/m3 under various initial ozone dosages (O3 (mg)/HMDS (mg) =1¡V5), atmospheres (N2, O2, and air), temperatures (28 oC, 46 oC, 65 oC and 80 oC), relative humilities (20%, 50%, 65% and 99%) and volumetric UV power inputs (0.87 W/L, 1.74 W/L, 4.07 W/L and 8.16 W/L) to assess their effects on the HMDS degradation rate. Results of this study demonstrate that the decomposition rates for the UV (185+254 nm) irradiation exceeded those for the UV (254 nm)/O3 process for all conditions. UV (185+254 nm) decompositions of HMDS displayed apparent first-order kinetics. A process with irradiation of UV (185+254 nm) to HMDS in air saturated with water at temperatures of 46¡V80 oC favors the HMDS degradation. With the above conditions and a P/V of around 8 W/L, k≈ 0.20 s−1, and over 90% of the initial HMDS was degraded in a time of 12s. The main mechanisms for the HMDS in wet air streams irradiated with UV (185+254 nm) were found to be caused by OH free radical oxidation produced from photolysis of water or O (1D) produced from photolysis of oxygen. Economic evaluation factors of UV (185+254 nm) and UV (254 nm)/O3 processes at various UV power inputs were also estimated.
90

Cellulose degradation in pulp fibers studied as changes in molar mass distributions

Berggren, Rickard January 2003 (has links)
<p>In this thesis, size-exclusion chromatography (SEC) of woodpolymers dissolved in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) has been used to characterize the molar massdistributions (MMD) of wood polymers in pulp fibers afterchemical degradation.</p><p>Characterization of birch kraft pulps subjected to ozonedegradation and acid hydrolysis, respectively, rendereddifferent changes in the MMD. Ozone degradation resulted inlarge redistributions of the original MMD, observed as thedevelopment of a distinct fraction of cellulose withintermediate molar mass. Acid hydrolysis resulted in minorchanges of the original MMD compared to ozonation. Fiberssubjected to acid hydrolysis were considerably weaker thanozonated fibers. These results indicated that there aredifferences in how the two chemicals degrade the fiber.</p><p>The solubility of softwood kraft pulp fibers was enhanced byderivatization of the fiber polymers with ethyl-isocyanateduring simultaneous dissolution in LiCl/DMAc. Thederivatization made it possible to achieve reliable estimationsof the MMD, and hence molar masses, of softwood kraft pulps.The derivatization procedure made it possible to dissolve 90 %of softwood kraft pulps with kappa numbers over 50.</p><p>Severe alkaline degradation of birch and Norway spruce woodchips was studied both by varying the pulping time and byvarying the initial alkali concentration. Differences werefound in the MMD of the two fiber types, and the alkalinedegradation was found to affect polymers in the entire MMD.</p><p>Multi-angular laser light scattering (MALLS) was used as adetection technique with SEC on cellulosic samples. The MMD andaverage molar masses obtained through directstandardcalibration with commercial standards were compared with MMDand molar masses as obtained by MALLS-detection. Largediscrepancies were found, and two methods of correcting forthese discrepancies were developed.</p><p>Theoretical simulations of polymer degradation wereperformed. Random, or homogeneous degradation was used as amodel for alkaline cellulose chain scission, and a resemblancewith experimental data was observed. End-wise depolymerizationof cellulose was also simulated and the results are discussedin the light of experimentally observed MMD.</p><p><b>Keywords:</b>cellulose, kraft pulp, birch, spruce,ozonation, acid hydrolysis, degradation, MMD, sizeexclusionchromatography, light scattering, molar mass, chainscission</p>

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