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Hydrothermal synthesis of iron oxide photo-fenton catalysts: the effect of parameters on morphology, particle size and catalytic efficiency

Pastrana-Martínez, Luisa; Gomes, Helder; Draži?, Goran; Faria, Joaquim; Silva, Adrián
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.48%
Iron oxide materials were synthesized by an easy and rapid hydrothermal method using different iron precursors (FeCl3?6H2O, Fe(NO3)3?9H2O and K4Fe(CN)6?3H2O), solution pHs (acid and basic) and reaction times (3 h and 6 h). The synthesized materials were thoroughly characterized by transmission electron microscopy and it was found that, depending on the synthesis conditions, iron oxide samples with crystalline or with amorphous structures could be obtained. Except for the materials synthesised from K4Fe(CN)6?3H2O and FeCl3?6H2O under acidic conditions all the samples show mean particle sizes below 70 nm. The materials were further tested as catalysts for the degradation of 100 mg l-1 diphenhydramine aqueous solutions by the photo-Fenton process at 25 °C, pH = 2.8, 100 mg l-1 of catalyst and 16 mM of H2O2 concentration. The best results in terms of pollutant removal and mineralization extent were obtained with the catalysts prepared from Fe(NO3)3?9H2O and K4Fe(CN)6?3H2O, under basic conditions, after 3 h of synthesis reaction time (complete degradation of diphenhydramine and total organic carbon removal higher than 60% after 60 min of reaction). Leaching of iron species from these catalysts was measured below 1.5 mg l-1, a value complying with European Union Directives.

Degradation of diphenhydramine pharmaceutical by photo-Fenton using magnetically recoverable iron oxide nanoparticles as catalyst

Pastrana-Martínez, Luisa; Pereira, Nuno; Lima, R.; Faria, Joaquim; Gomes, Helder; Silva, Adrián
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.48%
Iron oxide nanoparticles, with size ranging from 50 to 100 nm, were synthesized by a solvothermal method. The amounts of iron(III) chloride precursor (from 2.5 to 10.0 mmol) and sodium hydroxide (between 10 and 30 mmol) were varied along with the synthesis temperature (180 or 200°C). Depending on the synthesis conditions, samples with magnetic properties consisting of magnetite (Fe3O4), or by a mixture of magnetite and maghemite (c-Fe2O3), and samples with no magnetism consisting of hematite (a-Fe2O3), were obtained. The catalytic activity of the materials was studied for the degradation of diphenhydramine using the photo-Fenton process. All materials performed well on the degradation of this emerging pollutant. The best compromise between catalytic activity and stability was obtained with pure magnetite nanoparticles prepared at 180°C from a 4:1 molar ratio between sodium hydroxide and iron(III) chloride. This cat- alyst was used in further studies at different pH (2.8–11.0), catalyst loads (up to 200 mg L-1) and hydrogen peroxide concentrations (1–50 mM). Complete degradation of diphenhydramine with 78% of mineralization was achieved at relatively low leaching of iron species from the catalyst to the aqueous solution (1.9 mg L-1). Acidic pH (2.8) is preferable to neutral or alkaline pH (i.e. 6.0...

Photo-fenton degradation of poly(Ethyleneglycol)

SANTOS, Laís C; SCHMITT, Carla C; POLI, Alessandra L; NEUMANN, Miguel G
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.66%
Polyethyleneglycol (PEG) was photooxidized in a photo-Fenton system and results compared with the dark reaction. The products were analysed using GPC and HPLC. In the absence of light, PEG samples needed 490 min to reduce their w by 50%, whereas under UV irradiation, only 10 min were necessary. The exponential decay of w with a concomitant increase in polydispersity and number of average chain scission, characterized a random chain scission mechanism. The degradation products of PEG in both systems showed the presence of lower molecular weight products, including smaller ethyleneglycols and formic acid. The mechanism involves consecutive processes, were the larger ethyleneglycols give rise, successively, to smaller ones. This suggests that the mechanism involves successive scissions of the polymer chain. Irradiated samples decomposed faster than those kept in the dark This study proves that the foto-Fenton method associated with UV-light is a good reactant for PEG photodegradation.; Polietilenoglicol (PEG) foi fotooxidado usando o sistema foto-Fenton e comparando com a reação no escuro. Os produtos foram analisados por GPC e HPLC. As amostras tratadas na ausência de luz necessitaram 490 min para que a w decrescesse em 50%, enquanto que sob irradiação UV essa mesma proporção foi obtida em 10 min. O decaimento exponencial de w com um concomitante aumento na polidispersividade e o número de quebras de cadeia caracteriza um mecanismo de quebra de cadeia aleatório. Os produtos da degradação de PEG em ambos os casos mostram a presença de produtos de massa molecular menor...

Regeneration of Activated Carbon by (Photo)-Fenton Oxidation

MURANAKA, Cinthia T.; JULCOUR, Carine; WILHELM, Anne-Marie; DELMAS, Henri; NASCIMENTO, Claudio A. O.
Fonte: AMER CHEMICAL SOC Publicador: AMER CHEMICAL SOC
Tipo: article; proceedings paper; publishedversion
Português
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66.68%
This work aims to study the adsorption of phenol on activated carbons (ACs) and the consecutive in situ regeneration of carbon by Fenton oxidation. Two different operations have been carried Out: (1) a batch procedure in order to investigate the influence of Fe(2+) and H(2)O(2) concentrations; (2) continuous fixed bed adsorption, followed by a batch circulation of the Fenton`s reagent through the saturated AC bed. to examine the efficiency of the real process. Two different activated carbons have been also studied: a both micro- and mesoporous AC (L27) and an only microporous One (S23). In the batch reactor the best conditions found for pollutant mineralization in the homogeneous Fenton system are not the best For AC regeneration: a continuous reduction of adsorption capacity of L27 is observed after 3 oxidations, due to the decrease of both AC weight and surface area. Higher concentration of Fe(2+) and lower concentration of H(2)O(2) (2 times the stoichiometry) lead to a 50% recovery of the initial adsorption capacity during at least four consecutive cycles for L27, while about 20% or less for S23. In the consecutive continuous adsorption/batch Fenton oxidation process, the regeneration efficiency reaches 30-40% for L27 after two cycles whatever the feed concentration and less than 10% for S23. A photo-Fenton test performed on L27 shows almost complete mineralization (contrary to ""dark"" Fenton) and further improves recovery of AC adsorption capacity although not complete (56% after two cycles).

Photo-Fenton removal of water-soluble polymers

GIROTO, J. A.; TEIXEIRA, A. C. S. C.; NASCIMENTO, C. A. O.; GUARDANI, R.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.48%
This paper presents the results of experiments carried out in a laboratory-scale photochemical reactor on the photodegradation of different polymers in aqueous solutions by the photo-Fenton process. Solutions of three polymers, polyethyleneglicol (PEG), polyacrylamide (PAM), and polyvinylpyrrolidone(PVP), were tested under different. conditions. The reaction progress was evaluated by sampling and analyzing the total organic carbon concentration in solution (TOC) along the reaction time. The behavior of the different polymers is discussed, based oil the evolution of the TOC-time curves. Under specific reaction conditions, the formation and coalescence of solid particles was Visually observed. Solids formation occurred simultaneously to a sharp decrease in the TOC of the liquid phase. This may be favorable for the treatment of industrial wastewater containing polymers, since the photodegradation process can be Coupled with solid separation systems. which may reduce the treatment cost. (C) 2008 Elsevier B.V. All rights reserved.; CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior); CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico); FAPESP (Fundacao de Amparo Pesquisa do Estado de Sao Paulo)

Sequential injection analysis (SIA) and response surface methodology: A versatile small volume approach for optimization of photo-Fenton processes

SANTOS, Allan C. V. dos; MASINI, Jorge C.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.57%
Optimization of photo-Fenton degradation of copper phthalocyanine blue was achieved by response surface methodology (RSM) constructed with the aid of a sequential injection analysis (SIA) system coupled to a homemade photo-reactor. Highest degradation percentage was obtained at the following conditions [H(2)O(2)]/[phthalocyanine] = 7, [H(2)O(2)]/[FeSO(4)] = 10, pH = 2.5, and stopped flow time in the photo reactor = 30 s. The SIA system was designed to prepare a monosegment containing the reagents and sample, to pump it toward the photo-reactor for the specified time and send the products to a flow-through spectrophotometer for monitoring the color reduction of the dye. Changes in parameters such as reagent molar ratios. residence time and pH were made by modifications in the software commanding the SI system, without the need for physical reconfiguration of reagents around the selection valve. The proposed procedure and system fed the statistical program with degradation data for fast construction of response surface plots. After optimization, 97% of the dye was degraded. (C) 2009 Elsevier B.V. All rights reserved.; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPQ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Photo-Fenton oxidation of phenol and organochlorides (2,4-DCP and 2,4-D) in aqueous alkaline medium with high chloride concentration

Luna, Airton J.; Chiavone-Filho, Osvaldo; Machulek, Amilcar, Jr.; de Moraes, Jose Ermirio F.; Nascimento, Claudio A. O.
Fonte: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD; LONDON Publicador: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD; LONDON
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.67%
A highly concentrated aqueous saline-containing solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2.4-DCP) was treated by the photo-Fenton process in a system composed of an annular reactor with a quartz immersion well and a medium-pressure mercury lamp (450 W). The study was conducted under special conditions to minimize the costs of acidification and neutralization, which are usual steps in this type of process. Photochemical reactions were carried out to investigate the influence of some process variables such as the initial concentration of Fe2+ ([Fe2+](0)) from 1.0 up to 2.5 mM, the rate in mmol of H2O2 fed into the system (F-H2O2,F-in) from 3.67 up to 7.33 mmol of H2O2/min during 120 min of reaction time, and the initial pH (pH(0)) from 3.0 up to 9.0 in the presence and absence of NaCl (60.0 g/L). Although the optimum pH for the photo-Fenton process is about 3.0, this particular system performed well in experimental conditions starting at alkaline and neutral pH. The results obtained here are promising for industrial applications, particularly in view of the high concentration of chloride, a known hydroxyl radical scavenger and the main oxidant present in photo-Fenton processes. (C) 2012 Elsevier Ltd. All rights reserved.; CAPES; CAPES; CNPq; CNPq; ANP; ANP; FAPESP; FAPESP; FUNDECT; FUNDECT

Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene

Silva, Syllos S. da; Chiavone-Filho, Osvaldo; Barros Neto, Eduardo L. de; Nascimento, Claudio A. O.
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.64%
Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min(-1) for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H2O2 concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal. (C) 2011 Elsevier B.V. All rights reserved.; ANP (Agencia Nacional do Petroleo); ANP (Agencia Nacional do Petroleo); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior); CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); INCTEMA (Institutos Nacionais de Ciencia e Tecnologia de Estudos do Meio Ambiente); INCT-EMA (Institutos Nacionais de Ciencia e Tecnologia de Estudos do Meio Ambiente)

Tratamento de efluentes aquosos contendo clorofenóis por meio de processo oxidativo avançado foto-Fenton.; Treatment of wastewater containing chlorophenols by photo-Fenton advanced oxidation process.

Juárez Cardeña, Úrsula María
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: dissertação de mestrado Formato: application/pdf
Publicado em 06/03/2009 Português
Relevância na Pesquisa
66.7%
Nos últimos anos, os processos oxidativos avançados (POAs) têm emergido como métodos potencialmente poderosos para transformar poluentes orgânicos recalcitrantes em substâncias menos tóxicas. O presente trabalho visa estudar a degradação de clorofenóis 2,4-diclorofenol (2,4-DCF) e pentaclorofenol (PCF) em solução aquosa por meio do processo foto-Fenton. Os experimentos foram realizados em um reator fotoquímico, em regime batelada, com recirculação e admissão contínua de peróxido de hidrogênio. Os efeitos das concentrações iniciais de clorofenóis, H2O2 e Fe(II), bem como, da potência da lâmpada de vapor de mercúrio, foram estudados a partir de um planejamento experimental Doehlert em multiplos níveis e analisados segundo a metodologia de superfícies de respostas. A foto-oxidação foi monitorada por medidas da concentração de carbono orgânico total (TOC) e do espectro de absorção da solução ao longo do tempo e, em alguns casos, medidas de toxicidade por meio de bioensaios com Artemia sp. Os resultados dos experimentos realizados com 2,4-DCF evidenciaram degradação gradativa, com remoções de TOC superiores a 99%, após 1 hora de tratamento, além de remoção de toxicidade, mesmo para altas concentrações iniciais do poluente (até ca. 415 mgC L-1). Nos experimentos realizados com PCF observouse decaimento inicial de TOC bastante rápido (15 minutos)...

Estudo e otimização da degradação dos herbicidas hexazinona e diuron utilizando processos oxidativos avançados (POA): H2O2/UV e foto-Fenton; Study and optimization of the degradation of the herbicides diuron and hexazinone using advanced oxidation processes (AOP): H2O2/UV and photo-Fenton

Martins, Alysson Stefan
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: dissertação de mestrado Formato: application/pdf
Publicado em 27/02/2013 Português
Relevância na Pesquisa
66.81%
Agrotóxicos são frequentemente relatados na literatura em contaminações de ambientes aquáticos, sendo provenientes do lixiviamento de solos, do descarte inadequado de embalagens agrícolas, dentre outros. Nesse contexto, os processos oxidativos avançados (POA) têm sido estudados como alternativa para o tratamento desses compostos em meio aquoso. Os POA consistem na oxidação de compostos orgânicos pela formação de radicais livres com alto poder oxidante. Diante desses aspectos, o presente trabalho teve como proposta o estudo da degradação dos herbicidas hexazinona e diuron, aliada ao planejamento experimental do tipo composto central, a fim de otimizar o processo de degradação. Para tanto, realizaram-se as degradações através dos processos H2O2/UV e foto-Fenton em concentrações iniciais próximas a 7 e 20 mg L-1 para a hexazinona e diuron, respectivamente. Os experimentos foram conduzidos em um reator fotoquímico (200 mL a 25 °C) com aplicação de irradiação UV, proveniente de uma lâmpada de Hg (degradação H2O2/UV) e de luz negra (degradação foto-Fenton). No processo via H2O2/UV foram avaliadas a concentração de H2O2 (0,65 a 13,34 mmol L-1) e pH (2,77 a 11,23), e para o processo foto-Feton avaliou-se a concentração de H2O2 (0...

Estudo da tratabilidade do lixiviado de aterro sanitário pelos processos oxidativos avançados foto-Fenton, ozônio e ozônio combinado com peróxido de hidrogênio; Study of treatability of landfill leachate by advanced oxidation processes photo-Fenton, ozone and ozone combined with hydrogen peroxide

Monteiro, Luciano do Valle
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: dissertação de mestrado Formato: application/pdf
Publicado em 05/06/2012 Português
Relevância na Pesquisa
66.81%
O lixiviado de aterro sanitário possui constituição complexa e é altamente poluente. Neste contexto, os processos oxidativos avançados se destacam como pré-tratamento, objetivando a remoção ou diminuição da recalcitrância do lixiviado. Neste trabalho foram utilizados os Processos Oxidativos Avançados (POAs) foto-Fenton, ozônio e ozônio combinado com peróxido de hidrogênio. Avaliou-se a influência do pré-tratamento por air-stripping, a variação na produção de ozônio em 80 e 100%, a melhor dose de peróxido de hidrogênio correspondente a 20, 40 e 80% da dose de 6g O3/L empregada nos tratamentos com ozônio, a remoção de matéria orgânica, nitrogênio amoniacal total (NAT), alcalinidade, sólidos dissolvidos totais (SDT) (cloretos), produção de nitrito e nitrato, melhor razão molar [H2O2]/[Fe2+] para o tempo de contato de 80 min no foto-Fenton, uso do número médio de oxidação do carbono (NMOC) e a quantificação do ácido oxálico formado após a aplicação dos POAs. O tratamento por O3/H2O2 (1,2 g H2O2/L e produção de O3 em 80%) obteve a maior remoção de matéria orgânica, 0,14 g massa removida de Carbono Orgânico Total (COT) / massa consumida de O3 e 0,43 g/g para a Demanda Química de Oxigênio (DQO). Quanto ao foto-Fenton...

Estudo da degradação do metil parabeno utilizando processos Fenton, foto-Fenton e eletro-Fenton; Study of methyl paraben degradation using Fenton, photo-Fenton and electro-Fenton processes

Güere, Carlos Dante Gamarra
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: dissertação de mestrado Formato: application/pdf
Publicado em 15/04/2014 Português
Relevância na Pesquisa
66.77%
Os disruptores endócrinos são frequentemente relatados na literatura como contaminantes de ambientes aquáticos. Por isso, os processos oxidativos avançados (POAs) têm sido estudados como alternativa para o tratamento em meio aquoso. Os POAs consistem na oxidação de compostos orgânicos por radicais hidroxilas com alto poder oxidante. Diante desses aspectos, o presente trabalho tem como principal objetivo o estudo da degradação do metil parabeno (MeP) por processos Fenton, utilizando planejamento experimental e a análise dos modelos matemáticos, possibilitando a avaliação da influência das variáveis e determinando as melhores condições. As degradações de 300 mL de 100 mg L-1 de MeP com o processo Fenton foram realizadas em um reator de vidro onde as concentrações ótimas foram: 16 mg L-1 de Fe2+, 62 mg L-1 de H2O2, pH = 3, agitação constante e 30°C chegando a 100% de degradação em 20 minutos. Para o foto-Fenton, as degradações foram de 500 mL de 100 mg L-1 de MeP em um reator com lâmpada de mercúrio de 4 W , utilizando-se uma concentração de 4 mg L-1 de Fe2+ e 52 mg L-1 de H2O2, pH = 3, 30°C e agitação constante chegando a 100% de degradação em 16 minutos. Finalmente a degradação de 300 mL de 100 mg L-1 de MeP por eletro- Fenton foi realizada em um reator...

Degradation of sulfamethoxazole in water by solar photo-Fenton. Chemical and toxicological evaluation

Trovo, Alam G.; Nogueira, Raquel F. P.; Aguera, Ana; Fernandez-Alba, Amadeo R.; Sirtori, Carla; Malato, Sixto
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 3922-3931
Português
Relevância na Pesquisa
66.73%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 05/00172-0; In this work, the photocatalytic degradation of the antibiotic sulfamethoxazole (SMX) by solar photo-Fenton at pilot plant scale was evaluated in distilled water (DW) and in seawater (SW). Degradation and mineralization of SMX were strongly hindered in SW compared to DW. The influence of H(2)O(2) and iron concentration on the efficiency of the photocatalytic process was evaluated. An increase in iron concentration from 2.6 to 10.4 mg L(-1) showed only a slight improvement in SMX degradation and mineralization. However, an increase in H(2)O(2) concentration up to 120 mg L(-1) during photo-Fenton in DW decreased SMX solution toxicity from 85% to 20%, according to results of Daphnia magna bioassays. The same behaviour was not observed after photo-Fenton treatment in SW. Despite 45% mineralization in SW, toxicity increased from 16% to 86% as shown by Vibrio fischeri bioassays, which suggests that the intermediates generated in SW are different from those in DW. A SMX degradation pathway during the photo-Fenton treatment in DW is proposed. (C) 2009 Elsevier Ltd. All rights reserved.

Parameters affecting sulfonamide photo-Fenton degradation - Iron complexation and substituent group

Batista, Ana Paula S.; Pupo Nogueira, Raquel F.
Fonte: Elsevier B.V. Sa Publicador: Elsevier B.V. Sa
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.59%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); The photo-Fenton degradation of the sulfonamide antibiotics sulfadiazine (SDZ) and sulfathiazole (STZ) mediated by Fe(III)-oxalate was studied in this work. The influence of iron complexation. H2O2 concentration and pH on the initial SDZ and STZ degradation rate was evaluated. Degradation of both antibiotics is drastically improved in the presence of Fe(III)-oxalate in comparison to free iron, achieving complete degradation after 8 min irradiation at pH 2.5 in the presence of 5 mM H2O2 (equivalent to H2O2/antibiotic = 50). It was also possible to extend pH range of the photo-Fenton reaction by the use of Fe(III)-oxalate reaching more the 70% degradation at pH 6, however without significant mineralization. Comparison of the degradation kinetics of both sulfonamides indicated higher recalcitrance of STZ due to the lower electron density of its thiazol ring in relation to pyrimidine ring in SDZ. (C) 2012 Elsevier B.V. All rights reserved.

Photodegradation of lincomycin and diazepam in sewage treatment plant effluent by photo-Fenton process

Bautitz, Ivonete Rossi; Pupo Nogueira, Raquel F.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: info:eu-repo/semantics/conferencepaper Formato: 94-99
Português
Relevância na Pesquisa
66.48%
First, the effect of ferrioxalate or iron nitrate on the photo-Fenton degradation efficiency of the pharmaceuticals lincomycin (LCM) and diazepam (DZP) was evaluated. The degradation of both pharmaceuticals was improved in the presence of ferrioxalate in relation to Fe(NO(3)), either under black-light or solar irradiation. The degradation of the pharmaceuticals was then evaluated when present in an effluent from sewage treatment plant (STP) under black-light irradiation. Pharmaceuticals oxidation was not influenced by the matrix, since very similar results were obtained when compared to the experiments carried out in distilled water. However, DOC removal was slightly affected by the matrix, due probably to the generation of recalcitrant intermediates during effluent photodegradation and to the high content of inorganic carbon of STP effluent. Even so, high DOC removal percentages were achieved, 65% for lincomycin and 80% for diazepam after 60 min irradiation. (C) 2010 Elsevier B.V. All rights reserved.

Photo-Fenton process for treating biological laboratory wastewater containing formaldehyde

Fonseca, Janaína Conrado L.; Nogueira, Raquel F. Pupo; Marchi, Mary Rosa Rodrigues
Fonte: Editora Unesp Publicador: Editora Unesp
Tipo: Artigo de Revista Científica Formato: 25-33
Português
Relevância na Pesquisa
66.6%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Laboratórios e centros de pesquisa consomem uma grande variedade de substâncias químicas perigosas e, consequentemente, geram resíduos contendo-as, como por exemplo: resíduo de formaldeído. O formol é bastante empregado na conservação de peças anatômicas, gerando muitos litros desse resíduo por ano. O presente trabalho sugere o uso do processo foto-Fenton com irradiação solar para tratar resíduo contendo formaldeído. Alguns aspectos foram estudados como a concentração da fonte de ferro, da amostra e do peróxido de hidrogênio, além da aplicação de agitação magnética. O uso de ferrioxilato (0,5 mol L-1) mostrou ser mais eficiente na degradação da matéria orgânica quando comparado ao nitrato férrico. Já a concentração de peróxido necessária para tratar 500 mg C L-1 foi de 1 mol L-1. Sob essas condições todo formaldeído detectável foi degradado e foi possível remover 89% da matéria orgânica dissolvida na amostra em duas horas. Tais resultados são considerados satisfatórios para descartar na rede de esgoto, segundo a agência paulista de controle ambiental.; Laboratories consume great amounts of hazardous chemicals substances and consequently generate wastewater containing them...

Homogeneous photodegradation of CI Reactive Blue 4 using a photo-Fenton process under artificial and solar irradiation

Carneiro, Patricia A.; Pupo Nogueira, Raquel F.; Zanoni, Maria Valnice Boldrin
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 127-132
Português
Relevância na Pesquisa
66.48%
The oxidation of C.I. Reactive Blue 4 (RB4) by photo-Fenton process mediated by lerrioxalate was investigated under artificial and solar irradiation. The RB4 degradation in acidic medium (pH 2.5) was evaluated by the decrease in Total Organic Carbon (TOC) content and color, measured by the decrease in chromophore absorption band (600 nm). The influence of ferrioxalate and H2O2 concentrations on the dye degradation was studied and best results were obtained using 1.0 mM ferrioxalate and 10 nM of hydrogen peroxide. Under these experimental conditions, 80% of TOC and 100% of color removal were obtained for a 0.1 mM RB4 dye in 35 min of solar irradiation. (c) 2006 Elsevier Ltd. All rights reserved.

Simple and fast spectrophotometric determination of H2O2 in photo-Fenton reactions using metavanadate

Nogueira, RFP; Oliveira, M. C.; Paterlini, W. C.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 86-91
Português
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66.48%
This work proposes a spectrophotometric method for the determination of hydrogen peroxide during photodegradation reactions. The method is based on the reaction of H2O2 with amonium metavanadate in acidic medium, which results in the formation of a red-orange color peroxovanadium cation, with maximum absorbance at 450 nm. The method was optimized using the multivariate analysis providing the minimum concentration of vanadate (6.2 mmol L-1) for the maximum absorbance signal. Under these conditions, the detection limit is 143 mu mol L-1. The reaction product showed to be very stable for samples of peroxide concentrations up to 3 mmol L-1 at room temperature during 180 h. For higher concentrations however, samples must be kept refrigerated (4 degrees C) or diluted. The method showed no interference of Cl- (0.2-1.3 mmol L-1), NO3- (0.3-1.0 mmol L-1), Fe3+, (0.2-1.2 mmol L-1) and 2,4-dichlorophenol (DCP) (0.2-1.0 mmol L-1). When compared to iodometric titration, the vanadate method showed a good agreament. The method was applied for the evaluation of peroxide consumption during photo-Fenton degradation of 2,4-dichlorophenol using blacklight irradiation. (c) 2004 Elsevier B.V. All rights reserved.

Evaluation of the combined solar TiO2/photo-Fenton process using multivariate analysis

Nogueira, R. F P; Trovó, A. G.; Paterlini, W. C.
Tipo: Artigo de Revista Científica Formato: 195-200
Português
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The effect of combining the photocatalytic processes using TiO 2 and the photo-Fenton reaction with Fe3+ or ferrioxalate as a source of Fe2+ was investigated in the degradation of 4-chlorophenol (4CP) and dichloroacetic acid (DCA) using solar irradiation. Multivariate analysis was used to evaluate the role of three variables: iron, H2O2 and TiO2 concentrations. The results show that TiO2 plays a minor role when compared to iron and H2O2 in the solar degradation of 4CP and DCA in the studied conditions. However, its presence can improve TOC removal when H2O2 is totally consumed. Iron and peroxide play major roles, especially when Fe(NO3)3 used in the degradation of 4CP. No significant synergistic effect was observed by the addition of TiO 2 in this process. On the other hand, synergistic effects were observed between FeOx and TiO2 and between H 2O2 and TiO2 in the degradation of DCA. © IWA Publishing 2004.

Photo-fenton degradation of poly(Ethyleneglycol)

Santos,Laís C; Schmitt,Carla C; Poli,Alessandra L; Neumann,Miguel G
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 Português
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Polyethyleneglycol (PEG) was photooxidized in a photo-Fenton system and results compared with the dark reaction. The products were analysed using GPC and HPLC. In the absence of light, PEG samples needed 490 min to reduce their w by 50%, whereas under UV irradiation, only 10 min were necessary. The exponential decay of w with a concomitant increase in polydispersity and number of average chain scission, characterized a random chain scission mechanism. The degradation products of PEG in both systems showed the presence of lower molecular weight products, including smaller ethyleneglycols and formic acid. The mechanism involves consecutive processes, were the larger ethyleneglycols give rise, successively, to smaller ones. This suggests that the mechanism involves successive scissions of the polymer chain. Irradiated samples decomposed faster than those kept in the dark This study proves that the foto-Fenton method associated with UV-light is a good reactant for PEG photodegradation.