Degradació en planta pilot de colorants reactius mitjançant el procés de foto-Fenton assistit amb llum solar: aplicació del procés com a pre-tractament d'un procés biològic

Estudi elaborat a partir d’una estada a la Plataforma Solar de Almería entre desembre del 2006 i gener del 2007. S’ha dut a terme la degradació en planta pilot dels colorants reactius Procion Red H-E7B i Cibacron Red FN-R mitjançant el procés de foto-Fenton aplicat com a tractament únic i com a pretractament d’un procés biològic. El procés de foto-Fenton, assistit amb llum solar, es va realitzar en un fotoreactor solar tipus Col•lector Parabòlic Compost (CPC) i el tractament biològic en un Reactor de Biomassa Immobilitzada (RBI). Com a punt de partida, i amb l’objectiu d’estudiar la reproductibilitat del sistema, es van prendre resultats obtinguts d’experiments realitzats prèviament a escala de laboratori i amb llum artificial. El paràmetre Carboni Orgànic Total (COT) es va emprar com a indicador de l’eliminació dels colorants i dels seus intermedis. En aplicar únicament el procés de foto-Fenton com a tractament, concentracions de 10 mg•l-1 de Fe (II) i 250 mg•l-1 de H2O2 per degradar 250 mg•l-1 Procion Red H-E7B, i de 20 mg•l-1 de Fe (II) i 500 mg•l-1 de H2O2 per degradar 250 mg•l-1 Cibacron Red FN-R, van reproduir els resultants obtinguts al laboratori, amb uns nivells d’eliminació de COT del 82 i 86%, respectivament. A més, l’ús beneficiós de la llum solar en el procés de foto-Fenton, juntament amb la configuració del CPC, van incrementar la velocitat de degradació respecte als resultats previs, permetent la reducció de la concentració de Fe (II) de 10 a 2 mg•l-1 (Procion Red H-E7B) i de 20 a 5 mg•l-1 (Cibacron Red FN-R) sense pèrdues d’efectivitat. D’altre banda, el sistema combinat foto-Fenton/tractament biològic en planta pilot, unes concentracions d’oxidant de 225 mg•l-1 H2O2 per Cibacron Red FN-R i 65 mg•l-1 H2O2 per Procion Red H-E7B van ser suficients per generar solucions intermèdies biodegradables i alimentar així el RBI, millorant inclús els resultats obtinguts prèviament al laboratori.

Sistema de injeção em fluxo espectrofotométrico para monitorar peróxido de hidrogênio em processo de fotodegradação por reação foto-Fenton

A flow injection spectrophotometric system was projected for monitoring hydrogen peroxide during photodegradation of organic contaminants in photo-Fenton processes (Fe2+/H2O2/UV). Sample is injected manually in a carrier stream and then receives by confluence a 0.1 mol L-1 NH4VO3 solution in 0.5 mol L-1 H2SO4 medium. The product formed shows absorption at 446 nm which is recorded as a peak with height proportional to H2O2 concentration. The performance of the proposed system was evaluated by monitoring the consumption of H2O2 during the photodegradation of dichloroacetic acid solution by foto-Fenton reaction.

Utilização de reações foto-Fenton na prevenção de contaminações agrícolas

In this work the application of the photo-Fenton process for the treatment of washing water of herbicide containers using solar energy was studied. The influence of the H2O2 concentration and the iron source on the degradation of tebuthiuron and diuron was investigated. The degradation efficiency was strongly affected by the iron source. Using ferrioxalate, total mineralization of diuron and tebuthiuron was obtained either for the individual compounds or for a mixture containing both herbicides, while when using Fe(NO3)3, the maximum mineralization reached for both herbicides was only 50%.

Avaliação da reação foto-fenton na decomposição de resíduos de carrapaticida

Experimental procedures based on factorial design and surface response methodology were applied to establishe experimental conditions for the decomposition of a 1:400 (v/v) Supocade® (chlorfenvinphos 13.8% and cypermethrin 2.6%) solution, used to control cattle ticks. Experiments exploring photo-oxidative reactions were performed with and without UV radiation, fixing exposition time and pesticide volume, and varying the oxidant mixture. The use of 3.6 mmol L-1 Fe2+ plus 1.9 mol L-1 H2O2 plus UV radiation provided destruction of 94% of the original carbon content and reduction of aromatic, aliphatic and carbinolic compounds, evaluated by determination of residual carbon content by ICP OES and NMR analysis.

Fundamentos e aplicações ambientais dos processos fenton e foto-fenton

Wastewater and soil treatment processes based on Fenton's reagent have gained great attention in recent years due to its high oxidation power. This review describes the fundaments of the Fenton and photo-Fenton processes and discusses the main aspects related to the degradation of organic contaminants in water such as the complexation of iron, the use of solar light as the source of irradiation and the most important reactor types used. An overview of the main applications of the process to a variety of industrial wastewater and soil remediations is presented.

Potencial de aplicação do processo foto-fenton/solar como pré-tratamento de efluente da indústria de laticínios

Dairy wastewater is characterized by frequent episodes of drastic increases of organic content, giving rise to bulking filamentous bacteria and compromising the biological treatment process. This study reports the reduction of organic content of such wastewater by the application of the solar photo-Fenton process. For a wastewater containing 335, 2627 or 5400 mg C L-1 between 90% and 50% of the organic carbon content were removed after 3.5 h irradiation. The results show that the solar photo-Fenton process can be a good alternative for the abatement of organic content of dairy wastewater, especially in cases of organic content fluctuation, allowing an efficient biological treatment.

Degradação de benzeno, tolueno e xilenos em águas contaminadas por gasolina, utilizando-se processos foto-Fenton

In this work the potentiality of photo-Fenton processes were investigated toward the degradation of aromatic hydrocarbons (BTXs) from water contaminated with gasoline. The main results demonstrated that BTXs can be quickly degraded by photo-Fenton process assisted by solar or artificial UV-A radiation, degradation that leads to generation of characteristic phenolic transient species (ie. phenol, hydroquinone and catechol). In the treatment of contaminated water by photo-Fenton processes assisted by solar light, complete BTXs removal was observed in reaction times of about 5 min. Mineralization of about 90% was also observed by applying a multiple H2O2 addition system.

Tratamento de banhos de tingimento têxtil por processos foto-Fenton e avaliação da potencialidade de reuso

In this work the treatment of textile dyeing baths by a sequential reductive-oxidative process was evaluated, aiming its utilization in new dyeing process. The results demonstrated that reactive dyes can be easily degraded by reductive processes mediated by zero-valent iron, a fact that induces decolorizations of about 80%. Sequential photo-Fenton processes permit almost total removal of the residual color with elimination of 90% of the COD content. The reuse of treated residues permits the achievement of materials that attend practically all textile specifications, with exception of the color difference parameter (ΔE), which is unsatisfactory toward the importation standards, but adequate for the national market.

Degradação de corantes reativos por processo foto-fenton envolvendo o uso de peneira molecular 4A modificada com Fe3+

In this work the preparation and characterization of a supported catalyst intended for degradation of reactive dyes by Fenton-like processes is described. The photocatalyst was prepared by immobilization of Fe3+ into the molecular sieve (4A type) surface and characterized by x-ray diffractometry and infrared, Mössbauer and EPR spectroscopy. The solid containing 0.94% (w/w) of ferric ions was used in degradation studies of aqueous reactive-dyes samples with really promissory results. Generally, Vis-assisted photochemical processes leads to almost total decolorization of all tested dyes at reaction times lower than 30 min. It was also observed that the iron-molecular sieve matrix can be reused.

Degradação de corantes têxteis e remediação de resíduos de tingimento por processos Fenton, foto-Fenton e eletro-Fenton

In this work the degradation of textile dyes were evaluated, using Fenton, photo-Fenton and electro-Fenton processes. Under optimized conditions Fenton and photo-Fenton processes showed high decolorization capacity of the model dyes. The electro-Fenton process was carried out in an undivided electrochemical reactor (1000 mL) equipped with a carbon-felt cathode (253 cm²) and a platinum gauze anode (6 cm²). Under optimal conditions (J: 1.6 mA cm-2, Na2SO4: 0.075 mol L-1, pH: 3) H2O2 concentration of about 60 mg L-1 was observed. The addition of Fe2+ (15 mg L-1) induces Fenton reactions that permit almost total decolorization of textile dyes.

Degradação de poluentes emergentes por processos Fenton e foto-Fenton

A continuous photochemical treatment system was developed for aiming the treatment of aqueous solutions containing relevant micro-pollutants (microcystin-LR, sulfamethoxazole and 17-b estradiol). The continuous photo-Fenton process provided high degradation efficiency. However, contact time between samples and the irradiated region is short relative to total treatment time, indicating that observed changes are predominantly due to the Fenton process. Higher degradation efficiency was observed in systems operated using two treatment cycles, the first involving a batch Fenton process and the second a continuous photo-Fenton treatment.

Fotodegradação de fenol e clorofenóis por processo foto-Fenton mediado por ferrioxalato

A influência de parâmetros operacionais como a agitação da solução durante irradiação solar e a vazão de alimentação de um fotorreator com irradiação artificial foi avaliada na fotodegradação de 2-clorofenol (2CF) e 2,4-diclorofenol (DCF) por processo foto-Fenton mediado por ferrioxalato. Após avaliação destes parâmetros, os sistemas foram aplicados na fotodegradação de fenol e de mono, (2-clorofenol e 4-clorofenol), di (2,4-diclorofenol) e tri (2,4,6-triclorofenol) clorofenóis a fim de avaliar a eficiência de fotodegradação destes compostos sob irradiação solar e artificial. Foi observada pequena diferença nas porcentagens de remoção de carbono orgânico total (COT) e de geração de íons cloreto nos experimentos de fotodegradação de 2CF sem agitação e com agitação sob irradiação solar. Sob irradiação artificial, um aumento da vazão de alimentação do sistema resultou em menor porcentagem de remoção de COT, ao passo que uma maior velocidade de remoção foi obtida devido a um menor tempo de irradiação. Foi então utilizada uma vazão intermediária de 33,4 mL min-1. Sob irradiação solar, foram necessários 15 minutos de irradiação para a completa remoção de todos os clorofenóis, entretanto para fenol, a completa remoção foi atingida em 20 minutos. Sob irradiação artificial, os clorofenóis foram removidos entre 4,5 e 6,5 minutos de irradiação. A velocidade de degradação aumenta ligeiramente com o aumento do número de cloros ligados ao anel aromático tanto sob irradiação artificial como solar.

Estudo da aplicação do processo foto-Fenton solar na degradação de efluentes de indústria de tintas

Neste trabalho estudou-se a aplicabilidade do processo foto-Fenton utilizando irradiação solar no tratamento de dois efluentes (A e B) de uma indústria de tintas. Foi avaliada a influência da concentração inicial de peróxido de hidrogênio e ferro na remoção de carbono orgânico dissolvido (COD). Nos primeiros minutos de irradiação foi observada a descoloração e a remoção de odores. Para o efluente A, atingiu-se 75 % de remoção de COD durante 60 minutos de irradiação. Para o efluente B, adições múltiplas de peróxido de hidrogênio foram necessárias para aumentar a remoção de COD, 43 % em 60 minutos de irradiação. Os resultados obtidos mostram que o processo foto-Fenton solar pode ser aplicado ao tratamento dos efluentes gerados na indústria de tintas.

Tratamiento de una mezcla de pesticidas comerciales (HIERBAMINA ® GESAPRIM ® 90 WG) mediante el sistema foto-fenton en una planta piloto solar.

Tesis (Maestría en Ciencias con Orientación en Química Analítica Ambiental) UANL, 2010.

Degradación de pirazinamida mediante el proceso foto-fenton utilizando FeC?O? como fuente de hierro a pH 3, 4.5 y 6.

Tesis (Maestría en Ciencias con orientación en Química Analítica Ambiental) UANL, 2014.