Processo foto-fenton solar mediador por ferrioxalato (FeOx/H2O2/UV) aplicado ao tratamento de efluente têxtil

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Ambiental, Florianópolis, 2016O processo foto-Fenton é um Processo Oxidativo Avançado (POA) que consiste na reação de íons ferrosos com peróxido de hidrogênio. Este possui elevado poder de degradação de compostos persistentes, como os corantes, porém necessita de pH igual a 2,8 para atingir máxima degradação de poluentes sendo esta considerada a grande desvantagem do sistema. A inclusão de complexos de ferro no processo foto-Fenton tem sido encarada como uma alternativa para a estabilização do ferro, evitando sua precipitação em faixa mais ampla de pH. O complexo ferrioxalato de potássio (FeOx) é capaz, ainda, de aumentar consideravelmente o rendimento quântico de geração de Fe2+, produzindo maior quantidade de radicais hidroxila e evitar a formação de outros complexos poluentes. Aplicações mais interessantes referem-se ao uso de radiação solar, pois o FeOx estende a faixa de absorção para a região do visível, fazendo maior proveito desta fonte de radiação além de reduzir custos com lâmpadas e energia. Neste contexto, o objetivo geral deste trabalho foi avaliar a eficiência do processo foto-Fenton solar mediado por ferrioxalato (FeOx/H2O2/UV) na remoção da cor e carga orgânica de efluentes têxteis, bruto (EB) e pós-tratamento de lodos ativados (EP), sob as variações sazonais de incidência de radiação, temperatura e características do efluente durante o período de um ano. Os ensaios em escala piloto foram realizados em um reator Composto Parabólico Concentrado (CPC), o qual operou os efluentes simultaneamente em ensaios distribuídos ao longo do ano com duração de 90 minutos cada. Foram administradas dosagens decrescentes de peróxido de hidrogênio de 150, 125, 100, 75, 50, 25 mg.L-1, concentração de ferro de 50 mg.L-1, complexado com oxalato, e pH 5. Os resultados demostraram elevada capacidade de descoloração do processo com porcentagens de remoção da cor de 78% e 94,4% para EB e EP, respectivamente. Foi possível notar a grande diferença na redução dos espectros de absorção entre os dias ensolarados (EDS) e nublados (EDN). Em função da adição do complexo de ferro houve um grande aumento na turbidez, sólidos totais e sólidos suspensos de ambos efluentes. A degradação do complexante durante o processo no EP em dias ensolarados resultou na elevada sedimentabilidade dos sólidos do efluente final, originando um efluente clarificado. O sobrenadante de EP apresentou valores de ferro abaixo de 15 mg.L-1, concentração máxima exigida pela legislação para lançamento de efluentes. De maneira geral, conclui-se que o FeOx/H2O2/UV solar apresentou resultados positivos em ensaios ensolarados, diferentemente dos ensaios com tempo nublado.Abstract: The photo-Fenton process is an Advanced Oxidative Process (AOP) which is powerful in the degradation of persistent compounds, such as dyes, however, it requires pH 2,8 to reach maximum degradation of pollutants, which is considered this system greatest disadvantage. The inclusion of iron complexes to the photo-Fenton process has been seen as an alternative to stabilize iron, preventing its precipitation in a broader pH band. The potassium ferrioxalate complex is also able to increase considerably the amount of Fe2+ generated, producing higher number of hydroxyl radicals and preventing the formation of other pollutant complexes. More interesting applications regard the use of solar radiation since the FeOx expands the absorption band to the visible region, taking advantage of this radiation source in addition to reducing costs with lamps and energy. In such context, the main aim of this study was to evaluate the efficacy of the solar photo-Fenton process mediated by ferrioxalate (FeOx/H2O2/UV) in color removal and the organic load of textile effluents, crude (EB) and after the activated mud treatment (EP), under seasonal variations of radiation incidence, temperature and effluent characteristics throughout the period of a year. The tests in a pilot scale were carried out in a reactor Compound Parabolic Concentrator (CPC), which operated simultaneously with two effluents in testes distributed along the year with the duration of 90 minutes each. Decreasing doses of hydrogen peroxide, 150, 125, 100, 75, 50, 25 mg.L-1, were introduced, and the iron complexed with oxalate concentration was 50 mg.L-1 and pH 5. The results revealed the process high discoloration ability with 78% and 94,4% maximum color removal percentages for EB and EP, respectively. It was possible to observe the difference in reduction in the absorption spectra between sunny (EDS) and cloudy days (EDN). Due to the iron complex addition, there was great increase in turbidity, total solids and suspended solids for both effluents. The complexant degradation during the process in EP on sunny days resulted in high settleability of the solids in the final effluent, originating a light effluent. The EP supernatant presented iron values below 15 mg.L-1, the maximum concentration required by the law for effluent release. The general conclusion was that the FeOx/H2O2/UV presented positive results in tests on sunny days, unlike the results presented on cloudy days

Efeito da intercamada de nanopartículas de alumínio na formação do filme fino de poliamida em membranas de osmose reversa para a melhoria da resistência à bioincrustação

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Ambiental, Florianópolis, 2021.A crescente demanda por água doce para as atividades humanas está colocando uma gradativa pressão em fontes convencionais de água. Com o aumento da preocupação com a sustentabilidade do suplemento de água, há um aumento no interesse de produzir água por fontes não alternativas como água do mar, água subterrânea e efluentes secundários. Tais fontes alternativas geralmente são caracterizadas pela elevada concentração de sais e contaminantes que necessitam ser removidos por processo de dessalinização por osmose reversa. Dessa forma, as incrustações em membranas de osmose reversa são um dos principais problemas envolvidos no custo da aplicação dessa tecnologia. Para contornar esse problema a modificação da superfície das membranas compósitas de filme fino de poliamida (TFC-PA, sigla em inglês para Thin film composite polyamide) tem-se mostrado uma estratégia interessante para diminuir da incrustação. A aplicação de uma intercamada composta de nanomateriais na superfície da membrana suporte como uma base para a polimerização interfacial de formação da poliamida, promove mudanças em suas propriedades, que podem resultar na melhoria de membranas de dessalinização. Estudos têm mostrado que a permeabilidade e a seletividade da membrana podem ser aumentadas com a utilização uma intercamada de nanomateriais. Por outro lado, o potencial do uso dessa abordagem para melhorar as propriedades da membrana de poliamida no que se refere à incrustação e bioincrustação são pouco compreendidas. Nesta tese, foi investigado como o uso de uma intercamada inédita de nanopartículas de alumínio (NP-Al) como base para o processo de polimerização interfacial afeta a propensão à bioincrustação e a incrustação orgânica das TFC-PA. O desempenho foi avaliado por ensaios estáticos de deposição de bactéria e proteína, assim como bioincrustação dinâmica em sistema de filtração por OR. Dentre as três concentrações de NP-Al testadas, a incorporação de NP-Al em baixa e média concentrações apresentaram redução na adesão de bactéria e proteína, enquanto que na maior concentração de NP-Al, ambas as adesões de bactéria e proteína aumentaram. Tendência similar foi observada em condições dinâmicas de filtração, com baixas e médias concentrações de NP-Al, apresentando menor declínio de fluxo e menor formação de biofilme comparado com o controle e com membranas com elevada concentração de NP-Al. A melhoria das propriedades anti-incrustantes dessas membranas foram correlacionadas com mudanças na energia livre de coesão da camada de poliamida formada sobre a intercamada de NP-Al. Os resultados demonstram que utilizando uma intercamada de NP-Al, a química da superfície da poliamida pode ser alterada de maneira a reduzir a incrustação da membrana. Contudo, há um limite na quantidade de NP-Al incorporada na intercamada, resultando no aumento da incrustação devido ao efeito da aglomeração da NP-Al na estrutura da poliamida. Os resultados dessa tese trazem novas percepções em como nanopartículas podem ser adicionadas como base para a polimerização interfacial da poliamida com o intuito de melhorar a performance de membranas de dessalinização sem exposição de nanopartículas na superfície.Abstract: The growing demand for freshwater by human activities is putting an increasing pressure on conventional water sources. As concerns arise over the sustainability of water supply, there is an increased interest in producing clean water from alternative sources such as seawater, wastewater, or brackish water. These alternative sources are usually characterized by higher concentrations of salts and contaminants, which result in the need to use desalination processes by reverse osmosis. Fouling in reverse osmosis membranes is one of the main problems involved in the cost of applying this technology. Modification of the surface of thin film polyamide composite membranes (TFC-PA) has been shown to be an interesting strategy for reducing fouling. Applying an interlayer of nanomaterial to the support layer as a template to the interfacial polymerization results in a change in the polyamide properties that can be leveraged to improve the performance of desalination membranes. While studies have shown that permeability and selectivity can be increased using an interlayer of nanomaterials, the potential of using this approach to improve the polyamide properties relevant for fouling and biofouling control is less understood. In this dissertation, we investigated how using a novel interlayer of aluminum nanoparticles (Al-NP) to template the interfacial polymerization process affects the biofouling and organic fouling propensity of thin film composite membranes. Performance was measured by static bacteria and protein deposition assays as well as dynamic reverse osmosis biofouling experiments. Among the three Al-NP concentrations tested, the low and medium Al-NP loadings were found to reduce bacteria and protein adhesion while, at a high Al-NP loading, both bacteria and protein adhesion increased. A similar trend was observed in dynamic fouling conditions, with the low and medium Al-NP loadings experiencing less flux decline and lower biofilm volume on the membrane compared to the control or high Al-NP membrane. The superior antifouling properties of these membranes were correlated with the change in the free energy of cohesion of the polyamide layer formed on the Al-NP interlayer. Our results demonstrate that using an interlayer of Al-NP can alter the polyamide surface chemistry in a way that reduces membrane fouling; however, there is a threshold loading of Al-NP beyond which fouling propensity increases due to the effect of Al-NP agglomeration on the polyamide structure. The results shown in this dissertation provide useful insights into how nanoparticles can be added to the interlayer during interfacial polymerization to improve the performance of desalination membranes without exposing nanoparticles onto the surface

Membrane adsorption with polyacrylonitrile prepared with superfine powder activated carbon, case study: separation process applied in water treatment containing diclofenac

Polyacrylonitrile membranes (PAN) have high stability against chemical agents, making them suitable for a wide range of applications as such Ultrafiltration processes. Ultrafiltration membranes composed of PAN/Superfine powder activated carbon (S-PAC) mixtures can be a good research route, aiming the development of a new separation processes for water treatment. The association of materials to form a single product can have technological and economic advantages in separation processes. In this study, S-PAC impregnated into PAN membranes were prepared, characterized and used, as a case study, to remove diclofenac (DCF) from water. The membranes (PAN/S-PAC) were synthesized with different concentrations of S-PAC (0.2, 0.6, 1.0, 3.0 and 5.0 wt%) by a phase inversion process. The results of the TEM characterizations of the S-PAC indicated the presence of micro and nanoparticles (∼10 nm) and tending to form micrometric clusters. The infrared spectra of the membranes were characteristic of PAN; however, vibrational bands attributed to the S-PAC spectrum were also observed, which indicated an interaction between the materials. The case study showed an increase in the water flux and in the DCF rejection efficiency, for composite membranes (PAN/S-PAC) with higher concentration of S-PAC. The results of static adsorption tests indicated that the mechanism of DCF rejection occurred predominantly by adsorption. There were indications that the PAN/S-PAC membranes formed a composite material and the PAN/S-PAC (3.0) presented the best study composition given the results. Although the research is in its initial phase, the results indicated that the composition can improve many water treatment systems

Membrane adsorption with polyacrylonitrile prepared with superfine powder-activated carbon, case study: separation process applied in water treatment containing diclofenac

Polyacrylonitrile membranes (PAN) have high stability against chemical agents, making them suitable for a wide range of applications as such Ultrafiltration processes. Ultrafiltration membranes composed of PAN/Superfine powder activated carbon (S-PAC) mixtures can be a good research route, aiming the development of a new separation processes for water treatment. The association of materials to form a single product can have technological and economic advantages in separation processes. In this study, S-PAC impregnated into PAN membranes were prepared, characterized and used, as a case study, to remove diclofenac (DCF) from water. The membranes (PAN/S-PAC) were synthesized with different concentrations of S-PAC (0.2, 0.6, 1.0, 3.0 and 5.0 wt%) by a phase inversion process. The results of the TEM characterizations of the S-PAC indicated the presence of micro and nanoparticles (∼10 nm) and tending to form micrometric clusters. The infrared spectra of the membranes were characteristic of PAN; however, vibrational bands attributed to the S-PAC spectrum were also observed, which indicated an interaction between the materials. The case study showed an increase in the water flux and in the DCF rejection efficiency, for composite membranes (PAN/S-PAC) with higher concentration of S-PAC. The results of static adsorption tests indicated that the mechanism of DCF rejection occurred predominantly by adsorption. There were indications that the PAN/S-PAC membranes formed a composite material and the PAN/S-PAC (3.0) presented the best study composition given the results. Although the research is in its initial phase, the results indicated that the composition can improve many water treatment systems

Membrane adsorption with polyacrylonitrile prepared with superfine powder-activated carbon, case study: separation process applied in water treatment containing diclofenac

Polyacrylonitrile membranes (PAN) have high stability against chemical agents, making them suitable for a wide range of applications as such Ultrafiltration processes. Ultrafiltration membranes composed of PAN/Superfine powder activated carbon (S-PAC) mixtures can be a good research route, aiming the development of a new separation processes for water treatment. The association of materials to form a single product can have technological and economic advantages in separation processes. In this study, S-PAC impregnated into PAN membranes were prepared, characterized and used, as a case study, to remove diclofenac (DCF) from water. The membranes (PAN/S-PAC) were synthesized with different concentrations of S-PAC (0.2, 0.6, 1.0, 3.0 and 5.0 wt%) by a phase inversion process. The results of the TEM characterizations of the S-PAC indicated the presence of micro and nanoparticles (∼10 nm) and tending to form micrometric clusters. The infrared spectra of the membranes were characteristic of PAN; however, vibrational bands attributed to the S-PAC spectrum were also observed, which indicated an interaction between the materials. The case study showed an increase in the water flux and in the DCF rejection efficiency, for composite membranes (PAN/S-PAC) with higher concentration of S-PAC. The results of static adsorption tests indicated that the mechanism of DCF rejection occurred predominantly by adsorption. There were indications that the PAN/S-PAC membranes formed a composite material and the PAN/S-PAC (3.0) presented the best study composition given the results. Although the research is in its initial phase, the results indicated that the composition can improve many water treatment systems