Aplicação de oxidação eletroquímica avançada na eliminação de atenolol : reatores de simples e duplo compartimento

Esta tese de doutorado avaliou a influência de diferentes parâmetros operacionais visando otimizar a oxidação eletroquímica avançada (OEA) do Atenolol (ATN) em um reator de compartimento simples, como i) o material de ânodo, diamante dopado com 2500 mg/kg de boro suportado em nióbio (Nb/DDB2500) ou Ti/TiO2(70%)RuO2(30%); ii) a concentração do eletrólito de suporte sulfato de sódio de 0,014, 0,028 e 0,056 M (2, 4 e 8 g/L, respectivamente); iii) a densidade de corrente aplicada (5, 10, 20, 30 e 40 mA/cm²); iv) a adição de membranas Nafion®117, HDX200 e AMHPP no reator de compartimento simples, originando os reatores de compartimento duplo. Além disso, ensaios de voltametria foram empregados para avaliar o mecanismo de degradação do ATN. Os resultados evidenciaram que o ATN é efetivamente oxidado, por via direta e indireta, por meio da eletrogeração de radicais hidroxila (HO•) e radicais sulfato (SOସ •ି) em eletrodos de Nb/DDB2500. No entanto, em eletrodos do tipo ânodos dimensionalmente estáveis (ADE®) de Ti/TiO2(70%)RuO2(30%) a oxidação do ATN ocorre apenas por via indireta, pelos radicais HO• e SOସ •ି, devido à atividade do eletrodo para a reação de evolução de oxigênio (REO). O emprego das membranas entre os eletrodos proporcionou alterações nas características químicas das soluções em tratamento, especialmente no pH e condutividade elétrica. A membrana catiônica Nafion®117 permitiu a passagem do ATN entre os compartimentos, as membranas aniônicas HDX200 e AMHPP evitaram o transporte da molécula de ATN, porém houve fluxo de intermediários e/ou desprendimento de moléculas orgânicas provenientes da degradação das membranas aniônicas. A adição das membranas, conforme proposto pelo modelo estudado, não apresenta ser viável, pois o fluxo de moléculas orgânicas através das membranas e, principalmente, a degradação das membranas aniônicas utilizadas podem limitar o processo. Portanto, neste trabalho a maior degradação e mineralização do ATN foi alcançada com o reator de compartimento simples, aplicando-se as densidades de corrente de 30 e 40 mA/cm², com as concentrações de 0,014 e 0,056 M de Na2SO4 e com o eletrodo Nb/DDB2500. Nessas condições experimentais foi possível alcançar uma degradação de 100% e mineralização de 75% em 150 min de tratamento.Esta tesis doctoral evaluó la influencia de diferentes parámetros operativos con el fin de optimizar la oxidación electroquímica avanzada (OEA) del Atenolol (ATN) en un reactor de un solo compartimento, como i) el material del ánodo, diamante dopado con 2500 mg/kg de boro soportado en niobio (Nb/DDB2500) o Ti/TiO²(70%)RuO2(30%); ii) la concentración del electrolito soporte sulfato de sodio 0,014, 0,028 y 0,056 M (2, 4 y 8 g/L, respectivamente); iii) la densidad de corriente aplicada (5, 10, 20, 30 y 40 mA/cm²); iv) la adición de membranas Nafion®117, HDX200 y AMHPP en el reactor de un solo compartimento, dando lugar a los reactores de doble compartimento. Además, se utilizaron pruebas de voltamperometría para evaluar el mecanismo de degradación del ATN. Los resultados mostraron que el ATN se oxida efectivamente, directa e indirectamente, mediante la electrogeneración de radicales hidroxilo (HO•) y radicales sulfato (SOସ •ି) en electrodos Nb/DDB2500. Sin embargo, en electrodos de tipo ánodo dimensionalmente estable (ADE®) de Ti/TiO2(70%)RuO2(30%) la oxidación del ATN ocurre solo indirectamente, por los radicales HO• y SOସ •ି, debido a la actividad del electrodo para la reacción de evolución de oxígeno (REO). El empleo de las membranas entre los electrodos proporcionó cambios en las características químicas de las disoluciones en tratamiento, especialmente en el pH y la conductividad eléctrica. La membrana catiónica Nafion®117 permitió el paso de ATN entre los compartimentos, las membranas aniónicas HDX200 y AMHPP impidieron el transporte de la molécula de ATN, pero hubo un flujo de intermedios y/o desprendimiento de moléculas orgánicas provenientes de la degradación de las membranas aniónicas. La adición de membranas, según lo propuesto por el modelo estudiado, parece no ser viable, ya que el flujo de moléculas orgánicas a través de las membranas y, principalmente, la degradación de las membranas aniónicas utilizadas puede limitar el proceso. Por lo tanto, en este trabajo la mayor degradación y mineralización de ATN se logró con el reactor de un solo compartimiento, aplicando densidades de corriente de 30 y 40 mA/cm², con las concentraciones 0,014 y 0,056 M de Na2SO4 y con el electrodo Nb/DDB2500. Bajo estas condiciones experimentales fue posible lograr el 100% de degradación y el 75% de mineralización en 150 min de tratamiento.This doctoral thesis evaluated the influence of different operational parameters in order to optimize the electrochemical advanced oxidation (EAO) of Atenolol (ATN) in a single compartment reactor, such as i) the anode material, diamond doped with 2500 mg/kg of boron supported on niobium (Nb/DDB2500) or Ti/TiO2(70%)RuO2(30%); ii) concentration of the sodium sulphate supporting electrolyte 0.014, 0.028 and 0.056 M (2, 4 and 8 g/L, respectively); iii) applied current density (5, 10, 20, 30 and 40 mA/cm²); iv) addition of Nafion®117, HDX200 and AMHPP membranes in the single compartment reactor, giving rise to the double compartment reactors. In addition, voltammetry tests were used to evaluate the ATN degradation mechanism. The results showed that ATN is effectively oxidized, directly and indirectly, through the electrogeneration of hydroxyl radicals (HO•) and sulfate radicals (SOସ •ି) in Nb/DDB2500 electrodes. However, in dimensionally stable anode (DSA®) consisting of Ti/TiO2(70%)RuO2(30%), the oxidation of ATN occurs only indirectly, by HO• radicals and SOସ •ି, due to the electrode activity for the oxygen evolution reaction (OER). The use of membranes between the electrodes provided changes in the chemical characteristics of the solutions under treatment, especially in pH and electrical conductivity. The cationic membrane Nafion®117 allowed the passage of ATN between the compartments, the anionic membranes HDX200 and AMHPP prevented the transport of the ATN molecule, but there was a flow of intermediates and/or detachment of organic molecules from the degradation of the anionic membranes. The addition of membranes, as proposed by the studied model, does not appear to be viable, as the flow of organic molecules through the membranes and, mainly, the degradation of the used anionic membranes, can limit the process. Therefore, in this work, the highest ATN degradation and mineralization was achieved with the single compartment reactor, applying current densities of 30 and 40 mA/cmଶ, with the 0.014 and 0.056 M of Na2SO4 and with the Nb/DDB2500 electrode. Under these experimental conditions it was possible to achieve 100% degradation and 75% mineralization in 150 min of treatment

Study of the atenolol degradation using a Nb/BDD electrode in a filter-press reactor

[EN] The present paper deals with the atenolol (ATL) degradation by advanced anodic oxidation using a boron-doped diamond anode supported on niobium (Nb/BDD). Cyclic voltammetry performed on this electrode revealed that it presents a high quality (diamond-sp3/sp2-carbon ratio), high potential for OER and that ATL can be oxidized directly and/or indirectly by the electrogenerated oxidants, such as hydroxyl radicals, persulfate ions and sulfate radicals. Electrolysis experiments demonstrated that ATL degradation and mineralization follow a mixed (first and zero) order kinetics depending on the applied current density. At high applied current densities, the amount of OH radicals is very high and the overall reaction is limited by the transport of ATL (pseudo first-order kinetics) whereas for low applied current densities, the rate of OH radicals generation at the anode is slower than the rate of arrival of ATL molecules (pseudo-zero order kinetics). Estimated values of kzero and kfirst based on the assumption of pseudo-zero or pseudo-first order kinetics were carried oud as a function of the supporting electrolyte concentration, indicating that both parameters increased with its concentration due the higher production of sulfate reactive species that play an important role in degradation. Finally, MCE increased with the decrease of current density, due to the lower amount of OH present in solution, since this species could be rapidly wasted in parasitic reactions; and the increase of sulfate concentration due to the more efficient production of persulfate.The authors thank the financial support from the Ministerio de Economía y Competitividad (Spain) under projects CTQ2015-65202-C2-1-R and RTI2018-101341-B-C21, co-financed with FEDER funds. The authors thank to FAPERGS, CAPES, FINEP and CNPQ.Heberle, ANA.; García Gabaldón, M.; Ortega, EM.; Bernardes, AM.; Pérez-Herranz, V. (2019). Study of the atenolol degradation using a Nb/BDD electrode in a filter-press reactor. Chemosphere. 236:1-8. https://doi.org/10.1016/j.chemosphere.2019.07.049S1823

A influência da codigestão de óleo vegetal residual na geração de biogás por lodo de estação de tratamento de efluentes

A reciclagem de óleo traz inúmeros benefícios para a sociedade, diminuindo vários problemas relacionados ao seu descarte, sendo que, além disso, possibilita aumentar a geração e a utilização de energia na forma de biogás através da biodigestão anaeróbia, diminuindo a emissão de gases de efeito estufa. Por isto, neste trabalho pesquisou-se a geração de biogás através de lodo de estação de tratamento de efluentes suplementado com óleo vegetal residual (OVR). A geração de biogás ocorreu por meio de digestão anaeróbia no sistema em batelada sob condições mesofílicas (35 ºC). O experimento foi realizado inicialmente com 24 amostras divididas em quatro grupos representativos, sendo um controle (sem adição de OVR) e os demais suplementados com OVR nos percentuais 3%, 6% e 9 % do volume total das amostras (600 mL). O volume de biogás gerado foi controlado por um sistema automatizado para leitura em escala laboratorial e a qualidade do biogás medida a partir de um sensor específico para metano (CH4). Os resultados obtidos demonstraram que o OVR tem potencial para incrementar a geração de biogás, sendo que o tratamento suplementado com 9% de OVR apresentou maior incremento na geração de biogás.

Antibiotics mineralization by electrochemical and UV-based hybrid processes: evaluation of the synergistic effect

[EN] Antibiotics are not efficiently removed in conventional wastewater treatments. In fact, different advanced oxidation process (AOPs), including ozone, peroxide, UV radiation, among others, are being investigated in the elimination of microcontaminants. Most of AOPs proved to be efficient on the degradation of antibiotics, but the mineralization is on the one hand not evaluated or on the other hand not high. At this work, the UV-based hybrid process, namely Photo-assisted electrochemical oxidation (PEO), was applied, aiming the mineralization of microcontaminants such as the antibiotics Amoxicillin (AMX), Norfloxacin (NOR) and Azithromycin (AZI). The influence of the individual contributions of electrochemical oxidation (EO) and the UV-base processes on the hybrid process (PEO) was analysed. Results showed that AMX and NOR presented higher mineralization rate under direct photolysis than AZI due to the high absorption of UV radiation. For the EO processes, a low mineralization was found for all antibiotics, what was associated to a mass-transport limitation related to the low concentration of contaminants (200 ¿g/L). Besides that, an increase in mineralization was found, when heterogeneous photocatalysis and EO are compared, due to the influence of UV radiation, which overcomes the mass-transport limitations. Although the UV-based processes control the reaction pathway that leads to mineralization, the best results to mineralize the antibiotics were achieved by PEO hybrid process. This can be explained by the synergistic effect of the processes that constitute them. A higher mineralization was achieved, which is an important and useful finding to avoid the discharge of microcontaminants in the environment.The authors thank CAPES project number DGPU-2015/7595/14-0, CNPq, FAPERGS, Cyted and FINEP for the financial support.Da Silva, SW.; Heberle, AN.; Santos, AP.; Rodrigues, M.; Valentín Pérez-Herranz; Bernardes, A. 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Evaluation of direct photolysis, electrooxidation and photoelectrooxidation for rhodamine-b degradation

The focus of this study is to evaluate the efficiency of oxidation processes in the treatment of a solution containing Rhodamine-B (RhB) used in various industrial applications. The advanced oxidation processes of electrooxidation (EO) and photoelectrooxidation (PEO) were used. At the same time, direct photolysis (DP) was also applied. Total organic carbon (TOC) reduction and color removal were evaluated. There was an efficient color removal when DP was performed, and the color removal efficiency was the highest when NaCl was used as supporting electrolyte for PEO and EO. However, the TOC reduction was low, indicating that the degradation of the color does not correspond to the pollutant mineralization

Processos oxidativos avançados aplicados na degradação do retardante de chama 2,4,6-Tribromofenol

Os contaminantes de preocupação emergente são compostos químicos presentes numa variedade de produtos comerciais como medicamentos, produtos de higiene, retardantes de chama, surfactantes, dentre outros, podendo ser encontrados em ambientes naturais. Esses contaminantes não são usualmente monitorados ou ainda não possuem legislação regulatória correspondente, mas apresentam risco à saúde humana e ao meio ambiente. Dentre esses contaminantes de preocupação emergente, pode-se destacar o 2,4,6-Tribromofenol, um retardante de chama utilizado em dispositivos eletroeletrônicos. Esse retardante de chama apresenta persistência no ambiente, pode mimetizar alguns tipos de hormônios, também é biocumulativo e apresenta efeitos adversos sobre a saúde ambiental. Tratamentos convencionais de efluentes e água não são eficientes para degradação completa desses compostos. Com isso faz-se necessário o emprego de processos mais eficientes, como processos oxidativos e oxidativos avançados tais como a fotólise direta, fotocatálise heterogênea e a fotoeletrooxidação, tecnologias limpas que utilizam o elétron e o fóton como reagentes. Tais tecnologias têm sido propostas como opção para a degradação desses compostos, evitando assim a contaminação do solo, atmosfera e recursos hídricos Este trabalho foi realizado com uma solução contendo o retardante de chama 2,4,6-Tribromofenol, aplicando-se os processos de fotólise direta, fotocatálise heterogênea e fotoeletrooxidação. As amostras foram coletadas antes e após os processos oxidativos, caracterizadas por carbono orgânico total, espectroscopia de UV/Vis, pH, brometo total, fitotoxicidade e genotoxicidade, também foram avaliados os parâmetros de processo de cinética de degradação, consumo energético, fluência e voltametria cíclica. Verificou-se que a fotoeletrooxidação, de uma forma geral, foi o processo que apresentou os melhores resultados no tratamento do 2,4,6-Tribromofenol, seguido pela fotocatálise heterogênea e fotólise direta. O tempo de 140 min não foi suficiente para degradar e mineralizar todo o contaminante. Em termos de toxicidade a fotoeletrooxidação não apresentou sobprodutos tóxicos, entretanto a fotocatálise heterogênea e a fotólide direta, em algumas condições, demostraram intermediários fitotóxicos e ou genotóxicos. Neste contexto, o processo de fotoeletrooxidação torna-se uma opção na degradação do 2,4,6-Tribromofenol, evitando impacto sobre o meio ambiente.Contaminants of merging concern are chemical compounds present in a variety of commercial products such as medicines, personal care products, flame retardants, surfactants, among others, can be found in the environment. These contaminants are usually not monitored or have no corresponding regulatory legislation, but present risk to human health and the environment. Contaminants of merging concern among these, we highlight the 2,4,6-Tribromofhenol, a flame retardant used in elestronic devices. This flame retardant presents persistence in the environment, can mimic some types of hormones, it is also bioaccumulative and has adverse effects on environmental health. Conventional sewage and water treatment are not effective for complete degradation of these compounds. So is necessary the use of more efficient processes, such as oxidative and advanced oxidative processes as well as direct photolysis, heterogeneous photocatalysis and photoelectrooxidation, clean technology using the electron and photon as reagents. Such technologies have been proposed as an option for the degradation of these compounds, thus avoiding the contamination of soil, air and water resources. This work was carried out using a solution containing the flame retardant 2,4,6-Tribromophenol, applying direct photolysis, heterogeneous photocatalysis and photoelectrooxidation processes. The samples were collected before and after the oxidative processes, characterized by total organic carbon, spectroscopy UV/Vis, pH, total bromide, genotoxicity and phytotoxicity, were also evaluated the parameters process such as energy consumption, fluence and cyclic voltammetry. The photoelectrooxidation, in general, is the process that showed the best results in the treatment of 2,4,6-Tribromophenol, followed by heterogeneous photocatalysis and DP. The reactions time of 140 minutes was not enough to degrade and mineralize the entire contaminant. In terms of toxicity photoelectrooxidation showed no toxic by-products, however the FH and direct photolysis in some conditions, demonstrated phytotoxic and or genotoxic intermediaries. In this context, the photoelectrooxidation process becomes an option in the degradation of 2,4,6-Tribromophenol, avoiding environmental impact

Processos oxidativos avançados aplicados na degradação do retardante de chama 2,4,6-Tribromofenol

Os contaminantes de preocupação emergente são compostos químicos presentes numa variedade de produtos comerciais como medicamentos, produtos de higiene, retardantes de chama, surfactantes, dentre outros, podendo ser encontrados em ambientes naturais. Esses contaminantes não são usualmente monitorados ou ainda não possuem legislação regulatória correspondente, mas apresentam risco à saúde humana e ao meio ambiente. Dentre esses contaminantes de preocupação emergente, pode-se destacar o 2,4,6-Tribromofenol, um retardante de chama utilizado em dispositivos eletroeletrônicos. Esse retardante de chama apresenta persistência no ambiente, pode mimetizar alguns tipos de hormônios, também é biocumulativo e apresenta efeitos adversos sobre a saúde ambiental. Tratamentos convencionais de efluentes e água não são eficientes para degradação completa desses compostos. Com isso faz-se necessário o emprego de processos mais eficientes, como processos oxidativos e oxidativos avançados tais como a fotólise direta, fotocatálise heterogênea e a fotoeletrooxidação, tecnologias limpas que utilizam o elétron e o fóton como reagentes. Tais tecnologias têm sido propostas como opção para a degradação desses compostos, evitando assim a contaminação do solo, atmosfera e recursos hídricos Este trabalho foi realizado com uma solução contendo o retardante de chama 2,4,6-Tribromofenol, aplicando-se os processos de fotólise direta, fotocatálise heterogênea e fotoeletrooxidação. As amostras foram coletadas antes e após os processos oxidativos, caracterizadas por carbono orgânico total, espectroscopia de UV/Vis, pH, brometo total, fitotoxicidade e genotoxicidade, também foram avaliados os parâmetros de processo de cinética de degradação, consumo energético, fluência e voltametria cíclica. Verificou-se que a fotoeletrooxidação, de uma forma geral, foi o processo que apresentou os melhores resultados no tratamento do 2,4,6-Tribromofenol, seguido pela fotocatálise heterogênea e fotólise direta. O tempo de 140 min não foi suficiente para degradar e mineralizar todo o contaminante. Em termos de toxicidade a fotoeletrooxidação não apresentou sobprodutos tóxicos, entretanto a fotocatálise heterogênea e a fotólide direta, em algumas condições, demostraram intermediários fitotóxicos e ou genotóxicos. Neste contexto, o processo de fotoeletrooxidação torna-se uma opção na degradação do 2,4,6-Tribromofenol, evitando impacto sobre o meio ambiente.Contaminants of merging concern are chemical compounds present in a variety of commercial products such as medicines, personal care products, flame retardants, surfactants, among others, can be found in the environment. These contaminants are usually not monitored or have no corresponding regulatory legislation, but present risk to human health and the environment. Contaminants of merging concern among these, we highlight the 2,4,6-Tribromofhenol, a flame retardant used in elestronic devices. This flame retardant presents persistence in the environment, can mimic some types of hormones, it is also bioaccumulative and has adverse effects on environmental health. Conventional sewage and water treatment are not effective for complete degradation of these compounds. So is necessary the use of more efficient processes, such as oxidative and advanced oxidative processes as well as direct photolysis, heterogeneous photocatalysis and photoelectrooxidation, clean technology using the electron and photon as reagents. Such technologies have been proposed as an option for the degradation of these compounds, thus avoiding the contamination of soil, air and water resources. This work was carried out using a solution containing the flame retardant 2,4,6-Tribromophenol, applying direct photolysis, heterogeneous photocatalysis and photoelectrooxidation processes. The samples were collected before and after the oxidative processes, characterized by total organic carbon, spectroscopy UV/Vis, pH, total bromide, genotoxicity and phytotoxicity, were also evaluated the parameters process such as energy consumption, fluence and cyclic voltammetry. The photoelectrooxidation, in general, is the process that showed the best results in the treatment of 2,4,6-Tribromophenol, followed by heterogeneous photocatalysis and DP. The reactions time of 140 minutes was not enough to degrade and mineralize the entire contaminant. In terms of toxicity photoelectrooxidation showed no toxic by-products, however the FH and direct photolysis in some conditions, demonstrated phytotoxic and or genotoxic intermediaries. In this context, the photoelectrooxidation process becomes an option in the degradation of 2,4,6-Tribromophenol, avoiding environmental impact

Evaluation of an electrochemical membrane reactor for the removal of beta-blocker compound from water

[EN] As part of the Brazilian Popular Pharmacy Program, the beta-blocker Atenolol (ATN) is widely used, and its presence in the environmental ecosystems is a reality. Aiming the ATN removal, the use of an electrochemical membrane reactor was evaluated and compared to a membraneless one. The results show that the generation of SO4 center dot- in the membrane reactor occurs by the reaction of HSO4-/H2SO4 scavenging HO center dot-, whereas, in the membraneless reactor, the SO4 center dot- generation occurs mainly by the direct oxidation mechanism. Operating both reactors in the same hydrodynamic conditions, it was found that the concentrations of SO4 center dot- and S(2)O8(2)(-) are higher in the membrane reactor, leading to a greater concentration of these species being transported to the bulk solution, changing the kinetics, and presenting better results in electrochemical combustion (phi), mineralization current efficiency (MCE) and specific energy consumption (Es). Since the mass transport limitations were overcome in membrane reactor, the processes may find their good applications in water and wastewater treatment.The authors are grateful to the Brazilian funding agencies (FAPERGS, CAPES, CNPq and FINEP), to the Programa Iberoamericano de Ciencia y Tecnologia para el Desarollo (CYTED), and to the Ministerio de Ciencia, Innovacion y Universidades (Spain) under the project RTI2018-101341-B-C21, co-financed with FEDER fundsArenhart-Heberle, AN.; Vianna, GGF.; Da Silva, SW.; Pérez-Herranz, V.; Moura Bernardes, A. (2022). Evaluation of an electrochemical membrane reactor for the removal of beta-blocker compound from water. Journal of Water Process Engineering. 47:1-9. https://doi.org/10.1016/j.jwpe.2022.102830194