Abstract:ResumoEfluentes ricos em manganês, como os das indústrias extrativas, de vidro e cerâmicas, plantas de galvanização, entre outros, são considerados um problema ambiental devido principalmente ao seu poder toxicológico. O íon manganês é um poluente devido às suas propriedades organolépticas e é considerado um metal de difícil remoção devido à sua alta solubilidade, sendo usualmente encontrado em efluentes na forma do íon divalente Mn 2+ . Diversos métodos de tratamento têm sido aplicados a esses tipos de efluen… Show more
“…Manganese sorption on a cation-exchange resin (Sinco-430) was also modelled using the second-order equation and an activation energy of 6.34 kJ/mol was reported, which also suggests pore-diffusion control (Zhuang et al, 2020). Similarly, manganese adsorption on a spent zeolite was also described by the pseudo-second order equation and the activation energy was 55.6 kJ/mol, which can be also ascribed to pore-diffusion control (Figueiredo et al, 2018).…”
Present in soils, ground and surface waters, manganese is among the most common metals in Earth crust. It is also an essential trace element to the functioning of several enzymes in the human body. However, exposure to high manganese concentrations can also be harmful to humans with psychiatric and motor effects and therefore, manganese concentrations in drinking water and also industrial effluents are regulated. In the current work, the adsorption of Ca<sup>2+</sup>, Mg<sup>2+</sup> and Mn<sup>2+</sup> on three different ion-exchange resins: (i) aminophosphonic acid - chelating (Purolite S950), (ii) polyacrylic weak acid cation (Purolite C104E) and (iii) polystyrene strong acid cation (Purolite C100) was investigated. The results revealed that Purolite S950 had the highest Mn2+ uptake (37.9 mg/mL-resin or 0.69 mmol/mL-resin) as compared to Ca<sup>2+</sup> (3.2 mg/mL-resin or 0.08 mmol/mL-resin) and Mg<sup>2+</sup> (~0 mg/mL-resin) and was selected for further kinetics and equilibrium studies. The results indicated Purolite S950 as particularly suited to be applied in the treatment of neutral mine waters with high Mg/Mn ratios. Additionally, Purolite S950 showed a small affinity for Ca<sup>2+</sup> and therefore an efficient Mn<sup>2+</sup> removal will depend on the Ca/Mn ratio of the mine water under treatment. According to the kinetic analysis, manganese sorption on Purolite S950 was described by the pseudo-second order model (r<sup>2</sup> > 0.98) with an activation energy of 10.40 kJ/mol and thus pore-difussion was the rate controlling step of the process. In terms of equilibrium studies, manganese sorption on Purolite S950 followed the Langmuir model with maximum loadings of up to 41.5 mg/mL-resin. The thermodynamic modelling indicated an exothermic process (-85.0 kJ/mol, as standard enthalpy) with a standard entropy of -274 J/mol.K, which was ascribed to the release of two adsorbed H<sup>+</sup> ions for each Mn<sup>2+</sup> ion taken up from solution
“…Manganese sorption on a cation-exchange resin (Sinco-430) was also modelled using the second-order equation and an activation energy of 6.34 kJ/mol was reported, which also suggests pore-diffusion control (Zhuang et al, 2020). Similarly, manganese adsorption on a spent zeolite was also described by the pseudo-second order equation and the activation energy was 55.6 kJ/mol, which can be also ascribed to pore-diffusion control (Figueiredo et al, 2018).…”
Present in soils, ground and surface waters, manganese is among the most common metals in Earth crust. It is also an essential trace element to the functioning of several enzymes in the human body. However, exposure to high manganese concentrations can also be harmful to humans with psychiatric and motor effects and therefore, manganese concentrations in drinking water and also industrial effluents are regulated. In the current work, the adsorption of Ca<sup>2+</sup>, Mg<sup>2+</sup> and Mn<sup>2+</sup> on three different ion-exchange resins: (i) aminophosphonic acid - chelating (Purolite S950), (ii) polyacrylic weak acid cation (Purolite C104E) and (iii) polystyrene strong acid cation (Purolite C100) was investigated. The results revealed that Purolite S950 had the highest Mn2+ uptake (37.9 mg/mL-resin or 0.69 mmol/mL-resin) as compared to Ca<sup>2+</sup> (3.2 mg/mL-resin or 0.08 mmol/mL-resin) and Mg<sup>2+</sup> (~0 mg/mL-resin) and was selected for further kinetics and equilibrium studies. The results indicated Purolite S950 as particularly suited to be applied in the treatment of neutral mine waters with high Mg/Mn ratios. Additionally, Purolite S950 showed a small affinity for Ca<sup>2+</sup> and therefore an efficient Mn<sup>2+</sup> removal will depend on the Ca/Mn ratio of the mine water under treatment. According to the kinetic analysis, manganese sorption on Purolite S950 was described by the pseudo-second order model (r<sup>2</sup> > 0.98) with an activation energy of 10.40 kJ/mol and thus pore-difussion was the rate controlling step of the process. In terms of equilibrium studies, manganese sorption on Purolite S950 followed the Langmuir model with maximum loadings of up to 41.5 mg/mL-resin. The thermodynamic modelling indicated an exothermic process (-85.0 kJ/mol, as standard enthalpy) with a standard entropy of -274 J/mol.K, which was ascribed to the release of two adsorbed H<sup>+</sup> ions for each Mn<sup>2+</sup> ion taken up from solution
“…Os experimentos apresentaram grande dependência à concentração inicial dos metais nas soluções aquosas e o tempo de contato com o adsorvente, com taxas de remoções maiores no início do experimento e sendo um processo extremamente endotérmico (Figueiredo et al, 2018;João et al, 2018). A remoção de manganês atingiu resultados superiores a 90% e atua em uma faixa de pH levemente básica.…”
O descarte industrial de metais pesados, em especial, chumbo, cobre, cromo e manganês, promove a contaminação ambiental e afeta diretamente a saúde humana. Com a finalidade de minimizar o impacto gerado por esses contaminantes, a adsorção tem sido uma prática empregada em virtude de sua simplicidade e de seu baixo custo/benefício. Assim, materiais naturais como os compostos zeolíticos possuem grande eficiência na remoção desses metais. Dessa maneira, o objetivo deste trabalho é o de expor os resultados de uma revisão sistemática de literatura sobre o uso de zeólita como adsorvente no processo de remoção de íons de chumbo, cromo, manganês e cobre em solução aquosas. A pesquisa foi realizada em periódicos de bases de dados nacionais e internacionais, nos últimos seis anos, com eficiência de adsorção dos metais contaminantes superior a 70%. Na pesquisa realizada pôde-se constatar a elevada eficiência de remoção dos cátions por meio das zeólitas, grande parte, em razão de sua geomorfologia e aos tratamentos físico-químicos realizados.
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