Estudo do impacto da temperatura de calcinação nas propriedades adsortivas de nanofolhas de óxido de níquel
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Data
2021-06-23
Autores
Galvani, Giovana Mello
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Universidade Estadual Paulista (Unesp)
Resumo
Corantes sintéticos são compostos químicos largamente utilizados nos processos industriais e, devido sua toxicidade, seu correto manejo no tratamento de águas residuais é necessário. A adsorção é uma técnica altamente eficaz para remoção de uma ampla gama de poluentes, porém, sua aplicação é dependente das características dos materiais adsorventes utilizados. Nessa perspectiva, o presente trabalho teve como objetivo a avaliação do efeito de diferentes temperaturas de calcinação nas propriedades adsortivas de nanofolhas de óxido de níquel (II) (NiO) frente ao azo-corante aniônico Vermelho Congo. As nanofolhas de hidróxido de níquel (II) (Ni(OH)2) foram sintetizadas via método solvotérmico assistido por micro-ondas e para obtenção dos óxidos cada amostra foi calcinada por 2 horas na temperatura de 300-600 ºC com intervalos de 50 ºC. Os materiais foram caracterizados por difratometria de raios X, análise termogravimétrica, microscopia eletrônica de varredura com canhão de emissão de campo, microscopia eletrônica de transmissão, espectroscopia de raios X por dispersão de energia, espectroscopia por refletância total atenuada no infravermelho com transformada de Fourier, análise de área superficial e porosidade e medida de potencial zeta. Os resultados de adsorção foram avaliados por meio de espectrofotometria Ultravioleta-Visível. Os testes de capacidade adsortiva mostraram que o material NiO300 apresentou maior capacidade de adsorção do corante, que foi atribuída aos seus parâmetros de área e porosidade, e as variáveis de pH, temperatura, tempo de contato, concentração e dessorção foram testadas. Verificou-se que o pH 6 da solução e a temperatura de 35 ºC eram mais eficazes para o processo e o teste cinético mostrou que há forte interação entre adsorvente e adsorbato, com o equilíbrio alcançado a partir dos 120 minutos, tal reação foi classificada como de Pseudo-segunda ordem. A isoterma de adsorção apresentou padrão favorável, que foi ajustada pelo modelo de Langmuir e a capacidade de adsorção máxima do NiO300 foi de 259,74 mg.g-1 com 90% de remoção do corante. Os ensaios de dessorção mostraram que a eficiência do material pode ser recuperada em 50% e o processo adsortivo foi atribuído a mecanismos físicos de interação predominantes. Dessa maneira, os materiais estudados indicam alto potencial para adsorção da espécie aniônica testada contribuindo para os avanços de remoção de compostos tóxicos nos tratamentos de águas residuais.
Synthetic dyes are chemical compounds widely used in industrial processes and, due to their toxicity, their correct handling in wastewater treatment is necessary. Adsorption is a highly effective technique for removing a wide range of pollutants. However, its application depends on the characteristics of the adsorbent materials used. In this perspective, this work aimed to evaluate the effect of different calcination temperatures on the adsorptive properties of nickel (II) oxide (NiO) nanosheets against Congo Red anionic azo-dye. Nickel (II) hydroxide (Ni(OH)2) nanosheets were synthesized via a microwave-assisted solvothermal method and to obtain the oxides, and each sample was calcined for 2 hours at a temperature of 300-600 ºC with intervals of 50 ºC. The materials were characterized by X-ray diffraction, thermogravimetry analysis, scanning electron microscopy with field emission gun, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, surface area and porosity analysis and zeta potential measurement. Adsorption results were evaluated by Visible-Ultraviolet spectrophotometry. The adsorptive capacity tests showed that the NiO300 material had higher dye adsorption capacity, which was attributed to its area and porosity parameters, and the pH, temperature, contact time, concentration and desorption variables were tested. It was found that the pH 6 of the solution and the temperature of 35 ºC were more effective for the process and the kinetic test showed that there is a strong interaction between adsorbent and adsorbate, with the equilibrium reached after 120 minutes, this reaction was classified as of Pseudo-second order. The adsorption isotherm showed a favorable pattern, which was adjusted by the Langmuir model and the maximum adsorption capacity of NiO300 was 259.74 mg.g-1 with 90% dye removal. The desorption tests showed that the material efficiency could be recovered by 50% and the adsorptive process was attributed to predominant physical interaction mechanisms. Thus, the studied materials indicate a high potential for adsorption of the tested anionic species, contributing to advances in removing toxic compounds in wastewater treatments.
Synthetic dyes are chemical compounds widely used in industrial processes and, due to their toxicity, their correct handling in wastewater treatment is necessary. Adsorption is a highly effective technique for removing a wide range of pollutants. However, its application depends on the characteristics of the adsorbent materials used. In this perspective, this work aimed to evaluate the effect of different calcination temperatures on the adsorptive properties of nickel (II) oxide (NiO) nanosheets against Congo Red anionic azo-dye. Nickel (II) hydroxide (Ni(OH)2) nanosheets were synthesized via a microwave-assisted solvothermal method and to obtain the oxides, and each sample was calcined for 2 hours at a temperature of 300-600 ºC with intervals of 50 ºC. The materials were characterized by X-ray diffraction, thermogravimetry analysis, scanning electron microscopy with field emission gun, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, surface area and porosity analysis and zeta potential measurement. Adsorption results were evaluated by Visible-Ultraviolet spectrophotometry. The adsorptive capacity tests showed that the NiO300 material had higher dye adsorption capacity, which was attributed to its area and porosity parameters, and the pH, temperature, contact time, concentration and desorption variables were tested. It was found that the pH 6 of the solution and the temperature of 35 ºC were more effective for the process and the kinetic test showed that there is a strong interaction between adsorbent and adsorbate, with the equilibrium reached after 120 minutes, this reaction was classified as of Pseudo-second order. The adsorption isotherm showed a favorable pattern, which was adjusted by the Langmuir model and the maximum adsorption capacity of NiO300 was 259.74 mg.g-1 with 90% dye removal. The desorption tests showed that the material efficiency could be recovered by 50% and the adsorptive process was attributed to predominant physical interaction mechanisms. Thus, the studied materials indicate a high potential for adsorption of the tested anionic species, contributing to advances in removing toxic compounds in wastewater treatments.
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Palavras-chave
Adsorção, Óxido de níquel II, Método solvotérmico assistido por micro-ondas, Materiais bidimensionais 2D, Calcinação, Vermelho congo, Adsorption, Nickel (II) oxide, Microwave-assisted solvothermal method, Twodimensional materials 2D, . Calcination, Congo red