Ion exchange and adsorption of cadmium from aqueous media in sodium-modified expanded vermiculite

Autor(es)

de Carvalho Neves, Henrique Santana ; da Silva, Thiago Lopes ; Carlos da Silva, Meuris Gurgel ; Guirardello, Reginaldo ; Adeodato Vieira, Melissa Gurgel

• Tipo de documento: Artigo Científico
• Fonte: Environmental Science and Pollution Research; v. N/A, p. 17-pg., 2022-01-16.

Resumo

The use of mineral clays as alternative adsorbent has received attention due to their physicochemical characteristics, superficial negative charge, abundance of vermiculite (especially in Brazil), low cost, and chemical composition, which allows the material modification to increase the adsorptive capacity. This manuscript evaluated the use of expanded vermiculite (EV) and sodium-modified vermiculite (VNa) in the adsorption and ion exchange of Cd2+ ions. The sodification was successfully carried out making the ion exchange capacity greater in the modified clay, confirmed by EDX, cation exchange capacity (CEC), DRX, and FTIR analysis. The CEC was 210 and 233 mEq/100 g for the EV and VNa, respectively, with 97.8% exchangeable ion (Na+) in the VNa. FTIR spectra showed small variations in the groups related to ion exchange and XRD analysis indicated changes in the distance of the layers with loss of crystallinity after clay modification, which was recovered after cadmium adsorption. The kinetics became faster with an equilibrium time of 10 min for VNa and 45 min for EV. Cd2+ removal by vermiculite above 99% was achieved. Pseudo-second order model best described the kinetics, in which the resistance to mass transfer in external film is the limiting step of the process and, once this resistance is overcome, the ion exchange happens quickly. Despite the decrease in surface area after sodification, the adsorptive capacity increased 158% in the sodified adsorbent, from 0.107 mmol/g for EV to 0.276 mmol/g for VNa, under the evaluated conditions. (AU)

• Processo FAPESP: 17/18236-1 - Recuperação de íons metálicos nobres e íons terras-raras presentes em soluções aquosas por bioadsorção em partículas de blenda de sericina e alginato
• Beneficiário: Melissa Gurgel Adeodato Vieira
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/11353-8 - Centro Brasileiro de Pesquisa em Água (BWRC)
• Beneficiário: Lauro Tatsuo Kubota
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia