Cadmium removal from aqueous solutions by hydroxy-8 quinoleine intercalated bentonite

An Algerian bentonite was purified and modified by intercalation of 8-hydroxyquinolinium ion. These materials were characterized by X-ray diffraction, infrared spectroscopy, and thermal analysis. Comparative batch experiments were performed using bentonite–oxine complex (B–oxine) and sodic bentonite (B-Na) for removing cadmium from aqueous solutions. Kinetics study results of cadmium removal with B-Na and B–oxine fit a pseudo-second-order model. The adsorption isotherm data follow the Langmuir equation in which parameters were calculated. B–oxine has a better cadmium removal capacity (61.35 mg/g) than B-Na (29.41 mg/g). Calculated thermodynamic parameters using the van't Hoff equation showed that the removal process is endothermic with B–oxine and exothermic with B-Na. A mechanism of ion exchange followed by complexation–precipitation is suggested for cadmium removal with B–oxine.

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