Bioinspired Mesoporous Silica for Cd(II) Removal from Aqueous Solutions

The wide industrial use of cadmium, one of the most hazardous toxic metals, leads inevitably to an increased contamination of effluents. In this study, Cd(II) removal by bioinspired thiol-functionalized mesoporous silica has been carried out. SBA-15 mesoporous silica with a high specific surface area (>900 m(2) g(-1)) has been synthesized, and furthermore, 0.3 mmol g(-1) glutathione has been successfully grafted (SBA-GSH). The obtained material was able to capture Cd(II). Optimum Cd(II) adsorption parameters as a function of the pH, contact time, and initial Cd(II) concentration have been studied. An S-shaped isotherm and further Fourier-transform infrared characterization suggest a multi-site adsorption involving thiol and carboxylic groups, with an adsorption capacity of 1.04 mmol g(-1) that makes the SBA-GSH material a promising candidate for cadmium removal. Reusability studies have been performed in three cycles, and 90% of the adsorbed Cd(II) has been recovered using 0.01 M HNO3.