SBA-Ionic Liquid as an Efficient Adsorbent of Palladium, Silver, and Gold Ions

Organic ligand containing the imidazole heterocycle [N-methyl-N'-propyltrimethoxysilylimidazolium chloride] immobilizing on the surface of ordered mesoporous silica (SBA-15) can be chelate with different metal ions such as Au (III), Ag (I) and Pd (II). This functionalized SBA-IL showed an exceptional selectivity for the removal of precious metal ions from aqueous solution through batch techniques. Moreover, these precious metals could be desorbed from this functionalized SBA through simple acid treatment (HCl (0.5 M) for Au (III) and Pd (II) and HNO3 (0.5 M) for Ag (I)) and quantified by Flame Atomic Absorption Spectrometry (FAAS). The experimental data were analyzed by Langmuir and Freundlich isotherm models which the adsorption isotherm plots confirm the Langmuir model, demonstrating that the adsorption process is the uniform monolayer adsorption. Furthermore, the recovery experiments showed that the maximum adsorption capacity were 250, 130, 263 mg/g in pH=4 at room temperature