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 chelated with different metal ions such as Ag(I), Au(III), and Pd(II). This functionalized SBA-IL showed an exceptional selectivity for removing precious metal ions from an 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. The adsorption kinetics was investigated for Ag(I), Au(III), and Pd(II), which adsorption kinetics fit a pseudo-second-order rate equation. 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 was 250, 130, and 263 mg/g for Ag(I), Au(III), and Pd(II), respectively in pH = 4 at 25 ℃. Herein, the prepared SBA-IL is based on imidazolium chloride and also used for rapid removal of precious metals such as Au(III), Ag(I), and Pd(II) ions extracted and quantified by FAAS. Moreover, the adsorption kinetic and isotherm models were also studied. The recovery experiments showed a high adsorption capacity.