Adsorption of Gold(III), Copper(II), Nickel(II) on Amino Silica Hybrid Coated Magnetite

Abstract

Selective adsorption of Au(III) in multimetal systems Au3+/Cu2+/Ni2+ on Amino-Silica Hybrid coated Magnetite (ASHM) has been studied. ASHM was synthesized via a sol-gel process using magnetite that was obtained through coprecipitation of Fe2+/Fe3+ salts mixture with NH4OH as precipitating solution, sodium silicate solution of rice husk ash as a precursor and 3-aminopropyltrimethoxysilane (APTMS) as a source of amino. Adsorption kinetics was determined by pseudo-first-order and pseudo-second-order model, while the adsorption isotherm was analyzed studied by the Langmuir and Freundlich models. FTIR characterizations showed that ASHM has been successfully synthesized, indicated by the appearance of characteristic frequency at 570 cm−1 was stretching vibrations of Fe-O-Si, and the frequency at 3424 cm−1 was stretching vibrations of N-H. Adsorption kinetics studies showed that the adsorption of Au(III) on ASHM fit to pseudo-second-order model with adsorption rate constant was 1.21x10−3 g.mg−1min−1. ASHM adsorbent showed a linear plot of the Langmuir isotherm model with the adsorption capacity of Au(III) was 102,04 mg/g. Adsorption on multimetal showed that Au(III), Cu(II), Ni(II) were adsorbed with chemical interaction on the ASHM with capacity adsorption of Au(III) was higher than that of Cu(II) and Ni(II). ASHM has high enough selectivity for Au(III) toward Cu(II) and Ni(II) ions.