Selective adsorption of gold from complex mixtures using mesoporous adsorbents

Selective gold adsorption was investigated for the NH2-MCM-41 and SH-MCM-41 adsorbents prepared by grafting aminopropyl and thiolpropyl groups on the surface of the MCM-41 mesoporous silica. The single component adsorption of gold, copper and nickel from salt solutions, and the binary adsorption studies of Au3+/Cu2+ and Au3+/Ni2+ solutions were carried our for the two adsorbents. Gold adsorption from simulated gold mining Solution and gold electroplating wastewater were also reported. The NH2-MCM-41 and SH-MCM-41 displayed strong affinity for gold in the solution and both exhibited 100% selectivity for the gold in the binary Au3+/Cu2+ and Au3+/Ni2+ solutions. The NH2-MCM-41 is more suitable for the gold mining solution, while SH-MCM-41 is efficient for gold adsorption from the electroplating waste containing high amount of organics. The gold was recovered as high purity salt solution by elution with mineral acid for NH2-MCM-41 and thiolsulfate for SH-MCM-41. The regenerated adsorbent remained selective to gold and exhibited the same adsorption capacity as the fresh adsorbent. Also, the regenerated adsorbent performed well even after several reuses. (C) 2008 Elsevier B.V. All rights reserved.