Modification assisted Cu2O/MCM-41 nanoarchitecture toward efficient recovery of Au (III)

A Cu2O and thiourea functionalized MCM-41 (CMTU) nanoarchitecture was prepared for selective recovering of Au (III) from an acidic solution. The material was probed by using SEM-EDS, XPS, XRD, FTIR, and zeta potential to explicate the mechanisms involved in Au (III) recovery. Results revealed that Au (III) (as [AuCl4]-, pH = 3.0) initially was bound with NH2 and CS on the CMTU surface through electrostatic attraction and chelation, respectively. Then, Au (III) was readily reduced to Au (I) and Au (0) by Cu (I). The maximum adsorption capacity of Au (III) reached 3180.45 mg·g−1 at the initial pH = 3.0 at 318 K, and the adsorption process followed the Langmuir model and pseudo-second-order model. The calculated thermodynamic parameters expounded that Au (III) recovery by CMTU was a spontaneously endothermic process. Furthermore, CMTU showed excellent selectivity and reusability.