Preparation of bifunctional nanoarchitectures with simultaneously enhanced adsorption for Au(III)

The recovery of Au(III) by adsorption has attracted extensive attention since it promotes solving the problems of environmental pollution and resource waste. Herein, we prepared the functionalized MCM-41 (MCM-NH2-OH) and explored the synergistic adsorption effects for Au(III). The adsorption capacity of MCM-NH2-OH reached 1664.9 mg·g−1, which was 15.98 times and 2.99 times higher than MCM-NH2 (104.2 mg·g−1) and MCM-OH (556.0 mg·g−1), respectively. The fitting kinetics experiments demonstrated that Au(III) adsorption by MCM-NH2-OH was conformed to the pseudo-second-order kinetic model. The adsorption rate of MCM-NH2-OH (2.62 × 10-2 g·mg−1·min−1) was 346.1 times higher than MCM-NH2 (7.57 × 10-5 g·mg−1·min−1). The adsorption mechanism and the role of –NH2 and –OH groups were investigated by XPS, XRD, and FTIR. More Au(III) can be adsorbed on –NH2 groups by electrostatic attraction and chelation that provided electron acceptor for –OH groups, which further enhanced the reduction of Au(III) to Au(0). Further, MCM-NH2-OH exhibited superior selectivity and reusability for Au(III). Therefore, the synergy between –NH2 and –OH groups is suitable for efficient adsorption-recover of gold applied in actual wastewater.