Recovery of gold from waste solutions using a new RFB resin

The design and synthesis of highly active adsorption materials for recycling noble metals are essential to the high-tech industry. Here, a new adsorbent material namely resorcinol-formaldehyde-biuret (RFB) is prepared by grafting biuret onto the phenolic. Compared with the traditional methods, the preparation of RFB herein requires no hydrothermal process, which reduces cost. What's more, RFB prepared without the hydrothermal process exhibits better adsorption performance. Specifically, it has a high adsorption capacity of 1334 mg/g at room temperature and a fast adsorption rate that can adsorb a 10 mL of 100 mg/L gold ion solution within 10 min by just 5 mg RFB. Different factors such as pH, coexisting metal ions , and contact time that affects the adsorption process were systematically investigated. FT-IR, SEM, TEM, and XPS were used to characterize the adsorbent before and after adsorption. It is found that the adsorption isotherm and kinetics of RFB are consistent with the Langmuir isotherm model and the pseudo-second-order kinetic model, respectively. Further regeneration and cyclic adsorption indicate that RFB can be recycled at least four times. Besides, the reduction of 4-nitrophenol to 4-aminophenol was realized with the assist of Au-adsorbed RFB (RFB-Au). The strong soft-soft interaction between N, O atoms and Au atoms gives the material excellent gold ion adsorption capacity and selectivity . Findings herein can broaden the application of nitrogen-rich nanomaterials in gold ion recovery.