Selective and Effective Gold Recovery from Printed Circuit Boards and Gold Slag Using Amino-Acid-Functionalized Cellulose Microspheres

The hydrometallurgical recovery of gold from electronic waste and gold slag is a hot research topic. To develop a cost-effective and environmentally friendly adsorbent for gold recovery, four types of amino-acid (arginine, histidine, methionine, and cysteine)-functionalized cellulose microspheres were prepared via a radiation technique. The adsorption performance of the amino acid resins toward Au(III) ions was systematically investigated by batch experiments. The amino acid resins could absorb Au(III) ions at a wide pH range. The adsorption process was followed by the pseudo-second-order model and Langmuir model. The theoretical maximum adsorption capacity was calculated as 396.83 mg/g, 769.23 mg/g, 549.45 mg/g, and 636.94 mg/g for ArgR, HisR, MetR, and CysR, respectively. The amino acid resins could effectively and selectively recover trace Au(III) ions from the leaching solutions of printed circuit board and gold slag waste. Lastly, the mechanism underlying amino acid resin's Au(III) ion recovery capability was investigated by FTIR, XRD, and XPS analyses. This work describes a series of cost-effective gold adsorbents with excellent selectivity and adsorption capacity to boost their practical application.