Biomass-Based N, S Co-Doped Hierarchical Porous Carbon for Selective Adsorption of Au(III): Facile Gold Recovery from Secondary Wastes
Bing Zhan, Xi Hong, Chen Li, Xuejuan Chen, Shu Liu, Xiu‐Feng Hou
Abstract
High Resolution Image Download MS PowerPoint Slide Gold recovery from secondary resources has attracted more and more attention due to the rapidly developing economy and the demand for a green environment. However, it remains a challenge to develop effective and inexpensive adsorbents for reducing the cost of gold recovery. Here, a biomass-based N, S co-doped hierarchical micro- and mesoporous carbon adsorbent (BNS-HPC) was prepared from discarded boat-fruited sterculia seed pulp residue by a simple calcination process. The common reagents KCl and thioacetamide were used as a template and as a nitrogen and sulfur co-doped source, respectively. BNS-HPC has a super high BET surface area of 2503.34 m 2 g –1 and exhibits outstanding Au(III) adsorption performance. The maximum adsorption capacity is up to 368 mg g –1, which is much higher than the reported biomass-based carbon adsorbents, as well as excellent reusability through 12 adsorption–desorption cycles. The selectivity of Au(III) adsorption on BNS-HPC was explored in the presence of coexisting ions Cu(II), Fe(III), Ca(II), Mg(II), Zn(II), and Pb(II) as well as Ir(III), Pd(II), Pt(IV), and Rh(III). The adsorption kinetics, adsorption isotherm, and XPS results illustrate that the adsorption process was mainly chemical adsorption. Furthermore, BNS-HPC was applied for the recovery of gold from secondary wastes, including copper mineral residue, electronic waste, and deactivated catalyst, and the average recovery rates of Au(III) for 11 real samples with different gold contents were all over 97%.