Effects of carbon precursors and activation agents on the physicochemical characteristics and aurocyanide adsorption patterns of agro waste-based activated carbons

• Effects of precursor and activation agent on characteristics of ACs were investigated • Effects of activation agent on aurocyanide adsorption were markedly significant • Differences in the adsorption capacities of precursor-based ACs were insignificant • Identification of new mechanisms in addition to the [M n + ][Au(CN) 2 ‒ ] n ion pair The types of carbon precursors and chemical activation agents greatly influence the physicochemical properties of activated carbons (ACs). In this study, the physicochemical characteristics and aurocyanide adsorption patterns of ACs synthesized from different agro waste precursors and activation agents were carried out. FTIR, XRD, BET, DSC/TGA and XPS were used to effectively characterize the synthesized ACs. The physicochemical changes observed were more significant in the activation agent-based ACs than the precursor-based ACs owing to the different degrees of activation. ZnCl 2 -AC and KOH-AC were the best in terms of aurocyanide adsorption capacities, with experimental uptakes reaching 346.34 and 327.88 mg/g, respectively. These uptakes were higher than those of commercial ACs, Haycarb and Norit C-Gran. Physical adsorption, electrostatic, and π‒π interactions played a collective role in the effective binding of the aurocyanide complex onto the ACs.