Chang SH, Jampang AOA. Enhanced adsorption selectivity of Au(III) over Cu(II) from acidic chloride solutions by chitosan/palm kernel fatty acid distillate/magnetite nanocomposites.
Int J Biol Macromol 2023;
252:126491. [PMID:
37625756 DOI:
10.1016/j.ijbiomac.2023.126491]
[Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/19/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023]
Abstract
This work aimed to develop a modified chitosan adsorbent with enhanced adsorption selectivity for Au(III) over Cu(II) from acidic chloride solutions using low-cost and green raw materials. Various adsorbents, i.e., chitosan powder, chitosan microbeads, chitosan/palm kernel fatty acid distillate (PKFAD) microcomposites, magnetite nanoparticles, and chitosan/PKFAD/magnetite nanocomposites (CPMNs), were first evaluated for their ability to adsorb Au(III) and Cu(II) from single- and binary-metal solutions across different pH levels, followed by parametric analysis of Au(III) and Cu(II) adsorption from binary- and multi-metal solutions onto CPMNs, Au(III) desorption from Au(III)-loaded CPMNs, and reusability of CPMNs. Finally, Au(III)-loaded CPMNs were characterized with SEM-EDX, XRD, FTIR, and XPS to confirm the proposed adsorption mechanisms. Among all the adsorbents studied, CPMNs exhibited outstanding performance in adsorbing Au(III) from an equimolar binary Au(III)-Cu(II) solution, achieving the highest equilibrium adsorption capacity of 0.479 mmol/g (94.4 mg/g) without reaching saturation. Under optimal adsorption conditions of pH 3, 1 g/L CPMN dosage, and 90 min contact time, CPMNs adsorbed 96 % of Au(III) with a selectivity over Cu(II) exceeding 99 %. CPMNs demonstrated excellent reusability, maintaining over 80 % adsorption and desorption efficiencies for 5 cycles. The proposed adsorption mechanisms of CPMNs for Au(III) encompass electrostatic attraction, hydrogen bonding, solvation, and reduction.
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