Investigation of adsorption parameters for platinum and palladium onto a modified polyacrylonitrile-based sorbent

•A new polyacrylonitrile based sorbent was synthesized.•The sorbent was modified with thiourea and glutaraldehyde.•Desorption parameters of Pt/Pd-loaded sorbent was investigated.•Experimental data and the Freundlich isotherm were found to be in good agreement.

This study investigated the adsorption and desorption procedure of platinum (Pt) and palladium (Pd) onto a modified polyacrylonitrile (PAN)-based sorbent, which was designed with thiourea (TU) and glutaraldehyde (GA), from fire assay leaching solutions. Batch studies were performed and the key processing parameters were investigated in detail. The optimum pH value obtained for the adsorption of Pt and Pd by the PAN–TU–GA was 1.50. The Langmuir isotherm model described the adsorption of metal ions by the sorbent more accurately than the Freundlich model. Moreover, the activation energies (Ea) of Pt and Pd were 75.98 and 16.59 kJ/mol, respectively. Elution testing with 0.50 M HCl–0.50 M thiourea solution for both Pd and Pt achieved an elution rate of above 93% and showed no significant decrease after five adsorption–desorption cycles, indicating that PAN–TU–GA may be regenerated and reused. As a result, a reasonable amount of non-degradable polymer material may be appropriate in industrial recovery use. Finally, PAN–TU–GA, as well as the Pt–Pd-loaded sorbent, was characterized by various techniques, including Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF).

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