Effective recovery of some precious metals by using alternative quaternary amine types of anion-exchangers prepared from biofuel-extracted microalgal residues

Abstract

Trimethylamine- and triethylamine-immobilized adsorption gels were prepared from the oil-extracted microalgal residues. The FT/IR spectra and elemental analysis confirmed the immobilization of quaternary amine functional groups on the microalgal residue. Their adsorption behaviors for various metal ions in a hydrochloric acid solution were studied. Both adsorbents exhibited high selectivity for Pd(II) and Pt(IV) while showing no significant affinity for base metal ions. From the adsorption isotherms, the adsorption capacities for Pd(II) and Pt(IV) in 0.1 M HCl was found to be 2.95 and 1.33 mmol g⁻¹ for trimethylamine, and 2.57 and 1.54 mmol g⁻¹ for triethylamine type gels, respectively. These adsorbents are promising for the selective separation and recovery of Pd(II) and Pt(IV) and directly provide the sustainable means for the material development and benign environment.