Removal and mechanism of heavy metals and precious metals from aqueous solution by adsorption with livestock biomass with chemical treatment

This study examined the adsorption of heavy metals and precious metals from aqueous solution by livestock biomass as biosorbents and their treatment effect with reducing chemicals. The adsorption of copper, lead and cadmium was carried out using sheep wool, sheep manure and sheep fat. The copper adsorption was highest among three biosorbents. Sheep wool was treated with an aqueous solution of Na2S, NaOH, NaHSO3, and NaBH4 to enhance the adsorption ability. The Na2S treatment of sheep wool dramatically enhanced the adsorption amount of Au(III) and Cr(III) and was several effective for Cu(II) and Cr(IV). All adsorption results were confirmed with the Langmuir isotherm model in the equilibrium and Pseudo-second order model in the kinetics. From the adsorption properties and ESCA analysis of sheep wool adsorbed each metal, it was confirmed that Au(III) interacted with thiol and amino groups, Cu(II) and Cr(III) with a carboxyl group, and Cr(VI) with the amino group of sheep wool.