Biosorption and reduction of Au (III) to gold nanoparticles by thiourea modified alginate

In this study, modified alginate biosorbent has shown a remarkably selective adsorption of Au (III) ions from multi-metallic solutions containing equal moles of Au (III), Pd (II), Pt (IV), Co (II), Ni (II) and Cu (II) ions under acidic conditions. The maximum uptake capacity of Au (III) was found to be 8.47 mmol g−1 at 323.15 K. Adsorption of Au (III) by modified alginate biosorbent was accompanied by chemical reduction of Au (III), leading to the formation of gold nanocrystals and microcrystals. Biosorption and reduction of Au (III) in acidic media are mediated by the electrostatic and covalent interactions between Au (III) and hydroxyl, carboxyl, amino and CS functional groups of modified alginate adsorbent.