a b s t r a c t
Silk sericin and chitosan biosorbents are low cost and highly efficient biosorbents derived from waste
biomass. Both biosorbents displayed good capacity and excellent selectivity for gold adsorption. Silk
sericin and chitosan adsorbed respectively 1 and 3.3mmolg−1 of gold and have Kd values of 450 and
34,000, respectively. Experimental evidence showed that gold adsorbed on the amide groups of the
silk sericin, while gold and copper adsorbed on the amino groups of chitosan via charge-interactions
and complexation. Binary (Au–Cu), five (Au–Co–Ni–Cu–Zn) and six (Au–Pd–Co–Ni–Cu–Zn) component
separations consistently showed that silk sericin has better selectivity (SelAu > 2.4) than chitosan. It is
possible to recover gold at 99.5% purity by silk sericin and 90% if the solution contained palladium.