Biosorption of gold by immobilized fungal biomass.

The characteristics of polyvinyl alcohol (PVA) and calcium alginate as immobilization matrices were examined and compared for the uptake of gold by a fungal biomass. PVA-immobilized biomass showed superior mechanical strength and chemical stability. In addition, PVA beads were also stable under a wider range of pH (1-13). The lower mass transfer resistance in PVA beads was evident from kinetic studies which showed a significantly shorter period of time for the immobilized PVA beads to achieve 80% gold removal as compared with immobilized alginate beads. Calculated rate constants and maximum rates for the uptake of gold by both immobilized PVA and immobilized alginate biosorbent revealed a much more rapid uptake phenomenon by the former. BET analyses also indicated a larger surface area and larger pore size distribution in PVA beads, further indicating a lower resistance to mass transfer. Gold biosorption in the immobilized PVA bead could be modeled by both the Langmuir and Freundlich adsorption isotherms.