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. (C) 2001 Elsevier Science B.V. All rights reserved.