Comparative Analysis of Mechanisms of Cd2+ and Ni2+ Biosorption by Living and Nonliving Mucoromycote sp XLC

The biosorption of cadmium (Cd2+) and nickel (Ni2+) using living and nonliving biomass of Mucoromycote sp. XLC as a biosorbent was investigated in this study. The optimum conditions were established with batch biosorption experiments. The data from equilibrium experiments showed that all kinds of biosorbents fitted the Langmuir model. For the living and nonliving biosorbent, the predicted maximum Cd2+ uptake capacity was 79.65 mg g(-1) and 56.51 mg g(-1), while the maximum Ni2+ uptake capacity was 51.26 mg g(-1) and 44.32 mg g(-1), respectively. Acid digestion results indicated that intracellular metal ions might be the main reason for the metal uptake capacity difference between living and nonliving biosorbents. FTIR analysis and potentiometric titration indicated freeze dehydration-autoclaving treatment of nonliving biomass slightly changed the surface structure of the cell wall and the functional groups involved in biosorption were carboxylic, phosphoryl, amine and hydroxyl groups. Our results suggest the living biosorbent had a second biosorption process by intracellularly accumulating metal ions, hence possessing a higher Cd(2+)or Ni2+ uptake capacity than nonliving biosorbent.