Fungal cell with artificial metal container for heavy metals biosorption: Equilibrium, kinetics study and mechanisms analysis.

White-rot fungi show low-cost superiority as a promising biosorbent in heavy metal removal, but limited by its poor biosorption capacity. Herein, a novel biosorbent, functionalized Phanerochaete chrysosporium with intracellular mineral scaffold, was prepared for the biosorption of heavy metal ions. The functionalized fungi cells with intracellular mineral scaffold that serve as internal metal container exhibiting high biosorption efficiency for Pb(II) and Cd(II) ions. Adsorption isotherm models were employed to investigate the biosorption isotherm and determine the biosorption equilibrium. The Freundlich model shows better fit with the experimental data of both metal ions (R2 = 0.9866 and 0.9897 for Pb(II) and Cd(II) respectively). Three kinetic models, pseudo-first-order, pseudo-second-order and intra-particle diffusion models, were used to determine the biosorption kinetics. The pseudo-second-order model shows the better fit with the experimental data, and we suggests the rate-limiting step of the biosorption could be a chemisorption step which involves sharing or exchanging of electrons between adsorbent and adsorbate. Intra-particle diffusion model study result shows the biosorption process could be divided into three steps: a fast surface adsorption stage, a slow transfer stage from external to internal, and a stage of andante reaching equilibrium. The biosorption mechanism was carefully analyzed by various characterization methods.