Biosorption of nickel ion by chitosan-immobilized brown algae Laminaria japonica

Highly toxic nickel is released into the environment from a number of industrial processes, but current techniques for its removal are expensive and may cause secondary pollution. We developed a biosorbent of chitosan-immobilized brown algae (Laminaria japonica). The effects of different parameters on the adsorption capacity and biosorption- desorption of Ni ²⁺ from aqueous solution were evaluated. Kinetic studies showed that the adsorption of Ni ²⁺ by the immobilized algal beads followed second-order kinetics. When the adsorbent dose was increased, the biosorption capacity decreased and the removal efficiency increased. Ni ²⁺ biosorption by the immobilized algae cell beads was a good fit for the Langmuir and Freundlich isotherm models. In addition, the regenerated biosorbent by 1 mol L ^-1 HCl or 1 mol L ^-1 HNO ₃ could be reused, and maintained 90 % removal efficiency for at least three cycles.