• biosorption;
  • immobilization;
  • yeast;
  • cadmium(II);
  • chitosan

A new type of biosorbent—chitosan encapsulated Zygosaccharomyces rouxii (CZ) was used to remove Cd(II) from aqueous solution. The CZ with Z. rouxii biomass to chitosan of 4:10 (weight ratio) had high removal percentage of Cd(II) and regular spherical shape. Pseudo-second-order kinetic model (R2 > 0.9980) and Freundlich adsorption isotherm model (R2 = 0.9913) were suitable to describe the biosorption process. Effects of contact time, initial pH, initial Cd(II) concentration, and biosorbent dose on Cd(II) adsorption capacity of CZ were studied. CZ had a good performance when the initial pH ranged from 3.0 to 7.0 and could remove 95.15% Cd(II) from aqueous solution with suitable biosorbent dose (15 g L−1) when the initial Cd(II) concentration was 0.2 mmol L−1. Protein and nucleic acid leaching from CZ were greatly reduced compared with Z. rouxii biomass at different pH levels. In addition, five biosorption/desorption/regeneration cycles were proceeded to investigate the reusability of CZ. Laser particle size analyzer, scanning electron microscopy, and energy dispersive spectrometry and pHPZC were used to characterize CZ. This work suggested that CZ has good potential to remove Cd(II) from aqueous solution. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1101–1110, 2013