Adsorption of Pb2+ on chitosan cross-linked with triethylene-tetramine

A novel triethylene-tetramine cross-linked chitosan (CCTS) was synthesized via the cross-linking of triethylene-tetramine and epichlorohydrin activated chitosan. Its structure was characterized by elemental analysis, infrared spectroscopy and X-ray diffraction analysis, and the surface topography was determined with ESEM. The results were in agreement with expectations. The capacity of CCTS to adsorb Pb2+ ions from aqueous solutions was examined, and equilibrium and kinetic investigations were undertaken. The adsorption isotherms were fitted well by the Langmuir equation (R > 0.999). The maximum adsorbed amount, at pH 5.5, with an initial concentration of 3 mmol/L (621 ppm), was 378.8 mg/g. The adsorption process could be best described by a second-order equation (R = 1). This suggests that the rate-limiting step may be the chemical adsorption (chemisorption) step and not the mass transport. The separation factor used was 0 < R-L < 1. Therefore, it can be concluded that CCTS is an effective adsorbent for the collection of Pb2+.