The Effect of Tripolyphosphate as a Chitosan Cross-Linker on Cadmium (II) Ion Adsorption

Chitosan is a biosorbent for heavy metal ions, but its adsorption performance remains unsatisfactory. Modification of chitosan is expected to address this issue. In this study, chitosan was cross-linked with tripolyphosphate (TPP) at various concentrations and applied as a Cd (II) adsorbent. The characteristics of the chitosan powder were analyzed using an FTIR spectrophotometer to determine the degree of deacetylation of chitosan. FTIR spectra were also used to determine the functional groups of chitosan and tripolyphosphate-cross-linked chitosan. Tripolyphosphate in the form of sodium tripolyphosphate was varied with chitosan in ratios of 1:0, 2:1, and 1:1. The optimum conditions were obtained at pH 5 with 12 hours of contact time for a 1:0 ratio and 3 hours for ratios of 1:1 and 2:1. The maximum adsorption capacity of chitosan crosslinked with sodium tripolyphosphate with chitosan: sodium tripolyphosphate ratios of 1:1, 2:1, and 1:0 for Cd (II) ion adsorption was 333.3, 166.67, and 28.57 mg/g, respectively. The results showed that the greater the mass of sodium tripolyphosphate, the higher the maximum adsorption capacity. Keywords: chitosan, crosslinking, tripolyphosphate, Cd adsorption