Potential Effect of Modified Chitosan in Environmental Treatment: Metal Uptake, Ion Selectivity, and Bioactivity

Chitosan (CS) reacted with different organic reagents to give CS-CA, CS-CN, and CS-TEOF. CS-TEOF reacted with 2-aminothiophenol, 2-aminophenol, and phenyl hydrazine to give the CSTEOF-ATP, CSTEOF-AP and SCTEOF-PH, respectively. The modified chitosan derivatives represented the N-S, N-O and N-N, as chelating centres were treated with the aqueous solution containing a mixture of different metal ions (Cu2+, Cd2+, Fe3+, Co2+, Pb2+, Mn2+, Hg2+, Cr3+, Pd2+) in order to investigate their selectivity and their metal uptake capacity. The N-O chelating centre was selective Fe, Co, and Cu, while O-O was selective for Pb, Cr, Ca, Ni, Cd, and Pd. The N-S was selective to Cu(II) more than the N-N chelating centre. The removal capacity by modified chitosan ligands for Ca2+,Cd2+, Fe3+, Co2+, Pb2+, Mn2+ exceeded 80%. The morphology of the modified polymer and their metal complexes was studied. The bioactivity of chitosan was improved through modification with sulphur-containing compounds.