Chitosan modified with a polydentate crosslinker for metal-ion adsorption



The chemical modification on chitosan (CTS) was carried out by cross-linking it with precursor compound 3,3′-dimethoxy-4,4′-dihydroxy-5,5′-bis(N,N′- piperazine-1-yl methyl benzaldehyde), (PC) in order to improve the metal ion adsorption capacities and selectivity of the product. The resulting crosslinked chitosan derivative (CCTSL) was characterized by elemental analysis, Fourier transform infrared spectrum (FTIR), Differential Scanning calorimetry (DSC), Scanning Electron Microscopy (SEM) and powder X-ray diffraction (XRD) studies. Adsorption experiments (pH dependency, kinetics, and equilibrium) of CCTSL towards various metal ions (Mn2+, Fe2+, Co2+, Cu2+, Ni2+, Cd2+ and Pb2+) were investigated. The adsorption was dependent on pH of the solution, with a maximum capacity between pH 6.5 and 8.5. The adsorption kinetics data were best fitted with pseudo second-order model, which gave a correlation coefficient of 0.999. The adsorption process could be described with Langmuir isotherm (R = 0.999), which revealed that the maximum capacity for monolayer saturation was 79 mg Cu(II) per gram of CCTSL (1.24 mmol g−1). From the studies, we also infer that the order of metal adsorption capacities in mmol g−1 for the derivative is Cu2+ > Ni2+ > Co2+ ≥ Fe2+ ≥ Cd2+ ≥ Mn2+ ≥ Pb2+. Hence this material can be used to extract Cu2+ ions from industrial effluents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010