Synthesis and adsorption properties for metal ions of crosslinked chitosan acetate crown ethers

Two novel chitosan derivatives—crosslinked chitosan dibenzo-16-c-5 acetate crown ether (CCTS-1) and crosslinked chitosan 3,5-di-tert-butyl dibenzo-14-c-4 diacetate crown ether (CCTS-2)—were synthesized by the reaction of crosslinked chitosan with dibenzo-16-c-5 chloracetate crown ether and 3,5-di-tert-butyl dibenzo-14-c-4 dichloracetate crown ether with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal-binding agents in aqueous environments. Their structures were confirmed with elemental analysis, infrared spectral analysis, and X-ray diffraction analysis. In the infrared spectra of CCTS-1 and CCTS-2, the characteristic peaks of aromatic backbone vibration appeared at 1595 cm−1 and 1500 cm−1; the intensity of the NH and OH stretching vibration in the region of 3150–3200 cm−1 decreased greatly. The X-ray diffraction analysis showed that the peak at 2θ = 20° decreased greatly in CCTS-1 and CCTS-2. The adsorption and selectivity properties of CCTS-1 and CCTS-2 for Pb2+, Cu2+, Cr3+, and Ni2+ were studied. Experimental results showed that the two crosslinked chitosan derivatives had not only good adsorption capacities for Pb2+, Cu2+, but also high selectivity for Pb2+, Cu2+ in the coexistence of Ni2+. For aqueous systems containing Pb2+, Ni2+, or Cu2+, Ni2+, CCTS-1 only adsorbed Pb2+ or Cu2+. For aqueous systems containing Pb2+, Cr2+ and Ni2+, CCTS-2 had high adsorption and selectivity properties for Pb2+. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2069–2074, 1999