Synthesis and adsorption properties of chitosan-crown ether resins

Abstract

Two kinds of novel chitosan-crown ether resins, Schiff base type chitosan-benzo-15-crown-5 (CTS-B15) and chitosan-benzo-18-crown-6 (CTS-B18), were synthesized through the reaction between -NH₂ in chitosan and —CHO in 4′-formyl benzo-crown ethers. Their structures were characterized by elemental analysis and FT-IR spectra analysis. The elemental analysis results show that the mass fractions of nitrogen in CTS-B15 and CTS-B18 are much lower than those of chitosan. The results of FT-IR spectra of CTS-B15 and CTS-B18 reveal that there exist characteristic peak of C=N, N-H and Ar, and characteristic peak of pyr anoside in the chain of chitosan-crown ether resins, showing that the structures of chitosan-crown ethers are as expected. The adsorption properties of CTS-B15 and CTS-B18 for Pd²⁺, Cu²⁺ and Hg²⁺ were studied and the experimental results show that these adsorbents have both good adsorption characterization and especially high particular adsorption selectivity for Pd²⁺ when Cu²⁺ and Hg²⁺ are in coexistence, and the coefficients of selectivity of CTS-B15 and CTS-B18 for metal ions are K_Pd²⁺_/Cu²⁺=7.56, K_Pd²⁺_/Hg²⁺=68.00, K_Cu²⁺_/Hg²⁺=9.00 and K_Pd²⁺_/Cu²⁺=6.00, K_Pd²⁺_/Hg²⁺=19.00, K_Cu²⁺_/Hg²⁺=3.00, respectively.

Keywords

chitosan / chitosan-crown ethers / synthesis / adsorption