Preparation and selective adsorption properties of Cu2+ imprinted chitosan membranes

Abstract

In order to improve the selective adsorption capacity of the adsorbent and achieve efficient separation of target ions from solution, a novel ion imprinted chitosan composite membrane PVDF-(CTS-Cu/CMC)₃ was developed in this paper. The preparation of the imprinted membrane combined molecular imprinting technology with layer-by-layer self-assembly method, which could achieve selective separation of copper ions. The effects of polyelectrolyte assembly layers, assembly time, and crosslinking on the properties of the membrane were systematically investigated, and the membrane characteristics were characterized membrane characteristics by SEM, XRD, and FTIR. The experimental results indicate that under optimized preparation conditions (3 assembly layers, 0.25% crosslinker concentration, 45 min crosslinking time, 55°C crosslinking temperature) and adsorption conditions (pH 5, adsorption temperature 25°C, adsorption time 120 min), the maximum adsorption capacity of the imprinted membrane for Cu²⁺ was 98.18 mg/g. On this basis, the selective adsorption capacity for Cu²⁺ and other characteristics of the membrane were analyzed. In the multi-component system composed of Cu²⁺, Zn²⁺ and Fe²⁺, the selectivity coefficient of the imprinted membrane to Cu²⁺ reached 18, exhibiting good adsorption selectivity. In addition, the imprinted membrane had reusability, and the adsorption capacity was still as high as 60 mg/g after three adsorption–desorption cycles. This study provided a reference for improving the selectivity of chitosan-based membrane materials to copper ions.