Facile preparation of cyclodextrin polymer materials with rigid spherical structure and flexible network for sorption of organic contaminants in water

Abstract

Cross-linked cyclodextrin polymer (CDP) materials have high sorption capacity and selectivity toward organic contaminants in water, depending on the polymeric network. The network structure is difficult to predict, due to the exothermic nature of polymerization reactions for material preparation. Here, we prepared CDP composite materials with rigid bulk structure and flexible polymeric network through facile KMnO4 oxidation treatments of CDPs. These materials featured regular embedment of nanorod MnO2 particles in the polymeric matrix and had mechanical stability, associated with the oxidation of short chains of the polymeric network. The structure and properties of materials (e.g., the cross-linking degree, pore volume and CD unit content) were regulated by KMnO4 dosage, the majority of which were linearly increased or decreased with increasing oxidant doses. The cross-linking degree, pore volume and CD unit type/content of materials were found to pose important impacts on sorption capacity of CDP materials toward compounds. These property alterations accounted for a compromise of amounts and accessibility of sorption sites, consistent with the important sequence of sorption mechanisms of CDP materials (association complexation ≥ network meshing ≫ inclusion complexation). This compromise has practical interest in the preparation of CDP materials with more useful properties of sorbents. Reuse experiments of chosen CDP materials showed high removal efficiency and stability of materials toward pesticides in water. Removal efficiency of reused materials toward pesticides in water was increased by an average of 22.5%.