Cyclodextrin-epichlorohydrin polymers synthesis, characterization and applications to wastewater treatment: a review

Proposed and studied in the mid-1960s, water-insoluble cyclodextrin-epichlorohydrin polymers are of constant interest to the scientific community, particularly for their environmental applications. The unique feature of these materials is their ability to form inclusion complexes with various pollutants through host-guest interactions. This leads to many environmental applications including water and wastewater treatment, soil remediation, air purification and the concentration or elimination of target substances such as cholesterol. In the early 1990s, our group began working on the synthesis of water-insoluble cyclodextrin-based materials, their structural characterization and their application in the removal of pollutants present in wastewater. Here I summarizes the research conducted over the past 30 years by our group on water-insoluble cyclodextrin-epichlorohydrin polymers used as complexing materials to remove pollutants present in aqueous solutions. Our major findings are: (i) the synthesis of a series of water-insoluble materials with different functionalities in the form of gels or beads; (ii) their characterization by innovative solid-state NMR techniques; (iii) the demonstration of their efficiency as adsorbents in wastewater treatment and the explanation of the pollutant removal mechanisms according to the type of material used; (iv) the demonstration of a correlation between the structure of polymers and their adsorption properties; (v) the feasibility of the materials for the removal of pollutants as a tertiary treatment of wastewater in pilot-scale experiments using real effluents; and (vi) the use for the first time of bioassays based on lettuce seed germination to evaluate the usefulness of the process.