Beta-cyclodextrin adsorbents to remove water pollutants—a commentary

Abstract

Beta-cyclodextrin-based adsorbent is a promising adsorbent because it has unique characteristics and able to form host-guest complexes with various organic compounds. Adsorption using beta-cyclodextrin-based adsorbent has continuously improved by various preparation strategies and crosslinking agents. This commentary aims to highlight the preparation strategies, properties, and adsorption mechanisms of beta-cyclodextrin-based adsorbents. The adsorbents can be generally classified according to the preparation methods and display high adsorption capacity especially for dyes. Particularly, composite/nanocomposite beta-cyclodextrin-based adsorbents exhibit outstanding adsorption capacity even though the surface area is lower than that of porous and magnetic beta-cyclodextrin-based adsorbents. The beta-cyclodextrin/chitosan functionalized graphene oxide hydrogel with specific surface of 17.6 m2·g-1 yields an extraordinarily maximum adsorption capacity of 1499 mg·g-1 methylene blue, while beta-cyclodextrin/chitosan modified with iron(II, III) oxide nanoparticles displays a much greater maximum adsorption capacity at 2780 mg·g-1. The hydrophobic interaction, functional groups, hydrogen bonding, and electrostatic interaction govern the adsorption to a greater capacity. Although this commentary is not exhaustive, the preparation strategies and illustrated mechanisms provide useful insights into the adsorbent-adsorbate interactions, cost-effective analysis, challenges, and future directions of beta-cyclodextrin-based adsorbents in wastewater treatment.