β-cyclodextrin and its derivatives: application in wastewater treatment.

Water is one of the basic necessities of life and having clean water is extremely important for human health. In recent years, β-cyclodextrin (β-CD)-based polymers and nanosystems have been extensively studied as adsorbents for the purpose of water purification. They present high efficiency and capability to remove inorganic, organic, and heavy metal impurities from wastewater as compared to conventional methods of water purification. β-CDs are cyclic polysaccharides having specific dimension of hydrophobic cavities and hydrophilic functional groups. The hydrophobic cavities form inclusion complexes through host-guest interactions. The hydroxyl groups form sites of hydrogen bonding and electrostatic interaction with pollutants. Additionally, they are also the sites of modification to bring about different derivatisation and polymerization reactions in order to impart desirable properties for efficient adsorption material. This article comprises of various derivatives of β-cyclodextrins: their nanoparticulate systems and their characterization and applications to remove different types of impurities from wastewater. The chemical reactions for their synthesis and mechanism of adsorption are highlighted.