Cyclodextrin Polymers and Cyclodextrin-Containing Polysaccharides for Water Remediation

Abstract

Chemical pollution of water has raised great concerns among citizens, lawmakers, and nearly all manufacturing industries. As the legislation addressing liquid effluents becomes more stringent, water companies are increasingly scrutinized for their environmental performance. In this context, emergent contaminants represent a major challenge, and the remediation of water bodies and wastewater demands alternative sorbent materials. One of the most promising adsorbing materials for micropolluted water environments involves cyclodextrin (CD) polymers and cyclodextrin-containing polysaccharides. Although cyclodextrins are water-soluble and, thus, unusable as adsorbents in aqueous media, they can be feasibly polymerized by using different crosslinkers such as epichlorohydrin, polycarboxylic acids, and glutaraldehyde. Likewise, with those coupling agents or after substituting hydroxyl groups with more reactive moieties, cyclodextrin units can be covalently attached to a pre-existing polysaccharide. In this direction, the functionalization of chitosan, cellulose, carboxymethyl cellulose, and other carbohydrate polymers with CDs is vastly found in the literature. For the system containing CDs to be used for remediation purposes, there are benefits from a synergy that arises from (i) the ability of CD units to interact selectively with a broad spectrum of molecules, forming inclusion complexes and higher-order supramolecular assemblies, (ii) the functional groups of the crosslinker comonomers, (iii) the three-dimensional structure of the crosslinked network, and/or (iv) the intrinsic characteristics of the polysaccharide backbone. In view of the most recent contributions regarding CD-based copolymers and CD-containing polysaccharides, this review discusses their performance as adsorbents in micropolluted water environments, as well as their interaction patterns, addressing the influence of their structural and physicochemical properties and their functionalization.

Cyclodextrin usage in textile Industry

“…The remarkable property of CDs is that they can form integration complexes (host-guest complexes) with various compounds that are solid, liquid, and gaseous. CDs are extremely biocompatible, biodegradable, [12,22] and skin friendlier. [15]…”

Adsorption of Paraquat by Poly(Vinyl Alcohol)-Cyclodextrin Nanosponges

“…Adsorbents based-cyclodextrin have been widely used for environmental applications [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ] according to the special properties of cyclodextrin. β-cyclodextrin (β-CD) is a cyclic oligosaccharide containing seven units of d -glucose connected by α-(1,4) glycosidic linkages, which shows a well-defined structure with a hydrophilic exterior and a hydrophobic cavity.…”

“…Moreover, the development of cyclodextrin polymer has widely been established by various types of polymerization so as to improve the solubility for both the cyclodextrin polymer and the guest molecule and enhance the adsorption capacity towards organic compounds. Insoluble cyclodextrin polymers and their derivatives have been innovated for environmental applications [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ] and other fields [ 72 , 73 , 74 , 75 , 76 ]; they are also called “cyclodextrin nanosponges” because these nanomaterials display a sponge-like structure and a hyperbranched network with three-dimensional form and have a specific role in forming a functional crosslinker or other chemical reactants [ 52 ]…”

Comparative Studies of Mechanochemically Synthesized Insoluble Beta-Cyclodextrin Polymers

“…Various fields of life can exploit the favorable controlled-release properties of insoluble polymers, while their combination in Metal-Organic Networks (MOFs) has led to a new, versatile porous drug carrier [65][66][67][68]. Nowadays, the bulk production and low-to-moderate price of the most common CDs, particularly in the βCD, put CDs into the center of interest in the more price-sensitive applications from the pharmaceutical, topical use [69][70][71] to the compound-specific filters in the environmental chemistry [72,73].…”