Chitosan adsorbents for dye removal: a review

One of the most important decontamination techniques is considered to be adsorption. It is fast, simple, low cost with many opportunities to modify the initial materials after appropriate synthesis routes etc. Numerous adsorbent materials have been prepared in the last few years having as the ultimate scope to remove some pollutants especially from contaminated waters (effluents originating from industry). But the composition of each type of effluent varies. Dyes are some major components of industrial wastewaters. Chitosan (poly‐β‐(1 → 4)‐2‐amino‐2‐deoxy‐ d ‐glucose) is a nitrogenous (amino‐based) polysaccharide which is produced in large quantities by N ‐deacetylation of (its source compound) chitin. The major advantage of chitosan is the existence of modifiable positions in its chemical structure. Modification of the chitosan molecule by (i) grafting (inserting functional groups) or (ii) crosslinking reactions (uniting the macromolecular chains with each other) leads to the formation of chitosan derivatives with superior properties (enhancement of adsorption capacity and resistance in extreme medium conditions, respectively). This review summarizes the important contribution of chitosan derivatives to the dye removal process by adsorption.