Sorption of heavy metal ions onto carboxylate chitosan derivatives—A mini-review

•Preparation of some carboxylate chitosan (CCS).•Characterization of some CCS.•Removal of heavy metal using CCS.

Chitosan is of importance for the elimination of heavy metals due to their outstanding characteristics such as the presence of NH2 and –OH functional groups, non-toxicity, low cost and, large available quantities. Modifying a chitosan structure with –COOH group improves it in terms of solubility at pH ≤7 without affecting the aforementioned characteristics. Chitosan modified with a carboxylic group possess carboxyl, amino and hydroxyl multifunctional groups which are good for elimination of metal ions. The focal point of this mini-review will be on the preparation and characterization of some carboxylate chitosan derivatives as a sorbent for heavy metal sorption.