Cu(II) removal from wastewater using chitosan-based adsorbents: A review

Copper is one of the most well-known heavy metals; while it is an essential nutrient for living organisms, its excessive presence in wastewaters is equally hazardous, causing a variety of health problems. The most successful and low-cost approach for removing Cu(II) ions is adsorption, which employs synthetic and bio-based adsorbents. Chitosan, a chitin-derived biopolymer having hydroxyl and amino functional groups that may chelate Cu(II) ions, is a nontoxic, ecofriendly, and biocompatible biopolymer. Due to a scarcity of sufficient relevant studies, the current review's outline is systematically developed to analyze the recent progress of chitosan-based adsorbent for Cu(II) removal from wastewater and aqueous media. It summarizes and critically assess recent work involving various types of chitosan derivatives, their recyclability, adsorption mechanism, adsorption isotherm, and kinetics, and eventually it offers future perspectives of chitosan-based adsorbents in heavy metal removal from wastewater. Literature survey shows that functionalization of chitosan by crosslinking and polymer grafting improve adsorption capabilities with high potential of reusability. Slight acidic to neutral aqueous medium at room temperature acts favorably to optimize adsorption capacity. Adsorption pattern of Cu(II) on chitosan adsorbents best fits with Langmuir isotherm model, and the kinetics follows pseudo second order reaction. Binding of Cu(II) ions by chitosan-based adsorbents is mostly governed by the complexation (i.e., chelation/coordination) followed by electrostatic interaction, ion-exchange and surface precipitation mechanism. [Display omitted] •Chitosan-based materials are promising materials for the removal of Cu(II) from wastewater.•Chitosan-based aerogel showed the highest adsorption capacity.•Magnetic chitosan represented better recyclability.•Chitosan-based adsorbents has plenty of room to apply for efficient removal of copper ions from aqueous solutions.