metal removal

hg ii

pb ii

adsorption process

Chemosphere

Chitosan has received widespread attention as an adsorbent for pollutants because of its low cost and great adsorption potentials. Chitosan has abundant hydroxyl and amino groups that can bind heavy metal ions. However, it has defects such as sensitivity to pH, low thermal stability, and low mechanical strength, which limit the application of chitosan in wastewater treatment. The functional groups of chitosan can be modified to improve its performance via crosslinking and graft modification. The porosity and specific surface area of chitosan in powder form are not ideal, therefore, physical modification has been attempted to generate chitosan nanoparticles and hydrogel. Chitosan has also been integrated with other materials (e.g. graphene, zeolite) resulting in composite materials with improved adsorption performance. This review mainly focuses on reports about the application of chitosan and its derivatives to remove different heavy metals. The preparation strategy, adsorption mechanism, and factors affecting the adsorption performance of adsorbents for each type of heavy metal are discussed in detail. Recent reports on important organic pollutants (dyes and phenol) removal by chitosan and its derivatives are also briefly discussed. • Chitosan derivatives have received increased attention recently as adsorbents for heavy metal ions. • Chitosan derivatives with new properties have been produced via physical and chemical modification process. • The preparation strategies, adsorption mechanisms, and factors affecting the adsorption performance are summarized. • Ion-imprinting is a common technique to improve the ion selectivity of chitosan adsorbents. • Recent reports on important organic pollutants removal by chitosan derivatives are also discussed.

Research progress of adsorption and removal of heavy metals by chitosan and its derivatives: A review