Sustainable chitosan-based adsorbents for phosphorus recovery and removal from wastewater: A review

Phosphates are considered one of the main nutrient pollutants causing eutrophication and deterioration of water quality. Among those commonly used removal technologies, adsorption has shown effectiveness in removing phosphate from polluted water. Over the past decade, various chitosan-based materials (CSMats) have been widely developed and applied in desalination treatment of phosphate-containing wastewater due to their biocompatibility, nontoxicity, high phosphate adsorption capacities, and low-cost. This review summarized systematically the research progress on preparation and modification strategies of CSMats to accelerate the adsorption rate and enhance adsorption capacities of phosphate removal. Moreover, insights into the effect of experimental parameters (such as pH and coexisting ions) are also outlined. The desorption, regeneration and reutilization of exhausted CSMats has been discussed and analyzed. The contribution mechanisms (hydrogen bonding, electrostatic attraction, Lewis acid-base interaction, ligand/ion exchange, surface precipitation) of phosphate adsorption on CSMats are also summarized. Finally, present research gaps and challenges in the removal of phosphate adsorption on CSMats have been highlighted. In summary, the main purpose of this review is to provide the latest information helpful for preparing novel CSMats with better adsorption properties and promoting practical applications for desalination of phosphate-containing wastewater in future.