Chitosan-based aerogel microspheres for wastewater treatment

Abstract

This study aimed to present the effect of the mediums to dissolve chitosan on the morphology of obtained chitosan microspheres and find a suitable medium for preparing porous chitosan microspheres for adsorption application. Three acidic solutions, including acetic, ascorbic, and citric acids, were used to dissolve chitosan flakes. The prepared chitosan microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. The microspheres' inner morphologies depended on the mediums to dissolve chitosan. The highest porosity of the chitosan microspheres was obtained using an acetic solution, while the sample showed the highest crystallinity prepared in a citric solution. Besides, the chitosan microspheres prepared in the acetic solution had the most efficient methylene blue (MB) removal from water. Its maximum MB sorption capacity was 79.37 mg g⁻¹. The nonlinear pseudo second order kinetic model was the best kinetic fit for the interaction of MB with those chitosan microspheres. Moreover, the prepared microspheres showed good cyclic stability and easy recovery, suggesting their high feasibility in wastewater treatment.