Cross-Linked Chitosan/Cellulose Microspheres for Reusable Dye Adsorption and Post-Desorption Photo-Oxidative Treatment

Dye-containing wastewater remains an important environmental concern because many synthetic dyes are persistent and potentially harmful to aquatic organisms and human health. In this work, a biomass-based adsorbent was evaluated together with a separate post-desorption photo-oxidative treatment step. Cellulose (CL) and chitosan (CS) were used to prepare cross-linked CS/CL (C-CS/CL) microspheres for dye removal from water, with glutaraldehyde (GA) used to improve the structural stability of the microspheres. The synthesized C-CS/CL microspheres exhibited improved mechanical stability and pH-dependent dye adsorption, with preferential uptake of anionic dyes (acid blue 93 and acid black 1) and lower uptake of cationic dyes (methyl violet and methyl green). After adsorption, the dyes were eluted, allowing the C-CS/CL microspheres to be reused for repeated dye removal. The dye-containing eluate was subsequently subjected to UV/H 2 O 2 treatment, resulting in partial degradation of the model dyes. Overall, the C-CS/CL microspheres enabled preferential adsorption and repeated reuse, while the separate UV/H 2 O 2 step provided subsequent treatment of the dye-containing eluate. Graphical Crosslinked chitosan/cellulose microspheres provide stable, pH-responsive adsorption of anionic and cationic dyes and retain most adsorption capacity through ten reuse cycles. Adsorption is maintained in electrolyte, binary-dye, and real-water matrices. Regeneration releases dye-containing eluate for separate UV/H 2 O 2 treatment, which provides partial dye degradation as a complementary downstream oxidation step after desorption.