Biopolymer beads composed of gamma-irradiated chitosan and dental-waste-derived alginate for dye removal applications

Abstract

This study presents the synthesis and characterization of bio-beads composed of gamma-irradiated chitosan and alginate derived from dental waste for the removal and degradation of Congo Red (CR) dye. Dental-grade alginate, typically used for impression-making, is repurposed as a sustainable matrix. The synthesized bio-beads were characterized using BEI, HRTEM, XRD, HAADF-STEM, EDS, FTIR, and BET analysis. UV–vis spectroscopy was used to evaluate dye removal efficiency. The gamma-irradiated chitosan coating enhanced surface area (68.045 m²/g) and improved CR adsorption compared to non-irradiated chitosan. The gCS-AG beads exhibited excellent reusability, retaining over 80 % efficiency for 10 cycles. The synthesis is simple and eco-friendly, with irradiation improving chitosan solubility and surface binding. The study demonstrates the dual functionality of the beads in adsorption and partial dye degradation. Electrostatic interactions between protonated amine groups in chitosan and anionic sulfonate groups in CR play a dominant role in adsorption. Radical-induced cleavage of azo bonds under acidic conditions contributes to degradation. This work promotes waste valorization and green material development for wastewater treatment.