Kaolin-Gallic Acid Functionalized Gamma-Chitosan/Alginate Beads: A Novel Material for Chlorhexidine and Cetylpyridinium Elimination from Dental Effluents

Dental effluents often contain persistent cationic antiseptics, such as chlorhexidine gluconate (CHG) and cetylpyridinium chloride (CPC). These substances raise environmental concerns due to their widespread clinical use, antimicrobial persistence, and poor biodegradability. This study investigates the synthesis and evaluation of kaolin-gallic acid functionalized gamma-chitosan/alginate (γCS-AG/KA-GA) composite beads for the adsorption of CHG and CPC from aqueous solutions and real dental wastewater. The composite beads were prepared by ionic cross-linking of gamma-irradiated chitosan and alginate in a CaCl₂ bath. Kaolin and gallic acid were incorporated to enhance both structural stability and adsorption functionality. Comprehensive characterization techniques, including high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), confirmed the successful formation of a porous hybrid composite with an increased surface area of 68.9 m²·g^-1. Batch adsorption experiments showed rapid uptake of both antiseptics within 60 min, reaching equilibrium at 180 min. The adsorption behavior was well described by the Langmuir isotherm (<i>R</i> ² > 0.98) and the pseudo-second-order kinetic model (<i>R</i> ² ≈ 0.99), resulting in maximum adsorption capacities of 82.7 mg·g^-1 for CHG and 75.3 mg·g^-1 for CPC. When applied to authentic dental wastewater collected from the BTU Dental Clinic, the γCS-AG/KA-GA beads achieved a removal efficiency of 65 ± 3%. This slight reduction in performance compared to synthetic systems was attributed to ionic competition and matrix fouling. Overall, these results demonstrate that γCS-AG/KA-GA composite beads provide a promising, sustainable, and material-based approach to reducing antiseptic contamination in dental effluents and promoting greener dental wastewater management strategies.