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

## TL;DR

This paper introduces a new composite material that effectively removes antiseptics from dental wastewater, offering a sustainable solution for environmental protection.

## Contribution

The novel γCS-AG/KA-GA composite beads combine gamma-chitosan, alginate, kaolin, and gallic acid for antiseptic removal from dental effluents.

## Key findings

- The composite beads achieved maximum adsorption capacities of 82.7 mg·g–1 for CHG and 75.3 mg·g–1 for CPC in synthetic solutions.
- The material showed a 65 ± 3% removal efficiency in real dental wastewater, though slightly lower than in synthetic systems.
- Comprehensive characterization confirmed the formation of a porous hybrid composite with a surface area of 68.9 m2·g–1.

## Abstract

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 (R
2 > 0.98) and the pseudo-second-order kinetic model (R
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.