Quaternary Ammonium Functionalized Cellulose for Bromate Ion Removal: Structural Insights and Efficacy Evaluation

This study evaluates the potential of quaternary ammonium‐modified cellulose as a biosorbent for bromate (BrO₃ − ) removal from aqueous solutions. Elemental analysis and scanning electron microscopy (SEM) characterized the elemental composition and microstructural features of the biosorbent, whereas Fourier‐transform infrared (FTIR) spectroscopy elucidated its molecular structure. Experimental results revealed that BrO₃ − removal efficiency increased with the biosorbent dose, achieving approximately 58%, 78%, and 90% removal with 0.025, 0.05, and 0.2 g of sorbent, respectively. The removal was pH‐dependent, with efficiencies of 25%, 45%, and 76% at pH 2, 4, and 10, respectively, and the optimal removal was within the pH range of 6–8. Kinetic studies demonstrated rapid sorption, achieving 91% removal within 3 min. The Langmuir sorption isotherm model provided an excellent fit to the experimental data ( R 2 = 0.9987), indicating a maximum sorption capacity of 9.40 mg/g. Thermodynamic analyses confirmed a spontaneous and endothermic sorption process (∆ G ° = −8.11 kJ/mol; ∆ H ° = +2.22 kJ/mol). Desorption studies showed ≥ 99.9% efficiency using 0.1‐M H₂SO₄ and NaCl, with NaCl selected as the preferred regenerant to minimize acid consumption. The biosorbent retained over 90% removal efficiency across three regeneration cycles. These findings highlight the potential of quaternary ammonium‐modified cellulose as a sustainable and efficient material for BrO₃ − removal from water systems.