Optimization of As(V) removal using chitosan-coated bentonite from groundwater using Box–Behnken design: effects of adsorbent mass, flow rate, and initial concentration

Abstract

This work focused on the removal of As(V) using chitosan-coated bentonite (CCB) from groundwater in a fixed-bed system. Thomas and Yoon–Nelson models were applied to the experimental data in order to predict breakthrough curves and assess model parameters. Response surface methodology based on Box–Behnken design was utilized to optimize parameters such as adsorbent mass (6.0–8.0 g), flow rate (0.6–1.0 mL/min), and initial concentration (100–500 μg/g) and to evaluate the interactive effects of the variables on the As(V) adsorption capacity at breakthrough point. Results showed that the optimum As(V) uptake capacity at breakthrough point of 10.57 μg/g could be attained at initial concentration of 418.12 μg/g, CCB mass of 6.6 g, and flow rate of 0.65 mL/min. Based on the analysis of variance, the high value of coefficient of determination (R² ≥ 0.9712) indicates that the quadratic model best describes the experimental data, and the initial concentration is a significant factor on the As(V) adsorption capacity at breakthrough point.

Keywords:

• Arsenate
• Chitosan
• Fixed-bed
• Box–Behnken design
• Yoon–Nelson

Acknowledgments

The authors would like to thank the Taiwan National Science Council (NSC 99-2221-E-041-017) and Philippine DOST-ERDT scholarship for their financial support.