Box–Behnken Design for Optimizing the Synthesis Condition and Adsorption Capability of Covalently Crosslinked Chitosan/coal Fly Ash Composite

Abstract

The growing concern regarding the environmental protection has encouraged researchers to focus their efforts on developing better and more effective possibilities of removing pollutants. In this research, a biocomposite adsorbent of covalently crosslinked chitosan-epichlorohydrin/coal fly ash (CHT-ECH/CFA) was synthesized and applied for reactive red 120 dye (RR120) removal. The CHT-ECH/CFA was characterized by BET, pH potentiometric, pHpzc, XRD, FTIR and SEM-EDX. Box–Behnken Design (BBD) was employed to assess the effects of the adsorption key parameters such as CFA loading into CTH-ECH matrix, adsorbent dose, solution pH, working temperature and contact time. The optimized CFA loading, adsorbent dose, temperature, time, and pH were observed to be 50 %, 0.07 g, 45 °C, 60 min, and pH 4 respectively. From BBD, the highest removal of RR120 removal at optimum conditions was found to be 90.2%. The results showed that adsorption performance can be modelled perfectly by both Langmuir and Freundlich isotherm models with maximum adsorption capacity of 237.7 mg/g at 45 °C. Moreover, the adsorption kinetics were well fitted to the pseudo-second order model. Based on the findings from the experiments conducted, the hybrid biocomposite adsorbent offers adequate potential for the treatment of anionic dye-polluted water.