Tuning of Fly Ash Loading into Chitosan-Ethylene Glycol Diglycidyl Ether Composite for Enhanced Removal of Reactive Red 120 Dye: Optimization Using the Box–Behnken Design

Abstract

Crosslinked chitosan-ethylene glycol diglycidyl ether (CTS-EGDE) was modified by loading fly ash (FA) particles into its polymeric matrix to improve the adsorptive removal of reactive red 120 (RR120) dye. The Box–Behnken design was used to assist in the tuning of optimum synthesis and adsorption conditions, such as the loading ratio of FA particles (A: 0–50%), adsorbent dose (B: 0.02–0.08 g), solution pH (C: 4–10), temperature (D: 30 °C–60 °C), and time (E: 20–60 min). The highest removal rate (98.8%) of 50 mg/L RR120 dye was achieved under the following conditions: FA loading, 25% (CTS-EGDE/FA-25); adsorbent dose, 0.05 g; solution pH, 4; temperature, 60 °C; and time, 40 min. The maximum adsorption capacity of CTS-EGDE/FA-25 for RR120 was 220 mg/g at 60 °C. This work provides insights into the optimization of the synthesis of composite materials, which can potentially be applied in wastewater treatment.