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

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 degrees C-60 degrees 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 degrees C; and time, 40 min. The maximum adsorption capacity of CTS-EGDE/FA-25 for RR120 was 220 mg/g at 60 degrees C. This work provides insights into the optimization of the synthesis of composite materials, which can potentially be applied in wastewater treatment.