Efficient removal of reactive red 24 from aqueous solution through electron beam and aeration tank using response surface methodology

The present work examines the decolorization of reactive red 24 (RR24) from an aqueous solution via the electron beam (EB) and aeration method. Response surface methodology (RSM) with central composite design (CCD) was used to optimize the treatment with the four selected variables, i.e., absorbed dose, H2O2 concentration, initial pH (in EB system), and operation time (in the aerobic reactor). The predicted optimized conditions for the color removal were 4.5 kGy for absorbed dose, 4.0 mM for H2O2 concentration, 6 for initial pH, and 7.5 days for operation time. The experimental response of 97.14% color removal from these optimized conditions was in agreement with the value predicted by the model to within an error of 2.24%. The closeness of the predicted values and experimental results indicated that the quadratic model is adequate for predicting the decolorization process of coupled EB and aeration. Besides, modern density function theory (DFT) and natural bond orbital (NBO) calculations are also used to predict the decomposition reaction mechanism of RR24 under the influence of EB irradiation. This study demonstrated a practical method of eliminating reactive dyes by the hybrid of EB and biological methods.