Density Functional Theory Computations and Experimental Analyses to Highlight the Degradation of Reactive Black 5 Dye

Abstract The oxidative degradation of Reactive Black 5 (RB5) in aqueous solution was investigated using Fenton (FP), photo Fenton (P‐FP), sono Fenton (S‐FP), and sono photo Fenton (S‐P‐FP) processes. Degradation experiments showed efficient dye degradation for FP, P‐FP, S‐FP, and S‐P‐FP under optimal conditions. The half‐life values of the reaction calculated for first‐order reaction kinetics showed that the S‐FP process is faster than the FP and P‐FP processes. Using DFT calculations, the chemical reactivities of the studied chemical systems were analyzed. Especially the calculated chemical hardness values reflect the reactivities of the dye and the dye‐Fe 2+ complex. The calculated binding energy between the Fe 2+ ion and RB5 of 15.836 eV is compatible with the prediction made in the light of the principle of hard and soft acids and bases. The computed data supported the experimental observations.