Figure 7 indicates the interaction influence of pH value and initial TC concentration on the TC degradation rate. With increasing pH from acidic (5) to natural (7.5), the degradation rate slightly decreased, whereas with increasing pH from neutral (7.5) to alkaline (10), the degradation rate significantly enhanced. The TC degradation rate increased from 86.62 % to 94.25 % with increasing pH from 5 to 10, at TC concentrations of 30 mg/L. Under alkaline conditions (pH ≥10), alkaline-activated persulfate is the primary responsible for the production of SO4-•, O2-• and HO• radicals as following equations: [62, 63].10 S2O82−+2H2O→OH−HO2−+2SO42−+3H+11 HO2−+S2O82−→SO4−•+SO42−+H++O2−•12 SO4−•+OH−→SO42−+HO•