Oxidative Degradation of Phenol in Aqueous Solution by Using Heat, ZVI, AC, Heat/ZVI, or Heat/AC Activated Persulfate

Degradation of phenol by heat-activated, ZVI-activated, AC-activated, heat/AC-activated, and heat/ZVI-activated persulfate have been investigated. As a result, the degradation of phenol fitted well with pseudo-first order kinetic model. For the solution with phenol concentration of 100 mg/L, degradation efficiency of nearly 100% and reaction rate constant of 0.0506 min^-1 are realized by heat-activated persulfate when reaction temperature is 70±C, concentration of persulfate is 15 g/L, reaction time is 120 min under neutral pH. Besides, the highest degradation efficiency and reaction rate constant of phenol by ZVI-activated are respectively, 92.85% and 0.0198 min^-1 when concentration of ZVI is 5 g/L, concentration of persulfate was 15 g/L, and reaction time is 120 min under neutral pH. Furthermore, the highest degradation efficiency and reaction rate constant of phenol by AC-activated persulfate are 99.1% and 0.0373 min^-1, respectively with persulfate concentration of 5 g/L and AC concentration of 5 g/L under neutral pH in 120 min. Moreover, the heat/AC-activated and heat/ZVI-activated persulfate are showing obvious synergistic effect during degradation process of phenol, and the reaction rate constants of heat/AC-activated and heat/ZVI-activated persulfate are respectively, 0.0512 and 0.0561 min^-1. The radical scavenger experiments proved that both SO₄ ^- • and OH• are significant radicals in degradation of phenol by ZVI-activated and AC-activated persulfate, and SO₄ ^- • are predominant radicals in degradation of phenol.