Catalytic Degradation of Organic Contaminants by Microwave-Assisted Persulfate Activation System: Performance and Mechanism

In this study, a nickel ferrite (NiFe2O4) system was constructed to purify a phenol solution in water. During the process, the influences of several critical operating parameters including the NiFe2O4 amount, PS dosage, MW power, initial pH value, and different natural water anions were systematically studied. The results indicated that the constructed system performed excellently regarding the removal efficiency (97.74%) of phenol within 30 min. Meanwhile, the influence of co-existing anions such as Cl-, NO3-, H2PO4-, and HCO3- was also studied, which displayed an inhibiting action on phenol degradation, while HA facilitated it. To explore the reaction mechanism of this system, major free radical quenching experiments were conducted, and it was confirmed that both SO4 center dot(-) and HO center dot were primary radicals. Moreover, stability experiments confirmed the apt stability of the NiFe2O4 system. Besides, the mineralization and toxicity analysis performed during phenol degradation also confirmed the superiority of the as-constructed system. Furthermore, the possible degradation mechanism of phenol was proposed. Hence, this system could be applied in advanced wastewater treatment.

Automated summary

In this study, a nickel ferrite (NiFe2O4) system was developed for purifying phenol solutions in water. The effects of various operating parameters on the system's performance were investigated, including the amount of NiFe2O4, dosage of potassium persulfate (PS), microwave (MW) power, initial pH value, and different natural water anions. The results showed that the system achieved an excellent phenol removal efficiency of 97.74% within 30 minutes. The presence of co-existing anions such as chloride (Cl-), nitrate (NO3-), dihydrogen phosphate (H2PO4-), and bicarbonate (HCO3-) inhibited phenol degradation, while humic acid (HA) facilitated it. Free radical quenching experiments confirmed that sulfate radical (SO4 center dot(-)) and hydroxyl radical (HO center dot) were the primary radicals involved in the reaction mechanism. Stability experiments demonstrated the satisfactory stability of the NiFe2O4 system. Furthermore, mineralization and toxicity analysis confirmed the superiority of the as-constructed system in phenol degradation. The proposed degradation mechanism provides valuable insights for further applications of this system in advanced wastewater treatment.