Study on the co-catalytic performance and mechanism of MoO2 in oil-contaminated wastewater treated by Fenton system

Background In the treatment of organic wastewater, Fenton technology often produces iron sludge due to iron circulation obstruction, which inhibits the treatment efficiency and causes secondary pollution to the actual water. Methods In this study, MoO 2 was used as a cocatalyst to promote the effective cycling of Fe 2+ /Fe 3+ in the Fe 2+ /H 2 O 2 system, thus efficiently degrading total petroleum hydrocarbons (TPHs). The superiority of MoO 2 as co-catalyst was verified under different reaction conditions, and its mechanism was discussed. Findings The degradation rate of TPHs in the Fe 2+ /H 2 O 2 /MoO 2 system (0.069 min −1 ) was about 14 times that of Fe 2+ /H 2 O 2 system (0.005 min −1 ). Compared with the Fe 2+ /H 2 O 2 system, the Fe 2+ /H 2 O 2 /MoO 2 system not only had a wider pH adaptation range, but also could effectively remove TPHs under the interference of co-existing organic and inorganic anions. MoO 2 did not change the types of reactive species in Fenton system, but it enhanced the production of reactive oxygen species (ROS) by promoting the Fe 2+ /Fe 3+ cycling in the reaction system, and ·OH was the main reactive species of TPHs degradation.