Nickel-assisted iron oxide catalysts for the enhanced degradation of refractory DDT in heterogeneous Fenton-like system

- A novel Ni@FeOx catalyst was prepared for catalytic degradation toward DDT.
- Ni2+ and Ni0 promote Fe3+/Fe2+ cycle together to enhance catalytic activity.
- DDT decomposing by Ni@FeOx is mainly a successive dechlorination process.
- Optimized parameters are important to achieve high catalytic activity.

A novel Ni@FeOx composite was prepared via a facile hydrothermal method and their heterogeneous catalytic activity in Fenton-like reaction to decompose 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) pollutant was systematically investigated. FeOx was doped by nickel ions and modified by nickel particles in this process. In the Fenton-like reaction, 40%Ni@Fe3O4 could remove almost 90% of DDT within 8 h in the presence of H2O2, exhibiting much higher rate constant than any other systems with lower Ni content. It indicated that too much catalyst is unhelpful to increase the activity further, and excessive H2O2 even decreases the activity. The composite exhibits excellent activity at pH = 7, almost as high as in acid environment, superior to homogenous catalysts. According to GC-MS results, the decomposing process mainly is a successive dechlorination process, partially accompanied with the fragmentation of small molecular. The Ni2+ and Ni0 are deduced to promote the Fe3+/Fe2+ cycle together to provide abundant Fe2+ for Fenton reaction.

65