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

A novel Ni@FeO x 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. FeO x was doped by nickel ions and modified by nickel particles in this process. In the Fenton-like reaction, 40%Ni@Fe 3 O 4 could remove almost 90% of DDT within 8 h in the presence of H 2 O 2 , 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 H 2 O 2 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 Ni 2+ and Ni 0 are deduced to promote the Fe 3+ /Fe 2+ cycle together to provide abundant Fe 2+ for Fenton reaction .