Ball Milling-Induced Plate-like Sub-microstructured Iron for Enhancing Degradation of DDT in a Real Soil Environment

The remediation of soil contaminated by 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) has been a challenge. In this paper, the degradation performances of the ball milling-induced plate-like sub-microstructured zero valent iron (SMZVI) to DDT in a real soil environment is studied. It has been found that such SMZVI exhibits much higher degradation performances to DDT in soil than commercial ZVI powders under acidic conditions. More than 95% DDT could be degraded within 80 min in the 5 ppm DDT-contaminated soil with addition of 50 mg g^-1 SMZVI, which is much better than the previously reported results. The time-dependent DDT removal amount can be well described by the pseudo first-order kinetic model. Further experiments have revealed that the ZVI dosages, surfactant's and acidic additions, and the weight ratio of soil-to-water in the slurries are important to DDT degradation, and the degradation products were mainly DDD (a product with less chlorine). An acid-assisted ZVI-induced reductive dechlorination process is proposed, which can well explain the DDT degradation behaviors in soil and the influence from the other factors. This work not only deepens the understanding of DDT degradation in soils based on ZVI but also demonstrates that the SMZVI could be a promising material for DDT degradation in real environments.