Degradation of 4-chlorophenol by mixed Fe 0 /Fe 3 O 4 nanoparticles: From the perspective of mechanisms

Abstract

Fe 0 nanoparticles have beenwidely studied for pollution abatement in recent years; however, regarding the mechanism for pollutant degradation, studies have mainly focused on the reductive dechlorination by Fe 0 , and the dynamic process has not been clarified completely. As reported, someorganics could be degraded during the oxidation of Fe 0 byO 2 , and hydrogen peroxidewas supposed to be produced. In this study, Fe 3 O 4 , an oxidation product of Fe 0 , was used to treat the pollutant combining with Fe 0 nanoparticles, and 4-chlorophenol (4-CP) was used as the model pollutant. The results showed that the addition of Fe 3 O 4 nanoparticles hindered the removal of 4-CP by Fe 0 nanoparticles under anoxic conditions. However, the dechlorination efficiency was improved in the initial 6 h. Under aerobic conditions, the reused Fe 3 O 4 nanoparticles would improve the removal and dechlorination of 4-CP. Especially, the dechlorination efficiencywas obviously increased. It is proposed that the removal of 4-CP was due to the effects of both nanosized Fe 0 and Fe 3 O 4 - reducing action of Fe 0 and catalytic oxidation action of Fe 3 O 4 . The reducing action of Fe 0 was the major factor under anoxic conditions. And the catalytic oxidation action of Fe 3 O 4 became an important reason under aerobic conditions.