Degradation of 1,2,3-trichloropropane using peroxydisulfate activation by green tea iron nanoparticles

Abstract

The pollution of groundwater with 1,2,3-Trichloropropane (TCP) has raised significant concerns due to its toxicity and resistance to degradation. In this study, the degradation of TCP using peroxydisulfate (PDS) activation by green tea iron nanoparticles (G-INPs) was investigated and compared with traditional PDS oxidation activated by citric acid-Fe2＋(CA-Fe), which was commonly used as an effective PDS activator. Oxidation experiments and theoretical analysis were conducted to reveal the degradation efficiency and mechanism. The results showed that the TCP degradation efficiency was significantly enhanced in the G-INPs/PDS oxidation system compared to CA-Fe/PDS oxidation. The degradation efficiency was more than 77% after 48 hours (h) in G-INPs/PDS oxidation (0.625 mM Fe, 25 mM PDS, and 25°C with no pH adjustment) at an initial TCP concentration of 100 mg/L. In contrast, only 59% of TCP was degraded by CA-Fe/PDS using the same ferrous ion (Fe2＋) amount. The addition of G-INPs promoted the generation of hydroxyl radical (OH⋅ ), sulfate radical (SO4−⋅ ), and superoxide radical (O2-⋅ ), among which OH⋅ played a crucial role in the degradation process. The concentration of Fe2＋ in the G-INPs/PDS system after 48 h was twice as high as that in the Fe2＋/PDS system. The increased Fe2＋ content in the system facilitated the production of radicals, leading to improved degradation efficiency of TCP. Reaction product analysis further demonstrated that carbon dioxide (CO2) and hydrochloric acid (HCl) were the oxidation products of TCP degraded by G-INPs/PDS, and only a tiny amount (<5.5 wt%) of less toxic organic by-products were generated, including 1,3-dichloro-2-acetone, 1,2-dichloroethane and 1,1,2-trichloroethane. Conclusively, the G-INPs/PDS oxidation method seems to be a promising technology for removing high TCP contamination from wastewater or polluted groundwater.