Degradation of 1,2,3-trichloropropane by pyrite activating sodium percarbonate and the implications for groundwater remediation

1,2,3-trichloropropane (TCP) is a newly regulated groundwater contaminant, however, its remediation technology has not been fully investigated. In this research, pyrite (FeS2) was used as a novel activator of sodium percarbonate (SPC) for TCP degradation. TCP could be effectively removed by FeS2/SPC system with a much higher removal efficiency than the classic Fenton system. Free radical quenching test, hydroxyl radical probe reaction, EPR, XPS, XRD and SEM were used to elucidate the reaction mechanism. SPC was decomposed to produce H2O2, which was activated by Fe2+ dissolved from pyrite to produce HO center dot and O-2(-)center dot. Both HO center dot and O-2(-)center dot contributed to TCP degradation, but HO center dot played a more important role. The S elements of pyrite promoted the regeneration of Fe2+, thus enhancing the TCP degradation. The TCP removal efficiency significantly increased with increases in concentrations of pyrite and SPC and decreases in pyrite particle size and pH. Although HCO3-, Cl- and NOM inhibited TCP degradation by FeS2/SPC, the reaction system could still remove TCP in real groundwater. Overall, pyrite-activate SPC is a promising in-situ groundwater remediation technology.

Automated summary

In this study, pyrite was used as an activator of sodium percarbonate for the degradation of 1,2,3-trichloropropane. The FeS2/SPC system showed a higher removal efficiency of TCP compared to the classic Fenton system. The reaction mechanism was elucidated through various tests and it was found that HO· and O2^-· played a role in TCP degradation, with HO· being more important. The presence of S elements in pyrite promoted the regeneration of Fe2+ and enhanced TCP degradation. The TCP removal efficiency was influenced by the concentrations of pyrite and SPC, as well as the particle size and pH of pyrite.