Enhancement of 2,4,6-trichlorophenol degradation in groundwater via natural pyrite-activated percarbonate: Mechanistic insights and efficiency evaluation

Trichlorophenol (TCP), widely used in industrial applications, is highly toxic, persistent, and bioaccumulative, posing serious risks to groundwater and human health. This study investigates the catalytic activation of sodium percarbonate (SPC) by natural pyrite (FeS2) for the degradation of 2,4,6-trichlorophenol (2,4,6-TCP) in groundwater. Results demonstrated that the FeS2/SPC system achieved a 99.8 % degradation rate of 2,4,6-TCP (initial concentration: 10 mg/L) within 480 min under optimal conditions (FeS2 = 0.3 g/L, SPC = 0.2 mM, pH = 3). Mineralization efficiency reached 55.01 %, with a dechlorination efficiency of 53.84 %, indicating significant transformation of 2,4,6-TCP into less harmful products. Electron paramagnetic resonance (EPR) and radical scavenging experiments confirmed that HO & sdot; (49.8 %), 1O2 (31 %), and O2 & sdot; (19.2 %) were the primary reactive species responsible for degradation. Mechanistic analysis revealed that Fe2+ in the combined state (equivalent to Fe2+) is the dominant activator of SPC, while sulfur (S2 /S22 ) plays a crucial role in Fe3+/Fe2+ cycling, enhancing catalytic efficiency. GC-MS analysis identified degradation intermediates, and toxicity assessment confirmed reduced environmental risks compared to the parent compound. This study provides valuable insights into the FeS2/SPC Fenton-like system, offering a sustainable and efficient approach for remediating 2,4,6-TCP-contaminated groundwater.