Degradation of trichloroethylene in aqueous solution by FeS2 catalyst under innovative oxic environments

Abstract

Rapid growth and industrialization have become a major threat to water contamination with carcinogenic chlorinated hydrocarbons such as trichloroethylene (TCE). Therefore, this study aims to assess the TCE degradation performance through advanced oxidation process (AOP) using catalyst FeS₂ in combination with oxidants persulfate (PS), peroxymonosulfate (PMS), and hydrogen peroxide (H₂O₂) in PS/FeS₂, PMS/FeS₂, and H₂O₂/FeS₂ systems, respectively. TCE concentration was analyzed using gas chromatography (GC). The results found the trend for TCE degradation by the systems was PMS/FeS₂>PS/FeS₂>H₂O₂/FeS₂ (99.84, 99.63, and 98.47%, respectively). Degradation of TCE was analyzed at different pH ranges (3-11) and maximum degradation at a wide pH range was observed for PMS/FeS₂. The analysis using electron paramagnetic resonance (EPR) and scavenging tests explored responsible reactive oxygen species (ROS) for TCE degradation and found that HO• and SO₄^-• played the most effective role. The results of catalyst stability showed PMS/FeS₂ system the most promising with the stability of 99, 96 and 50% for the first, second and third runs, respectively. The system was also found efficient in the presence of surfactants (TW-80, TX-100, and Brij-35) in ultra-pure water (89.41, 34.11, 96.61%, respectively), and actual groundwater (94.37, 33.72, and 73.48%, respectively), but at higher reagents dosages (5X for ultra-pure water and 10X actual ground water). Furthermore, it is demonstrated that the oxic systems have degradation capability for other TCE-like pollutants. In conclusion, due to its high stability, reactivity, and cost-effectiveness, PMS/FeS₂ system could be a better choice for the treatment of TCE contaminated water and can be beneficial for field application.

Keywords: Advanced oxidation process; Iron pyrite; Potassium peroxymonosulfate; Scavengers; Surfactants.