Photocatalytic Degradation of Trichloroethylene Under Different Environmental Conditions: Kinetics and Carbon Isotope Effects

Photocatalytic degradation technology is an important tool for treating trichloroethylene (TCE) pollution in water bodies. While previous studies have focused on catalyst optimization and degradation kinetics for trichloroethylene (TCE) photocatalysis, the systematic impact of environmental conditions on carbon isotope effects (ε) and their mechanistic implications remains poorly understood. This limits the reliability of quantitative isotope analyses in field applications. We conducted a series of laboratory experiments on the photocatalytic degradation of TCE to investigate the kinetic and isotopic effects under different conditions. Increasing the concentration of TCE, anions (NO3− and HCO3−), and cations (Mg2+ and Ca2+) decreased the photocatalytic degradation of TCE. O2 will increase the degradation efficiency of TCE. The dose required to achieve maximum photocatalytic efficiency varies for different types of catalysts, which needs to be determined on a case-by-case basis. TCE photocatalytic degradation had a small carbon isotope effect (ε = −2.0 ± 0.2‰ to −3.2 ± 0.5‰), which was slightly affected by the catalyst dosage and species (TiO2 and ZnO), and concentrations of TCE, O2, and inorganic ions (NO3−, HCO3−, Mg2+, and Ca2+). The ε values are stable and reproducible and relatively insensitive to our selected environmental factors in this study, which can reduce the uncertainty of applying stable carbon isotope enrichment factors to quantify the photocatalytic reaction for remediation of TCE contaminated sites.