Dual effects of organic matter in the remediation of acetaminophen-contaminated soil by peroxymonosulfate

Abstract

Soil organic matter (SOM) is a critical component of soil, but its impact on the efficacy and mechanism of peroxymonosulfate (PMS)-based soil remediation technology has not been fully elucidated. This study revealed that SOM exerts dual effects in the remediation of acetaminophen (ACE)-contaminated soil by PMS, where both excessive and insufficient SOM levels can adversely impact ACE degradation efficiency. Protein-like and fulvic-like substances critically enhance ACE elimination by activating PMS when their volume ranges from 75.8 % to 87.2 %. Additionally, in the presence of PMS, humic-like substances can be converted into protein-like and fulvic-like substances. Ferromanganese oxide and amorphous iron also facilitate the degradation of ACE, with ferromanganese oxide playing a more significant role. The study identified singlet oxygen (¹O₂) and sulfate radicals (SO₄^•−) as the primary reactive oxygen species (ROS) responsible for the elimination process. Furthermore, the degradation rate of ACE indicated superior treatment efficacy under diverse pH conditions. The presence of Cl⁻ was noted to partially inhibit the degradation of ACE, while HCO₃⁻, Fe³⁺, and Mn²⁺ were observed to enhance the elimination process. Humic acid (HA) demonstrated a dual effect, while the impacts of NO₃⁻ and SO₄²⁻ on the system were relatively minor. The degradation intermediates were characterized, and their toxicity was evaluated through phytotoxicity assays. This study systematically revealed the dual role of SOM and provided novel insight into the application of PMS in soil remediation.