Behavior and fate of short chain chlorinated paraffins (SCCPs) in different oxidation reactions

Short chain chlorinated paraffins (SCCPs) have attracted extensive attention due to their adverse effects on soil organisms and humans. However, comprehensive understanding of the degradation of SCCPs is still limited. In this work, the behavior and fate of SCCPs during advanced oxidation processes (AOPs) in contaminated soil were studied. The concentration and congener profile of SCCPs before and after the oxidations were determined. Results showed that SCCPs (1 mg kg−1) could be effectively degraded within 120 h by four common oxidants, including hydrogen peroxide (H2O2), Fenton (H2O2/Fe2+), potassium permanganate (KMnO4), and sodium persulfate (Na2S2O8). The optimal degradation efficiency followed the order KMnO4 (93.3 %) > Na2S2O8 (91.9 %) > Fenton (90.4 %) > H2O2 (84.3 %). After the oxidation treatment, the relative abundance of C10Cl8∼10, C11Cl8∼10, C12Cl8∼10, and C13Cl8∼10 increased, among that C10H13Cl9 increased the most (1.71 % − 2.52 %, in mass ratio). While the relative abundance of C10Cl5∼7, C11Cl5∼7, and C12Cl6∼7 decreased significantly, and C11H18Cl6 decreased the most (−3.81 % − −6.18 %, in mass ratio). Density functional theory (DFT) calculations were used to explain these observations. Compared to carbon atomic percentage, chlorine atomic percentage had greater impacts on the degradation of SCCP congeners, which showed a significant negative correlation. However, four congeners consistently failed to follow this pattern, such as C12H21Cl5, C13H22Cl6, C12H16Cl10, and C13H18Cl10. This work is expected to provide data and technical support for remediation in typical SCCPs contaminated soil.