Application of SPME-GC/MS to Study the Sorption of Organophosphate Esters on Peat Soil

Organophosphate esters (OPEs) are classified as re-emerging pollutants, and studies on their environmental fate, e.g., sorption behavior on soil are still limited. In this paper, three OPEs, triphenyl phosphate (TPP), tris (1,3-dichloro-2-propyl) phosphate (TDCP), and tris (1-chloro-2-propyl) phosphate (TCPP) were selected, and their sorption characteristics on peat soil with high organic matter were investigated by direct immersion solid phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC/MS). The sorption kinetics of TPP, TDCP, and TCPP was found to confirm to the pseudo-second-order model, and intra-particle diffusion was not the only rate-controlling step for the sorption process. Linear, Freundlich, and Dubinin-Radushkevich isotherm models were used to analyze the sorption equilibrium data, and the best correlation was achieved by the linear isotherm model. The organic carbon normalized distribution coefficients (logK_oc) were calculated to be 3.45 for TPP, 2.83 for TDCP, and 2.23 for TCPP. Thermodynamics showed that the sorption of TPP, TDCP, and TCPP on Peat soil was spontaneous, exothermic, and physical in nature.