Sorption of Organophosphate Flame Retardants on Pahokee Peat Soil

Organophosphate flame retardants (OPFRs) 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 kinds of OPFRs, tri (n-butyl) phosphate (TnBP), tris (2-butoxyethyl) phosphate (TBEP), and tris (2-chloroethyl) phosphate (TCEP) were selected and their sorption properties on Pahokee peat soil with high organic matter were investigated by solid phase micro-extraction coupled with gas chromatography-mass spectrometry. The sorption kinetics of TnBP, TBEP, and TCEP was found to confirm to the pseudo-second-order kinetic model and the sorption rate was controlled by boundary layer diffusion. The Langmuir isotherm model expressed the sorption equilibrium data well, in which TnBP exhibited the strongest affinity to Pahokee peat soil followed by TBEP and TCEP. Sorption thermodynamics indicated that lower temperature was beneficial to the sorption process.