Partition kinetics of chlorobenzenes in a sediment-water system

Abstract

The partition kinetics of chlorobenzenes (CBs) in a sediment-water system were studied to provide a basis for understanding the compounds’ behaviour in the natural aquatic environment. A series of chlorobenzenes (CBs) 1,4-dichlorobenzene (DCB), 1,3,5-trichlorobenzene (TCB), 1,2,4,5-tetrachlorobenzene (TeCB), pentachlorobenzene (QCB), and hexachlorobenzene (HCB) were spiked to the sediment, and the concentrations of CBs both in sediment and water were measured at six different mixing time periods (0.17, 1, 4, 12, 24 and 48 h). A partition kinetics model was developed to determine kinetics rate constants. Adsorption rate constants increased (DCB 15.3; HCB 26.3 L kg−1 h−1) while desorption rate constants decreased (DCB 0.41; HCB 0.01 h−1) with KOW values. The times to reach equilibrium in the system were between 6.7 h (HCB) and 14.3 h (TeCB), with no specific pattern related to the KOW values of CBs. The kinetics of CBs were fitted to a first-order kinetics with a single-compartment model. QSAR analysis showed strong linear relationships between kinetics rate constants and physicochemical properties.