[Desorption kinetics of 1,2,4,5-tetrachlorobenzene in sediments].

Sediment desorption batch technique experiments were conducted to study the influence of different types of natural organic matter (NOM) of sediment, initial solid-phase solute loading levels and temperatures on the desorption rates of 1,2,4,5-tetrachlorobenzene. A 4-parameter biphasic first-order kinetic model described the desorption of 1,2,4,5-tetrachlorobenzene from the sediments. The results indicate that the rate constants k(s) for the slowly desorbing fraction of each sample is up to 2 orders of magnitude lower than the corresponding rate constants k(r), for the rapidly desorbing fraction, suggesting that the slow desorption is the rate-limiting step.

[Nonlinear sorption behaviors of chlorobenzenes on sediments].

Sorption isotherms of chlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene and 1,2,4,5-tetrachlorobenzene on 5 sediments were examined to understand its sorption behavior. All systems examined exhibits nonlinear sorption. All sorption isotherms are nonlinear as evidenced by the Freundlich n values of 5 sediments being between 0.