Identification of Tetrachloroethylene Sorption Behaviors in Natural Sorbents Via Sorption Models

초록

A number of different methods have been used for modeling the sorption of volatile organic chlorinated compounds suchas tetrachloroethylene/perchloroethylene (PCE). In this study, PCE was adsorbed in several natural sorbents, i.e., Pahokeepeat, vermicompost, BionSoil®, and natural soil, in the batch experiments. Several sorption models such as linear,Freundlich, solubility-normalized Freundlich model, and Polanyi-Manes model (PMM) were used to analyze sorptionisotherms. The relationship between sorption model parameters, organic carbon content ( foc), and elemental C/N ratio wasstudied. The organic carbon normalized partition coefficient values (log Koc = 1.50-3.13) in four different sorbents wereless than the logarithm of the octanol-water partition coefficient (log Kow = 3.40) of PCE due to high organic carbon contents. The log Koc decreased linearly with log foc and log C/N ratio, but increased linearly with log O/C, log H/C, and log(N+O)/C ratio. Both log KF,oc or log KF,oc decreased linearly with log foc (R2 = 0.88-0.92) and log C/N ratio (R2 = 0.57-0.76), but increased linearly with log (N+O)/C (R2 = 0.93-0.95). The log qmax,oc decreased linearly as log foc and log C/Nincreased, whereas it increased with log O/C, log H/C and log (N+O)/C ratios. The log qmax,oc increased linearly with(N+O)/C indicating a strong dependence of qmax,oc on the polarity index. The results showed that PCE sorption behaviorswere strongly correlated with the physicochemical properties of soil organic matter (SOM).

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