Experimental study of 2,4,6- trichlorophenol and pentachlorophenol solubilities in aqueous solutions : derivation of a speciation-based chlorophenol solubility model

摘要

In this study, we report the experimentally-determined solubility of 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), and we derive a speciation-based model for estimating the solubilities of other chlorophenols. At 25$ sp circ$C, the log molality of the protonated species of 2,4,6 TCP is $-$2.8 $ pm$ 0.2, whereas for PCP the value is $-$5.1 $ pm$ 0.4. The pK$ rm sb{a}$ values that best fit the solubility data for 2,4,6 TCP and PCP are 6.0 $ pm$ 0.3 and 4.5 $ pm$ 0.5, respectively. At 55$ sp circ$C, the log molality of protonated PCP increases to $-$4.7 $ pm$ 0.2 and the pK$ rm sb{a}$ value decreases to 4.1 $ pm$ 0.3. Addition of a Na-chlorophenol aqueous species to the model improves the fit to each dataset and, at 25$ sp circ$C, we calculate log stability constants values for NaPCP$ sp circ$ and NaTCP$ sp circ$ of 1.1 $ pm$ 0.5 and 0.9 $ pm$ 0.4, respectively. At 55$ sp circ$C, the stability constant for NaPCP$ sp circ$ is 0.7 $ pm$ 0.4. The results of this study enable estimations of chlorophenol solubilities under a wide range of conditions of environmental interest.