Solubilization of nitrotoluenes in micellar nonionic surfactant solutions

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• 作者：Dianne J. Luning Prak
• 关键词：Dinitrotoluene ; Trinitrotoluene ; Solubility ; Molar solubilization ratio ; Micelle-water partition coefficient
• 刊名：Chemosphere
• 出版年：2007
• 出版时间：August 2007
• 年：2007
• 卷：68
• 期：10
• 页码：1961-1967
• 全文大小：175 K

文摘

A key factor in selecting surfactants to enhance chemical or biological transformation or physical removal of an organic pollutant from contaminated soil is knowledge of the pollutant’s solubility behavior in the surfactant solution. This study investigated the influence of nonionic surfactant structure on the solubility of 4-nitrotoluene (NT), 2,3-dinitrotoluene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, and 2,4,6-trinitrotoluene (TNT) at room temperature. For a series of alkyl phenol ethoxylates (Tergitol NP-8 to NP-40), decreasing the ethoxylate chain length increased the solubility of these nitrotoluenes by a factor of two or less in 10 g l⁻¹ surfactant solutions, but did not significantly change their molar solubilization ratios (MSR, e.g. 0.02 for TNT) or their micelle–water partition coefficients (K_m, e.g. 3.4 for TNT). For Tergitol NP-8 solutions ranging from 1.0 to 12.4 g l⁻¹, no enhancement in NT solubility was found, suggesting that the cloud point was reached. The MSRs for Tween 80 were higher than those of Tween 20 and the MSRs of Brij-58 were higher than those for Brij-35. When comparing solutes, NT had the highest solubility and MSR (0.28–0.41), while TNT had the lowest solubility and MSR (0.02–0.03). A linear relationship between K_m values and octanol–water partition coefficients based on Triton X-100 predicted the log K_m values within 0.5 of their measured values. A linear solvation free energy correlation for K_m suggested the importance of solute volume and effective hydrogen bond basicity in the partitioning process while implying that the nitrotoluenes are solubilized in a polar portion of the micelle.