title: Water solubility enhancements of PAHs by sodium castor oil sulfonate microemulsions.
abstract: Water solubility enhancements of naphthalene(Naph), phenantherene(Phen) and pyrene(Py) in sodium castor oil sulfonate(SCOS) microemulsions were evaluated. The apparent solubilities of PAHs are linearly proportional to the concentrations of SCOS microemulsion, and the enhancement extent by SCOS solutions is greater than that by ordinary surfactants on the basis of weight solubilization ratio(WSR). The logK(em) values of Naph, Phen, and Py are 3.13, 4.44 and 5.01 respectively, which are about the same as the logK(ow) values. At 5000 mg/L of SCOS concentration, the apparent solubilities are 8.80, 121, and 674 times as the intrinsic solubilities for Naph, Phen, and Py. The effects of inorganic ions and temperature on the solubilization of solutes are also investigated. The solubilization is improved with a moderate addition of Ca2+, Na+, NH4+ and the mixture of Na+, K+, Ca2+, Mg2+ and NH4+. WSR values are enhanced by 22.0% for Naph, 23.4% for Phen, and 24.6% for Py with temperature increasing by 5 degrees C. The results indicated that SCOS microemulsions improve the performance of the surfactant-enhanced remediation (SER) of soil, by increasing solubilities of organic pollutants and reducing the level of surfactant pollution and remediation expenses.
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310028, China. lzzhu@mail.hz.zj.cn
authors.forename: Li-Zhong
authors.initials: LZ
authors.lastname: Zhu
authors.forename: Bao-Wei
authors.initials: BW
authors.lastname: Zhao
authors.forename: Zong-Lai
authors.initials: ZL
authors.lastname: Li
mesh_terms: D002368:Castor Oil / Q000031:analogs & derivatives* / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D004655:Emulsions / Q000378:metabolism*; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism*; D012995:Solubility; D013501:Surface-Active Agents / Q000378:metabolism*; D013696:Temperature
chemical_list: D002412:Cations; D004655:Emulsions; D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants; D013501:Surface-Active Agents; D002368:Castor Oil