Study On Solubilization Effects And Mechanisms Of Soil Organic Contaminants In Surfactant And Cyclodextrin Solutions

The thesis aims to improve the capacity and efficiency of solubilization agent, which could effectively remediate the organic polluted soils, in addition, related mechanisms are studied in order to increase remediation efficiency, decrease remediation cost and reduce the pollution of the solubilization agent to soil and groundwater. The major achievements in the paper are as follows:(1) The two-process-first-order kinetic equation is first deduced in this paper, it is found that micelle adsorption-diffusion and solute-diffusion coexist in the process of solubilization of pentachlorobenzene by POE(10).(2) The apparent solubilities of pentachlorobenzene, hexachlorobenzene and biphenyl are linearly increased with the increasing concentration of solubilization agent. Surfactant Brij30,POE(6),Brij35,POE(10) and Brij56 ( above critical micellar concentration) and 2-hydroxypropyl-beta-cyclodextrin can enhance the solubility of hydrophobic organic contaminants greatly.(3) Addition Na2SO4 lowers the critical micelle concentration(CMC) and the apparent free energy for micellization of POE(6), and increases its critical packing parameter(CPP) and micellar aggregation numbers. The solubilization capacity enhancement of HCB in POE(6) solution by Na2SO4 could be mainly due to an increasing volume of the hydrophobic environment in the micelle core.(4) Increasing temperature enhances the solubilization effect of HCB in Brij35 solution. The thermodynamic parameters indicate that the solubilization is entropically driven and spontaneous, higher temperature favors this process.(5) Cyclodextrin and surfactants can form complex, but the complex between BP and HPCD appears stronger than the complex between POE(10) monomers and HPCD. The solubilization effect of cyclodextrin/surfactant mixed solution is worse than the sum effect of POE(10) and HPCD, but at appropriate concentration proportion, the apparent solubility in mixed solution can be larger than that of any single solution. Cyclodextrin/surfactants mixed solution could be a new solubilization agent in the application of remediation.(6) The apparent solubility of PCB congener in surfactant solution is determined by its water solubility and its micelle-aqueous phase partition coefficient, while in 2-hydroxypropyl-beta-cyclodextrin(HPCD)solution, the fitness of molecule structure with the HPCD cavity has even more predominant effect on the solubilization efficiency than the water solubility and micelle-aqueous phase partition coefficient of the PCB congener.(7) The solubilization ability of surfactant has something to do with both its hydrophilic head and its hydrophobic tail; The mass solubilization ratio(WSR) of HCB and BP is linearly proportional to the NC/NEO (carbon number of the hydrophobic group/ the number of polyoxyethylene unit)ratio of the sufactant, the larger the NC/NEO ratio, the better solubilization ability of surfactant; This NC/NEO ratio can be an index of solubilization ability for surfactant to solubilize hydrophobic organic contaminants.(8) The hydrophobicity of the organic contaminants is the main driving force of solubilization process, the polarity of the surfactant micelle is less than the polarity of n-octanol. The micelle-aqueous phase partition coefficients (Kmc) of hydrophobic organic contaminants in all surfactant solution studied are positively correlate to their intrinsic molar volume(Vi) well, the larger the Vi value is, the easier for organic contaminants to dissolve in surfactant micelles; The intrinsic molar volume of hydrophobic organic contaminants is more reliable to predict the micelle-aqueous phase partition coefficients (Kmc) than their n-octanol water partition coefficients.