Influence Of Surfactant On Transport Of Organic Pollutants In Multimedia Environment

The influence rule and mechanism of surfactant on the transport and transform of pollutants in multimedia environment were reviewed. The frames, characters and the sorption properties to soil or sediment of surfactants were summarized. Based on the influence of surfactants on the characters of soil and solution, the environmental behavior of organic pollutants and heavy metals including transport, transform and bioavailability in soil and water medium were described. The effect of surfactants on Henry's law constants of organic pollutants was also involved.Based on the multimedia environment with complex pollution, the influence of surfactant on distribution of volatile organic compounds(VOCs) in the interface of water/gas was investigated. The experiment was designed without any dynamic factors. The influence rule and mechanism of surfactant with and without salt on the evaporative loss of VOCs were studied. The main conclusions of this work are drawn.(1)The main reason for the decrease of evaporative loss velocity of VOCs from static water was that the formation and increase of the surfactant micelle diminished the Henry's law constants of VOCs and the ratio of the concentration of VOCs at the liquid surface to that at the bulk liquid phase(a). For the decrease of a, kL the mass transfer constant in liquid film diminished. The more notable the solubility enhancement of VOCs by a surfactant was, the more obviously that surfactant diminished the evaporative loss velocity of VOCs. The positive relation was found between the restraining ability of a surfactant and the octanol-water partition coefficients(Kow) of VOCs. The ability of hydrophilic surfactants on diminishing the evaporative velocity of naphthalene was stronger markedly than the lipophilic surfactants, when the surfactants had concentrations of the same CMC (critical micelle concentration) multiple.(2)The solubility of surfactant altered corresponding to different water temperature and it caused the change of the influence rule of surfactant on theevaporation of VOCs. When water temperature descended, the critical concentration of restraining the evaporative loss velocity of VOCs for Brij30 decreased and there was no effect of CTMAB on the evaporation of VOCs below 15C. But the rule didn't change for SDBS. The restraining ability of SDBS was enhanced markedly with decreasing CMC caused by mixed salt. The positive relation was found between the enhancement effect and concentration of salt. The influence of salts on diminishing the CMC of SDBS was different and it was positive correlation to the charge size ratio of cation. Based on no correlation between the lessened effect on surfactant CMC and the restraining ability enhancement of surfactant by anion of salt, the size and amount of micelle were both considered to be important influencing factors on the evaporation of VOCs.The influence of surfactant on the distribution between sediment and water phase of soluble polar organic compounds was investigated. Aniline and p-nitrophenol were adsorbed on sediment mainly through adsorption, but that of phenol was mainly through partition. The results showed that based on the occurring of SDBS, the Koc*foc*on sediment was increased and the sorption capacities of aniline and p-nitrophenol on sediment was largened in the concentration range set in the experiment. The increscent multiple of distribution function on the sediment was positive correlation to KOW of organic compounds. The sorption of phenol was enhanced by surfactants below their CMCs, but diminished above their CMCs. The matrix sorption capacity appeared at the surfactant concentration set for 0.3CMC. No visible difference was observed among the restraining phenomena affected by surfactants.