Study Of Interactive Mechanism Of Humic Acid And Surfaetant And Their Combined Effects On Remediationof PAHs Contaminatcd Soil

With the increasing demand for crude and refined oil products, a number of Polycyclic Aromatic Hydrocarbons (PAHs) were generated during the processes of exploitation, refining, fuel combustion and transportation. PAHs are hydrophobic organic compounds which are ubiquitous in soil environment and are difficult to be removed using traditional remediation method. Surfactant enhanced remediation (SER) of PAHs is a promising scheme for PAH contaminated soil and groundwater through enhancing the solubility of PAHs, thus regulating their sorption/desorption behavior.In this study, two new surfactants and one traditional surfactant were investigated. They are Cationic Gemini Surfactant (CG12-3-12), biosurfactants Rhamnolipid, and the traditiona non-ionic surfactant (TX-100), respectively. The effects of individual surfacant and their mixture on the solubilization of PAHs were detailed discussed through comparing the critical micelle concentration (CMC), the molar solubilization ratio (MSR) and the standard free energy△GS0of solubilization. The effects of three surfactant on soluliblization followed the order of:CG12-3-12> Rhamnolipid> TX-100. Besides, When compared TX-100/CG12-3-12and TX-100/Rhamnolipid with the individual ones, it can be observed that there is a better solubilization ability in mixed surfactant system, which exhibited a synergistic effect. The TX-100/Rhamnolipid mixed system showed better synergistic solubilization capacity than TX-100/CG12-3-12mixed system.The adsorption behavior of three types of surfactants on three different kinds of soils (North soil samples, South soil samples and the Attapulgite) were studied. Sorption of all surfactants in both soils and attapulgite were fit well with the two-stage sorption model. The maximum adsorption capacity of two ionic surfactants were in the order of attapulgite> South soil> North soil. Using langmuir adsorption model to fit the adsorption data, it was found that the adsorption of TX-100, CG12-3-12and rhamnolipid on attapulgite and two soils samples can fit the Langmuir adsorption model better.Meanwhile, in order to explore a natural surface active substance which both environmental friendly and cost-effective, this topic try to use humic acid extracted from compost to remedy PAHs contaminated soil. Investing the desorption efficiency of PHE on different soils by HA, Gemini surfactant and their mixture. and comparing their adsorption behavior on the soils. Humic acid extracted from the compost had a good surface activity, the critical micelle concentration is350mg/L. The adsorption behavior on soils of compost HA and Gemini surfactant had a strong interaction. The adsorption quantity of both CG12-3-12and HA was significantly increased after CG12-3-12mixed with HA. There was a better desorption efficiency of PHE for single CG12-3-12and HA on both two soils. And the north soil has a better desorption efficiency of PHE by the mixed system than south soil obviously. There was a decreased desorption efficiency of PHE when CG12-3-12mixing HA with high concentraction. When the concentration of CG12-3-12in mixed system was3770mg/L, the mixed micelles of CG12-3-12and HA had the best desorption efficiency.