Selection Of Contaminated Soil Cleaning Agents And Desorption Of Petroleum Hydrocarbon

Chemical washing is one of the important methods for petroleum hydrocarbon contaminated soil remediation in oilfield.It is significant to select suitable surfactants matching with the structure and composition of oil pollutants during chemical washing process.Based on the oil composition in different oil contaminated soil,the appropriate surfactant and compatible additives are choosed to improve the efficiency of washing contaminated soil.The experimental method of combining artificial simulation and actual polluted soil was used to select high-efficiency washing agent.The washing process and the elution effect of different components of petroleum hydrocarbon in soil were investigated according to the characteristics of oil polluted soil in Liaohe Oilfield.The kinetics of desorption of petroleum pollutants by surfactants was studied.The oil pollutants in soil were prepared by simulated desorption,which provided technological parameters and scientific basis for soil washing and remediation.The main conclusions are as follows:?1?Nine kinds of surfactants were used to wash the oil contaminated soil to screen high efficiency chemicals and optimize the elution parameters.The mixed washing of anionic and nonionic surfactants was carried out to investigate the washing effect.The results show that SDBS,SYO-1,TX-100 and AEO are beneficial to the elution of petroleum.The washing effect can be improved by increasing the surfactant concentration,washing temperature,time and vibration strength.Under the best washing process?temperature 65?,time 60 min,strength 500 R/min?,the order of washing ability of the four surfactants is TX-100?0.25wt%?>SYO-1?0.25 wt%?>AEO?0.75 wt%?>SDBS?0.25 wt%?.SDBS and AEO have synergistic solubilization ability,and the elution rate reaches 81.69%.It has improved about13.6%,8%than the desortion efficiency when SDBS and AEO were used independently.?2?Under the best washing condition of surfactant,the actual greasy soil was washed by adding Na₂CO₃,Na₂Si O₃and Na OH.And the principle of increasing efficiency was analyzed by measuring the surface tension of additive solution.The removal efficiency of different components of petroleum was investigated by analyzing the elution rate of different components of petroleum.The results showed that the addition of additives is beneficial to the solubilization of surfactants to petroleum,and Na₂Si O₃is the best one.When it was combined with SDBS,the mixed agents achieved the most prominent solubilization effect,with the elution rate increased by 21.52%.Adding additives can reduce the surface tension of anionic surfactant solution system and improve the solubilization ability of surfactants.The change of the surface tension of the nonionic surfactant solution system is very small,even the surface tension becomes larger after adding the auxiliary agent,mainly because the"salt solution"effect increases the micelle elution rate.?3?The first-order kinetic equation,double constant equation,parabola diffusion equation and elovich equation were used to fit the kinetic curve of surfactant desorption of petroleum pollutants.The fitting degree from high to low was elovich equation>double constant path>parabola equation>first-order dynamic equation.Elovich equation and parabola equation can reach a very significant level,among which the fitting degree of elovich equation is the highest,and the correlation coefficient is 0.9860?0.9962,which shows that the main control step of surfactant desorption of oil in soil is the rapid and slow heterogeneous particle diffusion.