Application Of Solvent/surfactant Mixture System In Oily Sludge Washing

With the acceleration of industrialization and improvement of the quality of people’s life,the consumption and demand of crude oil and other energy resources continue to increase.Meanwhile,a large amount of oily sludge are being produced in the process of crude oil exploitation,storage,transportation and refining.Oily sludge is not only a kind of dangerous solid waste,but also a kind of valuable resource.If the oil phase can be recovered,it is of great significance to protect the environment and alleviate energy shortage.There are many treatment methods for resource utilization of oily sludge,such as solvent extraction,surfactant-enhanced washing,sludge pyrolysis,ultrasound treatment,etc.Each method has its own advantages and disadvantages.A single treatment method may not obtain the desired results because of the complex composition and extensive sources of oily sludge.Therefore,two or more treatment methods need to be combined.According to the principal of "like dissolves like",solvent extraction can recover most of the crude oil from oily sludge.At the same time,the usage of a large amount of organic solvents was facing the important problem.Surfactant-enhanced washing method has certain industrial application due to these advantages of simple operation,low requirements for devices.Ideal washing results and reasonable cost have obtained for oily sludge with low oil content.However,washing results might be unsatisfactory for oily sludge with high oil content and viscosity.In this study,based on surfactant-enhanced washing and solvent extraction,we learned the process of bitumen extraction from oil sands and prepared solvent/surfactant system to wash oily sludge.In addition,microemulsion has high solubilization capacity and ultra-low interfacial tension.Therefore,the preparation of microemlsion select organic solvent or mineral oil as oil phase to achieve high efficient oily sludge washing.Two aspects included in the dissertation are as follows:1.Solvent/surfactant washing detergents were prepared by mixing sodium ethoxylated alkyl sulfate(AES),D-OA,aqueous phase and organic solvent(e.g.toluene).The two surfactants showed high interfacial activity when the mass ratio was 1:1.According to the washing results of simulated oily sludge,the concentration of each component in the washing detergent was determined.Moreover,the effects of type of organic solvent and washing parameters,such as temperature,time and ionic strength on the washing effect were studied.Through the evaluation and comparison of SEM/EDX,water contact angle and other characterization technologies,it demonstrated that the vast majority of crude oil had been removed from solid phase.Meanwhile,ideal washing results were obtained for actual oily sludge.2.The emulsifier DAEC was prepared based on the preparation principle of D-OA.Single phase microemulsion was prepared by DAEC,Brij-30 and n-butanol.The conductivity of microemulsion showed the transition from W/O to bicontinuous and O/W.The pseudo-ternary phase diagrams were studied and obtained good results for solubilization of different oil phases.The effects of mass ratio of surfactants and salt concentration on solubilization capacity were discussed.Oily sludge had low residual oil ratio after washing by using the microemulsion.