The Effect Of Low Concentration Surfactant On The Solubilization Of Alkanes And The Solubilization Of Dodecane In Silica Sand Media

A new round of evaluation results of groundwater resources and environment have reported that nearly 70%of our population drink groundwater.Therefore groundwater is an important,source of drinking water.However,with the development of society,a large number of chemical pollutants enter the soil and groundwater system through many ways.About 300 million people in our country are drinking unsafe water.In groundwater pollution,the main pollutants are organic pollutants,which are characterized by extensive and complex.The major components of hydrophobic organic pollutants(HOCs)are petroleum,organochlorine pesticides and polycyclic aromatic hydrocarbons(PAHs).They generally have low water solubility,strong chemical and biological reactions,inert,and have varying degrees of toxicity and pathogenicity.Therefore,the effective restoration of groundwater pollution is conducive to human survival,health and development.At present,the remediation methods for such pollutants are mainly physical remediation,chemical remediation and bioremediation.Compared with the other two kinds of remediation technologies,biotechnology costs are low,and they are widely used and are not easy to produce secondary pollution.Rhamnolipid has been used widely in groundwater bioremediation as an anionic biosurfactant.However,because of the high cost of production,the application of it is limited at some extent.In this paper,the effect of flow velocity on solubilization and migration process of dodecane are investigated with the low concentration of rhamnolipid as the surfactant,dodecane as the target pollutant,and the flow rate indirectly as the flow velocity.The flow rate is controled from 0.1ml/min to 1.0ml/min.Finally,the effects of flow velocity on the solubilization and migration of dodecane are analyzed.The result of this study indicated that with the increasing of flow rate the concentration of monorhamnolipid and dodecane in the effluent are enhanced.However,when the flow rate enhances from 0.3 mL/min to 1.0 mL/min,the increase rate of dodecane concentration in effluent is significantly low,which suggests that within the scope of a certain velocity,flow velocity of surfactant solution has a promising acceleration the solubilization of dodecane and migration of monorhamnolipid.In this paper,the effects of low concentration surfactants on alkanes solubilized aggregates are investigated with the monorhamnolipid,SDBS and Triton X-100 as surfactant,dodecane and hexadecane as the target pollutant.With the use of measuring technique,DLS and cryo-TEM,we investigate the shape and particle size of solubilized aggregates which are solubilized by the surfactants,monorhamnolipid,SDBS,Triton X-100.with a concentration below or above the CMC.This study also inspect the effect of the concentration and type of surfactant and the length of alkane chain on the shape and particle size of the solubilized aggregates.The results of this paper indicated that the particle size of the low concentration surfactant solubilized aggregates is greater than that of the high.And with the same low concentration monorhamnolipid,the particle size of solubilized aggregates of dodecane is greater than that of hexadecane.However,when the concentration of monorhamnolipid is high,the result is inverse.And The particle size of alkanes solubilized aggregates is closely related to the type of surfactant.