Study On The Stability Of CTMAB Modified Lou Soil

As the development of industry and agriculture, the soil pollution has become increasingly serious. Since adsorption capability for organic pollutants of soil is weak, the organic pollutants are easy downward with the soil water, which may cause groundwater pollution. However, it is significant to process the research on how to effectively prevent and control the migration of organic pollutants in soils. Through the use of cationic surface modifier on soil, the adsorption and block area will form, which can fix organic pollutants.The key of this technology is the stability of the organic modification of soil. In the natural environment, organic pollutants always flow with lower water seepage in the downward migration, through the establishment of the CTMAB organic modified soil block area, whether can occur the desorption of organic modifiers, and organic modifiers will reduce, decreasing the adsorption of organic modified soil pollution effect. Literature about this problem has scarecely been seen.This article is based on previous researches, selected Shaanxi Guanzhong area calcareous-Lou soil as the test soil sample, a cationic surfactant-cetyltrimethylammonium bromide(CTMAB) as organic modifier, phenol simulation as organic pollutants. The study of system about CTMAB adsorption properties on the soil surface, environmental factors on the influence of organic modified soil desorption CTMAB, and in the process of migration of different environmental conditions on organic modified soil stability. The purpose is to explore the stability of cationic surfactant on calcareous soil modified, and provide the theory basis for the organic modified soil to prevent soil or groundwater from being polluted by organic pollutants.The main study conclusions are as follows:1 The adsorption equilibrium time of CTMAB in Lou soil was 10 h, the adsorption isotherm was nearly in type L, and the Langmuir model was appropriate to fit the CTMAB adsorption isotherm. The adsorption of CTMAB in Lou soil affected by temperature is small; The influence of pH to the adsorption of CTMAB shows pH6≈pH8>pH7; With the increase of ionic strength, the adsorption quantity of Lou soil for CTMAB also increased significantly in the range of 0.01~0.1 mol·L-1. The adsorption mechanism of CTMAB in Lou soil was ion exchange and hydrophobic cooperation.2 The desorption isotherms of CTMAB on organic modified Lou soil was in L type. The adsorption quantity of CTMAB on Lou soil was much larger than the desorption quantity. The larger the modification ratio, the greater the desorption quantity of CTMAB desorption.When CaCl2 as desorption solution, the adsorption of high proportion modified soil to CTMAB showed a negative effects when the temperature rises, and there was little effect on low proportion modified soil. The influence of desorption quantity of pH showed pH7>pH6≈pH8; Ionic strength increases have inhibitory effect on CTMAB desorption.When phenol as the desorption solution, there was little effect on desorption of CTMAB of temperature; the effect of the adsorption of low proportion modified soil to CTMAB was little on pH, but shows inhibitive effect in partial acidic or alkaline conditions. The effect is not significant of change of the ionic strength of low proportion modified soil, but the desorption of CTMAB showed reduce of 100% modified soil with the increase of ionic strength. The impact on CTMAB desorption quantity of the concentration of phenol is less relatively.The same conditions, two kinds of solution of CTMAB desorption effect of CaCl2 solution is stronger than phenol solution, the relative desorption rate r(CaCl2) was greater than r(phenol).3 In the whole process of migration, the stability of the modified soil by low modification ratio was little, while the modified proportion(100%CEC) modified soil stability decreased slightly. The effect of pH on the stability of organic modified soil is relatively unstable for the modified soil under neutral condition, and the stability of modified soil can be improved by the acidic and alkaline conditions. Increase in ionic strength can significantly increase the stability of the organic modified soil; between 5~10 cm, with increasing the thickness of the modified soil, organic modified soil stability increases; with the increase of proportion of modified soil modified, organic modification of stability of soil small changes.The stability of CTMAB modified Lou soil is mainly affected by hydrophobic keys, through hydrophobic combine of CTMAB instability and desorption easy, ion exchange adsorption of CTMAB stability is relatively stable.