The Effect Of Surfactant On Soil Capillary Water Rise Characteristics

Surfactants are widely used in soil in-situ of and soil remediation.Although this method has many advantages,but with the use of a large number of surfactants is bound to cause secondary pollution of the soil and even change some of the original nature of the soil.In addition,the long-term use of surfactants can also result in increased of surfactants'concentrations surfactant-water system.Surfactants are a class of"amphiphilic"substances that can directly affect the surface tension of the soil solution and thus affect the capillary water rise height of the soil.Which is an important parameter in the environmental remediation design project.In the one hand,capillary water rise can provide water for the plants,on the other hand,it will lead to soil salinization.In order to further understand the effect of surfactants on the characteristics of capillary water rise,three surfactants which commonly used in soil remediation were selected:sodium dodecylsulfate,Tween 40,and Tween 80,and the rise of capillary water by the standpipe method.Experiments were carried out to study the effects of the above three surfactants on capillary water rise height,capillary water rise velocity,and soil water distribution.At the same time,a new theoretical method for the improvement of saline soil based on surfactants can reduce the rise of soil capillary water.The specific conclusions are as follows:?1?The rise of capillary water in soil is affected by the surfactant.With the increase of the concentration of surfactants the height of capillary water decreases gradually,showing the concentration dependence.?2?The capillary water rise height?H?and time?t?show a power function.The relationship of SDS,TW40,and TW80 solutions capillary water rise height satisfy the equation:H=mtⁿ.The relationship between capillary water rise height and time in SDS at 0CMC,1CMC,2CMC is:H_SDS=13.53t^0.1962,H_SDS=10.83t^0.2219,H_SDS=8.758t^0.2297;The relationship between capillary water rise height and time in TW40 at 0.33CMC,1CMC,1.67CMC is:H_TW40=11.74t^0.4050,H_TW40=10.69t^0.2993,H_TW40=10.02t^0.2076;The relationship between capillary water rise height and time in TW80 at 0.33CMC,1CMC,1.67CMC isH_TW80=11.20t^0.2020,H_TW80=10.40t^0.1906,H_TW80=9.316t^0.2163.?3?The speed of capillary water rise can be obtained by formula of the relationship between the height of capillary water rise and time and the increase rate of capillary water decreases with the increase of surface active concentration.The water content of the soil decreases with increasing surfactant concentration.?4?SDS can reduce the capillary water rise height of sodium chloride solution,So SDS can be applied to saline-alkali soil reclamation.the application of an amount of 10g?kg^-1is appropriate.