Investigation Of Removing Efficiency Of Pesticides From Soils By Using3Kinds Of Biosurfactants

Soil is an important part of the human environment, is an essential, non-renewable natural resources, but also the survival of all living creatures, an important foundation for the growth of crops.According to research, after the pesticide application, only10%to20%dependent onthe plant, and more than50%to60%remains in the soil, it is likely to cause soil contaminated by pesticides. HCHs, DDTs and seven chlorine are the earliest large-scale use Organic chlorine pesticides in China, because of strong toxicity and not easy to be degraded,its been listed by the Stockholm Convention on persistent organic pollutants in1995. Although being banned the production and use, its remain high residues in soil because ofnature stable. Acetochlor is one of herbicides which uesd a lot in current, and used morethan30years in China. Cypermethrin is a high poisoning in widely used pyrethroid pesticides, these are long existed in soil due to the difficult degradation.In this paper, HCHs(α-666,β-666,γ-666,δ-666), DDTs(p,p’-DDE, p.p’-DDD, o.p’-DDT, p.p’-DDT), heptachlor, acetochlor and cypermethrin, represented as an object to simulate the contaminated soil.Three kinds of biosurfactants (APG0810, APG1214and saponin) was studiedto repair the effects of pesticide contaminated soil, including:(1) The effect of two kinds of alkyl glucosides solution (APG0810and APG1214) of different concentrations, ultrasonic time and solution dosage to the removal of contaminated soil sites.(2) The effect of saponin solution of different concentrations, ultrasonic timeand solution dosage to the removal of pesticides in soil contaminated sites.(3) The effects of different concentrations of APG0810and saponin mixedsolution to the removal of pesticide residues in soil (4) APG0810and saponin mixed solution applied research for the higher concentration of pesticide contaminated soil.The results are as follows:(1) Respective38.94%~77.76%and25.52%~57.53%of thepesticides were removed when using20mL20g/L APG0810and10mL5g/L APG1214wit h ultrasonication30min (2)21.79%~91.63%of the pesticides were removed when using20mL20g/L saponin with ultrasonication30min.(3)The mixture of AGP0810and saponin had better removing efficiency of40.31%~98.62%than using any single surfactant.(4) The compound of APG0810and saponinalso have a good ability to remove effect on high pesticide contamination soil.Analysis of experimental results, some main conclusions are obtained as follows:(1)Three kinds of surfactants have a good removalinpesticides soil, and remove effect have relationship with the nature of the pesticide, the nature of the surfactant, the stability of pesticides and surfactants micelle and other factors related to external conditions.(2) The removal of pesticides and their octanol-water partition coefficient (lgKow) has the basic negative correlation, the greater lgKow, the more difficult dissociate from soil particles. The pesticide with a higher value of a high lgKowhas a high solubilization ratio, the surfactant helps to improve the ability of a hydrophobic pesticide dissolved in water.(3) Different surfactant concentration required to achieve maximum removal rate is positively correlated with the CMC value, APG1214<saponin <APG0810. Because with the lower CMC vaule,thesurfactant begins to produce micellar solubilizationat low concentrations.(4) Pesticides and micelles have better stability will help the removal.(5) The effect of ultrasound has a strengthening effect on the removal, ultrasonic time influence to removal is increased and then decreased with time after the rise again. Ultrasound30min can reach the maximum removal efficiency. Ultrasound removal large surfactant enhanced better.(6) With the amountof the surfactant increase, the pesticide removal increases. But after more than a certainamount, then the amount has no more effect on the removal rate. Micellar solution has the greatest solubilization pesticides, too much solution will lower ultrasonic acoustic energy density.(7) Mixed surfactant has bettersolubilization effect than a single surfactant because the surfactant complex synergistic effect solubilization, lower CMC vaule and less soiladsorption. While the high pesticide contaminated soil removal also have some effect.The experimental results provide some reference value in the future eluting restorationproject for the actual pesticide contaminated land.