Influence Of Surfactant On Single Sorption And Competitive Sorption Of Pesticides In Soil

Sorption of organic pollutants by soil/sediments plays an important role in their transport, fate and bioavailability in natural environment. Surfactants, in natural environment, affect the sorption behaviors (single sorption and competitive sorption) of organic pollutants onto soils/sediments, and they offers a potential way to protect soils/ground-water or to remediate the polluted soils/ groundwater. In this dissertation, the sorption behaviors and mechanisms of three pesticides and the effects of surfactants on the sorption were discussed in detail. The main original conclusions of this dissertation are:Equilibration technique was involved in this study. The pre-experiments indicated the time of equilibration sorption spent was 24 hours. In the single sorption experiment, sorption rates for three pesticides (chlorpyrifos, bifenthrin and fipronil) in clay and caly loam were higher than those in clay sand. The sorption rates of chlorpyrifos for clay, clay sand and clay loam were 93.01%, 83.81%, and 90.88%, repectively. Bifenthrin's were 97.77%,70.57%,93.22% and fipronil's were 93.01ï¼…,83.81%,90.88%. In addition, chlorpyrifos and bifenthrin have stronger soil sorption abilities than fipronil. Result analyzed by linear regression indicated that organic compound of soils plays important role on sorption of the three pesticides. Chlorpyrifos, Bifenthrin and Fiproni's sorption parameters changed little in competitive sorption though there was competitive sorption in the experiments.Surfactants, including tween-80, ABSCa and SDBS, had effects on sorption abilities of the three pesticides in this study. The different concentration of surfactants, which ranged from 0%CMC to 200%CMC, made all the three pesticides' sorption parameter fell at first below 100%CMC and then rose above 100%CMC.The study of surfactants' effects on competitive sorption reflected chlorpyrifos, bifenthrin and fipronil's sorption parameters fluctuated with addition of tween-80, ABSCa and SDBS. Surfactants raised chlorpyrifos's sorption ability with fipronil, but it was opposite with fipronil. Bifenthrin's sorption ability fell no matter of surfactants and competitive compounds. When come to fipronil, its sorption ability in clay sand rised with tween-80, on the other side, it fell sharply in clay and clay loam. ABSCa and SDBS's addtion resulted in rising of sorption ability in different types of soils.Solution of water (Sw), HLB and organic compound, affects three pesticides' sorption in soil remarkably, which was indicated by multi linear regression.