Effect Of Surfactant On Sorption Of Organic Pesticides In Soil/Sediments

The method of KI-I2 spectrophotometry used in determining nonionic surfactants had been performed, by which the sorption behaviors to soil/sediments of nonionic surfactants were investigated. Based on interference experiment, the influence and mechanism of the surfactants on the transport of organic pesticide pollutants in the interface of soil/ sediment -water were studied. The mainly results were summarized as follows:The wavelength for determination of nonionic surfactants 500 run and the reactive time with KI-I2 developer was 120 min respectively; The work curves of Brij35 Brij30 TritonX-100 and Tween-80 were highly linear (correlation coefficient was at the range from 0.9971 to 0.9995) and their linear ranges were 0.2²5 mg/l 0.4²5 mg/l 1.5⁵0 mg/1 and 0.5⁵0 mg/1, respectively; Furthermore, the spectrophotometric method was stable for acid condition and free from interference by most of metal ions, anion or cationic surfactants and soil extractions. Al³⁺ and Fe³⁺ tend to hydrolysis and seriously interfere with determination of nonionic surfactants. However, such a interference could be eliminated by adjusting solution to acidic environment. The determination method was successfully applied to the determination of sorption isotherms of four nonionic surfactants on soil/sediments tested.The Langmuir model was appropriate for describing the sorption isotherms of Brij35, Tween-80 and TritonX-100 in four soil/ sediments, but sorption isotherms of Brij30 were agree to S model, and the sorption isotherms exhibited a saturate sorption in soil/sediments at Brij35, Tween-80, TritonX-100 and Brij30 equilibrium concentrations about 110 mg/1, 55 mg/l, 200 mg/1 and 25mg/l, respectively. Except for Sediment 2, the saturate sorption amounts of four nonionic surfactants in four soil/sediments were in the order of Brij30> Tween-80 > TritonX-100> Brij35. These nonionic surfactants sorption behaviors could be explained by 5-sorption phase sorption model.The parathion-methyl sorption to soil/sediments involved primarily a partition into...