The Sorption Behaviors Of Chlorpyrifos Onto Sediments

The sorption mechanism of pesticides onto sediments is reviewed. This part set forth the physical chemical property of sediments, the property of pesticides, temperature on sorption of pesticides onto sediments. The mathematics model of sorption is also described.The sorption behaviors of chlorpyrifos to sediments are studied. Results show that the sorption isotherms of chlorpyrifos on sediments is nonlinear at lower equilibrium concentrations, but linear at moderate to high concentrations. The sorption of chlorpyrifos to sediments is dominated by adsorption at low concentrations and by partition at high concentrations. The sorption of chlorpyrifos to sediments is mainly controlled by the organic contents of sediments.The effects of coexisted organic compounds on sorption behavior of chlorpyrifos to sediments from water are studied. Results show that the competitive sorption of phenol and pyrene against chlorpyrifos to sediments is presented and phenol is more powerful competitors than pyrene. With the concentration of phenol increasing, the sorption isotherms of chlorpyrifos to sediments tend towards linear. When the concentration of phenol is 50 mg/L, the sorption isotherms of chlorpyrifos to sediments is completely linear, which shows that the adsorption of chlorpyrifos to sediments is competed by phenol.The effects of anion and nonionic surfactants on sorption of chlorpyrifos to sediments are investigated. Results show that the sodium dodecyl sulphate (SDS), an anion surfactant, reduces the sorption of chlorpyrifos to sediments, while the Triton X-100, an nonionic surfactant, enhances sorption when their concentrations are lower than the critical micelle concentration in water.