Dissertation
Dissertation > Environmental science, safety science > Environmental pollution and its prevention > Agricultural chemicals,toxic chemicals, pollution and its prevention

Study on Bensulfuron-methyl Adsorption on Soils, Fe & Al Oxides

Author LiuYongHong
Tutor DongYuanYan
School Huazhong Agricultural University
Course Pesticides
Keywords Variable Charge Soil Fe and Al Oxide Bensulfuron-methyl Adsorption Kinetics
CLC X592
Type Master's thesis
Year 2005
Downloads 172
Quotes 2
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With the wild use of sulfonylurea herbicides, the scientists paid more attention to their environmental behaviors gradually. An adsorption study on bensulfuron-methyl (BSM) on three synthsized metal oxides and two variable charge soils, and the effects of pH, metal ion Zn2+ on tested samples, have been carried out. The characteristics of adsorption kinetics have been investigated using the static, stirred and vortex batch techniques for GZ-soil (Guangzhou Soil), HN-soil (Hunan Soil) and Al oxide. At the same time, the morphologys and characteristics of the oxides and the surface adsorbed BSM were characterized with the techniques of FT-IR, XRD, TG At the same time, the BSM was analyzed with HPLC. The results showed:The forms of isotherms of BSM adsorption by soils and oxides were two types: One was that the magnitude of BSM adsorption increased rapidly as the concentration of BSM increased, the other was that the magnitude of BSM adsorption increased slowly with the increase concentration of BSM, and at last their equilibriums were reached. The data of the BSM adsorption by soils and oxides were discribed with the Langmuir Freundlich terkim equations. Compared with these equations, the Freundlich isotherm equation was the optional one. The other models in point were Langmuir terkim equations. The magnitude of BSM adsorption is as follows: hematite<GZ-soil<goethite<HN-soil<Al oxide.Within the range of BSM concentrations, the magnitude of BSM adsorption on the tested samples descreased with increase in pH of the solution; and the magnitude of BSM adsorption increased with increase in concentration of BSM. When different concentrations of Zn2+ were added into the tested samples, the effect of the Zn2+ was different. The amount of BSM adsorption on soil decreased comparing with that of without Zn2+. However, the magnitude of BSM adsorption on oxides increased largely. The tendencys of increase or decrease were different because of their characteristics and composition.The zero-order equation, first-order equation, parbolic diffusion equation,double-parameter equation quation, Elovich equation were typed for discribing the static, stirred and vortex batch techniques kinetics of BSM adsorption on three tested samples. The results showed that the adsorption data could be satisfactorily described with the first-order equation. For Al oxide, the amount of BSM adsorption descreased, and the soils increased with the raising of temperature, respectively. Compared with these equations, first-order equation was the optional one. The other equations in point were zero-order equation, parbolic diffusion equation, double parameter equation quation, Elovich equation.According to the kinetic plot for the adsorption of BSM on tested samples, it can be seen that the amount of BSM adsorbed increased with in temperature of the system on tested soils samples. On Al oxide, however, the tendency was opposite.Kinetics of BSM adsorption was investigated on Al oxide and two soils using the static, stirred and vortex batch techniques. Observed rate coefficients obtained from static, stirred and vortex batch systems were combined and used to calculate rate coefficients for film diffusion (Jcp), intraparticle diffusion (kp), and reaction kinetics (Icr) in a static system. This study elucidates that, in low temperature (28 °C), in GZ-soil and HN-soil, film diffusion was rate-determinding step. In Al oxide, High temperature (38’C), reaction kinetics was the rate-limiting step.The study on bensulfuron-methyl could offer scientific basis for how to effectively use the pesticide and reduce the pollution. At the same time, it would assess their mobility, transformation, and would take effective and scientific measures to monitor and manage the contamination, to repair the soil environment

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