Adsorption Of Bensulfuron-methyl On Several Clay Minerals, Oxides And Soils In Middle-south Area Of China

A study of adsorption processes and mechanisms of a relatively new sulfonyluera herbicide, bensulfuron-methyl on 4 oxides (goethite, ferrihydrite, amorphous alumina ,birnessite), 3 clay minerals (kaolinite, montorillonite HM, montorillonite BM ) and 5 soils (Hainan latosol, Chenxian red earth, Heshengqiao brown red earth, Xiaogan yellow Brown earth, Zaoyang tan earth) in middle-south area of China has been carried out through a batch of equilibrium methods , FT-IR and X diffraction.1. The chlorsulfuron and bensulfuron-methyl were purified from industrial product as standard samples and were indentified and titrated. The content of chlorsulfuron and bensulfuron-methyl of purified samples, which can be used as the standard sample of commodity inspection and the analysis of residue, are almost the same as that of standard samples.2. The adsorption of bensulfuron-methyl by each soils can be described though Langmuir 's equation, relatively only a few of these adsorptions fit Fruendlich 's equation . pH5.0,the The maximum absorbing capacities ( g g-1) were according to : Hainan latosol (18.68) > Chenxian red earth (15.00) > Heshengqiao brown red earth (13.69) > Xiaogan yellow Brown earth (13.11) > Zaoyang tan earth (12.76).3. Multivariate linear regression analysis of the adsorptions of bensulfuron-methyl by each soils shows that were interrelated to the physical and chemical characteristics of the soils. The pH of the systems shows evidently negative correlation, the content of organic matter, the content of oxides of iron and alumina, the content of clay and the point of zero charge show significant positive correlation.4. The adsorption of bensulfuron-methyl by each oxides and clay minerals can be described though Langmuir's equation ( H type or L type ). The maximum absorbing capacities ( g g-1 ) were that Bentonite BM (184.3)>Bentonite HM (167.4)>amorphous alumina (44.65)> goethite (39.85) > ferrihydrite (31.32)> kaolinite (19.49)> birnessite (10.67). Otherwise, only a few of these adsorptions fit Fruendlich 's equation .5. The adsorption of bensulfuron-methyl by each oxides and clay minerals was controlled by the pH of each system. The adsorption percentage was independent of the amount of bensulfuron-methyl added, and markedly decreased with the increasing pH.6. The effects of F-1 ,C1-1 to each adsorption were also examined. The results indicated that the absorbing capacities were decrease by the concentrations of F-1 and CI-1 increase, especially in amorphous alumina and goethite systems.7. A FT-IR study on bensulfuron-methyl adsorption by goethite has been carried out. The results showed that: The adsorption was occurred through the carbonyl group, sulfonyl group of bensulfuron-methyl with the hydrate hydroxyl groups (-OH2+) on the surface of the oxides of iron and alumina, and a possible mechanism was that the adsorption was conducted by means of charge-dipole interaction though hydrogen bond.8. The strong adsorption of bensulfuron-methyl by the bentonite (main component is montmorillonite) has been analysis by x-ray diffraction. The results showed that bensulfuron-methyl can go into the interlayer of the montmorillonite and bond with the exchangeable cation through hydrogen bond.