Cu And Zn Adsorption Onto Clay And Clay Minerals In The Surficial Sediments

The content of sediments is weathering mineral with rock and soil fine particles, which suspended in the form of surface water runoff into rivers, lakes or the ocean and set in the underwater environment in the form of deposition conditions, the clay minerals is the most important natural colloidal sediments. Water migration of metals into solid material has great significance. Fe/Mn oxides, organic matter and clay minerals affect the absorption of heavy metal or organic, also heavy metals in the Fe/Mn oxides and organic matter content of clay minerals under the influence of clay because of its uniqueness. Clay, with broad surface area, high ion exchange capacity (for 120-150meq/100g vermiculite), size (﹤2μm), and the largest proportion in sediments makes it easy for adsorption of heavy metals and organic pollutants in aquatic environments. Because of the small size, clay may bring pollutants return to the water and form secondary pollutants.Many research shows that in sediments, the clay minerals, Fe/Mn/Al oxides and organic matter have adsorption ability, but they didn't compare the different of adsorption contribution. Documents that have also played a major role in the solid phase material is strong adsorption capacity of Fe/Mn oxides and organic matter, but they didn't consider that the clay minerals as organic matter and Fe/Mn oxides substrate material in the solid phase can adsorb heavy metals. To the discussion group with the previous study, and learn more about the migration and transformation of heavy metals in the water. Object-oriented discussion group selected this study has been conducted extensive research in the Songhua River (the section of Jilin City). Clay minerals and clay were extracted from surface sediments, and then inspecting the adsorption ability of clay, clay and surface sediments, and clay minerals and residues.Clay and surface sediments adsorb Cu and Zn, then compare the adsorption characteristics, Using the method of laboratory simulation adsorption-statistical analysis discuss heavy metal adsorption characteristics of the components of clay (organic, Fe/Mn oxides, Clay minerals); extraction of natural clay minerals in the surface sediments. Selective extract Fe/Mn oxides and organic matter in surface sediments and analysis of the solid phase material, then Using the method of laboratory simulation adsorption-statistical analysis discuss the major chemical components of solid-phase--iron oxide, manganese oxide, organic matter and clay minerals adsorb heavy metal, then compared the different of absorption capacity. Solid-phase adsorption characteristics are considered an important influence of heavy metals in the water. The results show that:(1) Organic matter removal can be achieved 70%, Fe/Mn oxides removal rate of 98% and 91% respectively, reached the separation results. Stokes rule is used of extracting clay minerals from surface sediment, and using the XRD method identify the composition of clay minerals, which was found to contain illite, Montmorillonite/illite mixed-layer and kaolinite, the residue mainly contain quartz and feldspar.(2) Cu and Zn in the clay minerals were well satisfied Langmuir adsorption isotherm (r = for 0.959 and 0.996). The adsorption two heavy metal capacity of the clay minerals is Cu>Zn. This can be interpreted two different metals hydrolysis constants, in the same pH conditions the greater the hydrolysis constants, the more vulnerable to hydrolysis and the metal-hydroxyl ions greater proportion, and clay minerals with a permanent negative charge, heavy metal cation adsorption through electrostatic adsorption, So metal-hydroxyl ion adsorption onto clay minerals stronger than metal ions. Meanwhile, Cu and Zn adsorbed on clay minerals larger than residue in the adsorption capacity, clay mineral particles as small, porosity, larger surface area, it has a special and complex layer structure, and it is a decision adsorption, ion-exchange and other special nature of the distensibility, as a result, clay minerals have stronger adsorption ability. The higher pH and the metal concentrations decreased more. In other words, and reached equilibrium reaction system in the pH value is reduced also high concentrations of heavy metals in the same context reaction pH values change more.(3) Components in the surface sediments adsorb Cu ability order: Manganese oxide > organic > residue > iron oxide > clay minerals; Components in the surface sediments adsorb Zn ability order: residue > iron oxide > clay minerals > organic > manganese oxide.(4) Cu and Zn adsorption on clay component were satisfied the Langmuir adsorption isotherm, Cu and Zn adsorption on clay stronger than Cu and Zn adsorption on surface sediments, Cu adsorption on the surface sediments and clay are stronger than Zn adsorption on the surface sediments and clay.(5) The order of Cu adsorption on clay is: clay minerals > organic > Fe/Mn oxides. The order of Zn adsorption on clay is: clay minerals > organic > Fe/Mn oxides. Cu and Zn adsorptions on the clay were satisfied the Langmuir adsorption isotherm. In the clay components, the adsorption capacity is Cu >Zn.(6) Cu and Zn adsorption on the clay component smaller than adsorption on the surface sediments.