Sorption Mechanisms Of Diuron And Phenanthrene Onto Soils And Carbon Adsorbent And Study Of Their Bioavailability

The migration and ultimate destination of organochlorine pesticides and polycyclic aromatic organic compounds in the environment system strongly depends on the adsorption and desorption effects by natural particles.In this paper,I put diuron and phenanthrene as the research object and tried to research the sorption mechanisms of diuron and phenanthrene onto soils and carbon adsorbent. And pot experiment was designed, which was used to study the bioavailability of diuron and phenanthrene. The results demonstrated that:(1)The adsorption isotherms of diuron and phenanthrene in four adsorbents of Nansha river sediment, Inner Mongolia soil, Donghai plantash and Shishou plantash were researched:The datas were fitted to the Freundlich,the Langmuir and the Polanyi-Mane models. The best fitting adsorption model is the Freundlich. When the temperature changeing, the adsorption behavior of four adsorbents were affected. The physical and chemical property and surface character of absorbents had significance influence. The pore structure and the specific surface area are the important factors on adsorption, in addition, carbon content, particle structure, functional groups, would also affect the adsorption process.(2)The adsorption kinetics of diuron and phenanthrene in Nansha river sediment, Inner Mongolia soil, Donghai plantash and Shishou plantash were researched. The datas were fitted to the pseudo second order kinetics equation, diffusion within spherical particles model and Elovich equation.The best fitting adsorption kinetic is the pseudo second order kinetics equation. Adsorption kinetics curves showed that the adsorption process was divided into two phases:rapid adsorption and slow adsorption.the adsorption equilibrium for diuron can reach in 20 hours, phenanthrene in 34h.(3)Biomass ashes were added in Nansha river sediment and Inner Mongolia soil, studying their adsorption capacity. The study founds:after adding the biomass ashes, the maximum adsorption capacity qmax and KF were greater than the Nansha river sediment and Inner Mongolia soil alone. This show that adding biomass ash can enhance the adsorption capacity, which provides a theoretical basis for the pot experiment feasibility.(4)The study of corn and ryegrass growth in pot experiment found:Diuron in soil have a great impact on plant growth. Phenanthrene in soil will cause a certain impact for corn and ryegrass growth, but lower than diuron. After adding the biomass ash in contaminated soil, plant growth situation got improved.promoting the plant growth rate and the germination rate, increasing biomass.(5) The bioavailability study of diuron and phenanthrene found:Detecting the concentrations of diuron and phenanthrene in soil and plant roots find that, after adding biomass ashes, the utilization rate of diuron and phenanthrene by corn and ryegrass decreases 10%-20%. Adsorption experiment found that biomass ashes have strong adsorption ability, which may be the important reason of reducing the bioavailability of diuron and phenanthrene.