Transport,Transformation Of NZVI In Soil And Its Effect On Seeding Development Of Peanut

Nanoscale zero valent iron(NZVI) is zero valent iron particle material at least twodimensional scale of 1-100 nm. Because NZVI has an efficient reduction property, it is used widely in soil and groundwater contamination as one of the new kinds of treatment agents. So, more and more NZVI was exposed into the soil environment, however, the existential state or form transformation, breakthrough regularity in soil and it is unclear of the migration mechanism of NZVI with soil colloids together.In addition, the effect of NZVI on germination or development of plant was still undisclosed. Based on the above issues, the brekthrough, adsorption and transformation of NZVI in the soil were investigated, and the effect of NZVI on peanut seed germination and plant development was also studied in this dissertation. Results were supposed to provide technical support and theoretical guide for the impacting of NZVI on the ecological environment. The maily research results were as follows:1. The NZVI was prepaired by use the liquid phase reduction method, and the NZVI was also characterized by through transmission electron microscopy( TEM), X-ray diffraction(XRD) and X-ray photoelectron spectrometry(XPS), the results were that the iron particles size is about 20-80 nm, and the valence is zero-valence, are in accordance with the requirements of targets NZVI.2. The soil column leaching experiment was used to research the breakthrough of NZVI in quartz sand, sandy soil and diatomaceous packed colum, and the effects of different soil colloid on the transport of NZVI in soil packed column was also investigated. Under the same conditions of leaching medium, the treatment with NZVI added with polyvinylpyrrolidone(PVP) was collected higher concentration of iron than those of cetyl trimethyl ammonium bromide(CTAB) and sodium dodecyl sulfate(SDS) treatments; In addition, diatomite packed column adsorbed or blocked more NZVI than that of quartz sand packed column; Under the same conditions of dispersant and leaching medium, the downward speed of soil colloids cooperation with NZVI was higher than that of without soil colloids.3. In the adsorption experiments, the brown soil, fluvo-aquic soil and Lime concretion black soil was selected as the adsorbent to research the adsorption isotherm, absorption kinetic curve and desorption kinetics of NZVI. The Langmuir model can be fitted well to simulate isothermal adsorption experiment. The Lime concretion black soils have the highest adsorption quantity of NZVI than other soils. The NZVI adsorption equilibrium time in Lime concretion black soil, brown soil and fluvo-aquic soil was 8, 24 and 24 hours, respectively, and these results can be simulated by use first order dynamic equation. The results will be used to provide preliminary theoretical support for further studing the mechanism of adsorption and desorption.4. Under constant temperature incubation conditions, the crystal structure and morphology of the valence and transformation of NZVI in brown soil, fluvo-aquic soil and Lime concretion black soil was studied by use X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). With the increasing of incubation time, the sizes of NZVI are all increased in all the three kinds of soils. However, the morphology of NZVI in Lime concretion black soil has changed into the irregular form. The oxidation rate of NZVI was the fastest in fluvo-aquic soils than that of other soils, and the valence state of NZVI was completely into ferric iron after 24 hours incubation, and the slowest was found in the Lime concretion black soil.5. It was also revealed that the low concentrations of NZVI(10-160μmol/L) can promote the peanut seed germination and seedling development, however, the seed germination and seedling growth was inhibited under the high concentration of NZVI(320 μmol / L).