纳米零价铁在土壤中的迁移转化及其对花生幼苗生长的影响

发布时间：2018-05-24 17:46

本文选题：纳米零价铁 + 土壤胶体　；参考：《山东农业大学》2015年硕士论文

【摘要】：纳米零价铁(Nanoscale Zero-Valent Iron,简称NZVI)是至少两维尺度在1-100 nm的零价态铁颗粒状物质。由于NZVI具备高效的还原性能,其作为土壤及地下水污染物的新型处理剂,已得到广泛应用。但是,过量的NZVI进入到土壤环境中,其存在或转化的状态、迁移规律及其与土壤胶体协同迁移的机制还不清楚;另外,NZVI是否会对种子萌发、植物生长产生影响及其影响程度等问题存在争议。本试验基于上述问题,分别探究了NZVI在土壤中的迁移、吸附、形态转化及其对花生种子萌发及幼苗生长的影响,为今后研究NZVI在土壤环境中的迁移转化规律以及评价其对植物生长发育的影响提供初步的技术支撑和理论依据。主要结果如下:1、通过液相还原法制备了NZVI,利用透射电子显微镜(TEM)、X射线衍射仪(XRD)等手段对其进行了测试和表征,证实该铁粒粒径约在20-80nm范围之内,价态为零价,符合NZVI的有关试验要求。2、采用土柱淋溶试验探究了NZVI在石英砂、砂土及硅藻土三种淋溶介质中的迁移规律,同时还研究了不同分散剂及土壤胶体对NZVI在土柱中迁移规律的影响。结果表明,在相同的淋溶介质条件下,与添加十六烷基三甲基溴化铵(CTAB)和十二烷基硫酸钠(SDS)分散剂的处理相比,添加聚乙烯吡咯烷酮(PVP)分散剂的处理,其土柱中淋溶出了相对浓度较高的NZVI;另外,三种淋溶介质相比,硅藻土对NZVI的吸附量最大,淋出的NZVI相对较少,石英砂柱淋出的NZVI相对较多;在相同分散剂和淋溶介质的条件下,土壤胶体与NZVI协同向下迁移的速度和浓度均高于不加土壤胶体的试验处理。3、在吸附试验中,探究了三种土壤(棕壤、潮土、砂姜黑土)对NZVI的等温吸附曲线及吸附动力学曲线。其中,Langmuir模型能够很好的模拟等温吸附试验,砂姜黑土对NZVI的吸附量最大;砂姜黑土、棕壤和潮土对NZVI的吸附平衡时间分别为8小时、24小时和24小时,符合一级吸附动力学模型,为今后探究NZVI在土壤中的吸附解吸机制提供了初步的理论支撑。4、采用恒温培养法,结合X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)及透射电子显微镜(TEM)等仪器研究了NZVI在棕壤、潮土、砂姜黑土等三种不同土壤中的形态、价态及形貌转化规律。其中,在三种土壤中,随着培养时间的增加,NZVI的粒径均增大,此外在砂姜黑土中NZVI的形貌发生变化,由规则的球形转化为不规则的团聚形态。潮土中NZVI的氧化速率最快,24小时之后NZVI完全转化为三价铁态,在砂姜黑土中转化最慢。5、通过种子萌发及砂培试验,探明了NZVI在低浓度(10-160μmol/L)下对花生种子及幼苗生长起到促进作用,在高浓度(320μmol/L)时对种子萌发及幼苗生长出现抑制作用。
[Abstract]:Nanoscale Zero-Valent Iron-nanoscale (NZVI) is a zero-valence iron granular substance with at least two dimensional scales of 1-100 nm. Because of its high efficiency, NZVI has been widely used as a new treatment agent for soil and groundwater pollutants. However, the presence or transformation of excessive NZVI in soil environment, the migration law and the mechanism of co-migration with soil colloids are not clear. The influence of plant growth and its influence degree are controversial. Based on the above questions, the effects of NZVI on seed germination and seedling growth of peanut were studied. It provides a preliminary technical support and theoretical basis for studying the law of NZVI migration and transformation in soil environment and evaluating the effect of NZVI on plant growth and development in the future. The main results are as follows: 1. NZVI was prepared by liquid-phase reduction method and characterized by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the iron particle size is about within the range of 20-80nm and the valence state is zero. According to the test requirements of NZVI, the migration of NZVI in quartz sand, sand and diatomite was studied by means of soil column leaching test, and the effects of different dispersants and soil colloids on the migration of NZVI in soil column were also studied. The results showed that under the same leaching medium, the polyvinylpyrrolidone (PVP) dispersant was treated with polyvinylpyrrolidone (PVP) as compared with the treatment with cetyltrimethylammonium bromide (CTAB) and dodecyl sodium sulfate (SDS) dispersants. In addition, compared with the three kinds of leaching media, diatomite has the largest adsorption amount of NZVI, less NZVI leaching and more NZVI leaching from quartz sand column. Under the condition of the same dispersant and leaching medium, the velocity and concentration of soil colloid and NZVI migration down in cooperation were higher than that in the treatment without soil colloid. In the adsorption experiment, three kinds of soil (brown soil, aquic soil) were studied. NZVI isotherm adsorption curve and adsorption kinetics curve. The Langmuir model can simulate the isothermal adsorption test very well, and the adsorption capacity of NZVI on the black soil is the largest, and the equilibrium time of adsorption of NZVI on the black soil, brown soil and aquic soil is 8 hours to 24 hours and 24 hours respectively, which is in accordance with the first-order adsorption kinetic model. In order to explore the mechanism of adsorption and desorption of NZVI in soil, the mechanism of adsorption and desorption of NZVI in soil was studied by means of isothermal culture method, X-ray diffractometer, X-ray photoelectron spectrometer (XPS) and transmission electron microscope (TEM). Morphology, Valence and Morphology Transformation of three different soils in Shajiang Black soil. In the three soils, the particle size of NZVI increased with the increase of culture time, in addition, the morphology of NZVI changed from regular spherical to irregular agglomeration in shajiang black soil. The oxidation rate of NZVI in aquic soil was the fastest after 24 hours, NZVI was completely transformed into trivalent iron state, and the transformation was the slowest in shajiang black soil. Through seed germination and sand culture experiments, it was proved that NZVI promoted peanut seed and seedling growth at low concentration of 10-160 渭 mol / L. At a high concentration of 320 渭 mol / L, it inhibited seed germination and seedling growth.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S565.2;S153

【参考文献】