巴关河渣场周边受污染土壤及粘土矿物对钒、铬、镉的吸附—固定效果研究

发布时间：2018-04-29 23:08

本文选题：土壤 + 粘土矿物　；参考：《成都理工大学》2015年硕士论文

【摘要】：巴关河渣场位于攀枝花市西区,巴关河至北向南穿过该渣场。渣场东临大山,西临攀枝花苏铁自然保护区,南北距离约300米就有居民区。渣场于1993年投入运营,现在是攀钢排弃高炉渣的唯一场所,随着攀钢生产规模逐年提高,排渣量也逐年增大,现在每年出渣量已约为320万吨,使得渣场承载能力已接近使用极限。在大量废渣堆弃的过程中,钒、铬、镉等有害重金属会随雨水淋滤及大气扬尘等方式迁移到附近土壤中,造成较严重的土壤污染,进而对生态环境和附近居民的健康带来危害。本论文以巴关河渣场周边土壤作为研究对象,分别在巴关河渣场上游、渣场附近和渣场下游区域采集土壤样品,采用地质累积指数对土壤的污染程度进行评价。研究结果表明,渣场周边土壤已较严重地被钒、铬、镉污染,因此被污染的土壤就会成为一个潜在的污染源,对附近居民的安全带来隐患。考虑土壤本身具备强大的吸附能力和自净化能力,借助静态吸附实验重点研究已污染土壤对钒、铬、镉的吸附—固定特征,结合土壤的矿物组成、表面电荷特征、铁锰铝氧化物含量及比表面积等表征结果,对土壤吸附钒、铬、镉的机理进行较深入的探讨,进而对已污染土壤对附近居民区的潜在危害性进行合理评价。研究表明:巴关河渣场周边土壤中钒、铬、镉的受污染程度较严重。其中,巴关河上游区域土壤的钒、铬、铬均呈中度污染;渣场附近区域土壤钒和镉呈中度污染,铬呈中度污染到强污染;下游区域土壤钒和镉呈中度污染,铬呈中度污染到强污染。吸附时间对吸附量的影响实验研究表明:污染土样和污染液接触24h内,污染土样对V的吸附速率快,吸附量和去除率增势显著,去除率增至90%,因此静态吸附实验吸附时间设定为24h。虽然污染土样已属于中度污染,但对钒仍然有较好的吸附能力和自净化能力。污染液初始浓度对土壤吸附量的影响实验研究表明:钒、镉初始浓度在0mg/L~450mg/L之间时,5个土样对钒和镉的吸附量总体呈现随初始浓度的增大而增大的趋势,且受污染土样在高浓度(450mg/L)污染液中对钒和镉仍具有较好的吸附—固定能力。但是巴关河渣场周边的土壤对铬基本已不具备自净化的能力,必须要进行污染治理。p H值对土壤吸附量的影响实验研究表明:在实验范围内,4号和15号污染土样对钒的吸附量基本呈现随p H值的增大而降低的趋势;对镉的吸附量均随着p H值的增大而增大;对铬没有明显规律。利用吸附等温方程式对4号和15号污染土样吸附钒、铬、镉进行线性拟合,研究表明:两种污染土样对钒和镉的吸附特征更符合Langmuir方程吸附模型,即土样对钒和镉的吸附属于单分子层吸附,为不可逆吸附;两种污染土样对铬的吸附特征更符合Freundlich方程吸附模型,即土样对铬的吸附属于不均匀表面吸附,为可逆吸附。受污染土样的XRD物相分析结果表明:主要矿物成分均为石英及粘土矿物,此外还有斜长石、透闪石、方解石、钾长石及黄铁矿等。而粘土矿物主要为蒙脱石、伊利石、绿泥石。土样表面会同时带正电荷和负电荷,两种电荷不具加和性,正电荷有利于土壤吸附阴离子,负电荷有利于土壤吸附阳离子。土样的永久负电荷(CECp)主要起因于层状粘土矿物蒙脱石、伊利石中的类质同像置换作用,正电荷(AEC)则主要源于粘土矿物(蒙脱石、伊利石、绿泥石及高岭石等)破碎表面或结构层边缘上八面体结构面中的Al、Fe、Mn的水合氧化物或羟基。p H值是影响土壤表面正电荷和负电荷数量的最重要的因素。在p H值相近的情况下,土样对VO3-的吸附量与其正电荷(AEC)的大小基本呈现正相关性关系,即土样表面正电荷(AEC)的增大有利于VO3-的吸附—固定。p H值减小,有利于土壤表面正电荷的增大,进而有利于吸附呈阴离子形式存在的VO3-,表现为在酸性介质中土壤对钒的吸附量增大。与Cr2O72-相比土壤对VO3-具有特定选择吸附性。p H值增大时,有利于土壤表面负电荷的增大,进而有利于土壤吸附呈阳离子形式存在的Cd2+,表现为在碱性条件下对镉的吸附量增大。粘土提纯前后的土样对钒、镉、铬的吸附实验研究表明,提纯粘土对钒和镉的吸附效果优于天然土样,而铬无明显规律。与天然土样相比,提纯粘土中透闪石、方石英和钠长石含量明显降低,粘土矿物总含量虽有所增大,但还含部分石英,因此提纯方法有待改进。SEM/EDS分析显示:4号和15号提纯土样吸附钒后均能被能谱检测出,且所吸附的钒分布较均匀,没有明显的富集区域,但土样吸附镉后不易被检测出,吸附铬后则很难被检测出来,其原因可能和土样对钒、铬、镉的吸附位置有关。
[Abstract]:The Bagang River slag field is located in the West District of Panzhihua City, the bagun river goes to the north and south through the slag field. The slag field is on the mountains in the East and the Panzhihua cycad Nature Reserve in the west, and there is a residential area about 300 meters in the north and south. The slag field is put into operation in 1993. It is now the only place for Pangang to discarded blast furnace slag. As the scale of Panzhihua steel production increases year by year, the amount of slag discharge is also by year by year. In the process of a large number of waste residue, the harmful heavy metals such as vanadium, chromium, cadmium and other harmful heavy metals will be migrated to the nearby soil, resulting in more serious soil pollution and the health of the ecological environment and nearby residents. This paper takes the soil around the bagagan River slag field as the research object. The soil samples are collected in the upstream of the bagun River slag field, near the slag field and the downstream area of the slag field, and the soil pollution is evaluated by the geological accumulation index. The results show that the soil on the periphery of the slag field has been seriously polluted by vanadium, chromium and cadmium. Contaminated soil will become a potential source of pollution, causing hidden dangers to the safety of nearby residents. Considering the strong adsorption capacity and self purification capacity of the soil itself, the adsorption and fixation characteristics of vanadium, chromium and cadmium in contaminated soil are studied with the help of static adsorption experiments, combined with the mineral composition of the soil, surface charge characteristics, iron manganese The mechanism of the adsorption of vanadium, chromium and cadmium in soil was deeply discussed, and the potential harmfulness of the contaminated soil to nearby residential areas was reasonably evaluated. The study showed that the pollution degree of vanadium, chromium and cadmium in the surrounding soil of the bagun River slag field was serious. The vanadium, chromium and chromium in the soil are moderately polluted, the soil vanadium and cadmium in the soil near the slag field are moderately polluted, the chromium is moderately polluted to the strong pollution, the soil vanadium and cadmium in the downstream area are moderately polluted, and the chromium is moderately polluted to the strong pollution. The experimental study on the effect of adsorption time on the adsorption capacity is that the contaminated soil and the polluted liquid are in contact with the 24h, and the contaminated soil sample is V The adsorption rate was fast, the adsorption capacity and removal rate increased significantly, and the removal rate increased to 90%. Therefore, the static adsorption experimental adsorption time was set to 24h. although the contaminated soil samples had been moderately polluted, but the adsorption capacity and self purification ability of vanadium were still better. The experimental study on the effect of initial concentration of the contaminated liquid on soil adsorption showed that the initial concentration of vanadium and cadmium was initial. When the concentration is between 0mg/L~450mg/L, the total adsorption of 5 soil samples on vanadium and cadmium increases with the increase of the initial concentration, and the contaminated soil has a better adsorption and fixation ability to vanadium and cadmium in the high concentration (450mg/L) polluted liquid, but the soil around the bagun River slag field has no self purification energy. The experimental study on the effect of.P H on soil adsorption capacity of pollution control shows that the adsorption of vanadium in the 4 and 15 contaminated soil samples decreased with the increase of P H value; the adsorption amount of cadmium increased with the increase of P H value; The adsorption of vanadium, chromium and cadmium on 4 and 15 contaminated soil samples is linear. The study shows that the adsorption characteristics of two kinds of contaminated soil samples to vanadium and cadmium are more in line with the Langmuir equation adsorption model, that is, the adsorption of vanadium and cadmium to vanadium and cadmium belongs to the single molecular layer adsorption and irreversible adsorption, and the adsorption characteristics of the two contaminated soil samples are more in accordance with the Freundlich equation. The adsorption of chromium on the soil sample is an uneven surface adsorption and reversible adsorption. The results of XRD phase analysis of contaminated soil samples show that the main mineral components are quartz and clay minerals, in addition to plagioclase, tremolite, calcite, potassium feldspar and pyrite, and clay minerals are mainly montmorillonite, illite, chlorite and soil sample. The surface will have both positive and negative charges at the same time. The two charges have no additivity, the positive charge is beneficial to the adsorption of anions in the soil, and the negative charge is beneficial to the adsorption of cations. The permanent negative charge (CECp) of the soil is mainly due to the montmorillonite in the layered clay mineral, the isomorphism in the illite, and the positive charge (AEC) mainly derived from clay ore. The most important factor affecting the positive and negative charge quantity of soil surface, such as Al, Fe, Mn and.P H, is the most important factor affecting the surface positive charge and negative charge in the eight surface structure surface of the fractured surface or the edge of the structural layer. The adsorption amount of the soil sample to VO3- and its positive charge (AEC) is larger than that of the P H value. The increase of positive charge (AEC) on the surface of the soil is beneficial to the adsorption of VO3-, which is beneficial to the decrease of the fixed.P H value, which is beneficial to the increase of the positive charge on the surface of the soil, which is beneficial to the adsorption of the VO3- in the form of anion in the form of the acid, which shows that the amount of adsorption of the soil to vanadium increases in the acid medium. Compared with Cr2O72-, the soil to VO3- is compared to VO3-. The increase of the specific selective adsorption.P H value is beneficial to the increase of the negative charge on the surface of the soil, which is beneficial to the adsorption of soil in the form of Cd2+ in the form of cation, which shows the increase of the adsorption of cadmium under the alkaline condition. The adsorption of vanadium, cadmium and chromium on the soil samples before and after the purification of clay shows that the adsorption of clay to vanadium and cadmium The effect is better than natural soil, but chromium has no obvious regularity. Compared with natural soil sample, the content of tremolite in clay, the content of quartzite and albite is obviously reduced, although the total content of clay minerals is increased, but also contains some quartz, so the purification method needs to be improved by.SEM/EDS analysis. The adsorption of vanadium on the 4 and 15 pure soil samples can be detected by energy spectrum. It is found that the distribution of the adsorbed vanadium is more uniform, and there is no obvious enrichment area, but the soil sample is not easily detected after the adsorption of cadmium, and it is difficult to be detected after the adsorption of chromium. The reason may be due to the adsorption position of soil to vanadium, chromium and cadmium.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;P579

【参考文献】