【摘要】：近年來,隨著鉻礦的開采和冶煉,鉻鹽的加工制造,印染、制革等行業(yè)迅速發(fā)展,鉻成為環(huán)境中重要的重金屬污染物。鉻鹽生產(chǎn)過程中的跑冒滴漏和鉻渣堆防護(hù)措施的缺失,使得鉻鹽生產(chǎn)場(chǎng)地成為我國(guó)地下水鉻污染最嚴(yán)重的區(qū)域之一。鉻化合物進(jìn)入地下水-巖系統(tǒng),受鉻的存在形態(tài)、地下水賦存狀態(tài)及地下水水質(zhì)、含水層介質(zhì)理化性質(zhì)等多種因素影響,在地下水-巖界面發(fā)生遷移轉(zhuǎn)化,研究其遷移轉(zhuǎn)化規(guī)律,對(duì)修復(fù)和治理被鉻污染的地下水具有重要的指導(dǎo)意義。本研究針對(duì)陜西商南鉻鹽生產(chǎn)場(chǎng)地鉻渣堆污染問題,開展了關(guān)于堆存鉻渣理化性質(zhì)、鉻渣浸出毒性及鉻在水-巖界面遷移轉(zhuǎn)化的一系列批實(shí)驗(yàn)和柱實(shí)驗(yàn)研究,實(shí)驗(yàn)結(jié)果表明:(1)鉻渣顆粒粒徑分布不均勻,經(jīng)過風(fēng)化以后,表面密實(shí)。鉻渣浸出液中鉻元素主要以Cr(VI)的形式存在,每千克的鉻渣中約含有6.7gCr(VI)。鉻渣浸出液的pH較高,且浸取劑pH對(duì)鉻渣浸出液pH影響不大,酸性浸取劑更易使Cr(VI)釋放出來。(2)由于不同土壤介質(zhì)的理化性質(zhì)不同,Cr(VI)在其中的遷移轉(zhuǎn)化機(jī)制也不相同。亞粘土、紅壤和黃土對(duì)Cr(VI)的吸持量與含鉻溶液初始濃度有一定的相關(guān)性。實(shí)驗(yàn)的三種土壤介質(zhì)對(duì)Cr(VI)的吸持過程均可采用Langmuir和Freundlich方程進(jìn)行擬合。擬合結(jié)果說明,亞粘土和紅壤表面可能存在不同類型的吸附位,且這些吸附位對(duì)Cr(VI)的結(jié)合力不同,而黃土的吸附行為可能為單分子層吸附;Cr(VI)在三種土壤介質(zhì)中的吸持過程都能夠采用準(zhǔn)二級(jí)反應(yīng)動(dòng)力學(xué)方程進(jìn)行擬合,表明吸持由化學(xué)反應(yīng)過程主導(dǎo)。(3)亞粘土、紅壤和黃土介質(zhì)對(duì)含鉻溶液中鉻的吸持作用主要包括:吸附作用、還原作用、絡(luò)合作用。當(dāng)含鉻溶液濃度超過地下水質(zhì)量標(biāo)準(zhǔn)10倍時(shí),三種土壤對(duì)Cr(VI)的吸持能力大小為:紅壤亞粘土黃土。吸持后,三種土壤介質(zhì)中殘?jiān)鼞B(tài)鉻所占比例均為最大,且不易釋放,水溶態(tài)和可交換態(tài)較少,其他形態(tài)存在比例與土壤介質(zhì)的有機(jī)質(zhì)含量、鐵、錳、鋁氧化物含量等有關(guān)。(4)當(dāng)pH小于12時(shí),亞粘土、紅壤和黃土對(duì)含鉻溶液pH的變化具有一定的緩沖能力。另外,外源有機(jī)質(zhì)的添加量對(duì)鉻的吸持影響也較大。
[Abstract]:In recent years, with the mining and smelting of chromium ore, the processing and manufacture of chromium salt, printing and dyeing, leather making and other industries, chromium has become an important heavy metal pollutant in the environment. Because of the leakage of chromium salt and the lack of protection measures, chromium salt production site has become one of the most seriously polluted areas in China. Chromium compounds enter the groundwater rock system, which are affected by the existing form of chromium, the state of groundwater occurrence and groundwater quality, the physical and chemical properties of aquifer media, and so on, and the migration and transformation take place at the interface between groundwater and rock. The study of its migration and transformation is of great significance for remediation and treatment of chromium contaminated groundwater. A series of batch and column experiments on the physicochemical properties of chromium slag, leaching toxicity of chromium slag and migration and transformation of chromium at water-rock interface were carried out to solve the pollution problem of chromium slag in Shangnan chromium production site in Shaanxi Province. The experimental results show that: (1) the particle size distribution of chromium slag is not uniform and the surface is dense after weathering. Chromium is mainly in the form of Cr (VI) in the leachate of chromium slag, and there is about 6.7gCr (VI). In every kilogram of chromium slag. The pH of chromium residue leachate was high, and the leaching agent pH had little effect on pH, and acid leaching agent could release Cr (VI) more easily. (2) the physicochemical properties of different soil media were different. The migration and transformation mechanism of Cr (VI) is also different. There is a certain correlation between the absorption of Cr (VI) and the initial concentration of chromium-containing solution in the clay, red soil and loess. The sorption process of Cr (VI) in three soil media was fitted by Langmuir and Freundlich equations. The fitting results show that there may be different types of adsorption sites on the surface of subclay and red soil, and the binding forces of these sites to Cr (VI) are different, while the adsorption behavior of loess may be monolayer adsorption. The adsorption process of Cr (VI) in three kinds of soil media can be fitted by quasi-second-order reaction kinetic equation, which indicates that adsorption is dominated by chemical reaction process. (3) Clay. The adsorption of chromium in chromium-containing solution by red soil and loess medium mainly includes adsorption, reduction and complexation. When the concentration of chromium-containing solution exceeded the groundwater quality standard by 10 times, the absorbability of Cr (VI) to the three soils was as follows: the red soil subclay loess. After sorption, the proportion of residual chromium in the three kinds of soil media was the largest, and it was not easy to release, the water soluble and exchangeable forms were less, and the other forms were related to the content of organic matter, iron, manganese, iron and manganese in the soil media. (4) when pH is less than 12:00, the changes of pH in chromium-containing solution can be cushioned by subclay, red soil and loess. In addition, the addition of exogenous organic matter has a great effect on the absorption of chromium.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X523

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本文編號(hào)：2418931