本文選題：土壤 + 重金屬　； 參考：《廣西大學(xué)》2015年碩士論文

【摘要】：土壤鉻(Cr)污染對(duì)糧食安全、生態(tài)系統(tǒng)以及人類健康具有很大的潛在危害,已成為全球性的重大環(huán)境問題。土壤清洗技術(shù)是被廣泛使用的一種高效修復(fù)方法,該技術(shù)的關(guān)鍵是有效的清洗劑。生物表面活性劑因其環(huán)境友好性成為新型的土壤清洗劑,被用于清洗土壤中的Cu、Zn、Pb、Ni、Cd等重金屬,但其對(duì)Cr的應(yīng)用研究較少。因此本文以單一人工鉻污染土壤為供試材料,通過振蕩提取實(shí)驗(yàn),分別研究了兩種生物表面活性劑鼠李糖脂和皂角苷去除鉻的可行性,探討了濃度、pH值、振蕩時(shí)間、土水比、提取次數(shù)和提取劑組合六個(gè)因素對(duì)鉻去除率的影響,分析了不同提取劑處理后土壤Cr形態(tài)和Cr(VI)的變化情況。所得結(jié)論如下：(1)鼠李糖脂和皂角苷能夠有效地去除污染土壤中的重金屬鉻。提高生物表面活性劑濃度、增加提取次數(shù)以及延長(zhǎng)振蕩時(shí)間,均有助于提高鉻去除率；堿性條件有利于鼠李糖脂對(duì)鉻的去除,而皂角苷在酸性范圍對(duì)鉻的去除效果較好；在一定程度上,降低土水比可以提高鉻去除率；在鼠李糖脂濃度為10 g.L-1,pH=10,土水比為1：20,提取時(shí)間為24 h,提取次數(shù)為5次的條件下,土壤的鉻去除率可達(dá)96.08%；濃度為10 g.L-1, pH=5.5,土水比為1：20,提取時(shí)間為24 h,提取次數(shù)為5次時(shí),皂角苷對(duì)土壤中鉻的去除率為79.96%。(2)提取劑多種組合兩步提取實(shí)驗(yàn)的結(jié)果表明：將EDTA(Ethylene Diamine Tetra acetic Acid)和鼠李糖脂的混配體系應(yīng)用于對(duì)污染土壤中鉻的去除是可行的,E-R (EDTA-Rhamnolipid)組合和R-E (Rhamnolipid-EDTA)組合對(duì)鉻的累積去除率分別為85.70%和83.85%；檸檬酸和皂角苷組合體系的提取先后順序會(huì)影響鉻的累積去除率,C-S (Citric acid-Saponin)組合對(duì)鉻的去除率合計(jì)為80.70%,S-C (Saponin-Citric acid)組合對(duì)鉻的累積去除率為65.44%。(3)鼠李糖脂能夠有效去除土壤中鉻的酸提取態(tài)和可還原態(tài),可以去除部分可氧化態(tài)鉻,只能去除少量殘?jiān)鼞B(tài)鉻,去除率分別為94.47%、84.17%、25.82%和7.64%；皂角苷主要能夠去除土壤中鉻的酸提取態(tài)和可還原態(tài),去除率分別為43.98%和51.84%,對(duì)可氧化態(tài)鉻和殘?jiān)鼞B(tài)鉻的去除效果較差。鼠李糖脂和皂角苷對(duì)土壤中Cr(Ⅵ)的去除率分別為66.59%和58.02%；與處理前土壤對(duì)比,鼠李糖脂和皂角苷處理后的土壤Cr(Ⅵ)占土壤總鉻的比例分別降低了9.54%和18.66%。鼠李糖脂和皂角苷均能降低Cr(Ⅵ)在土壤中的含量和比重,從而減輕Cr(Ⅵ)對(duì)環(huán)境的危害。
[Abstract]:Soil Cr (Cr) pollution has a great potential harm to food security, ecosystem and human health, and has become a major global environmental problem. Soil cleaning technology is widely used as a highly effective remediation method, the key of which is effective cleaning agent. Biosurfactants have become a new soil cleaning agent because of their environmental friendliness, and have been used to clean the heavy metals such as CuOZnZnPbPbPbPbN / NiOCD in the soil. However, the application of biosurfactants to Cr is seldom studied. Therefore, the feasibility of removal of chromium by two biosurfactants, rhamnolipid and saponins, was studied by oscillatory extraction experiment with single artificial chromium contaminated soil. The pH value, oscillating time and soil-water ratio of the two biosurfactants were discussed. The effects of extraction times and extractant combinations on Cr removal rate were studied. The changes of soil Cr morphology and CRV I after different extractant treatments were analyzed. The conclusion is as follows: rhamnolipid and saponins can effectively remove chromium from contaminated soil. Increasing the concentration of biosurfactant, increasing the extraction times and prolonging the oscillation time can improve the removal rate of chromium, while the alkaline conditions are favorable to the removal of chromium by rhamnolipid, while the removal effect of saponins is better in the acidic range. To a certain extent, reducing the ratio of soil to water can improve the removal rate of chromium, under the condition that the concentration of rhamnolipid is 10 g 路L ~ (-1) pH ~ (-1), the ratio of soil to water is 1: 20, the extraction time is 24 h, the times of extraction is 5 times. The Cr removal rate of soil can reach 96.08, when the concentration is 10 g 路L ~ (-1), pH is 5.5, the ratio of soil to water is 1: 20, the extraction time is 24 h, and the extraction times are 5 times. The results of two-step extraction experiment show that it is feasible to apply the mixture of EDTA(Ethylene Diamine Tetra acetic Acid) and rhamnolipid to the removal of chromium from contaminated soil. The cumulative removal rates of chromium in combination with R-E Rhamnolipid-EDTA were 85.70% and 83.85, respectively, and the order of extraction of citric acid and saponins would affect the cumulative removal rate of chromium. The total chromium removal rate of the combination was 80.70S-C Saponin-Citric acidin (80.70S-C Saponin-Citric acidin) and the total chromium removal rate was 80.70S-C Saponin-Citric acid.The extraction order of citric acid and saponin was 80.70S-C Saponin-Citric acidin. Rhamnolipid can effectively remove the acid and reductive forms of chromium in soil. Only a small amount of residual chromium can be removed, and the removal rates are 94.477.17% 25.82% and 7.64%, respectively. Saponin can mainly remove the acid extract and the reducible form of chromium in the soil. The removal rates were 43.98% and 51.84% respectively. The removal efficiency of oxidizable chromium and residual chromium was poor. The removal rates of Cr (鈪，

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