几种螯合剂对土壤重金属、氟污染的萃

发布时间：2018-08-21 09:45

【摘要】：湖南省作为世界“有色金属之乡”,多年的开采使得土壤受到严重的重金属污染,寻于一种有效的重金属污染去除方法具有极强的现实意义。本研究拟选取湖南省郴州和衡阳市的污染土壤作为研究对象,依据萃取效率较高、环境友好和易于分离的原则选择6种螯合剂对土壤污染物进行萃取试验,以期选取合适的萃取剂,为进一步去除土壤重金属、砷及氟提供合理的方法。在选取的两种土样中,重金属形态以有机物及硫化物结合态为主。弱碱性土样S中,Pb、Zn、Cu、Cd的主要形态是有机物及硫化物结合态,分别占其总量的64.91%、38.52%、56.35%和23.18%。酸性土样W中,Zn和Cu的主要形态是有机物及硫化物结合态,分别占其总量的37.45%和46.55%,Cd的主要形态是可交换及碳酸盐结合态,占其总量的45.25%,Pb的形态分布比较均匀。两种土样中As均以残渣态为主。通过选取6种螯合剂的萃取试验表明,各螯合剂对土壤中的各重金属污染及砷、氟离子都有一定的萃取效果。柠檬酸对Pb和Zn具有较强的萃取能力,半胱氨酸对As和F有较强的萃取效果,而EDTA尽管对Zn萃取效果较差外,对Pb、Cu、Cd和As或F均表现了极强的萃取能力。从综合结果来看,EDTA无论对于弱碱性土壤还是酸性土壤,在以上6中螯合剂中是最好的的萃取剂。对于酸性土壤,EDTA不仅表现了极强的萃取能力,而且其萃取液也较易分离,因此对于酸性土壤EDTA可以为较理想的萃取液；但对于弱碱性土壤,尽管EDTA和柠檬酸有较强的萃取能力,但其萃取液的连续分离性较差,而半胱氨酸不仅有较强的萃取能力,而且其萃取液易于分离,因此可能是较好的选择。
[Abstract]:Hunan Province, as the "hometown of non-ferrous metals" in the world, has been polluted by heavy metals for many years, so it is of great practical significance to find an effective method to remove heavy metal pollution. Based on the principles of high extraction efficiency, environmental friendliness and easy separation, six chelating agents were selected to extract soil pollutants in Chenzhou and Hengyang, Hunan Province. In order to select the appropriate extractant, to further remove heavy metals, arsenic and fluorine in the soil to provide a reasonable method. In the two soil samples, organic compounds and sulfides are the main forms of heavy metals. The main forms of Pb ~ (2 +) ~ (2 +) Zn ~ (2 +) Cu ~ (2 +) in weak alkaline soil S are organic compounds and sulfides, which account for 64.91% ~ 38.52% and 23.18% respectively. The main forms of Zn and Cu in acidic soil samples are organic compounds and sulfides, which account for 37.45% and 46.55% of the total amount of CD, respectively. The main forms of CD are exchangeable and carbonate bound, and the speciation distribution of 45.25% Pb is relatively uniform. The residual state of as in the two kinds of soil samples is dominant. The extraction experiments with six chelating agents showed that each chelating agent had a certain effect on the extraction of heavy metals and arsenic and fluorine ions in soil. Citric acid can extract Pb and Zn, cysteine can extract as and F, while EDTA can extract Pb, Cu, CD, as and F, even though it has a poor effect on Zn. The results show that EDTA is the best extractant in the chelating agent of the 6 above mentioned in both weak alkaline soil and acidic soil. For acidic soil, EDTA not only shows very strong extraction ability, but also its extract is easy to separate, so it is ideal for acid soil EDTA, but for weak alkaline soil, although EDTA and citric acid have strong extraction ability, However, the continuous separation of its extracts is poor, and cysteine not only has strong extraction ability, but also is easy to separate, so it may be a better choice.
【学位授予单位】：湖南农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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