梯度扩散薄膜技术（DGT）应用于土壤重金属有效态测定的分析研究

发布时间：2018-03-25 00:22

本文选题：梯度扩散薄膜技术(DGT)　切入点：土壤重金属　出处：《北京交通大学》2017年硕士论文

【摘要】：由于我国土壤重金属元素污染形式严峻,土壤重金属元素缺乏准确地、快捷地方法来评价其污染程度,因此本文以新型DTPA-LDH-DGT研制、吸附过程研究和应用为背景,将DGT技术应用于土壤重金属元素生物有效态含量的测定,结果表明:(1)DGT测得铜、镉、铅元素的有效态含量与土壤理化性质的相关性R2依次为0.25、0.35、0.24;化学方法测得的有效态含量与土壤理化性质的相关性R2依次为0.47、0.64、0.61,表明DGT相比于化学方法测得的结果与土壤理化性质的相关性要小,在实际应用中DGT更加适用于土壤重金属生物有效态含量的测定。(2)DGT测得铜、镉、铅元素的有效态含量与水稻中的重金属含量相关性比土壤总量与水稻中重金属相关性高(R2=0.77、0.83、0.85,R2= 0.67、0.65及不相关),能够充分说明DGT测定的土壤重金属生物有效态是可靠的,结果更加准确。(3)DTPA-LDH-DGT对重金属铜、镉和铅三种元素的扩散系数依次为6.23×10-6cm2s-1、6.09×10-6cm2s-1 和 8.03×10-6cm2s-1,对三种元素的吸附量均可在3h之内达到总量的90%,洗脱效率均为95%以上,比传统的Chelex-DGT的洗脱效率80%要高,在洗脱方面更有优势。(4)两种DGT在0.1 μmol/L铜、镉和铅混合液的竞争吸附过程中,Chelex-DGT对铅的吸附量大于镉,镉吸附量大于铜,DTPA-LDH-DGT对铅的吸附量大于铜,铜吸附量大于镉,两者均是对铅的优先吸附,但对铜和镉吸附顺序不同,DTPA-LDH-DGT对镉和铅的吸附性能与Chelex100相比相差不大,但是对铜的吸附量比Chelex-DGT高出3倍。(5)pH对铜、镉和铅离子混合液的竞争吸附的影响规律为随pH的升高而增多,增至7以上则趋于稳定。有机质对铜、镉和铅离子混合液的竞争吸附的影响规律为有机态重金属的吸附量相比离子态重金属有所降低,吸附顺序没有变化,两种DGT均是对铅吸附量最高,铜和镉吸附量依次低于铅。
[Abstract]:Because of the severe pollution form of heavy metal elements in soil in China, and the lack of accurate and quick method to evaluate the pollution degree of heavy metal elements in soil, the background of this paper is the development of new DTPA-LDH-DGT, the research and application of adsorption process. The DGT technique was applied to the determination of the bioavailability of heavy metal elements in soil. The results showed that Cu and CD were determined by DGT. The correlation between the available form content of lead and the physical and chemical properties of soil is 0.250.35 ~ 0.24, and that of chemical method is 0.47 ~ 0.64 ~ 0.61, which indicates that DGT is better than that of chemical method in comparison with soil. The correlation of soil physical and chemical properties is small, In practical application, DGT is more suitable for the determination of bioavailability of heavy metals in soil. The correlation between the available content of lead and the content of heavy metals in rice is higher than that between the total amount of soil and the heavy metals in rice. The correlation between the total amount of lead and the total amount of heavy metals in rice is higher than that of the total amount of soil and the correlation of heavy metals in rice. The correlation between the available contents of lead and the content of heavy metals in rice is higher than that of the total amount of soil and the correlation of heavy metals in rice. The results showed that the diffusion coefficients of DTPA-LDH-DGT for heavy metals copper, cadmium and lead were 6.23 脳 10 ~ (-6) cm ~ (-2) 路s ~ (-1) 6.09 脳 10-6cm2s-1 and 8.03 脳 10 ~ (-6) cm ~ (-2) 路s ~ (-1) respectively. The adsorption capacity of the three elements could reach 90% of the total amount within 3 hours, and the elution efficiency was more than 95%, which was 80% higher than that of traditional Chelex-DGT. In the competitive adsorption process of 0. 1 渭 mol/L copper, cadmium and lead mixtures, Chelex-DGT adsorbs more lead than cadmium, and cadmium is larger than copper (DTPA-LDH-DGT). Both of them were preferentially adsorbed to lead, but the adsorption order of copper and cadmium was different. The adsorption performance of DTPA-LDH-DGT on cadmium and lead was similar to that of Chelex100, but the adsorption capacity of copper was 3 times higher than that of Chelex-DGT. The effect of the competitive adsorption of cadmium and lead ion mixed solution increased with the increase of pH, and increased to more than 7, which tended to be stable. The results showed that the adsorption capacity of organic heavy metals was lower than that of ionic heavy metals, and the adsorption order was not changed. The adsorption amount of lead was the highest in both DGT, and the adsorption capacity of copper and cadmium was lower than that of lead in turn.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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