酸改性凹凸棒重金属钝化剂的制备及效果研究

发布时间：2018-11-22 18:43

【摘要】：土壤是人类赖以生存的主要自然资源,也是人类生态环境的重要组成部分。随着工农业的快速发展,土壤-植物-环境系统中重金属的污染日益严重。近年来,无论在中国还是在世界范围内,如何控制和减轻重金属对环境的污染和危害已成为一个日益突出的问题。本课题以凹凸棒为原材料,按不同的酸改性时间12h、24h、36h、48h、72h、96h和108h,不同的H_2SO_4体积分数2.5%、5%、7.5%、10%、12.5%、15%、20%制备酸改性凹凸棒钝化剂49种。采用重金属污染土壤钝化实验、玉米植物重金属富集实验,挑选出5种最优酸改性凹凸棒重金属钝化剂。通过重金属污染土壤钝化实验,分析研究酸改性凹凸棒钝化剂对污染土壤重金属的钝化效果。这对于研究重金属污染土壤的原位钝化修复有重要意义,为大规模土壤重金属修复提供依据,同时为地方特色矿产资源的高端产品开发和应用提供新方法。(1)不同种类的酸改性凹凸棒分别对重金属Cu、Cr、Zn、Ni污染土壤钝化处理,重金属Cu、Cr、Zn、Ni的酸溶态含量随酸处理H_2SO_4体积分数的变化总体上均呈先下降后上升的趋势;重金属Cu、Cr、Zn、Ni的酸溶态含量随酸改性时间的变化总体上均呈先下降后上升的趋势。(2)酸改性H_2SO_4体积分数显著影响玉米重金属Cu、Cr、Zn、Ni的富集含量;酸改性时间显著影响玉米重金属Cu、Cr、Zn、Ni的富集含量。(3)选出5种最优酸改性凹凸棒重金属钝化剂S45、S54、S55、S56、S65,酸改性条件:H_2SO_4体积分数分别为10%、12.5%、12.5%、12.5%、15%,酸改性时间分别为72 h、48 h、72 h、96 h、72 h。(4)重金属污染土壤的pH随5种钝化剂添加量的增加而减小,但均低于对照组的pH值;钝化剂添加处理组EC值均高于对照组的EC值,同时均随添加量的增加而升高。(5)污染土壤中重金属Cu、Zn、Ni水溶态含量随钝化剂添加量的增加先减小后趋于稳定,钝化剂添加量显著影响对重金属Cu、Zn、Ni水溶态含量,同时Cu、Zn、Ni水溶态含量最低时与对照组相比分别降低了47.69%、63.17%、83.65%。(6)污染土壤中重金属Cu、Zn、Ni的DTPA提取态均随钝化剂添加量的增加先减小后趋于稳定,钝化剂添加量显著影响对重金属Cu、Zn、Ni的DTPA提取态含量,同时Cu、Zn、Ni的DTPA提取态最低时与对照组相比分别降低了23.31%、45.93%、61.45%。(7)随着5种钝化剂添加量的增加实际污染土壤中重金属Cu的酸溶态和还原态含量显著减小,Cu的氧化态和残渣态含量显著增加;重金属Zn的酸溶态和氧化态含量显著减小,Zn的还原态和残渣态含量显著增加;重金属Ni的酸溶态含量显著减小,Ni的还原态、氧化态和残渣态含量显著增加。重金属迁移率大小为CuZnNi,污染土壤中重金属Cu、Zn、Ni的迁移率随酸改性凹凸棒重金属钝化剂添加量的增加而逐渐降低,同时钝化剂添加量显著影响重金属Cu、Zn、Ni迁移率。
[Abstract]:Soil is not only the main natural resource for human survival, but also an important part of human ecological environment. With the rapid development of industry and agriculture, the pollution of heavy metals in soil-plant-environment system is becoming more and more serious. In recent years, whether in China or in the world, how to control and reduce the pollution and harm of heavy metals to the environment has become an increasingly prominent problem. In this subject, attapulgite was used as the raw material, and in accordance with the different modification time of 12h ~ 24h ~ (36h) ~ 48h ~ _ 49 kinds of acid-modified attapulgite passivator were prepared by 20%. Five optimal acid modified attapulgite heavy metal passivators were selected by experiments of heavy metal polluted soil passivation and maize plant heavy metal enrichment. The effects of acid-modified attapulgite passivator on heavy metal passivation in contaminated soil were studied by experiments. This is of great significance for the study of in situ passivation and remediation of heavy metal contaminated soils, and provides a basis for the remediation of heavy metals on a large scale. At the same time, it provides a new method for the development and application of high-end products of local characteristic mineral resources. (1) different kinds of acid-modified attapulgite are used to passivate heavy metal Cu,Cr,Zn,Ni contaminated soil and heavy metal Cu,Cr,Zn, respectively. The acid soluble state content of Ni decreased first and then increased with the change of H_2SO_4 volume fraction. The acid soluble content of heavy metal Cu,Cr,Zn,Ni decreased first and then increased with the change of modification time. (2) the content of Cu,Cr,Zn,Ni in maize was significantly affected by the volume fraction of acid-modified H_2SO_4. The concentration of heavy metal Cu,Cr,Zn,Ni in maize was significantly affected by the time of acid modification. (3) five optimal acid modified attapulgite heavy metal passivators S45OS5OS5OS5OS5C65 were selected. The acid modification conditions were as follows: the volume fraction of H_2SO_4 was 10% and 12.5%, respectively. The modification time of acid was 72 h ~ 48 h ~ 72 h ~ 96 h, respectively. 72h. (4) the pH of heavy metal contaminated soil decreased with the increase of the amount of five passivating agents, but lower than the pH value of the control group. The EC value of the passivator added treatment group was higher than that of the control group, and both of the EC values increased with the increase of the amount of the passivating agent. (5) the water soluble content of Cu,Zn,Ni in polluted soil decreased first and then stabilized with the increase of the amount of the passivating agent. The addition of passivator significantly affected the water soluble content of heavy metal Cu,Zn,Ni, and the lowest content of Cu,Zn,Ni decreased 47.69% 63.17%, respectively, compared with the control group. (6) the DTPA extractions of heavy metal Cu,Zn,Ni in polluted soil decreased first and then stabilized with the increase of the amount of passivating agent. The addition of passivating agent significantly affected the content of DTPA extract of heavy metal Cu,Zn,Ni and Cu,. Compared with the control group, the DTPA extraction state of Zn,Ni was 23.31% lower than that of the control group, 45.93% lower than that of the control group. (7) with the increase of the amount of five passivating agents, the acid soluble and reductive state contents of heavy metal Cu in polluted soil decreased significantly, while the oxidation state and residual state content of Cu increased significantly; The content of acid soluble state and oxidized state of heavy metal Zn decreased significantly, the content of reducing state and residue state of Zn increased significantly, the content of acid soluble state of heavy metal Ni decreased significantly, the content of oxidized state and residual state of Ni increased significantly. The mobility of heavy metal Cu,Zn,Ni in CuZnNi, contaminated soil decreased with the increase of the amount of heavy metal passivator in acid-modified attapulgite, and the amount of passivating agent significantly affected the mobility of heavy metal Cu,Zn,Ni.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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