重金属复合污染土壤固定修复中钝化剂筛选及其作用机制

发布时间：2018-01-11 11:03

本文关键词：重金属复合污染土壤固定修复中钝化剂筛选及其作用机制　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于工业的飞速发展及各种人类活动的干扰,农田土壤重金属污染已严重威胁到农作物食品安全及人体健康。面对土壤重金属污染,在众多的修复技术中,化学钝化修复技术因其修复快、时间短、操作易、成本低而备受关注。该修复技术的关键在于钝化剂的选择。本研究为筛选出能有效钝化复合污染土壤中多种重金属的钝化剂,首先通过野外调查和预实验选择了钢渣、磷矿粉、坡缕石和木炭作为钝化剂,在室内条件下,采用重金属生物有效态单级提取(二乙三胺五醋酸(DTPA)提取)和重金属各赋存形态分级提取两种方法,研究了钝化剂在不同添加浓度(0,5%,20%,钝化剂与土壤质量比)下,对重金属(Pb、Cd、Cu、Zn、As)的生物有效态及各赋存形态的影响,评价了各钝化剂对重金属钝化效果；其次,于室内进行了盆栽试验,研究了4种钝化剂对芹菜、胡萝卜、番茄的生物量及不同部位重金属吸收的影响；最后通过室内等温吸附解吸试验,采用x射线衍射法(XRD)和比表面-孔径分布仪测定了钝化剂的物相组成、比表面积和孔径特征,进一步探讨了4种钝化剂与重金属之间的相互作用机制。主要研究结果表明：(1)研究区域土壤重金属Pb、Zn、Cu、Cd、As含量严重超过国家土壤环境质量标准(GB 15618-1995)的二级标准。与对照相比,在施加20%的浓度处理下,坡缕石、钢渣、磷矿粉能降低土壤中5种重金属的生物有效态含量,差异显著；20%坡缕石、钢渣、磷矿粉处理均能使土壤pH值显著提高。(2)土壤重金属各赋存形态的分级提取结果表明,20%坡缕石能使植物易吸收的土壤可交换态Pb显著减少,而使难吸收的残渣态Pb显著增加；20%坡缕石、钢渣或磷矿粉能显著降低土壤中可交换态Cd含量；20%钢渣或20%磷矿粉处理后可交换态和碳酸盐结合态Zn含量明显减少,坡缕石处理使残渣态Zn显著增加；钢渣或20%磷矿粉能显著增加残渣态Cu含量；添加20%磷矿粉后生物难吸收的钙型砷含量显著增加。(3)与对照相比,20%的钢渣、磷矿粉、木炭处理均能使胡萝卜、番茄株高显著增加；20%的坡缕石能使胡萝卜株高显著增加。钢渣和坡缕石处理能使胡萝卜生物量显著增加；4种钝化剂添加处理后,芹菜生物量与对照相比显著增加。钢渣、磷矿粉能显著降低胡萝卜地上、地下部分的As含量,坡缕石、钢渣、磷矿粉能显著降低番茄可食部位(果实)中的As含量。4种钝化剂均显著降低芹菜叶中的As含量。相比对照,4种钝化剂均能显著降低芹菜根叶和胡萝卜地下部的Cd含量。4种钝化剂处理能显著降低芹菜茎中的Pb含量；坡缕石、钢渣、磷矿粉处理后,能显著降低胡萝卜地下部的Pb含量；磷矿粉和坡缕石处理后能显著降低番茄可食部位(果实)中的Pb含量。(4)室内等温吸附解吸试验结果表明,钢渣、坡缕石、磷矿粉对重金属离子Cu、Cd、Pb、As、Zn都有很好的吸附作用；吸附等温线符合Langmuir方程和Freundlich方程。4种钝化剂随初始浓度的增加,对5种重金属离子Cu、Cd、 Pb、As、Zn的吸附量均有增加的趋势。在相同初始浓度条件下,4种钝化剂对重金属离子的吸附量不同。在相同的平衡浓度条件下,4种钝化剂对Cu的吸附量表现为坡缕石钢渣磷矿木炭；对的Cd的吸附量表现为钢渣磷矿粉≈坡缕石木炭；对的Pb吸附量表现为磷矿粉坡缕石钢渣木炭；对As的吸附量表现为在低浓度条件下钢渣磷矿粉坡缕石木炭,而在高浓度条件下,木炭、磷矿粉、坡缕石对As的吸附量较为接近；对的Zn吸附量表现为钢渣坡缕石磷矿粉木炭。(5)解吸试验表明,钢渣对重金属离子Cd、As、Zn的解吸量较小,磷矿粉、木炭、坡缕石对5种重金属离子的解吸量均随吸附量的增大而增大,具体为：在最大吸附量处,4种钝化剂对Zn的解吸量为木炭磷矿粉坡缕石钢渣；对As的解吸量为坡缕石木炭磷矿粉钢渣；对Pb的解吸量为木炭坡缕石钢渣磷矿粉；对Cd解吸量为木炭坡缕石磷矿粉钢渣；对Cu解吸量为木炭钢渣磷矿粉坡缕石。比较发现4种钝化剂中木炭对5种重金属离子的解吸量均较大。(6)4种钝化剂中,木炭和坡缕石具有较大的比表面积和孔容,对重金属的钝化机制可能以物理吸附和离子交换吸附为主；钢渣和磷矿粉虽然比表面和孔容较小,但具有较高的pH值,对重金属的钝化机制可能以化学沉淀反应为主。
[Abstract]:Due to the rapid development of industrial interference and various human activities, soil heavy metal pollution has been a serious threat to food safety and human health. In the face of soil heavy metal pollution, in the repair of all kinds of technologies, chemical remediation technology for the repair time is short, fast, easy operation, low cost and concern. The key to the repair technology is the selection of passivator. This study selected the passivation agent can effectively passivated various compound pollution of heavy metals in soil, firstly, through field investigation and experiment selected steel slag, phosphorite powder, palygorskite and charcoal as a passivating agent under indoor conditions with heavy metal bioavailability of single stage extraction (two B three amine five acetic acid (DTPA) extraction) two methods and the heavy metal speciation extraction, passivation agent is added in different concentrations (0,5%, 20%, passivator and soil mass ratio), the money Genera (Pb, Cd, Cu, Zn, As) affect the bioavailability and speciation, evaluation of the effect of the passivation agent for heavy metal passivation; secondly, in the indoor pot experiment, 4 kinds of Passivator on celery, carrot, tomato and heavily influence the biomass of different parts of absorption finally through the interior; isothermal adsorption desorption experiment, using X ray diffraction (XRD) and the passivation determination of specific surface area pore distribution for phase composition, specific surface area and pore characteristics, to further explore the interaction mechanism between the 4 kinds of passivating agent and heavy metals. The main research results are as follows: (1) study on Regional soil heavy metals Pb, Zn, Cu, Cd, As content is more than the national soil environmental quality standard (GB 15618-1995) level two standard. Compared with the control, the concentration of applied 20%, palygorskite, steel slag, phosphate rock powder can reduce 5 kinds of heavy metals in soil organisms Available content, significant difference; 20% palygorskite, steel slag, rock phosphate treatment can significantly increase pH values in soils. (2) the extraction of soil heavy metals in the species showed that 20% palygorskite can make the plant easily absorbed by soil exchangeable Pb decreased significantly, while the hard suction residue Pb increased significantly; 20% palygorskite, steel slag or phosphate powder can significantly reduce the exchangeable Cd concentration in soil; 20% or 20% slag phosphate powder after treatment of exchangeable and carbonate fractions of Zn were significantly reduced, palygorskite treatment residual Zn increased significantly; steel slag or 20% phosphate powder can significantly increase the content of residual Cu; calcium phosphate powder after adding 20% content of arsenic in biological difficult absorption increased significantly. (3) compared with the control group, 20% steel slag, phosphorite powder, charcoal treatment can make the carrot, tomato plant height increased significantly; 20% palygorskite can make Hu Luo, the plant height was significantly Increase of steel slag and palygorskite treatment can make the carrot biomass significantly increased; 4 passivation agent is added after the treatment, the celery biomass increased significantly comparing with the control. The steel slag, phosphate powder can significantly reduce the carrot, As content in the underground part of palygorskite, steel slag, phosphate powder can significantly reduce edible tomato part (fruit) content of As.4 in passivation agent significantly decreased As content in celery leaves. Compared to the control, 4 kinds of passivating agent can significantly reduce celery root leaf and root Cd content of carrot.4 passivation agent can significantly reduce the content of Pb in celery stalk; palygorskite, steel slag after treatment, phosphate rock powder, can significantly reduce the Pb content of carrot root; phosphate powder and palygorskite after treatment can significantly reduce the tomato edible parts (fruit) Pb content. (4) indoor isothermal adsorption desorption test results show that steel slag, palygorskite, phosphorite powder on heavy metals Cd, ion Cu, Pb, As, Zn have good adsorption effect; adsorption isotherm accords with the increase of Langmuir equation and Freundlich equation.4 passivation agent with the initial concentration of the 5 kinds of heavy metal ions Cu, Cd, Pb, As, Zn adsorption were increased. Under the same initial concentration condition 4, the adsorption of heavy metal ions on the passivation agent is different. In the equilibrium concentration under the same conditions, the adsorption capacity of 4 passivation agent on Cu performance of palygorskite phosphate slag charcoal; adsorption capacity of Cd for the performance of steel slag is phosphate palygorskite charcoal; adsorption amount of Pb on the performance of phosphate rock palygorskite slag powder charcoal; adsorption performance of As in steel slag under the condition of low concentration phosphate powder palygorskite charcoal, while in high concentration, charcoal, phosphorite powder, the adsorption capacity of Palygorskite on As is close to Zn; the adsorption capacity of steel slag for the performance of palygorskite phosphorus powder charcoal (5) desorption. The test shows that the slag of heavy metal ions Cd, As, Zn small amount, phosphorite powder, charcoal, palygorskite for 5 kinds of heavy metal ions adsorption desorption increase with the increase of the amount, in particular: the maximum adsorption capacity, 4 kinds of Passivator on Zn desorption of phosphate powder for charcoal palygorskite slag; on As desorption of palygorskite charcoal phosphate slag; on Pb desorption for charcoal palygorskite phosphate slag; on Cd desorption for charcoal palygorskite phosphate slag; on Cu desorption for charcoal slag phosphate powder of palygorskite. Compared 4 kinds of charcoal in passivation agent for 5 kinds of heavy metal ion desorption were larger. (6) 4 kinds of passivator, charcoal and palygorskite has larger surface area and Kong Rong passivation mechanism of heavy metals by physical adsorption and ion exchange adsorption; steel slag and phosphate rock surface and Kong Rong although smaller, but out With high pH value, the passivation mechanism for heavy metals may be dominated by chemical precipitation.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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