土壤重金属吸附材料的筛选及机理探讨

发布时间：2018-03-09 13:34

本文选题：保水剂　切入点：凹凸棒　出处：《扬州大学》2017年硕士论文　论文类型：学位论文

【摘要】：土壤重金属污染涉及食品安全的重要环境问题。重金属离子通过植物吸收进入食物链,或者因渗漏作用进入地下水和土壤中,对人类的生存及生态环境造成严重的威胁,因此对土壤重金属污染的治理已经迫在眉睫。铅、镉、铜重金属污染土壤后会长时间存留在土壤中,当累计到一定量时就会对人类和生态环境的健康造成极大的威胁。近年来,科学工作者正在努力研究新型材料用于土壤重金属的修复治理。基于保水剂所具有较强的重金属吸附能力,其已被作为重金属污染土壤的修复候选材料之一。此外凹凸棒、硅藻土、生物炭等环保型矿物材料也被作为土壤重金属的候选修复材料加以关注。本文首先利用电镜技术对保水剂(聚丙烯酸钠)、凹凸棒、硅藻土、生物炭吸附重金属铅、镉、铜的表面结构和元素组成进行了表征,然后通过吸附和解吸试验确认了它们对铅、镉、铜的吸附能力。在此基础上,通过向铅、镉、铜污染土壤中添加不同用量保水剂、凹凸棒、硅藻土、生物炭后的黑麦草盆栽试验,探讨了保水剂、凹凸棒、硅藻土、生物炭对黑麦草吸铅、镉、铜以及对土壤重金属形态转化的影响,为将保水剂、凹凸棒、硅藻土、生物炭应用于污染土壤的修复提供了参考数据,并从理论上对添加这些材料对土壤中重金属形态和转化的影响进行了探讨。试验结果表明:1.通过电镜扫描图得知,保水剂吸附重金属离子前其表面是光滑平整的,在吸附铅、镉、铜离子后其表面结构凹凸不平,具有不同的表征特点;而凹凸棒、硅藻土、生物炭吸附金属离子前后其表征结构未发生明显变化。2.四种材料在不同重金属浓度下的吸附实验表明,它们对铅的最大吸附能力排序为:保水剂凹凸棒生物炭硅藻土,分别达到:461.6 mg·g-1、198.0 mg·g-1、123.3 mg·g-1、73.3 mg·g-1;它们对镉的最大吸附能力排序为:保水剂生物炭凹凸棒硅藻土,分别为131.3 mg·g-1、30.9mg·g-1、19.6 mg·g-1、19.4 mg·g-1;它们对铜的最大吸附能力排序为保水剂凹凸棒生物炭硅藻土,分别为 77.6 mg·g-1、23.6 mg·g-1、13.6 mg·g-1、1.5mg·g-1;材料CEC值的大小排序也证明了保水剂吸附铅、镉、铜的能力最大。3.解吸试验表明,被保水剂、凹凸棒、硅藻土、生物炭吸附的铅、镉、铜离子与材料的结合方式主要是通过螯合作用和络合作用,而通过离子交换方式吸附的量很少。4.保水剂可促进易溶性铅、镉、铜向难溶性铅、铜的转化,而黑麦草可促进难溶性铅、镉、铜的溶解。两者共同作用虽可明显导致难溶性铅、镉、铜的减少,但溶解出的铅、镉、铜将率先被保水剂所吸附,从而减少了对植物的供应,导致黑麦草地上部的铅、镉、铜含量降低。5.凹凸棒可改变土壤铅、镉、铜形态但无钝化金属离子的作用。黑麦草的存在促进了难溶的残渣态铅、镉、铜向可氧化态和还原态、酸溶态的转化,在施加凹凸棒与种植黑麦的同时,凹凸棒明显抑制了黑麦草对金属离子铅、镉、铜的吸收。6.硅藻土可改变土壤铅、镉、铜形态但无钝化金属离子的作用。黑麦草的存在促进了难溶的残渣态铅、镉、铜向可氧化态和还原态、酸溶态的转化,在施加硅藻土与种植黑麦的同时,硅藻土抑制了黑麦草对金属离子铅、镉、铜的吸收,特别对抑制黑麦草吸收铜效果显著。7.生物炭可改变土壤铅、镉、铜形态,但无钝化金属离子的作用。黑麦草的存在促进了难溶的残渣态铅、镉、铜向可氧化态和还原态、酸溶态的转化,黑麦草所吸收铅、镉、铜离子的体内含量因生物炭的添加而降低,生物炭对抑制黑麦草吸收铅、镉效果显著。
[Abstract]:The important environmental problem of soil heavy metal pollution involving food safety. Heavy metal ions entering the food chain through plant uptake, or due to leakage into the soil and groundwater, causing a serious threat to human survival and ecological environment, so the remediation of contaminated soil has been imminent. Lead, cadmium, copper contaminated soil after a long time remaining in the soil, when accumulated to a certain amount will be on the ecological environment and people's health caused great threat. In recent years, scientists are working on new material for the remediation of soil heavy metal. Based on water retaining agent has strong adsorption capacity of heavy metals, which has been used as one of the candidate materials for the remediation of heavy metal contaminated soil in addition, attapulgite, diatomite, biochar and other environmental mineral materials were used as candidate repair materials to soil heavy metals Pay attention. This paper by electron microscope on the water retaining agent (sodium polyacrylate), attapulgite, diatomite, biological activated carbon adsorption of lead, cadmium, copper surface structure and elemental composition were characterized by adsorption and desorption experiments confirmed on lead, cadmium, copper adsorption capacity. On this basis, through the to lead, cadmium and copper in soil contaminated with different amount of super absorbent, attapulgite, diatomite, ryegrass, pot experiment biochar, discusses the water retaining agent, attapulgite, diatomite, biochar lead, cadmium and copper uptake of ryegrass, influence on the transformation of soil heavy metals, the water retaining agent, attapulgite repair, diatomite, biochar applied to contaminated soil reference data, and theoretically to add these material effect on heavy metal speciation and transformation in soil were discussed. The experimental results show that: 1. by SEM that Paul The adsorption of heavy metal ions on the surface of the water is smooth, in the adsorption of lead, cadmium, uneven surface structure of copper ions, with different characteristics and characterization; attapulgite, diatomite, indicated that the adsorption of biochar before and after adsorption of metal ions and the characterization of the structure did not change significantly.2. four materials in different heavy metals concentration. They lead to, the maximum adsorption capacity for sorting: water retaining agent attapulgite biochar diatomite, respectively: 461.6 Mg - g-1198.0 Mg - g-1123.3 Mg - g-1,73.3 Mg - g-1; the maximum adsorption capacity of cadmium are ranked as: SAP biological activated carbon attapulgite diatomite, were 131.3 Mg - g-1,30.9mg - Mg - g-1,19.6 g-1,19.4 mg g-1; their maximum adsorption capacity for copper sort of absorbent attapulgite biological carbon diatomite, were 77.6 Mg - g-1,23.6 Mg - g-1,13.6 Mg - g-1,1.5mg - g-1 materials; CEC value Sequencing also proved water adsorption of lead, cadmium, copper desorption experiments showed that the ability of.3., by the water retaining agent, attapulgite, diatomite, biological activated carbon adsorption of lead, cadmium, copper ion and the combination of materials is mainly through chelation and complexation and adsorption by ion exchange of the small amount of.4. water can promote the soluble lead, cadmium, copper and lead to insoluble copper, transformation, and ryegrass can promote the solubility of lead, cadmium, copper dissolution. Both can obviously lead to insoluble lead, cadmium, copper is reduced, but the dissolution of lead, cadmium, copper will the first is water adsorption, thus reducing the supply of plants, resulting in ryegrass aboveground lead, cadmium, copper content decreased.5. attapulgite can change the soil lead, cadmium, copper forms but no passivation of metal ions. Promoting the residual lead, insoluble cadmium copper can be oxidized to ryegrass. State and reduction Acid soluble state, the transformation in applying attapulgite and planting rye and Ryegrass on metal ions lead, inhibited attapulgite cadmium, copper absorption of.6. diatomite can change the soil lead, cadmium, copper forms but no passivation of metal ions. Ryegrass was enhanced by the presence of residual lead, insoluble the cadmium, copper to be oxidized and reduced, acid soluble conversion, in applying diatomite and planting rye and ryegrass inhibited the diatomite to metal ions lead, cadmium, copper uptake, especially on the inhibition effect of copper uptake of ryegrass significantly.7. biochar can change the soil lead, cadmium, copper speciation, but no passivation of metal ions. Promoting the residual lead, the insoluble cadmium of ryegrass, copper to be oxidized and reduced, acid soluble conversion, ryegrass absorbed lead, cadmium, copper ion content in vivo decreased due to the addition of biochar, inhibition of biological carbon Ryegrass absorbs lead, and the effect of cadmium is remarkable.

【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;O647.3

【参考文献】