改性粘土矿物修复重金属污染底泥的稳定性研究

发布时间：2018-02-24 13:42

本文关键词： 重金属底泥稳定化有机膨润土锰基硅藻土酸改性海泡石　出处：《安徽建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：南淝河是合肥市的母亲河,它由西向东贯穿市区,接纳沿岸工矿企业生产污水和生活废水,致使河水和表层沉积物受到不同程度的重金属污染。为了缓解水体压力,减少重金属危害,本研究采用向污染底泥中添加稳定化剂的方法对表层底泥进行无害化处理。该方法依靠固化/稳定化技术,固化侧重于添加如水泥、石灰之类的固化剂,包裹污染物以形成浸出性较低的固体材料,并且在固化剂和污染物之间不涉及化学作用;稳定化注重于转化污染物的有毒形态至稳定状态,削弱污染物的可溶性和迁移性,是通过化学方式降低污染物毒性的修复技术。稳定化剂选择膨润土、硅藻土和海泡石,并经过十六烷基三甲基溴化铵有机改性、氢氧化钠和氯化锰无机改性及盐酸改性进行处理,得到有机膨润土、锰基硅藻土和酸改性海泡石。改性处理的影响主要在于不仅增加了粘土矿物的表面积,也扩大了膨润土的层间距、增加了硅藻土电负性并在其表面形成了氢氧化锰、清除了海泡石杂质并打通了内部通道和增加了Si-OH含量,从而提升各稳定化剂对重金属的吸附能力。底泥样品采集自南淝河长江路桥河段,并经预处理备用。实验分为两阶段:第一阶段向天然污染底泥中分泵添加10%质量比的稳定化剂,进行为期两月的稳定化实验,定期取样,辅以毒性浸出实验和BCR顺序提取实验,考察稳定化剂对低浓度污染底泥中重金属释放情况和形态分布的影响;第二阶段则于实验室中人工配制高浓度重金属溶液,并混于天然污染底泥中,熟化30天,然后重复阶段一实验过程,考察稳定化剂对高浓度污染底泥中重金属释放情况和形态分布的影响。同时,每阶段另设对比组,按照同一实验过程将改性前粘土矿物混于底泥中,考察改性后粘土矿物吸附重金属的能力是否得到改善。本研究获得结论如下:(1)经BCR顺序提取法测得底泥中重金属Cu、Pb、Cr各形态含量,计算得到每种重金属总量分别为166.63 mg·kg-1、36.84 mg·kg-1、249.15 mg·kg-1,远超于本地区土壤背景值和化学基线值,且生物有效态含量皆超过50%以上,存在较大生物风险。(2)天然污染底泥各重金属的浸出浓度较低,中性条件下浸出浓度皆在1.2mg·kg-1以下,酸性条件下浸出浓度在3.2mg·kg-1以下:中性浸提时,MB、MD、MS对Pb和Cr的浸出抑制率分别为68.67%、26.67%、42%和16.67%、20.83%、18.33%;酸性浸提时,MB、MD、MS对Pb和Cr的释放均产生抑制作用,抑制率分别为:31.79%、39.749%、19.87%和10%、30%、10%。形态分布结果表明,MB、MD、MS均可用于修复低浓度重金属污染底泥Pb和Cr污染,并对Pb污染具有修复优势,大量弱酸提取态F1和可还原态F2向可氧化态F3和残渣态F3转化,F3与F4联合增幅基本在75%以上。综上所述,三种稳定化剂对低浓度重金属污染底泥中的Pb和Cr具有修复效果。(3)高浓度重金属污染底泥各重金属的浸出浓度较高,MB组Cu的浸出抑制率最高,中性和酸性条件下分别为30.09%和22.54%;MD组对Cu、Pb、Cr浸出皆具有抑制作用,两种浸出条件下对Pb和Cr抑制效果较为突出,抑制率分别为30.99%和33.97%(中性)、60.71%和51.05%(酸性);MS组则对Cu表现出一定抑制效果,中性和酸性条件下抑制率分别为19.67%和14.94%。形态分布结果表明,MD组Pb的弱酸提取态F1降低了51.98%,Cr的弱酸提取态降低了36.96%,其他组形态分布变化微弱。综上所述,锰基硅藻土对高浓度重金属污染底泥中的Pb和Cr具有较明显的修复效果。(4)对比组实验显示,改性方法的使用抑制了粘土矿物本身重金属的浸出量,侧面说明了改性方法提升了各粘土矿物对重金属的吸附性能。在修复低浓度重金属污染底泥时,因浸出量过低,导致改性的粘土矿物的优势未能完全发挥;在修复高浓度重金属污染底泥时,改性组MB和MS对Cu和Pb的浸出皆有明显抑制优势,MD则对Cu、Pb、Cr的浸出均有抑制优势,特别是抑制Pb的作用尤为突出。
[Abstract]:Nanfeihe river is the mother river of Hefei. It runs through the city from west to East, accepting and living sewage along the industrial and mining enterprises production, resulting in water and surface sediments polluted by heavy metals in different degrees. In order to alleviate the pressure of water, reduce the hazards of heavy metals, the method of adding stabilizing agent to the contaminated sediments on the surface sludge harmless treatment. This method relies on the solidification / stabilization technology, focused on adding curing curing agent such as cement, lime and so on, wrapped to form a solid material leaching of pollutants is low, and does not involve the chemical interaction between the curing agent and stabilizing pollutants; focus on the transformation of pollutants toxic form to steady state soluble contaminants and mobility, weakening, is to reduce the toxicity of pollutants by chemical remediation technology. Stabilizing agent of bentonite, diatomite and sepiolite, and After sixteen alkyl three methyl bromide organic modification, sodium hydroxide and manganese chloride inorganic modification and hydrochloric acid modified processing, organic bentonite, diatomite and sepiolite modification of manganese based acid. The effect of modification treatment mainly lies in not only increases the surface area of clay minerals, also expanded the bentonite layer spacing increases the electronegativity of diatomite and its surface formed manganese hydroxide, removing impurities and sepiolite opened up the internal channel and increase the content of Si-OH, so as to enhance the ability of stable adsorption agent on heavy metals. Sediment samples were collected from the South Feihe River in Luqiao reach of Yangtze River, and the pretreatment experiment reserve. The two stage is the first stage to the natural sediment pollution in pump agent stable 10% mass ratio of the added stabilization experiment, two month regular sampling, extraction experiments with the leaching test and BCR sequence, stability study Fixed agent on the influence and distribution of the release of low concentration of heavy metals in contaminated sediments; the second stage in the laboratory of artificial high concentration of heavy metal solution, and mixed with natural sediment pollution, aging for 30 days, and then repeat the process on the stabilization stage, the effects of additives on the situation and distribution of heavy metal in high concentration the pollution in the sediment. At the same time, each stage of a comparison group, according to the same process before modification of clay minerals mixed in the sediment, effects of modified clay mineral adsorption ability is improved. The research conclusions are as follows: (1) by BCR sequential extraction method for heavy metal Cu, Pb in the sediment Cr, various forms of content, calculate the total amount of each kind of heavy metals were 166.63 Mg - kg-1,36.84 Mg - kg-1249.15 Mg - kg-1, far beyond the local soil background value and chemical baseline, and bio available content Is more than 50%, there is a big risk. (2) the leaching concentration of the heavy metals pollution of natural sediment is low, under neutral conditions, the leaching concentration are in the 1.2mg below kg-1, the leaching concentration under acidic conditions in the 3.2mg kg-1 the following: neutral leaching, MB, MD, MS, Pb and Cr on leaching inhibition rates were 68.67%, 26.67%, 42% and 16.67%, 20.83%, 18.33%; acid leaching, MB, MD, MS on the release of Pb and Cr were inhibited, the inhibition rate were 31.79%, 39.749%, 19.87% and 10%, 30%, 10%. distribution. The results showed that MB, MD, MS are for the repair of low concentration of heavy metal pollution in sediments of Pb and Cr pollution, and has the advantages of repair Pb pollution, a large number of weak acid extractable F1 and reducible to F2 can be oxidized F3 and residual F3 conversion, F3 and F4 growth in more than 75%. To sum up, three kinds of stabilizing agent with low concentration of heavy metal pollution in the sediment of Pb and Cr Repair effect. (3) high leaching concentration of heavy metal pollution in sediments of the heavy metal leaching, MB group Cu the highest inhibition rate, neutral and acidic conditions were 30.09% and 22.54%; MD group of Cu, Pb, Cr leaching has inhibitory effect, two kinds of leaching conditions on Pb and Cr suppression effects more prominent, the inhibition rate were 30.99% and 33.97%, 60.71% and 51.05% (neutral) (acid); MS group of Cu showed a certain inhibitory effect, neutral and acidic conditions inhibition rates were 19.67% and 14.94%. distribution. The results show that the MD group of Pb acetic acid extractable F1 decreased 51.98%, Cr acid extractable was reduced by 36.96%, the other group distribution changed slightly. In summary, manganese based diatomite has repair effect is obvious for the high concentration of heavy metal pollution in the sediment of Pb and Cr. (4) shows the contrast experiments, using the modified method of inhibiting clay minerals itself heavily The leaching amount of the side of the modified method to improve the adsorption properties of the clay minerals in the heavy metal pollution of heavy metals. Low concentration of sediments, due to leaching amount is too low, resulting in modified clay minerals advantage not fully play; heavy metal pollution in high concentration sediments, modified group MB and MS leaching Cu and Pb have obvious inhibitory advantages, MD on Cu, Pb, Cr were inhibited leaching, especially the inhibitory effect of Pb is particularly prominent.

【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X522

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