本文選題：重金屬污染土 + 固化��； 參考：《合肥工業(yè)大學(xué)》2017年碩士論文

【摘要】：隨著我國(guó)工業(yè)化的快速推進(jìn),重金屬污染問題日益嚴(yán)峻,重金屬污染土修復(fù)成為人們最為關(guān)注的環(huán)境問題之一,基于以往的研究,固化穩(wěn)定法被認(rèn)為是處理重金屬污染場(chǎng)地最為有效的方法之一。通過尋求新的、具有經(jīng)濟(jì)效益的固化劑,并揭示其固定化機(jī)理,將會(huì)進(jìn)一步促進(jìn)固化修復(fù)技術(shù)的發(fā)展,更好地解決實(shí)際工程問題。本文以國(guó)家自然科學(xué)基金項(xiàng)目(No.41172273)和國(guó)家自然科學(xué)基金項(xiàng)目(No.41372281)為依托,采用水泥和堿渣作為固化劑,分析討論了固化鋅、鉻污染土的無(wú)側(cè)限抗壓強(qiáng)度特性、淋濾特性、電阻率特性、微結(jié)構(gòu)特性及其變化規(guī)律。得到的主要結(jié)論如下:(1)基于無(wú)側(cè)限抗壓強(qiáng)度結(jié)果,無(wú)側(cè)限抗壓強(qiáng)度會(huì)隨著養(yǎng)護(hù)齡期的增大而增大,隨著初始重金屬離子濃度的增加而降低;在較高重金屬濃度下,養(yǎng)護(hù)后的強(qiáng)度仍能達(dá)到美國(guó)對(duì)重金屬污染土的修復(fù)標(biāo)準(zhǔn)0.35MPa;固化鉻污染土無(wú)側(cè)限抗壓強(qiáng)度高于固化鋅污染土的無(wú)側(cè)限抗壓強(qiáng)度。(2)TCLP淋濾試驗(yàn)結(jié)果表明,浸出液中重金屬離子濃度隨著養(yǎng)護(hù)齡期的增大而降低,隨著初始重金屬離子摻量增加而增大;根據(jù)U.S.EPA的TCLP試驗(yàn)規(guī)定,濾出液中鋅離子濃度的最高限值為10mg/L,鉻離子濃度的最高限值為5mg/L,在較低重金屬離子濃度下,濾出液中鋅、鉻離子溶出量均能達(dá)到環(huán)境要求,在高濃度時(shí),部分固化劑配比摻量下的鋅離子的浸出量未能達(dá)到環(huán)境要求。(3)基于無(wú)側(cè)限抗壓強(qiáng)度和淋濾試驗(yàn)結(jié)果,水泥和堿渣固化鉻污染土的固化效果比固化鋅污染土效果要好,主要是因?yàn)殇\離子對(duì)水化反應(yīng)阻礙作用明顯,鉻離子更易以絡(luò)合物沉淀的形式填充在土體顆�？紫吨小�(4)基于無(wú)側(cè)限抗壓強(qiáng)度和TCLP淋濾試驗(yàn)結(jié)果:對(duì)于鉻污染土,較低濃度下(Cr0.1、Cr0.5),最優(yōu)固化劑摻量配比:固化劑總摻量20%,水泥堿渣配比2:8。較高濃度下(Cr1):固化劑總摻量30%,水泥堿渣配比3:7;對(duì)于固化鋅污染土,較低濃度下(Zn0.1、Zn0.5),最優(yōu)固化劑摻量配比:固化劑總摻量30%,水泥堿渣配比5:5。較高濃度下(Zn1):固化劑摻量30%,水泥堿渣配比3:7。(5)固化土體的平均電阻率隨著養(yǎng)護(hù)齡期的增加而增大。水泥摻量一定,堿渣摻量提高,平均電阻率越高。平均電阻率隨著初始重金屬離子摻量增大而降低。電阻率與無(wú)側(cè)限抗壓強(qiáng)度正相關(guān),與淋濾液重金屬濃度負(fù)相關(guān)。電阻率增大,主要是因?yàn)樗磻?yīng)產(chǎn)物吸附、包裹、沉淀重金屬離子并填充在孔隙內(nèi)部,土體變得致密,使得土體連通性變差、孔隙液中游離的陽(yáng)離子變少。(6)基于掃描電鏡結(jié)果,隨著養(yǎng)護(hù)齡期的增大,CSH、CAH和AFt等水化產(chǎn)物增加。Zn~(2+)對(duì)水化反應(yīng)具有明顯的阻礙作用,土體中除了少量的Ca(OH)_2之外,幾乎看不到水化產(chǎn)物生成;XRD試驗(yàn)結(jié)果表明隨著養(yǎng)護(hù)齡期的增加,水化產(chǎn)物含量增加,重金屬離子含量降低,水化產(chǎn)物增多,宏觀表現(xiàn)為土體無(wú)側(cè)限抗壓強(qiáng)度增大,重金屬離子固化效果增強(qiáng),土體導(dǎo)電性能變差,電阻率增大。
[Abstract]:With the rapid development of industrialization in China, the problem of heavy metal pollution is becoming more and more serious. Remediation of heavy metal contaminated soil has become one of the most concerned environmental problems. Solidification stabilization method is considered to be one of the most effective methods to deal with heavy metal contaminated sites. By looking for new and economically effective curing agents and revealing their immobilization mechanism, the development of curing and repairing technology will be further promoted and the practical engineering problems will be solved better. Based on National Natural Science Foundation Project No. 41172273) and National Natural Science Foundation Project No. 41372281), using cement and alkali slag as curing agent, the characteristics of unconfined compressive strength and leaching of solidified zinc and chromium contaminated soil are analyzed and discussed in this paper. Electrical resistivity, microstructure and its variation. The main conclusions are as follows: (1) based on the results of unconfined compressive strength, the unconfined compressive strength increases with the increase of curing age and decreases with the increase of initial concentration of heavy metal ions. The strength after curing can still reach the standard of 0.35 MPa for heavy metal contaminated soil, the unconfined compressive strength of solidified chromium contaminated soil is higher than that of zinc contaminated soil, and the results of TCLP leaching test show that the strength of cured chromium contaminated soil is higher than that of zinc contaminated soil. The concentration of heavy metal ions in leaching solution decreases with the increase of curing age and increases with the increase of initial heavy metal ion content. The maximum limit of zinc ion concentration in filtrate is 10 mg / L, and the highest limit value of chromium ion concentration is 5 mg / L. At low heavy metal ion concentration, the leaching amount of zinc and chromium ions in filtrate can meet the environmental requirements. Based on the unconfined compressive strength and leaching test results, the solidification effect of cement and alkali slag solidified chromium contaminated soil is better than that of zinc contaminated soil. The main reason is that zinc ion has obvious hindrance to hydration reaction, chromium ion is more likely to be filled in soil particle pores in the form of complex precipitation) based on unconfined compressive strength and TCLP leaching test results: for chromium contaminated soil, At lower concentration, the optimum ratio of solidifying agent is 20%, and the ratio of cement alkali slag is 2: 8. At higher concentration, the total amount of curing agent is 30, and the ratio of cement and alkali slag is 3: 7. For the soil contaminated with zinc, the optimum ratio of the amount of solidified agent is 30%, and the ratio of cement and alkali slag is 5: 5%. The average resistivity of solidified soil increases with the increase of curing age when the content of curing agent is 30 and the ratio of cement and alkali slag is 3: 7. 5. The higher the content of alkali slag is, the higher the average resistivity is. The average resistivity decreases with the increase of initial heavy metal ion content. The resistivity was positively correlated with the unconfined compressive strength and negatively correlated with the concentration of heavy metals in leachate. The resistivity increases mainly because the hydration reaction product adsorbs, encapsulates, precipitates heavy metal ions and fills in the pores, so that the soil becomes compact and makes the soil less connected. On the basis of SEM results, the hydration products such as CSHH CAH and AFT increased with the increase of curing age. The XRD results showed that with the increase of curing age, the hydration product content increased, the heavy metal ion content decreased, and the hydration product increased. The solidification effect of heavy metal ions is enhanced, the conductivity of soil becomes worse and the resistivity increases.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X53

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