發(fā)布時(shí)間：2018-04-09 05:22

  本文選題：重金屬污染土　切入點(diǎn)：干濕循環(huán)　出處：《合肥工業(yè)大學(xué)》2017年碩士論文

【摘要】：利用固化/穩(wěn)定法處理重金屬污染土已得到國內(nèi)外學(xué)者的廣泛認(rèn)可,其固化效果顯著且經(jīng)濟(jì)可行。然而,在復(fù)雜多變的自然環(huán)境中,干濕交替的氣候變化可能會(huì)改變固化土體強(qiáng)度及化學(xué)穩(wěn)定性,從而影響土體的固化效果。因此,進(jìn)行固化重金屬污染土在干濕循環(huán)作用下的強(qiáng)度、淋濾、微結(jié)構(gòu)等方面的研究,不僅有助于進(jìn)一步了解固化土體修復(fù)機(jī)理,也可以對(duì)固化土體的長期穩(wěn)定性做出進(jìn)一步的預(yù)測(cè)和維護(hù)。基于此,本文以國家自然科學(xué)基金項(xiàng)目(No.41172273)和國家自然科學(xué)基金項(xiàng)目(No.41372281)為依托,以堿渣和水泥固化重金屬污染土為研究對(duì)象,通過干濕循環(huán)試驗(yàn)、強(qiáng)度試驗(yàn)、淋濾試驗(yàn)以及微結(jié)構(gòu)試驗(yàn),探討了固化鉻/鋅污染土在干濕循環(huán)作用下的性質(zhì)變化規(guī)律。取得以下主要研究成果:(1)通過對(duì)不同類型固化污染土進(jìn)行強(qiáng)度穩(wěn)定性研究得出,固化鉻污染土隨干濕循環(huán)次數(shù)的增加,累計(jì)質(zhì)量損失的增大呈現(xiàn)先慢后快的趨勢(shì),而固化鋅污染土則呈現(xiàn)先快后慢的趨勢(shì),且總體質(zhì)量損失鋅大于鉻;固化鉻、鋅污染土強(qiáng)度均隨干濕循環(huán)的作用先增大后減小,前期增長幅度較小,后期降低幅度較大;固化鉻污染土強(qiáng)度大于鋅污染土,最后兩者的強(qiáng)度接近,土體均遭到嚴(yán)重破壞;同級(jí)干濕循環(huán)作用下,30%固化劑摻量的土體強(qiáng)度大于20%固化劑摻量。(2)通過對(duì)干濕循環(huán)作用下固化重金屬污染土的化學(xué)穩(wěn)定性研究發(fā)現(xiàn),固化鋅、鉻污染土浸泡液pH值與Ca~(2+)浸出量均隨干濕循環(huán)的次數(shù)增大逐漸減小;對(duì)于浸出Ca~(2+)離子總量,固化鉻污染試樣小于鋅試樣,固化劑摻量20%的試樣小于30%。通過TCLP和半動(dòng)態(tài)淋濾試驗(yàn)發(fā)現(xiàn),TCLP試驗(yàn)中,不同固化劑摻量的固化鉻和鋅污染土浸出液的pH值均隨土樣干濕循次數(shù)增加逐漸減小;TCLP浸出液中鉻、鋅的浸出濃度均隨干濕循環(huán)的作用先減小后增大。鉻離子浸出量總體小于鋅;半動(dòng)態(tài)淋濾試驗(yàn)中,浸泡液pH值在一個(gè)小范圍內(nèi)波動(dòng);半動(dòng)態(tài)淋濾試驗(yàn)中,累計(jì)離子浸出量隨浸泡時(shí)間的增加逐漸增加,隨試樣經(jīng)受干濕循環(huán)次數(shù)增多而增大;兩種固化土體中的離子擴(kuò)散系數(shù)均隨干濕循環(huán)次數(shù)增加先減小后增大,且鋅大于鉻。(3)通過SEM和XRD微觀分析方法探討了干濕循環(huán)次數(shù)、離子類型和固化劑摻量等因素對(duì)固化土體的微結(jié)構(gòu)影響。與土體宏觀性質(zhì)改變相互印證,進(jìn)一步科學(xué)完善的解釋重金屬污染土的固化機(jī)理。
[Abstract]:The treatment of heavy metal contaminated soil by solidification / stabilization method has been widely recognized by scholars at home and abroad, and its solidification effect is remarkable and economical and feasible.However, in the complex and changeable natural environment, the soil solidification strength and chemical stability may be changed by the alternate climate change of dry and wet, thus affecting the solidification effect of soil.Therefore, to study the strength, leaching and microstructure of solidified heavy metal contaminated soil under dry and wet cycle is not only helpful to further understand the mechanism of solidified soil remediation.Further prediction and maintenance of long-term stability of solidified soil can also be made.Based on this, this paper takes National Natural Science Foundation Project No. 41172273) and National Natural Science Foundation Project No. 41372281) as the research object, takes alkali slag and cement solidified heavy metal contaminated soil as the research object, through dry-wet cycle test, strength test,Leaching tests and microstructure tests were carried out to investigate the properties of solidified chromium / zinc contaminated soils under dry and wet cycling.Through the study of the strength stability of different types of solidified contaminated soils, it is concluded that with the increase of dry-wet cycles, the cumulative mass loss increases with the increase of dry and wet cycles.On the other hand, the solidified zinc contaminated soil showed a tendency of fast and then slow, and the total loss of zinc was larger than that of chromium, and the strength of solidified chromium and zinc contaminated soil increased first and then decreased with the effect of dry and wet cycle, and the increase range was small in the early stage, and the decrease was larger in the later stage.The strength of solidified chromium contaminated soil is higher than that of zinc contaminated soil, and the strength of the last two soils is close to that of zinc contaminated soil.The soil strength of 30% curing agent is larger than that of 20% curing agent under the same order dry and wet cycle.) the chemical stability of heavy metal contaminated soil solidified under dry and wet cycle is studied, and it is found that zinc is solidified.The pH value of the soaking solution and the leaching amount of Ca~(2 gradually decreased with the increase of the number of dry and wet cycles, and for the total amount of leaching Ca~(2, the amount of solidified chromium contaminated sample was less than that of zinc sample, and the content of solidifying agent was less than 30%.Through TCLP and semi-dynamic leaching tests, it was found that the pH value of the leaching solution of solidified chromium and zinc contaminated soil with different content of curing agent decreased gradually with the increase of dry and wet cycles of soil samples.The leaching concentration of zinc decreased firstly and then increased with the effect of dry and wet cycle.In the semi-dynamic leaching test, the pH value of the solution fluctuated in a small range, and in the semi-dynamic leaching test, the accumulated ion leaching amount increased with the increase of soaking time.The ion diffusion coefficient in both solidified soils decreased first and then increased with the increase of dry and wet cycles, and zinc was larger than chromium. 3) the times of dry and wet cycles were discussed by SEM and XRD microanalysis.The effect of ion type and the amount of curing agent on the microstructure of solidified soil.The mechanism of solidification of heavy metal contaminated soil is explained scientifically and perfectly with the change of macroscopical properties of soil.
【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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