【摘要】：我國土壤重金屬污染日趨嚴重,植物修復技術日趨成熟,未來植物修復技術的廣泛應用必將帶來修復后超積累植物處置的問題。因此,急需開展對其處置過程中能源回收利用與污染物控制的技術研究。本文首先總結了國內(nèi)外處置超積累植物各種技術的研究進展,分析了傳統(tǒng)處置技術的現(xiàn)狀和特點,對比超臨界水氣化技術,體現(xiàn)出超臨界水氣化的特點與優(yōu)勢,說明研究的意義與應用前景。其次,選用超積累植物蜈蚣草作為研究對象在管式爐內(nèi)進行熱解試驗。分析得到熱解溫度對重金屬有重要影響,溫度的升高促進重金屬遷移,金屬揮發(fā)強度依次是Pb≈CdZnCrCu≈Ni;熱解處理可以使重金屬在殘渣中富集,有利利后續(xù)重金屬回收利用,提高工藝經(jīng)濟性;熱解溫度的提高可以降低殘渣重金屬浸出濃度,浸出率的降低表明殘渣中重金屬向更穩(wěn)定形態(tài)轉變。在間歇式超臨界實驗臺上進行蜈蚣草超臨界水氣化試驗,結果表明反應溫度提高促進Cu、Pb和Zn向固相沉積,Cd向液相遷移;溫度升高促進As、Cd、Cu向殘渣態(tài)(F4)轉變,少量Zn會向可還原態(tài)(F2)和可氧化態(tài)(F3)轉變;反應壓力的提高促進了 Cu、As和Zn從液相析出回到固相,隨著壓力的提升,更多的酸提取態(tài)(F1)和可還原態(tài)的Cd向可氧化態(tài)和殘渣態(tài)轉變,也促進Pb從可氧化態(tài)向殘渣態(tài)轉變,Zn向可氧化態(tài)轉變;停留時間的延長促進As、Cd和Zn溶于液相,更多的Pb、Cu從液相中析出沉降;反應停留時間促進As、Zn、Pb向殘渣態(tài)轉變,Cd、Cu向可氧化態(tài)轉變。超臨界水氣化后,Cu和As主要留在固相產(chǎn)物內(nèi),Cd、Pb和Zn三種重金屬經(jīng)過反應后主要溶解在液相產(chǎn)物中,但會隨著反應條件的改變,改變遷移方向;殘渣中的重金屬主要以殘渣態(tài)存在,四種形態(tài)的含量:F4F3F2F1。通過對比熱解和超臨界水氣化后殘渣的浸出毒性,以及對應工況參數(shù),體現(xiàn)了超臨界水氣化處理技術具有較明顯優(yōu)勢。最后對超臨界水氣化中重金屬的遷移轉化和形態(tài)分布機理進行了討論,通過實驗數(shù)據(jù)建立動力學經(jīng)驗模型,并對下一步進行的實驗研究做出展望。
[Abstract]:Soil heavy metal pollution is becoming more and more serious in China, and phytoremediation technology is becoming more and more mature. In the future, the widespread application of phytoremediation technology will bring about the problem of superaccumulation of plant disposal after remediation. Therefore, it is urgent to carry out technical research on energy recovery and pollutant control in the process of its disposal. In this paper, the research progress of supercritical water gasification technology at home and abroad is summarized, and the present situation and characteristics of traditional treatment technology are analyzed. Compared with supercritical water gasification technology, supercritical water gasification shows the characteristics and advantages of supercritical water gasification. The significance and application prospect of the research are explained. Secondly, the hyperaccumulative plant Pteris vittata was selected as the object of study. The results show that the pyrolysis temperature has an important effect on heavy metals, and the increase of temperature promotes the migration of heavy metals, and the volatilization intensity of metals is Pb 鈮，

本文編號：2344479