超积累植物热解与超临界水气化过程中重金属迁移特性研究
发布时间：2018-11-20 08:59
【摘要】：我国土壤重金属污染日趋严重,植物修复技术日趋成熟,未来植物修复技术的广泛应用必将带来修复后超积累植物处置的问题。因此,急需开展对其处置过程中能源回收利用与污染物控制的技术研究。本文首先总结了国内外处置超积累植物各种技术的研究进展,分析了传统处置技术的现状和特点,对比超临界水气化技术,体现出超临界水气化的特点与优势,说明研究的意义与应用前景。其次,选用超积累植物蜈蚣草作为研究对象在管式炉内进行热解试验。分析得到热解温度对重金属有重要影响,温度的升高促进重金属迁移,金属挥发强度依次是Pb≈CdZnCrCu≈Ni;热解处理可以使重金属在残渣中富集,有利利后续重金属回收利用,提高工艺经济性;热解温度的提高可以降低残渣重金属浸出浓度,浸出率的降低表明残渣中重金属向更稳定形态转变。在间歇式超临界实验台上进行蜈蚣草超临界水气化试验,结果表明反应温度提高促进Cu、Pb和Zn向固相沉积,Cd向液相迁移;温度升高促进As、Cd、Cu向残渣态(F4)转变,少量Zn会向可还原态(F2)和可氧化态(F3)转变;反应压力的提高促进了 Cu、As和Zn从液相析出回到固相,随着压力的提升,更多的酸提取态(F1)和可还原态的Cd向可氧化态和残渣态转变,也促进Pb从可氧化态向残渣态转变,Zn向可氧化态转变;停留时间的延长促进As、Cd和Zn溶于液相,更多的Pb、Cu从液相中析出沉降;反应停留时间促进As、Zn、Pb向残渣态转变,Cd、Cu向可氧化态转变。超临界水气化后,Cu和As主要留在固相产物内,Cd、Pb和Zn三种重金属经过反应后主要溶解在液相产物中,但会随着反应条件的改变,改变迁移方向;残渣中的重金属主要以残渣态存在,四种形态的含量:F4F3F2F1。通过对比热解和超临界水气化后残渣的浸出毒性,以及对应工况参数,体现了超临界水气化处理技术具有较明显优势。最后对超临界水气化中重金属的迁移转化和形态分布机理进行了讨论,通过实验数据建立动力学经验模型,并对下一步进行的实验研究做出展望。
[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，
本文编号：2344479
[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，
本文编号：2344479
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