零价铁去除医疗垃圾焚烧飞灰中重金属的研究

发布时间：2018-06-11 13:17

本文选题：医疗飞灰 + 零价铁　；参考：《河南师范大学》2017年硕士论文

【摘要】：医疗垃圾焚烧飞灰中富集着大量的重金属,如何实现医疗飞灰无害化和资源化利用目的,对于重金属的污染控制具有重要意义。零价铁对医疗飞灰进行脱毒技术的应用,为危险废物的处理提供一种新的途径。本文介绍了医疗飞灰的研究背景、处理技术以及反应机理,提出利用零价铁去除医疗焚烧飞灰中重金属的方法。主要以医疗焚烧飞灰中重金属为研究对象,试验了不同影响因素,如:不同pH值,零价铁的投加量,溶液反应温度,不同反应时间以及不同粒径零价铁对重金属去除的影响,研究飞灰残渣浸出毒性,零价铁表面重金属XPS分析,探讨了零价铁对医疗飞灰重金属去除机理,最后通过医疗飞灰洗脱装置对医疗飞灰进行连续脱毒试验,并针对零价铁脱毒后医疗飞灰的毒性进行分析,以此增加飞灰资源化效率。本次探究主要得出以下结论:(1)医疗垃圾焚烧飞灰中富集着大量的重金属,如Zn、Cu、Pb、As、Cr、Ni、Cd的含量分别为38852.5、6967.2、2719.7、458.2、360.7、301.6和60.3mg/kg。远高于我国土壤背景值,表明医疗飞灰具有很强的危害性,TCLP浸出实验表明,Zn、Pb和Cu等重金属浸出浓度最大,且浓度范围超出危险废物鉴别标准,对环境具有较高潜在风险。(2)零价铁在不同pH条件下处理效果明显不同。pH值为4时,医疗飞灰中含量较高的Cu、Pb、Zn等元素在零价铁处理下效果更加明显,而在洗脱液pH值为2时,零价铁对飞灰中Cr、Cd、As的处理效果相对明显,温度的变化对飞灰重金属的去除影响较小。高温环境和相对较低的温度都不利于零价铁对医疗飞灰的处理。过量零价铁的投加对医疗飞灰重金属的去除效率贡献不大,零价铁与医疗飞灰反应时间不同,重金属去除率也不一样,当反应12h时,Cu、Zn和Cr的浸出达到最低。粒径越小,零价铁还原性越高,处理效果明显,但其稳定性降低。(3)医疗飞灰残渣毒性鉴别实验中,TCLP实验表明,医疗飞灰中Zn的浸出浓度由原样的702mg/L下降到97mg/L,Pb的浸出浓度由19.54mg/L降到了0.13mg/L,Cd的浸出由1.43mg/L降到了0.29mg/L,PBET体外模拟实验表明飞灰残渣在极端条件下进入人体内,在蛋白质等有机物作用下重金属的浸出浓度增大,而长期浸出实验MEP中医疗飞灰Cu、Pb和Zn浸出浓度有所增加,Zn的累积浸出浓度超过了危险废物毒性鉴别标准,仍然具有较高的环境风险。(4)X射线光电子谱(XPS)对零价铁混合物进行表征,由零价铁反应物XPS总图谱可知,零价铁表面出现了Zn、Cu、Cr、Cd和Pb的特征峰,表明这些重金属反应后吸附在零价铁表面。Cu_2p电子结合能谱出现在932.4eV和952.2eV,两个峰分别为Cu(0)和Cu(Ⅱ),Cu(Ⅱ)的去除主要以化学还原形式发生,Cd主要以Cd(Ⅱ)形式存在,并未出现Cd(0)的特征峰。(5)不同毒性鉴别方法中重金属浸出比例不同,TCLP实验中,Pb和Zn的可交换态溶出占比例较高,PBET和MEP实验中不同价态重金属均有浸出,尤其交换态和碳酸盐结合态,说明这两种体系中溶出能力较强,而飞灰的处理需由飞灰的特性及实际环境进行综合判定。(6)工业铁屑脱毒装置对医疗飞灰进行脱毒结果表明,经过零价铁脱毒柱脱毒,医疗飞灰TCLP中Zn、Cu、Pb和Cd毒性浸出浓度进一步降低,分别为13.15、5.75、0.09和0.01mg/L,远低于危险废物浸出标准。且飞灰综合评价浸出浓度均能满足生活垃圾填埋场入场标准,说明医疗飞灰的无害化效果明显。
[Abstract]:A large number of heavy metals are enriched in the fly ash of medical waste incineration. How to realize the harmless and resource utilization of medical fly ash is of great significance to the pollution control of heavy metals. The application of zero valent iron to medical fly ash is used to provide a new way for the treatment of hazardous waste. The study of medical fly ash is introduced in this paper. Background, treatment technology and reaction mechanism, the method of removing heavy metals in medical incineration fly ash by zero valent iron is proposed. The main factors are the heavy metal in the fly ash of medical incineration, and the different influence factors, such as the pH value, the dosage of zero valent iron, the temperature of the solution reaction, the different reaction time and the heavy gold with different particle size zero valent iron are tested. In the influence of removal, the toxicity of fly ash residue leaching and the analysis of heavy metal XPS on zero valent iron surface were studied. The mechanism of the removal of heavy metals from medical fly ash by zero valent iron was discussed. Finally, the continuous detoxification test of medical fly ash was carried out by medical fly ash elution device, and the toxicity of medical fly ash after zero valent iron detoxification was analyzed in order to increase the cost of fly ash. The main conclusions are as follows: (1) a large number of heavy metals are enriched in the fly ash of medical waste incineration, such as Zn, Cu, Pb, As, Cr, Ni, and Cd, respectively, 38852.56967.22719.7458.2360.7301.6 and 60.3mg/kg. are far higher than the soil background values of our country, indicating that the medical fly ash has a strong harmfulness, TCLP leaching experiments show that Z, Z The concentration of heavy metals such as N, Pb and Cu is the largest, and the concentration range exceeds the hazardous waste identification standard. (2) when the treatment effect of zero valent iron is obviously different under different pH conditions, the.PH value is 4, the higher content of Cu, Pb, Zn and other elements in the medical fly ash are more obvious under the zero valent iron treatment, but in the pH value of the eluent. At 2, the treatment effect of zero valent iron on Cr, Cd and As in fly ash is relatively obvious. The change of temperature has little effect on the removal of heavy metals in fly ash. High temperature environment and relatively low temperature are not conducive to the treatment of medical fly ash by zero valent iron. The addition of excessive zero valent iron contributes little to the removal efficiency of medical fly ash heavy gold, zero valent iron and medical flight. When the reaction time is different, the removal rate of heavy metals is different. When the reaction 12h, the leaching of Cu, Zn and Cr is the lowest. The smaller the particle size, the higher the reducibility of the zero valent iron, the treatment effect is obvious, but the stability is reduced. (3) the TCLP experiment shows that the leaching concentration of Zn in the medical fly ash is decreased from the original 702mg/L. To 97mg/L, the leaching concentration of Pb was reduced from 19.54mg/L to 0.13mg/L, the leaching of Cd was reduced from 1.43mg/L to 0.29mg/L. In vitro simulation experiment of PBET showed that the residue of fly ash entered human body under extreme conditions, and the leaching concentration of heavy metals increased under the action of protein and other organic substances, while the long-term leaching experiment of MEP traditional Chinese medicine for fly ash Cu, Pb and Zn leaching concentration were found. The cumulative leaching concentration of Zn was higher than the hazardous waste toxicity identification standard and still had high environmental risk. (4) the X ray photoelectron spectroscopy (XPS) was used to characterize the zero valent iron mixture. It was known from the XPS total Atlas of the zero valent iron reactant that the characteristic peaks of Zn, Cu, Cr, Cd and Pb appeared on the surface of the zero valent iron, indicating the adsorption of these heavy metals after the reaction. The.Cu_2p electron binding energy spectrum of the zero valent iron surface appears in 932.4eV and 952.2eV, two peaks are Cu (0) and Cu (II), Cu (II) is removed mainly by chemical reduction, Cd mainly exists in the form of Cd (II), and there is no characteristic peak of Cd (0). (5) the proportion of heavy metals leaching in different toxicity identification methods is different, TCLP experiments, Pb and Zn can be found. The exchange state dissolution accounts for a higher proportion. The different valence heavy metals in PBET and MEP experiments have been leached, especially the exchange state and the carbonate binding state, which indicates that the dissolution of these two systems is strong, and the treatment of fly ash should be determined by the characteristics of fly ash and the actual environment. (6) the detoxification result of the industrial iron detoxification device for medical fly ash The results showed that the toxic leaching concentration of Zn, Cu, Pb and Cd in the medical fly ash TCLP was further reduced by the zero valent iron detoxification column, respectively, 13.15,5.75,0.09 and 0.01mg/L, which were far below the standard of hazardous waste leaching, and the comprehensive evaluation of the leaching concentration of fly ash could meet the standard of the domestic waste landfill site, which showed that the harmless effect of medical fly ash was obvious.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X799.5

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