基于柠檬酸发酵液淋洗去除土壤重金属的研究
本文选题:柠檬酸发酵液 切入点:土壤 出处:《云南民族大学》2017年硕士论文 论文类型:学位论文
【摘要】:土壤淋洗修复技术得以发展和应用的关键在于找到一种经济、环保、适用的淋洗液,新型淋洗液的开发和现有淋洗液的改良在淋洗技术的研究和应用中都显得极其重要。本课题采用制备的柠檬酸发酵液为淋洗液进行重金属污染土壤的淋洗修复,以重金属复合污染高原红壤和矿区Pb污染土壤为作用对象开展研究,着重对柠檬酸发酵液和柠檬酸发酵液与皂素复合淋洗液的淋洗性能进行了探究。具体研究内容如下:1、土壤理化性质及重金属赋存形态分析:以Pb、Cu、Cr、Cd复合污染高原红壤为例,对土壤pH、含水量、有机质、阳离子交换量、碱解氮、粒径分布等基本理化参数进行了测定;建立了重金属含量分析方法,进行了加标回收实验,并采用BCR形态分析法对重金属在土壤中的赋存形态进行了分析。2、柠檬酸发酵液的制备及其淋洗性能研究:以黑曲霉为菌种,通过微生物发酵技术制备了柠檬酸发酵液,采用振荡淋洗实验对其淋洗效果进行了探究,Pb、Cu、Cr、Cd的去除率分别为:48.19%、30.56%、43.65%、58.43%,优于柠檬酸溶液的去除效果。探究了柠檬酸发酵液浓度、液固比、pH、淋洗时间对去除率的影响,动力学拟合表明双常数方程和Elovich方程能较好的描述Pb、Cu、Cr、Cd的解吸行为,且Elovich方程优于双常数方程,重金属的淋洗去除是一个非均相扩散过程。对淋洗前后的土壤重金属进行了BCR形态分析,结果表明,酸可提取态Pb、Cu、Cr、Cd的去除效果最好,其次是可还原态,可氧化态和残渣态的去除则不明显。采用FTIR、XRD、SEM技术对淋洗前后的土壤进行了光谱学特性分析,结果表明,柠檬酸发酵液对土壤的矿物组成仅有一个较小的影响,对土壤体系的结构不造成破坏。3、基于柠檬酸发酵液的复合淋洗体系的构建和应用:采用柠檬酸发酵液和皂素构建了一个复合淋洗体系,对Pb、Cu、Cr、Cd均有较好的淋洗去除效果,其中,Pb的去除率明显高于单独使用柠檬酸发酵液或皂素溶液的去除率。在后续研究中,将复合淋洗液应用于矿区Pb污染土壤的淋洗修复,解吸动力学过程可用双常数方程和Elovich方程进行拟合。探究了复合淋洗液对不同粒径土壤中Pb的去除效果,结果表明,较大粒径土壤中的Pb相对更容易去除。在单因素实验的基础上,采用星点设计-响应面分析法探究了皂素浓度、液固比和淋洗时间对淋洗去除效果的影响,各因素的影响程度为:液固比淋洗时间皂素浓度,且淋洗时间和液固比间存在交互作用,此外,响应面优化条件下,Pb的去除率达到56.20%,与预测值接近。淋洗前后土壤Pb的BCR形态分析表明,复合淋洗液能够有效去除活性态Pb。
[Abstract]:The key to the development and application of soil leaching and remediation technology is to find an economical, environmentally friendly, and suitable leaching solution. The development of new leaching solution and the improvement of existing leaching solution are very important in the research and application of leaching technology. The effects of heavy metals on red soil in plateau and Pb contaminated soil in mining area were studied. The elution properties of citric acid fermentation broth and citric acid fermentation broth combined with saponin were studied. The contents of the study are as follows: 1. Physical and chemical properties of soil and analysis of heavy metal species. The physical and chemical parameters of soil pH, water content, organic matter, cation exchange capacity, alkali-hydrolyzed nitrogen and particle size distribution were determined. The forms of heavy metals in soil were analyzed by BCR speciation analysis. The preparation of citric acid fermentation broth and its elution performance were studied. The citric acid fermentation broth was prepared by microbial fermentation with Aspergillus Niger as strain. The elution effect was studied by oscillatory elution experiment. The removal rates of CD and CD were: 1: 48.19 and 30.5656 / 43.65 respectively, which was superior to that of citric acid solution. The effects of the concentration of citric acid fermentation broth, the ratio of liquid to solid pH, and the elution time on the removal rate were investigated. The kinetic fitting shows that the double constant equation and Elovich equation can better describe the desorption behavior of PbCU / Cr-CD, and the Elovich equation is superior to the double constant equation. The leaching and removal of heavy metals is a heterogeneous diffusion process. The BCR speciation analysis of heavy metals in soils before and after leaching shows that the removal efficiency of acid extractable PbCU Cr-Cr and CD is the best, followed by the reducible state. The results showed that the citric acid fermentation liquid had only a small effect on the mineral composition of the soil, and the spectroscopic properties of the soil before and after leaching were analyzed by FTIRN XRDX SEM. The results showed that the effect of citric acid fermentation broth on the mineral composition of the soil was only a little less than that of the citric acid fermentation broth. Construction and application of compound leaching system based on citric acid fermentation broth: a compound leaching system was constructed by using citric acid fermentation broth and saponin. The removal rate of Pb was significantly higher than that of citric acid fermentation broth or saponin solution alone. In the follow-up study, the compound eluate was applied to the leaching and remediation of Pb contaminated soil in mining area. The desorption kinetics can be fitted by double constant equation and Elovich equation. On the basis of single factor experiments, the effects of saponin concentration, liquid-solid ratio and elution time on the elution removal efficiency were investigated by star design-response surface analysis. The influence degree of each factor is as follows: the concentration of saponin in liquid-solid ratio elution time, and the interaction between elution time and liquid-solid ratio, in addition, Under the optimum conditions of response surface, the removal rate of Pb reached 56.20, which was close to the predicted value. The BCR speciation analysis of soil Pb before and after leaching showed that the compound eluate could effectively remove active Pb.
【学位授予单位】:云南民族大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:X53;TQ921.1
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