生物质炭对BDE-99在土壤体系中吸附解吸行为及影响因素研究

发布时间：2018-02-16 15:51

  本文关键词： 生物炭 BDE-47 BDE-99 吸附解吸　出处：《北京林业大学》2015年硕士论文　论文类型：学位论文

【摘要】：多溴联苯醚具有良好的阻燃效果,被广泛应用在工业生产中。由于其具有较高的生物富集效应和致癌性,且其在环境中的暴露水平日益提高,因此掌握多溴联苯醚在环境介质中的迁移转化途径非常有必要。本文选取全球污染比较广泛的2,2',4,4',5-五溴联苯醚(BDE-99)和2,2',4,4'-四溴联苯醚(BDE-47)作为研究对象,探究了其在土壤介质及生物炭组分上的吸附解吸行为,同时考察了生物炭添加量及环境温度对BDE-99在土壤介质上吸附解吸行为的影响。本论文中,生物炭样品随着热解温度升高,含氧官能团逐渐减少,脱氧作用加剧,烷烃缩合增强,极性程度降低,芳香性特征表现明显。炭化温度的升高促进了生物炭样品内部孔隙结构形成。对于BC300和BC500,中孔和微孔是其主要孔结构；对于BC700,微孔为其主要孔结构。双室一级动力学模型能较好地拟合BDE-47/BDE-99在生物炭及土壤样品上的吸附过程,其中快吸附过程占主导地位。BDE-47/BDE-99在生物炭及土壤样品上的吸附过程是自发进行的。BDE-47/BDE-99在生物炭样品上的吸附呈现非线性,其吸附能力为BC700BC500BC300。对于BC300和BC500,孔隙的吸附作用存在于吸附过程中,同时有部分吸附发生微孔或介孔的表面上；对于BC700,在吸附过程中,微孔的吸附贡献比较大。BDE-47/BDE-99在生物炭样品上存在明显的解吸滞后现象,相对于BC300、BC500,BC700的解吸滞后程度比较显著,其主要是因为BC700能够提供更多的高能吸附位点。土壤样品对BDE-99的吸附呈非线性,土壤样品随着吸附初始浓度升高,单点分配系数(Koc)逐渐减小。有机质含量是影响土壤样品对BDE-99吸附的主要因素。相对于生物炭样品,BDE-99在土壤样品上的解吸滞后性变化规律不明显,主要可能因为土壤样品中不存在高能吸附位点和低能吸附位点的显著区分。生物炭添加含量及环境温度对BDE-99在生物炭混合土壤体系上的吸附解吸行为也存在显著影响。生物炭的添加增强了土壤体系对BDE-99的吸附能力,吸附的非线性程度有所增加,BDE-99在土壤体系上的解吸滞后程度明显增强。环境温度从10℃升高到35℃,BDE-99在生物炭混合土壤上的解吸滞后程度有所减弱。
[Abstract]:Polybrominated diphenyl ethers (PBDEs) have good flame retardancy and are widely used in industrial production. Because of their high bioconcentration and carcinogenicity, PBDEs are exposed to a higher level of exposure to the environment. Therefore, it is necessary to master the translocation and transformation pathway of PBDEs in environmental media. In this paper, we select the globally polluted PBDEs BDE-99 and BDE-47. In this paper, the adsorption and desorption behavior of BDE-99 in soil media and biochar components were investigated, and the effects of biochar addition and ambient temperature on the adsorption and desorption behavior of BDE-99 on soil media were also investigated. In this paper, the adsorption and desorption behavior of biochar samples increased with the increase of pyrolysis temperature. The oxygen functional groups decreased gradually, the deoxidation increased, the condensation of alkanes increased, and the degree of polarity decreased. The aromaticity characteristic is obvious. The increase of carbonization temperature promotes the formation of pore structure in biological carbon sample. For BC300 and BC500, mesoporous and micropore are the main pore structures. For BC700, micropore is the main pore structure. The two-chamber first-order kinetic model can fit the adsorption process of BDE-47/BDE-99 on biochar and soil samples. The adsorption process of BDE-47 / BDE-99 on biochar and soil samples was spontaneous and the adsorption of BDE-47 / BDE-99 on biochar was nonlinear. The adsorption capacity of BC700BC500BC300. for BC300 and BC500, the adsorption of pores exists in the adsorption process, and some micropores or mesoporous surfaces occur at the same time, for BC700, during the adsorption process, The adsorption contribution of micropore is relatively large. BDE-47 / BDE-99 has obvious desorption hysteresis in biochar samples, and the desorption hysteresis degree of BC300, BC500 and BC700 is more significant than that of BC300, BC500, BC700, BC700, BC500 and BC700. The main reason is that BC700 can provide more high energy adsorption sites. The adsorption of BDE-99 on soil samples is nonlinear, and soil samples increase with the initial concentration of adsorption. The content of organic matter is the main factor affecting the adsorption of BDE-99 on soil samples. It is possible that there is no significant difference between high energy adsorption sites and low energy adsorption sites in soil samples. The adsorption and desorption behavior of BDE-99 on biochar mixed soil system is also significant due to the addition of biochar and ambient temperature. The addition of biochar enhanced the adsorption ability of BDE-99 in soil system. The degree of nonlinearity of adsorption increased and the desorption hysteresis degree of BDE-99 in soil system increased obviously, and the degree of desorption hysteresis of BDE-99 in biochar mixed soil decreased from 10 鈩，

本文编号：1515876