磺胺嘧啶在土壤及组分中的吸附迁移特征及模拟

发布时间：2018-01-16 21:25

  本文关键词：磺胺嘧啶在土壤及组分中的吸附迁移特征及模拟　出处：《青岛大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 磺胺嘧啶 吸附迁移 土壤 Hydrus-1D 数值模拟

【摘要】：随着抗生素使用量的逐年增加,抗生素污染问题已成为环境领域的研究热点之一,而土壤作为重要的环境介质,其抗生素污染也成为一个不容忽视的问题。磺胺类抗生素作为全球最广泛使用的抗生素之一,每年都有大量药物排入水土环境中,且排放水平逐年提高。磺胺类抗生素在水土环境中的降解速度较慢,危害甚大。本文以磺胺嘧啶(Sulfadiazine,SDZ)为研究对象,通过大量的室内实验,研究其在土壤及土壤组分中的吸附迁移行为,以便为抗生素在土壤和地下水中的污染评价及修复提供科学依据。本文的研究主要包括两部分内容:一是不同阳离子类型、有机质含量和重金属条件下,SDZ在土壤中吸附的实验,以及pH、阳离子类型、离子强度对SDZ在土壤组分(高岭石、蒙脱石和腐殖酸)中的吸附实验,并对反应前后的高岭石、蒙脱石和腐殖酸进行傅里叶红外光谱(Fourier transform infrared,FTIR)表征,分别用Langmuir、Freundlich和线性方程对静态吸附特征进行拟合;二是探讨了SDZ在原状和填装土柱中的迁移特征,用Hydrus-1D软件对其进行模拟获得相关参数,并对不同流速下SDZ的迁移行为进行预测。得出以下结论:(1)在土壤的静态吸附实验中,阳离子价态、有机质和重金属含量均对SDZ的吸附产生影响。离子价态越低,有机质含量越高,SDZ吸附量越大;当Cd浓度为10.0 mg/kg时,会促进SDZ的吸附,当Cd浓度为1.0、300.0 mg/kg时会抑制SDZ吸附,当Cd浓度为100.0 mg/kg时对SDZ的吸附无影响;Cd、Cu、Pb存在时,SDZ吸附量大小的顺序为CdCuPb。用Freundlich方程和Langmuir方程拟合实验数据的R2均在0.96以上,但由于吸附偏线性,Langmuir方程并不能很好地解释SDZ的吸附特征,线性方程拟合的R2均在0.98以上,模拟结果最好。(2)SDZ在土壤及其组分中的动态吸附实验表明,SDZ在土壤及其组分中的吸附在24 h左右达到平衡,达到吸附平衡时吸附量大小顺序为腐殖酸高岭石土壤蒙脱石。在土壤组分的静态批平衡实验中,pH、离子类型和离子强度对SDZ在不同土壤组分中的吸附有不同的影响。这些因素对SDZ在高岭石中的吸附影响,均不明显;在蒙脱石中,SDZ吸附量与pH呈正相关,与离子强度呈负相关;除Na+会降低SDZ在蒙脱石中的吸附外,K+、Ca2+、Mg2+影响不大;对于腐殖酸,除离子类型对SDZ的吸附有一定影响,pH和离子强度的影响也不大。Freundlich方程拟合的R2在0.8以上,Langmuir方程拟合的R2在0.78以上,线性方程拟合的R2在0.92以上,线性方程对这些吸附特征拟合效果更好。(3)SDZ在同一土壤剖面不同深度处所取原状土中迁移的穿透曲线是不同的,在原状土柱Ⅱ(15.0-30.0 cm)中的穿透曲线相较于原状土柱Ⅰ(0.0~15.0 cm)的发生左移,即较深层土壤中,SDZ的迁移速度更快。这主要是受土壤理化性质的影响,前者的有机质含量、阳离子交换量(CEC)比后者低,而pH比后者高,从而减少了SDZ的吸附,增强了其流动性。(4)不同化学因素对SDZ在填装土柱中的迁移产生不同影响。阳离子价态越高、有机质含量越少,SDZ的出流浓度峰值越高、出流越快、迁移性越强;当土壤中Cd含量为10.0 mg/kg,SDZ在土壤中的迁移速度最慢,峰值最低,其它浓度Cd对SDZ的迁移影响不大;当Cu、Pb和Cd的含量相同时,SDZ的含Cu土壤中,迁移最快,其相对浓度峰值可达0.8;其次为含Pb土壤,在含Cd土壤中迁移最慢。出流液中pH变化均呈现先下降后逐渐趋于平稳,EC变化不大,出流液中的Ca2+浓度则均呈现先下降后上升的趋势。(5)用单点吸附模型(OSM)、两点吸附模型(TSM)和两区模型(TRM)分别对SDZ在原状土中的迁移过程进行模拟并用TRM对不同水流下SDZ的迁移行为进行预测。结果表明,TRM对SDZ的迁移过程拟合最好,TSM中瞬时吸附所占比例很小,所以SDZ在原状土中基本上不存在瞬时吸附,TRM表明不动水体也是SDZ吸附的重要组成部分。TRM的R20.91,RMSE0.061,拟合结果优于OSM和TSM。在用TRM模拟过程中,当水流速度从0.017 cm/min增加到0.030 cm/min再到0.100 cm/min,磺胺嘧啶在土壤中的迁移速度也不断加快,出流浓度也越来越高,当流速为0.100 cm/min时,SDZ可快速穿过土层进入地下水。(6)分别用OSM和TSM对填装土柱中SDZ的迁移进行模拟。结果表明,OSM的R20.881,RMSE0.069,TSM的R20.907,RMSE0.051,瞬时吸附f所占分数较高,说明SDZ在迁移过程中存在较大程度的瞬时吸附。与OSM相比,TSM能更好地模拟SDZ的迁移过程。两个模型拟合的系数α均较小。
[Abstract]:With the usage of antibiotics increased year by year, antibiotics pollution problem has become one of the research focus in the field of environment, and the soil environment as an important medium, the antibiotics pollution has become a problem that can not be ignored. Sulfa antibiotics as the world's most widely used antibiotics, every year a large number of drugs into the soil and water environment. And the level of emissions increased year by year. The degradation speed of sulfonamide antibiotics in the soil water environment, the harm is very great. In this paper, sulfadiazine (Sulfadiazine, SDZ) as the research object, through a lot of experiments, to study the migration behavior in soil and soil adsorption component, so as to provide scientific basis for the evaluation of antibiotics in pollution in the soil and groundwater and repair. This paper mainly includes two parts: one is the different types of cation, the content of organic matter and heavy metals in soil conditions, SDZ The soil adsorption experiments, and pH, cationic type, ionic strength of SDZ in soil components (kaolinite, montmorillonite and humic acid) in the adsorption experiments, and before and after the reaction of kaolinite, montmorillonite and humic acid by Fourier transform infrared spectroscopy (Fourier transform infrared, FTIR) were respectively Langmuir, Freundlich and linear the equation to fit the static adsorption characteristics; two is to explore the characteristics of SDZ migration in undisturbed and filled in the soil column, were simulated to obtain the relevant parameters by Hydrus-1D software on it, and the different flow velocity SDZ migration behavior prediction. Draw the following conclusions: (1) in the static adsorption experiment of soil, cation valence state, heavy metals and organic matter content were affected. The adsorption of SDZ ion valence lower organic matter content was high, the adsorption capacity of SDZ increased; when the concentration of Cd was 10 mg/kg, will promote the adsorption of SDZ, when the concentration of Cd 1.0300.0 mg/kg can inhibit the adsorption of SDZ, when the Cd concentration was 100 mg/kg adsorption had no influence on the SDZ; Cd, Cu, Pb, SDZ adsorption quantity in the order of CdCuPb. Freundlich equation and Langmuir equation fit the experimental data of R2 were above 0.96, but due to the adsorption of Langmuir equation and partial linear. Can not well explain the adsorption characteristics of SDZ, the linear equation of R2 was above 0.98, the best (2). The simulation results show that the dynamic SDZ adsorption in soil and its components, the adsorption of SDZ in soil and its components in the balance in about 24 h, the equilibrium adsorption capacity of the order as the soil humic acid kaolinite montmorillonite. In soil component static batch equilibrium experiment, pH, have different effects on adsorption of ionic type and ionic strength of SDZ in different soil fractions. The influence of these factors on the adsorption of SDZ on kaolinite, were Is not obvious; in montmorillonite, the adsorption capacity of SDZ was positively correlated with pH and negatively correlated with the ionic strength; in addition to the Na+ will reduce the absorption of SDZ in montmorillonite using, K+, Ca2+, Mg2+ had little effect; for humic acid, in addition to a certain effect of ion adsorption type on SDZ, effects of pH and ionic strength of the little.Freundlich equation R2 is above 0.8, the Langmuir equation R2 in more than 0.78, linear equation R2 in more than 0.92 linear equations for these adsorption characteristics of the fitting effect is better. (3) SDZ in the same soil profile in different depth spaces through curve migration in undisturbed soil is different, in the original column II (15.0-30.0 cm) breakthrough curve compared to the undisturbed soil column 1 (0.0~15.0 cm) the left shift is deeper in the soil, the migration speed of SDZ is faster. This is mainly influenced by the physicochemical properties of the soil, organic matter content of the former, cation exchange 閲，

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