生物炭对西北黄土中农药敌草隆和西维因吸附行为影响的研究

发布时间：2018-04-27 17:49

本文选题：黄土 + 生物炭　；参考：《兰州交通大学》2017年硕士论文

【摘要】：外源生物炭(Biochar)可提高黄土肥力,改良土壤环境。研究不同外源性生物炭对高纬度寒旱地区黄土中有机污染物吸附行为的影响,对于了解该类污染物在黄土地区的归趋具有重大意义。本论文分别以玉米秸秆和松针为原材料,在不同温度下(200、400和600℃)制备生物炭,同时利用电镜扫描,孔径测定、元素分析和红外光谱等方法对所制生物炭进行表征分析,并采用批量法对其进行动力学和热力学等吸附性能的测试。分析不同来源和不同温度下制备的生物炭对两种典型农药敌草隆(diuron)和西维因(carbaryl)在西北黄土中吸附性能的影响,确定其平衡吸附模型,并对温度、pH、初始浓度等影响因素进行了探讨。研究结果如下:(1)生物炭表征分析结果显示,生物炭表面含有羟基、羧基、羰基等基团,且随着生物炭热解温度的升高和热解时间的延长,生物炭灰分含量和碳化程度增强的同时产率和有机质含量下降。随着生物炭热裂解温度的升高,孔体积增大,孔径减小,生物炭孔壁逐渐变薄,内部孔结构增大,微孔数量增多。碳含量随生物炭热解温度的升高而增大,氢和氧含量逐渐降低,生物炭芳香性增加,而极性降低。(2)黄土对两种有机农药的吸附实验结果显示,西维因和敌草隆在黄土上的动力学吸附过程均分为快反应和慢反应两个阶段,动力学吸附过程较符合Pseudo-second-order和Intraparticle diffusion吸附模型,热力学吸附较符合Freundlich模型,吸附过程均为放热过程。溶液pH和粒径对土壤颗粒吸附敌草隆和西维因都有着不同程度的影响,当溶液pH在3~10范围内变化时,对黄土中敌草隆吸附行为影响不大,但对西维因的吸附变化却有着显著影响。(3)生物炭吸附两种有机污染物的实验结果显示,不论是对敌草隆还是对西维因的吸附过程中,MBC-600和PBC-600的吸附量都远大于200℃和400℃条件下制得的生物炭的吸附量,动力学吸附过程较符合Pseudo-second-order动力学吸附模型,热力学吸附符合Freundlich方程,吸附过程中ΔGθ0、ΔHθ0、ΔSθ0,表明两种有机污染物在生物炭上的吸附为自发进行且体系混乱程度增大的吸热过程。对贡献量分析研究表明:敌草隆和西维因在较低温度下制备的生物炭上的吸附以分配作用为主,表面吸附作用的贡献量随生物炭热解温度的升高而增大,对两种有机污染物的吸附主要由分配作用和表面吸附共同完成。(4)有机污染物敌草隆和西维因在添加外源生物炭黄土上的吸附影响实验结果显示,添加生物炭可以显著提高敌草隆和西维因在黄土上的饱和吸附量,动力学符合Pseudo-second-order吸附模型,热力学符合Freundlich等温吸附模型;吸附自由能E在实验温度范围内均小于8kJ·mol~(-1),表明其吸附过程以物理吸附为主。生物炭添加量和热裂解温度的不同对黄土吸附敌草隆有着显著的影响,黄土对有机物的吸附作用主要被生物炭所控制。体系温度和溶液初始浓度对吸附行为均有较大影响;pH仅对西维因吸附行为影响较大,对敌草隆吸附量无显著影响。(5)有机污染物在柴油污染黄土上的吸附实验结果表明,与第三章未受污染黄土对敌草隆和西维因的动力学吸附相比较,柴油污染黄土对有机污染物的吸附平衡时间基本无太大变化,生物炭的添加加速了柴油污染黄土对两种污染物的吸附过程,缩短了吸附平衡时间。动力学过程更符合Pseudo-second-order模型;不论是对敌草隆的吸附,还是对西维因的吸附,添加生物炭的柴油污染黄土对其的ΔGθ0、ΔHθ0、ΔSθ0,表明此吸附为自发进行吸热过程。添加MBC-400的不同柴油污染强度的黄土对敌草隆的吸附量有所提高,但还是受到柴油污染强度的影响,吸附量随着污染强度的增加而降低。
[Abstract]:Exogenous biological carbon (Biochar) can improve the fertility of loess and improve the soil environment. It is of great significance to study the effect of different exogenous biological charcoal on the adsorption behavior of organic pollutants in loess region of high latitudes and cold drought areas. Biocharcoal was prepared at (200400 and 600 C), and the biological charcoal was characterized by electron microscope scanning, pore size determination, element analysis and infrared spectroscopy. The kinetic and thermodynamic adsorption properties of the biological charcoal were tested by batch method. The biological charcoal prepared from different sources and different temperatures was analyzed for two typical farmers. The influence of diuron and carbaryl on the adsorption properties of the northwest loess, the equilibrium adsorption model was determined, and the influence factors such as temperature, pH and initial concentration were discussed. The results were as follows: (1) the results of biological charcoal characterization showed that the surface of biological charcoal contains hydroxyl, carboxyl, carbonyl groups, and with the heat of biological charcoal. With the increase of thermal cracking temperature, the pore volume increased, the pore size decreased, the pore wall of biological carbon became thinner, the inner pore structure increased and the number of micropores increased. Carbon content followed the pyrolysis temperature of biological charcoal. The content of hydrogen and oxygen gradually decreased, the aromatic property of biological carbon increased and the polarity decreased. (2) the adsorption experiments of two kinds of organic pesticides on Loess showed that the kinetic adsorption process on the loess was divided into two stages, fast reaction and slow reaction, and the kinetic adsorption process was in accordance with Pseudo-second-order and Intr. Aparticle diffusion adsorption model, thermodynamic adsorption is more consistent with the Freundlich model, and the adsorption process is exothermic process. Solution pH and particle size have different effects on the adsorption of diuron and West dimension of soil particles. When the solution pH changes in the range of 3~10, the adsorption behavior of diuron in the loess is not much affected, but the absorption of diffusion in the loess is not significant. The attached change has significant influence. (3) the experimental results of adsorption of two organic pollutants by biological carbon show that the adsorption amount of MBC-600 and PBC-600 is far greater than that of 200 and 400 degrees centigrade, and the kinetic adsorption process is more consistent with the Pseudo-second-order movement. The mechanical adsorption model and thermodynamic adsorption conform to the Freundlich equation. The adsorption process is delta G theta 0, Delta H theta 0, and delta S theta 0, indicating that the adsorption of two organic pollutants on biological charcoal is spontaneous and the system chaotic degree increases, and the contribution analysis study shows that the absorption of diuron and signet on the biological carbon prepared at lower temperature. The contribution of the surface adsorption is increased with the increase of the pyrolysis temperature of biological carbon. The adsorption of two kinds of organic pollutants is mainly done by the distribution and surface adsorption. (4) the effects of the adsorption of organic pollutants on the addition of exogenous biological carbon yellow soil Carbon can significantly increase the saturated adsorption of diuron and West VIN on loess, the kinetics conforms to the Pseudo-second-order adsorption model, thermodynamics conforms to the Freundlich isothermal adsorption model, and the adsorption free energy E is less than 8kJ. Mol~ (-1) within the experimental temperature range, indicating that the adsorption process is mainly physical adsorption. The amount and thermal cracking of biological carbon are added. The difference of temperature has a significant influence on the adsorption of diuron on the loess. The adsorption of organic matter to the organic matter is mainly controlled by biological carbon. The temperature and initial concentration of the solution have great influence on the adsorption behavior; pH only has a great influence on the adsorption behavior of the virus. (5) the organic pollutants are in diesel oil. The results of adsorption experiments on contaminated loess show that the adsorption equilibrium time of diesel polluted loess to organic pollutants is basically not much changed compared with the third chapter of unpolluted loess to the kinetic adsorption phase of anti - chlor and West Wein. The addition of bio carbon accelerates the adsorption process of two kinds of pollutants from diesel polluted loess and shortens the adsorption. Equilibrium time. The kinetic process is more consistent with the Pseudo-second-order model. Whether it is the adsorption of Chira on the enemy, or the adsorption of signet, the diesel oil contaminated by biochar on its delta G theta 0, Delta H theta 0, and delta S theta 0, indicating that this adsorption is a spontaneous endothermic process. The amount of adsorption increased, but it was still affected by the pollution intensity of diesel oil, and the amount of adsorption decreased with the increase of pollution intensity.

【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X592

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