本文選題：表面元積分法 + 擴展DLVO理論��； 參考：《中國農(nóng)業(yè)大學》2017年博士論文

【摘要】：充分了解納米顆粒在不同物理和化學條件下與多孔介質之間的相互作用,對預測其在自然環(huán)境和工程環(huán)境中的應用、對水土環(huán)境中污染物運移的影響以及對動植物健康的危害具有極其重要的意義。很多研究人員發(fā)現(xiàn)膠體在多孔介質當中的運移,特別是在不利條件下,受到表面粗糙度的影響較大。目前描述表面粗糙度大多是采用規(guī)則的幾何形狀進行模擬,不能準確地表征收集器表面形貌。生物炭對污染物吸附去除方面大多集中于采用批量平衡吸附方法進行機理研究,缺乏對污染物在生物炭修復土壤中遷移的研究。因此,本文一方面采用分形幾何的方法模擬石英砂粗糙表面,研究乳膠納米顆粒與分形粗糙表面之間的相互作用勢能;另一方面通過土柱實驗研究二氧化硅納米顆粒和啶蟲脒在生物炭改性石英砂多孔介質中的協(xié)同運移。具體的研究結果如下:第一,采用表面元積分和擴展DLVO理論結合的方法進行了不同粒徑的乳膠納米顆粒與分形表面之間相互作用勢能的計算。通過運用Weierstrass-Mandelbrot函數(shù)并設置不同的分形維數(shù)D和分形粗糙參數(shù)G形成了表面粗糙度不同的分形表面。通過分析在不同分離距離條件下乳膠納米顆粒與兩個代表性的分形表面之間的橫向相互作用勢能圖發(fā)現(xiàn),相互作用勢能的大小變化與分形粗糙參數(shù)G成正相關關系,而且總體上呈現(xiàn)吸附-排斥-吸附的趨勢。30 nm乳膠顆粒相比于10 nm乳膠顆粒而言,與分形表面之間的相互作用面積較大,從而得到的相互作用勢能也較大,而且分布比較均勻。乳膠納米顆粒與分形表面之間排斥勢能占優(yōu)分布的分離距離會隨著離子強度和粒徑的不同而發(fā)生變化。當分離距離為0.1 nm的時候,存在依賴于離子強度和粒徑的"臨界表面粗糙度"影響乳膠納米顆粒與分形表面之間吸附勢能占優(yōu)的分布。從乳膠納米顆粒與分形表面之間的縱向相互作用勢能圖發(fā)現(xiàn),不管是高于零平面還是低于零平面的凸起部位都會降低初級勢阱和排斥勢壘,而凹陷部位會增強次級勢阱和排斥勢壘。第二,通過研究乳膠納米顆粒與分形表面之間的排斥勢壘、平均粘附效率以及典型部位的相互作用勢能來分析乳膠納米顆粒的吸附和解吸情況。乳膠納米顆粒與分形表面之間的排斥勢壘會隨著分形維數(shù)D的減小或者分形粗糙參數(shù)G的增大而減小。乳膠納米顆粒與分形表面之間相互作用排斥勢壘圖中的"白斑"區(qū)域分布于分形表面最低點附近。"白斑"區(qū)域的分布受離子強度、分形維數(shù)D和分形粗糙參數(shù)G的影響。在低離子強度條件下,"白斑"區(qū)域容易發(fā)生30 nm乳膠顆粒的解吸,而在高離子強度條件下有利于30 nm乳膠顆粒的吸附。平均粘附效率隨著分形維數(shù)D的減小或者分形粗糙參數(shù)G的增大而減小。不同的離散尺度對30nm乳膠顆粒的平均粘附效率幾乎沒有影響。在離子強度為10 mM時存在"臨界粒徑"影響乳膠納米顆粒平均粘附效率的變化,而其它離子強度條件下平均粘附效率隨著乳膠顆粒粒徑的增大而減小。在低離子強度下低于零平面的粗糙表面的凸起部位有利于乳膠納米顆粒的解吸;在高離子強度條件下,光滑表面的凸起部位有利于乳膠納米顆粒的吸附。低于零平面的粗糙表面的凹陷部位乳膠納米顆粒的吸附和解吸現(xiàn)象受乳膠粒徑和離子強度的影響比較復雜。第三,開展了農(nóng)藥啶蟲脒和二氧化硅納米顆粒在石英砂和生物炭改性多孔介質中的協(xié)同運移研究。農(nóng)藥啶蟲脒在石英砂多孔介質中幾乎沒有滯留,而在生物炭改性多孔介質當中的滯留很多且與pH有顯著的相關關系。在離子強度為10 mM NaCl和pH6.4的條件下,農(nóng)藥啶蟲脒在生物炭改性多孔介質中的吸附和微生物降解是最多的。生物炭吸附啶蟲脒的機制包括π-πEDA和孔隙吸附。運用包含一階吸附常數(shù)、一階解吸常數(shù)和降解常數(shù)的對流-彌散方程能夠準確地描述啶蟲脒在多孔介質當中的穿透曲線。采用對流-彌散方程擬合得到的參數(shù)可知,啶蟲脒的吸附速率不會受到pH的影響,原因是啶蟲脒是非離子型化合物不會通過質子化或者是去質子化方式與生物炭結合。啶蟲脒的解吸速率不會受到溶液化學條件的影響,從而證明啶蟲脒的解吸是一個物理過程(孔隙擴散)。背景溶液為NaCl時,二氧化硅納米顆粒在石英砂和生物炭改性多孔介質中的運移幾乎沒有影響;而當背景溶液為CaCl2時,二氧化硅納米顆粒在生物炭改性多孔介質中的吸附增多,特別是在離子強度為10 mM的時候,前三個孔隙體積幾乎沒有二氧化硅納米顆粒流出。通過SEM-EDX分析,發(fā)現(xiàn)二氧化硅納米顆粒與生物炭表面某些官能團通過Ca2+的橋連作用而結合到一起。啶蟲脒和二氧化硅納米顆粒協(xié)同運移通過占據(jù)吸附位點從而起到相互促進的作用。本研究表明:采用分形幾何能夠更加準確地描述表面形貌,能夠準確預測納米顆粒與收集器表面之間的相互作用;采用生物炭修復土壤的過程必須要考慮污染物與納米顆粒在不同化學條件下的協(xié)同作用,才能夠達到更好的修復效果。
[Abstract]:It is very important to predict the interaction between nanoparticles and porous media under different physical and chemical conditions, to predict its application in natural environment and engineering environment, to influence the transport of pollutants in soil and water environment and to the health of animals and plants. Many researchers have found that colloids are in porous media. The migration, especially in the adverse conditions, is greatly influenced by the surface roughness. At present, the surface roughness is mostly simulated by the rule geometry, and the surface morphology of the collector can not be collected accurately. In the study, there is a lack of research on the migration of pollutants in the remediation of soil by biological carbon. Therefore, on the one hand, the fractal geometry method is used to simulate the rough surface of quartz sand and study the potential energy of the interaction between the latex nanoparticles and the fractal rough surface. On the other hand, the silica nanoparticles and Acetamiprid in the biological carbon are studied by the soil column experiment. The research results are as follows: first, the interaction potential energy between the latex nanoparticles and the fractal surface of different particle sizes is calculated by combining the surface integral and the extended DLVO theory. The Weierstrass-Mandelbrot function and the different fractal dimension D are used. The fractal roughness parameter G forms a fractal surface with different surface roughness. By analyzing the potential energy map of the transverse interaction between the latex nanoparticles and the two representative fractal surfaces, it is found that the change of the potential energy of the interaction is positively related to the fractal rough parameter G, and it is presented as a whole. The adsorption - rejection - adsorption trend of.30 nm latex particles, compared with 10 nm latex particles, has a larger interaction area between the fractal surface and the fractal surface. Thus the potential energy of the interaction is larger and the distribution is more uniform. The separation distance between the latex nanoparticles and the fractal surface is superior to the ionic strength and the ionic strength. When the separation distance is different, when the separation distance is 0.1 nm, the "critical surface roughness" dependent on the ionic strength and particle size affects the dominant distribution of the adsorption potential between the latex nanoparticles and the fractal surface. The potential energy diagram of the longitudinal interaction between the latex nanoparticles and the fractal surface is found to be higher than zero. The initial potential well and the repulsive barrier will be reduced by the plane or the convex part below the zero plane, and the secondary potential well and the exclusion barrier will be enhanced in the depression. Second, the absorption of the latex nanoparticles and the fractal surface, the average adhesion efficiency and the interaction potential energy of the typical parts are studied to analyze the absorption of the latex nanoparticles. The exclusion barrier between the latex nanoparticles and the fractal surface decreases with the decrease of the fractal dimension D or the increase of the fractal roughness parameter G. The "leukoplakia" region in the exclusion barrier map between the latex nanoparticles and the fractal surface is distributed near the lowest point of the fractal surface. The distribution of the "white spot" area is affected by the distribution of the "white spot" area. The influence of ionic strength, fractal dimension D and fractal roughness parameter G. Under low ionic strength, 30 nm latex particles are easily desorbed in the "white spot" region, while the adsorption of 30 nm latex particles is favorable under high ionic strength. The average adhesion efficiency decreases with the decrease of the fractal dimension D or the increase of the fractal roughness parameter G. The same discrete scale has little effect on the average adhesion efficiency of 30nm latex particles. When the ionic strength is 10 mM, the "critical particle size" affects the change of the average adhesion efficiency of latex nanoparticles, while the average adhesion efficiency decreases with the increase of the size of the latex particles under the other ionic strength conditions. Under low ionic strength, the average adhesion is lower than the zero level. The convex parts of the surface of the surface are beneficial to the desorption of latex nanoparticles. Under high ionic strength, the protruding parts of the smooth surface are beneficial to the adsorption of latex nanoparticles. The adsorption and desorption of latex nanoparticles under the rough surface below the zero plane are compared with the effects of latex particle size and ionic strength. Third, the synergistic transport of acetamiprid and silica nanoparticles in quartz sand and Biocharcoal modified porous media was carried out. The pesticide acetamiprid had almost no retention in the porous medium of quartz sand, but there was a lot of retention in the porous medium of biological carbon, and there was a significant correlation with pH. The ionic strength was 10 m. Under the conditions of M NaCl and pH6.4, the adsorption and microbial degradation of Acetamiprid in biological carbon modified porous media is the most. The mechanism of acetamiprid by Biocharcoal includes Pi Pi EDA and pore adsorption. The convection diffusion equation containing first order adsorption constant, first order desorption constant and degradation constant can accurately describe Acetamiprid in the form of acetamiprid The penetration curves in porous media. Using the parameters obtained by convection diffusion equation, the adsorption rate of acetamiprid is not affected by the pH, because the acetamidine is nonionic and does not combine with the protonations or deprotonations. The desorption rate of acetamiprid is not subject to the chemical conditions of the solution. It is proved that the desorption of acetamiprid is a physical process (pore diffusion). When the background solution is NaCl, the migration of silica nanoparticles in quartz sand and Biocharcoal modified porous media is almost not affected. When the background solution is CaCl2, the adsorption of silica nanometers in the porous medium of biological carbon is increased. Especially when the ionic strength is 10 mM, the first three pore volume is almost without silica nanoparticles. Through SEM-EDX analysis, it is found that the silica nanoparticles are combined with some functional groups on the surface of biological carbon through the bridging action of Ca2+. Acetamiprid and two oxygen silicon nanoparticles are transported together by occupying adsorption. This study shows that the fractal geometry can describe the surface morphology more accurately, and can accurately predict the interaction between the nanoparticles and the collector surface. The synergistic effect of pollutants and nanoparticles under different chemical conditions must be considered by using biological carbon to repair the soil. A better repair effect can be achieved.
【學位授予單位】：中國農(nóng)業(yè)大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：X53

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本文編號：2113020