【作者】 曾建平；

【导师】 贡雪东；

【作者基本信息】 南京理工大学 ， 材料科学与工程， 2013， 博士

【摘要】 无磷水处理剂在水处理中有重要应用,无磷化是未来水处理剂的发展方向。本论文对一些常用无磷阻垢缓蚀剂与晶体相互作用进行了分子动力学(MD)模拟,通过比较无水条件下和水溶液中的结合能、形变能和对关联函数等,研究了它们的阻垢和缓蚀作用机理,揭示了溶剂化效应对阻垢缓蚀作用影响的本质,为新型阻垢缓蚀剂的研发提供了理论指导。全文大体包括两部分内容：一是模拟研究常见无磷阻垢剂的阻垢作用机理。在无水(真空)条件下和水溶液中对四种常用聚合物阻垢剂,即聚丙烯酸(PAA)、水解聚马来酸酐(HPMA)、聚环氧琥珀酸(PESA)和聚天冬氨酸(PASP),分别与方解石(CA)(104)与(110)面、硬石膏(AD)(001)与(020)面和羟基磷灰石(HA)(001)与(110)面所形成的48种阻垢作用模型采用COMPASS力场进行NVT系综MD模拟。发现无水条件下和水溶液中4种聚合物阻垢剂均能阻止钙垢的生长,但水溶液中的模拟结果与实验结果更一致。两种情况下4种聚合物阻垢剂与各钙垢晶面相互作用时均能发生明显的形变。分析对关联函数g(r)Total、g(r)Ca(Crystal)-O(-C=O)、 g(r)Ca(Crystal)-O(-OH)、g(r)Ca(Crystal)-O(Water)、g(r)H(Polymer)-O(Water)和g(r)H(Polymer)-O(Crystal)均表明无水条件下和水溶液中聚合物阻垢剂与成垢晶体在近程区域有成键(含氢键)作用,在远程区易形成非键作用。在模拟体系中各物质之间的相互作用主要由非键作用提供。根据各聚合物重复单元在B3LYP/6-31G*水平下的自然电荷,发现聚合物O原子易与成垢晶体中的Ca原子形成库仑作用。对碳酸钙垢,水溶液中4种聚合物阻垢剂与CA(104)和(110)面相互作用的结合能大小排序均为：PESA> PASP> HPMA> PAA,同一聚合物阻垢剂与CA(110)面的结合能大于与(104)面的结合能。水分子的存在使聚合物阻垢剂与方解石晶体之间的结合能减小了。对硫酸钙垢,水溶液中聚合物阻垢剂与AD(001)面的模拟结果更接近实验结果。水溶液中4种聚合物阻垢剂与AD(001)和(020)面相互作用的结合能大小排序均为：PESA> PASP> HPMA> PAA,同一聚合物阻垢剂与AD(001)面的结合能小于与(020)面的结合能,与实验结果比较吻合。水分子的存在使聚合物阻垢剂与AD(001)面之间的结合能大大减小了,而使其与AD(020)面的结合能增大了。水分子的存在削弱了HPMA和PAA的形变,而使PASP和PESA的形变加剧了。对磷酸钙垢,水溶液中聚合物阻垢剂与HA(001)面的模拟结果更接近实验结果。聚合物阻垢剂与HA相互作用的温度或能量的波动比CaCO3剧烈,但与硬石膏相当。水溶液中4种聚合物阻垢剂与HA(001)相互作用的结合能大小排序为：HPMA> PASP>PESA>PAA;同一聚合物阻垢剂与HA两晶面的结合能相差不大,与实验结果比较吻合。无水条件下结合能的排序不符合实验结果,水分子的存在使HPMA和PESA的形变削弱,而使PASP和PAA的形变加剧。水分子的存在使得聚合物阻垢剂并不能直接与成垢晶体发生相互作用,而主要是通过水分子间接进行。用MD模拟研究水溶液中阻垢剂的阻垢机理时水分子的存在非常重要,即在构建相互作用的模型时水分子不能被忽略。二是模拟研究了无磷缓蚀剂对金属的缓蚀作用机理。对碳钢,在无水条件和水溶液中对聚合物缓蚀剂水解聚马来酸酐(HPMA)、聚环氧琥珀酸(PESA)和聚天冬氨酸(PASP)与Fe(001)和(110)面的缓蚀作用进行分子动力学(MD)模拟研究。结果发现,对同一聚合物缓蚀剂来说,与Fe不同晶面的结合能均有Ebind(001)<ind(110)(PESA除外),且水溶液中和无水条件下聚合物缓蚀剂的结合能大小排列均为PASP>HPMA>PESA,同时,水溶液中聚合物与Fe晶体的结合能比无水时的结合能要小得多。聚合物缓蚀剂在克服自身的形变而与Fe晶面紧密结合,从而阻止腐蚀介质与碳钢的结合,起到了缓蚀的作用。聚合物缓蚀剂并不能完全突破水结构而吸附于铁表面,使得缓蚀效果不佳,即水分子的存在影响了聚合物缓蚀剂与Fe晶体的相互作用。水分子的存在影响了聚合物缓蚀剂分子的形变程度。从对关联函数的分析,可知聚合物缓蚀剂分子和水分子中的O原子分别与Fe晶体中的Fe原子之间形成了非键作用。溶剂化效应在模型构建中存在着不可忽略的影响。对铜表面的缓蚀作用,围绕着苯并三氮唑母体(BTA)用羟基进行修饰,一共得到6种无磷缓蚀剂苯并三氮唑及其衍生物。运用MD模拟方法对该6种缓蚀剂与Cu20(001)面的相互作用在无水条件下和水溶液中进行研究,发现后者与实验结果更吻合。同一温度下水溶液中6种BTA及其羟基衍生物与Cu20(001)晶面相互作用的结合能大小排序为：1-OH-BTA>4-OH-BTA>7-OH-BTA>BTA>5-OH-BTA>6-OH-BTA。水分子的存在对缓蚀剂分子与Cu20晶体相互作用的结合能有着重要的影响。水溶液中分子结构不同导致温度对苯并三氮唑及其衍生物的缓蚀作用不同。不同温度下1-OH-BTA与Cu20(001)晶面的结合能排序为343K>323K>333K,而BTA与Cu20(001)晶面的结合能强弱为323K>333K>343K。从非键作用能和对关联函数可知,缓蚀剂分子与Cu20晶体相互作用体系的结合能Ebind主要来自库仑能变(包括离子键)的贡献。发现呈负电性的功能团能与难溶铜盐表面上带正电的铜离子通过库仑相互作用而产生较强的吸附行为,从而阻止腐蚀介质与金属铜的进一步作用,即防止了金属的腐蚀。1-OH-BTA/200H2O/Cu2O(001)体系中部分水分子与Cu20晶体和1-OH-BTA均存在着化学键或氢键作用,即用分子动力学研究时水分子是不能被忽略的。总之,本文对无磷阻垢缓蚀剂的结构-性能关系进行了系统的分子动力学模拟研究,解释了其作用机理,揭示了溶剂化效应对阻垢缓蚀性能影响的本质,做出了具有开拓和创新性的工作。更多还原

【Abstract】 Non-phosphorous water treatment agent has an important application in water treatment and phosphate-free of agents is the way of the future. In this paper, the interaction models between common non-phosphorus scale and corrosion inhibitors and scale crystals with and without wate were simulated. The binding energies, deformation energies and pair correlation functions from molecular dynamics (MD) simulations with and without water were calculated and compared. The mechanisms of inhibiting scale and corrosion of the inhibitors have been investigated, and the essence of solvent effect on scale and corrosion inhibition has been revealed. The results obtained can provide a theoretical guidance to developing new scale and corrosion inhibitors. The whole work can be divided into two parts:The first part focused on the inhibition mechanism of non-phosphorus scale inhibitors with MD method. The interaction models between polymer inhibitors Polyacrylic acid (PAA), hydrolyzed polymaleic anhydride (HPMA), polyepoxysuccinic acid (PESA), and polyaspartic acid (PASP) and scale crystal surfaces including the (104) and (110) surfaces of calcite (CA) crystal, the (001) and (020) surfaces of anhydrite (AD) crystal, and the (001) and (110) surfaces of hydroxyapatite (HA) crystal with and without the present of water were constructed, respectively. The resulted48models simulated with COMPASS force field and NVT-MD method one by one.4polymer inhibitors can inhibit the growth of calcium scale. They deform obviously with and without when they interact with scale crystals. The results of models with water are closer to the experimental data. The pair correlation functions (PCFs) g(r)Total,g(r)Ca(Crystal)-o(-C=O)、 g(r)Ca(Crystal)-O(-OH), g(r)Ca(Crystal)-O(Water), g(r))H(Polymer)-O(Water) and g(r)H(Polymer)-O(Crystal) imply the bonding (including H-bond) interactions with and without water are formed between polymer inhibitors and scale crystals in shorter range, while the non-bond interactions are formed in longer range. The interactions between all the species in the models are mainly contributed from the non-bond interaction. Natural bond orbital (NBO) charges of the repeat units of polymer inhibitors were calculated by B3LYP/6-31G*method. The Coulomb interaction is formed between the O atoms of polymer inhibitors and the Ca atoms of scale crystal.For calcium carbonate, the binding energies between4polymer inhibitors and the (104) and (110) surfaces of CA crystal with water have the order of PESA> PASP> HPMA> PAA. The binding energy of the same polymer inhibitor on the (110) surface of CA is greater than that on CA(104). Water molecules decrease the binding energies of the four polymer inhibitors on the surfaces of calcite crystal.For calcium sulphate, the results from MD simulation between polymer inhibitors and AD(001) with water are closer to the experimental data. The sequence of binding energies between4polymer inhibitors and AD (001) and (020) with water is PESA>PASP> HPMA>PAA. The binding energy of the same polymer inhibitor on AD(001) is smaller than that on AD(020). Water molecules weaken the deformations of HPMA and PAA, but aggravate those of PASP and PESA.For calcium phosphate, the results from MD simulation with water between polymer inhibitors and HA (001) are more consistent with the experimental results. The temperature and energy fluctuations of the interaction MD model between polymer inhibitors and HA are severer than those between them and CA, but are almost equivalent to those between them and AD. The binding energies between4polymer inhibitors and the (001) surface of HA with water have the order of HPMA> PASP> PES A> PAA. The binding energy does not vary much between the same polymer and the two surfaces of HA. The results of MD simulations with water are in line with the experimental reports. Water molecules weaken the deformations of HPMA and PES A, but aggravate those of PASP and PAA.These may show that polymer inhibitor interacts with scale crystal surface indirectly through the water molecules, i.e., the water molecules play an important role in investigating the action mechanism of scale inhibitor in solution by MD simulation and can not be ignored when the interaction models are constructed.The second part concentrates on the study of the inhibition mechanism of non-phosphorus corrosion inhibitors to metals with MD method. For carbon steel, the corrosion inhibiton models between hydrolyzed polymaleic anhydride (HPMA), polyepoxysuccinic acid (PESA), and polyaspartic acid (PASP) and the (001) and (110) surfaces of Fe crystal with and without water were simulated with MD method. The results show that.Ebind(001) of the same polymer inhibitor is smaller than Ebind(110)(except PESA). The orders of the binding energies of polymer inhibitors with and without water are PASP> HPMA> PESA, but the binding energy of the former is much smaller than that of the latter. Polymer inhibitor can overcome its intense deformation and closely combine with the face of Fe crystal, and prevent the corrosive medium association with carbon steel, which leads to corrosion inhibition. Because polymer inhibitors can not completely break water molecules and adhere to the surface of Fe crystal, the corrosion inhibition effect is not good. Water molecules affect the interaction between polymer inhibitor and Fe crystal, and affect the deformation of polymer inhibitors, too. From the pair correlation functions, the non-bond interactions are formed between O (inhibitor)-Fe and O (H2O)-Fe. Solvent effect is not negligible in the construction of the model.For the surface of copper, the interactions between6benzotriazole derivatives obtained by modifying benzotriazole with hydroxyl and the (001) surface of Cu2O with and without water were simulated with MD method. The results show that the MD simulation result with water is more consistent with the experiment results. At the same temperature, the sequence of the binding energies of different benzotriazoles with Cu2O (001) in water solution is1-OH-BTA>4-OH-BTA>7-OH-BTA>BTA>5-OH-BTA>6-OH-BTA. Water molecules have an important influence on the interaction between corrosion inhibitors and Cu2O crystal. Because of the difference of molecular structures, the corrosion inhibitions of benzotriazole derivatives are different at various simulation temperatures. Under different temperatures, the order of binding energies of1-OH-BTA with Cu2O(001) is343K>323K>333K, but that of BTA is323K>333K>343K. From non-bond energy and pair correlation functions, the binding energies between corrosion inhibitors and Cu2O crystal are mainly contributed by the Coulomb interaction. Strong adsorption can be raised by the Coulomb interaction between the negatively charged functional groups in corrosion inhibitors and the positive copper ions in the Cu2O(001) face, and further interaction between aggressive media and copper can then be restricted. So the corrosion of copper can be avoided. Chemical bonds or hydrogen bonds are formed in the system of1-OH-BTA/H2O/Cu2O(001). Water molecules can not be ignored in MD simulations, tooAll in all, MD simulations were employed to systematically investigate the relationship between structures and properties of non-phosphorus scale and corrosion inhibitors. The inhibition mechanisms of them are explained, the essences of solvent effect on scale and corrosion inhibition are revealed, and the studies are precursory and originally innovative in front of multi-subject crossing research fields. The research projects assigned by National Natural Science Foundation and Key Laboratory for Ecological-Environment Materials of Jiangsu Province have been successfully completed.更多还原