十八胺基超分子缓蚀剂分散体系的构筑及其在管线钢表面的组装机理

Octadecylamine is usually used as vapor protective agent in thermal systems. However, owing to the weak polarity and gauche defect of alkyl chain, it is hardly for ODA to uniformly dispersed and adsorbed at the water/metal interface. We will construct a supramolecular dissolution and dispersion system based on ODA, and discuss its protective mechanism for carbon steel of condensate pipe line. To avoid gelation and resinification of final production, cyclodextrin derivatives and crosslinking agent with low molecular weight will be applied; after dispersion, the supramolecular host can be obtained. Supramolecular assemblies between host and ODA will be constructed through extraction process in nonpolar solvent. Based on the difference between orbital binding energy and non-covalent interaction, the internal bonding strength of assembly can be controlled through adjusting the degree of dispersion, ratio of host/guest and stability constant to ensure the forced release of ODA. Using steel 20 as the substrate, the information of stability, phase distribution coefficient, discrete step and configuration of ODA can be obtained via interface analysis, electrochemistry and empirical calculation. The law of molecular transport, release and re-recognition and self-assembly of supramolecular inhibitor will be summarized, and the continuous process of controllable dissolved dispersion-inhibition-recognition and assembly-recycling will also be built. This work can provide new approach for functional studying the insoluble organic corrosion inhibitor; in addition, the achievements of our study have significant meaning for condensation water to get rid of corrosion products and be recycled without polishing.

十八胺（ODA）常用作热力设备运行与停用的气相保护剂，由于弱分子极性与烷基链扭转缺陷，其无法在水/金属界面均匀分散与吸附。课题拟构筑ODA基超分子可控溶解分散体系，探讨其对凝结水管线的保护机理。采用环糊精衍生物，在小分子交联剂辅助下，避免产物凝胶或树脂化，经分散形成主体，利用反相溶剂萃取与ODA组装成超分子缓蚀剂；比较轨道结合能与非共价作用的能量差异，通过调节分散度、组装计量比与稳定常数，控制组装体内部结合强度，确保ODA可在碳钢表面定位与被迫释放；以20#钢为基材，借助界面分析、电化学与经验计算，获取缓蚀剂在高温扰动水相中稳定性、相分配系数、界面ODA离散步长与构型等信息，总结分子传输、释放及再识别与组装规律；建立可控溶解分散-靶向识别-释放缓蚀-再识别组装-循环利用的连续过程，为难溶难分散缓蚀剂的功能化研究提供新方法，对实现凝结水免受管线腐蚀物污染与无须精制直接含能回用具有重要意义。

十八胺（ODA）具有极性端氨基与较长低极性烷基链，在常温常压下易挥发并通过端氨基吸附于金属表面形成疏水层有效阻隔O2、CO2与腐蚀性离子。然而，鉴于较低的分子极性，ODA难溶于水，无法在水相发挥高效缓蚀作用。主持人在基金（21606005）的支持下，结合北京市自然科学基金面上项目与北京市青年拔尖人才计划等的资助，将分子识别与自组装理论引入缓蚀剂研究，通过自制环糊精连续衍生化装置，实现宏量制备环糊精衍生物（CDs），并以其及CDs低聚物（CDP）为主体、ODA为客体，经反相溶剂萃取精准构筑主、客体组装比为1:1和2:1的分子组装体（CDDA）。借助动态失重、电化学与表面分析等方法，结合分子对接、动力学模拟与基于密度泛函理论的量子化学计算，全面阐释CDDA的形成机制及在蒸汽凝结水中于20#钢表面的组装机理。主体与ODA在水相组装的相溶解度曲线呈Bs型，即低浓度主体以1:1型组装为主，高浓度时则完成2:1组装；基于Lamarckian遗传算法的分子对接结果表明ODA烷基链-CH2-单元可与CDs空腔内部仲羟基形成氢键，键能达-38.60 kJ/mol；分子动力学模拟结果显示2:1组装时，两个CDs倾向于以窄端口相对排列。动态失重与电化学分析均显示CDDA可有效减缓凝结水对20#钢的腐蚀并降低水体中的全铁含量，属于阳极抑制为主的混合型缓蚀剂。经CDDA处理后的碳钢表面呈疏水性且仅检测到客体的价键信息，说明借助组装，ODA可有效溶解分散于水中，并输运至钢/液界面后被释放。动力学模拟捕捉到与实验推测相同的吸附历程，同时ODA呈现一定角度倾斜吸附于金属表面，结合能高达1862.02 kJ/mol；ODA的独特吸附构型源于其特殊电子结构。现场实验结果显示，投放CDDA后，凝结水中的全铁含量可稳定在约60 μg/L，低于GB 1576-2008的期望值，混合少量软化水后可作补水回用，利于节能减排。现已超额完成任务书约定的所有内容：已发表SCI论文11篇，EI论文3篇，核心期刊1篇，会议论文6篇，另有接收待刊论文4篇（2篇SCI收录），授权发明专利2件，现场应用超分子缓蚀剂案例1项；主持人入选核心期刊《工业水处理》青年编委。