曼尼希碱缓蚀剂的制备和性能测试

发布时间：2018-04-16 16:36

  本文选题：缓蚀剂 + 曼尼希碱　； 参考：《陕西科技大学》2017年硕士论文

【摘要】：金属的腐蚀问题已经成为一个严重的社会问题,不仅造成了大量的经济损失,更带来了巨大的安全隐患。使用缓蚀剂是减缓金属腐蚀的有效手段。曼尼希碱缓蚀剂由于较好的稳定性和分散性、低毒高效等,而受到广泛应用。但是,目前使用的缓蚀剂大多有添加量较大,在高酸度条件下缓蚀效果不明显等缺点。曼尼希碱中含有氮、氧等杂原子,这些杂原子中都有未被共用的孤对电子,可以进入金属原子的空轨道,在金属表面形成吸附。本课题为了制备缓蚀性能较好的缓蚀剂,依据缓蚀剂缓蚀机理,选取曼尼希反应需要的醛、酮、胺,对它们进行相互组合反应,测定所得产物缓蚀效率。实验结果表明以甲醛、邻甲苯胺、苄叉丙酮为反应物和以甲醛、邻甲苯胺、对甲氧基苯乙酮为反应物所制备的缓蚀剂缓蚀效率较高,分别命名为MNX-A和MNX-B。通过单因素实验和正交实验考察了反应温度、反应时间、反应pH、醛酮胺摩尔比对缓蚀剂缓蚀效率的影响,筛选缓蚀剂MNX-A和MNX-B的最佳制备条件。缓蚀剂MNX-A的最佳制备条件为反应温度70℃、反应时间2h、反应pH为3、醛酮胺摩尔比为1:1:1,此条件下缓蚀剂对N80钢的缓蚀效率为93.95%,分离产率为83.14%。MNX-B的最佳制备条件为反应温度60℃、反应时间3h、反应pH为2、醛酮胺摩尔比为1:1:1,此条件下缓蚀剂对N80钢的缓蚀效率为92.45%,分离产率为86.34%。借助核磁共振确定了MNX-A和MNX-B的主产物的结构,与目标产物一致。通过挂片失重法,测定了缓蚀剂的缓蚀效率随腐蚀温度、腐蚀时间、盐酸浓度、缓蚀剂浓度的变化。缓蚀剂MNX-A和MNX-B的缓蚀效率随腐蚀温度的升高和盐酸浓度的增大,先增大后减小;随缓蚀剂浓度的升高和腐蚀时间的延长,先增大后基本不变;在N80钢表面的吸附都符合Langmuir等温吸附模型,吸附ΔG0分别为-33.49kJ/mol和-32.64k J/mol,都位于-20kJ/mol~-40kJ/mol之间,表明缓蚀剂在金属表面既有化学吸附又有物理吸附。分散性实验表明,在测定条件下缓蚀剂浓度低于1500mg/L时,缓蚀剂分散性良好。通过极化曲线分析可知缓蚀剂MNX-A和MNX-B腐蚀电位位移都小于85mV,表明为阴极抑制为主的混合型缓蚀剂;依据腐蚀电流密度计算出的缓蚀效率与挂片失重法得到的缓蚀效率基本一致。通过分析交流阻抗图,模拟出缓蚀剂在盐酸溶液中的电路图,分析溶液中缓蚀剂分布状态,推测缓蚀机理。通过扫描电镜观察金属表面形态,发现添加缓蚀剂后,N80钢表面的腐蚀得到了有效的控制。选取多种复配剂对缓蚀剂MNX-A和MNX-B进行复配,讨论了在缓蚀剂添加量为10mg/L、20mg/L、50mg/L时,复配剂浓度对复合缓蚀剂缓蚀效率的影响。其中KI、六次甲基四胺、硫脲对MNX-A和MNX-B均表现出了良好的协同作用。钼酸钠在缓蚀剂浓度为20mg/L时表现出良好的协同作用。
[Abstract]:The corrosion of metals has become a serious social problem, which not only causes a lot of economic losses, but also brings huge hidden dangers to safety.The use of corrosion inhibitor is an effective way to reduce metal corrosion.Mannich base corrosion inhibitor is widely used because of its good stability and dispersion, low toxicity and high efficiency.However, most of the corrosion inhibitors used at present have some disadvantages, such as large amount of corrosion inhibitor and low inhibition effect under high acidity.There are nitrogen, oxygen and other hetero-atoms in Mannich base, all of which have unshared lone pairs of electrons, which can enter the empty orbit of metal atoms and form adsorption on metal surface.In order to prepare corrosion inhibitor with good corrosion inhibition performance, according to the corrosion inhibition mechanism of the inhibitor, the aldehyde, ketone and amine needed for Mannich reaction were selected, and the corrosion inhibition efficiency of the products was determined.The experimental results show that the corrosion inhibitor prepared with formaldehyde, o-toluidine, benzyl acetone as reactant, formaldehyde, o-toluidine and p-methoxyacetophenone as reactants has higher corrosion inhibition efficiency, and is named MNX-A and MNX-B, respectively.The effects of reaction temperature, reaction time, reaction pH, molar ratio of aldehyde, ketone and amine on the corrosion inhibition efficiency of corrosion inhibitor were investigated by single factor experiment and orthogonal experiment. The optimum preparation conditions of inhibitor MNX-A and MNX-B were selected.The optimum preparation conditions of corrosion inhibitor MNX-A were as follows: reaction temperature 70 鈩，

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