具表面活性噻二唑衍生物的合成与缓蚀性能研究

发布时间：2018-08-01 16:49

【摘要】：碳钢是一种被广泛应用的金属材料,但由于它的化学特性较为活泼,使得其在应用中容易发生腐蚀。因此,腐蚀领域学者们对碳钢的腐蚀防护问题一直都很关注。合理添加缓蚀剂被认为是一种经济、高效的防护手段。本论文合成了两个具有表面活性的噻二唑类缓蚀剂,主要研究成果如下:以三聚氯氰、正己胺、正辛胺、2-巯基-5-甲基-1,3,4-噻二唑(MMTD)、N,N-二甲基-1,3-丙二胺作为反应原料,合成了两个噻二唑衍生物:MTC_6T和MTC_8T,并通过ESI-MS、~1H NMR、FT-IR对其进行结构表征。MTC_6T和MTC_8T降低0.5 M H_2SO_4溶液表面张力的能力明显优于MMTD。当MTC_6T和MTC_8T的添加量分别达到0.2 mM、0.1 mM后,随浓度的进一步增加表面张力改变较小,此时的浓度为临界胶束浓度。失重法、电化学测试、量子化学计算及扫描电镜测试结果表明:MMTD、MTC_6T和MTC_8T的缓蚀效率随着缓蚀剂浓度的增大而逐渐提高;随温度的升高而逐渐降低。三个噻二唑衍生物在硫酸溶液中均属于混合型缓蚀剂,缓蚀剂的加入降低了碳钢表面的双电层电容,腐蚀反应阻力增大。最高占据轨道能量(EHOMO)为MTC_8T高于MTC_6T,最低空轨道能量(ELUMO)为MTC_8T低于MTC_6T,因此在腐蚀介质中较MTC_6T活泼。扫描电镜测试中,MTC_6T和MTC_8T保护下的金属表面平整,显著抑制了坑蚀的发生。吸附热力学及动力学研究结果表明:硫酸溶液中MMTD在碳钢表面的吸附符合Fr eundlich等温吸附;而MTC_6T及MTC_8T在碳钢表面的吸附符合Langmuir等温吸附,该过程是自发进行的,温度升高阻碍吸附过程;MTC_6T和MTC_8T在碳钢表面的吸附是以化学吸附为主的混合型吸附。温度一定的条件下,缓蚀剂浓度增加,使得指前因子Ar和表观活化能Ea都增大。Ea值满足Ea(MTC_8T)Ea(MTC_6T)Ea(MMTD),这进一步证实了MTC_8T的缓蚀效果最优。
[Abstract]:Carbon steel is a kind of widely used metal material, but it is easy to corrode because of its active chemical properties. Therefore, the corrosion protection of carbon steel has always been concerned by scholars in the field of corrosion. The reasonable addition of corrosion inhibitor is considered to be an economical and efficient means of protection. In this paper, two surface-active thiadiazole corrosion inhibitors were synthesized. The main research results are as follows: cyanuric chloride, n-hexylamine, n-octylamine 2-mercapto -5-methyl-1-thiadiazole (MMTD) were used as raw materials for the reaction. Two derivatives of thiadiazole, MTC6T and MTCIM _ 8T, were synthesized, and their structures were characterized by ESI-MSI ~ 1H NMR-FT-IR. The ability of MTC_8T to reduce the surface tension of 0.5 M H_2SO_4 solution was obviously better than that of MMTD. When the addition of MTC_6T and MTC_8T reached 0.2mmM and 0.1mm respectively, the surface tension changed slightly with the further increase of concentration, and the concentration was critical micelle concentration. The results of weightlessness method, electrochemical test, quantum chemistry calculation and scanning electron microscopy showed that the corrosion inhibition efficiency of MTC_8T and MTC6T increased with the increase of the concentration of inhibitor, and decreased with the increase of temperature. The three thiadiazole derivatives are all mixed corrosion inhibitors in sulfuric acid solution. The addition of corrosion inhibitor reduces the double layer capacitance of carbon steel surface and increases the corrosion reaction resistance. The highest occupied orbital energy (EHOMO) is higher than that of MTC _ s _ (6) T, and the lowest empty orbit energy (ELUMO) is lower than that of MTC _ s _ (6) T, so it is more active than MTC_6T in corrosive medium. The metal surface under the protection of MTC6T and MTC_8T was smooth in scanning electron microscopy (SEM), which significantly inhibited the occurrence of pit erosion. The results of thermodynamics and kinetics show that the adsorption of MMTD on carbon steel in sulfuric acid solution conforms to the Fr eundlich isotherm adsorption, while the adsorption of MTC_6T and MTC_8T on the surface of carbon steel conforms to Langmuir isotherm adsorption. The adsorption of MTCST6T and MTC_8T on carbon steel surface is a mixture of chemisorption and chemisorption. With the increase of the concentration of the inhibitor at a certain temperature, both the pre-exponential factor ar and the apparent activation energy EA are increased. The value of EA (MTC_8T) Ea (MTC_6T) Ea (MMTD),) further proves that the inhibition effect of MTC_8T is optimal.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.42

【参考文献】