烟酸、吖啶、黄连素对热浸镀钢材的缓蚀作用及其量化构效关系

IOCAS-IR > 海洋环流与波动重点实验室

	烟酸、吖啶、黄连素对热浸镀钢材的缓蚀作用及其量化构效关系
	鞠虹
学位类型	博士
	2008-01-11
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	热浸镀层缓蚀剂量子化学计算电化学方法恒电量方法
摘要	为了找到在热浸镀钢材表面清洗处理过程中替代铬酸的缓蚀、清洗剂，本论文通过量子化学计算方法、失重实验、电化学测试和扫描电镜分析等方法系统研究了环境友好型缓蚀剂——烟酸、吖啶和黄连素对热浸镀锌、5%铝-锌和55%铝-锌钢材在盐酸介质中的缓蚀作用及其量化构效关系。量化计算结果表明，这三种杂环化合物均具有多个吸附活性中心的平面结构。Mulliken电荷、最高占据轨道（HOMO）能量和最低空轨道（LUMO）能量分布显示活性中心主要集中在氧原子、氮原子和杂环周围。三种化合物可能通过这些活性中心吸附在镀层表面以阻止镀层电极反应，且其前线轨道同镀层表面锌原子的前线轨道能够相互作用，使得杂环化合物分子可通过在镀层钢材表面形成吸附膜而阻止镀层表面锌在盐酸介质中的溶解。失重和电化学测试的结果表明，三种化合物对三种热浸镀钢材在盐酸介质中均是高效的环境友好型缓蚀剂，最高缓蚀效率可达99%以上；其中黄连素的缓蚀效果最好，在浓度为1.0×10-4M时缓蚀效率就已达到80%以上。实验结果同时表明，三种缓蚀剂通过单分子层的化学吸附方式吸附在镀层表面以阻滞酸液对镀层的腐蚀，其吸附遵从Langmuir吸附等温式。扫描电镜分析结果也显示了在盐酸介质中三种缓蚀剂能够很好地抑制镀层的腐蚀。几种实验方法得到的结果能够很好地吻合，同时又都验证了量子化学计算的推测。另外，通过恒电量方法和量化构效关系(QSAR)研究了盐酸介质中烟酸、吖啶和黄连素对热浸镀钢材的缓蚀机理。恒电量实验验证了失重实验和电化学测试的结果：烟酸、吖啶和黄连素是混合型缓蚀剂，三种缓蚀剂通过活性中心吸附在镀层材料表面，同时抑制镀层的阴阳极反应以减缓镀层在盐酸溶液中的腐蚀。量化构效关系显示缓蚀效率与最高占据轨道能量（EHOMO）成正相关关系，与前线轨道能量差ΔE（ELUMO-EHOMO）成负相关关系；三种缓蚀剂通过提供电子与镀层材料表面锌原子相互作用而起到缓蚀作用。最后，以铬酸清洗方法作参照，使用缓蚀酸液清洗方法对热浸镀钢材的腐蚀产物进行去除，结果显示，缓蚀酸液清洗方法可替代铬酸对热浸镀钢材进行腐蚀产物去除和绿色清洗。
其他摘要	For purpose of finding chromate-substituting inhibitor in finishing process of hot dip coated steels, inhibition effects and quantitative structure activity relationship of environment-friendly inhibitors—nicotinic acid, acridine, and berberine, for hot dipping Zn, 5%Al-Zn, and 55%Al-Zn coated steels in diluted HCl solution was investigated using quantum chemical calculation method, weight loss test, electrochemical measurement, and scanning electronic microscope analysis. Quantum chemistry calculation results showed that these three heterocyclic compounds had planar structure with a number of active centers. The populations of the Mulliken charge, the highest occupied molecular orbital (HOMO) energy, and the lowest unoccupied molecular orbital (LUMO) energy were showed that the active centers were mainly focused around oxygen, nitrogen atoms, and the heterocyclic. The corrosion inhibition of hot dip coatings was discussed in terms of blocking the electrode reaction by adsorption of the molecules at the active centers on the electrode surface. And frontier orbital of the three compounds could interact with the frontier orbital of Zn atom of coating surface; thus they might form an adsorption barrier film on the coating surface to decrease the corrosion rate of zinc. Weight loss test and electrochemical measurement results indicated that nicotinic acid, acridine, and berberine were effective and environmental friendly corrosion inhibitors for the three hot dip coatings in HCl solutions, and the highest inhibition efficiency was up to 99%. Among the three inhibitors, berberine showed the best performance with inhibition efficiency up to 80% when at a relatively lower concentration of 1.0×10-4 mol/L. It also was found that the adsorption of the three compounds on coating surface followed Langmuir adsorption isotherm with single molecular layer, and molecules adsorbed on the coating surface probably by chemisorption. The surface morphology also showed that the surface corrosion of hot dipped coatings could decrease remarkably after these three inhibitors added in hydrochloric acid. The inhibition efficiency obtained using different techniques showed a good agreement with each other, and both confirmed the presumption from the quantum chemical calculation. Moreover, the inhibition mechanism of nicotinic acid, acridine, and berberine for the hot dip coating steels in hydrochloric acid was studied by coulostat method and quantitative structure–activity relationship (QSAR). The coulostat method confirmed the results of the weight loss test and electrochemical measurement that nicotinic acid, acridine, and berberine were mixed-type inhibitors. And they adsorbed on the coating surface through active centers adsorption style to suppress both anodic and cathodic processes. The results of QSAR showed that the inhibition efficiency increased with the increasing values of EHOMO of inhibitor, and increased with the ΔE decreasing. And these three inhibitors acted as inhibition effect by electron donating to Zn atom of the coating surface. Finally, the effects of removing corrosion products for hot dip coating steels by inhibited hydrochloric acid were contrasted with the chromic acid. The results showed that the finishing method of inhibited hydrochloric acid could perform as a chromate-substituting method of removing corrosion products and efficient environment-friendly finishing method for hot dip coated steels in finishing process.
页数	140
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/469
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	鞠虹. 烟酸、吖啶、黄连素对热浸镀钢材的缓蚀作用及其量化构效关系[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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