【作者】 刘新；

【导师】 胡文彬；

【作者基本信息】 天津大学 ， 材料科学与工程， 2021， 博士

【摘要】 海水循环冷却技术以其资源丰富、环境污染小、可节约淡水资源等优点引起了人们的关注。而常用金属设备碳钢在循环冷却海水中的腐蚀是一个严重而不可忽视的问题。目前,多功能负载型缓蚀剂由于可以实现缓蚀剂的持续释放,延长对碳钢的保护作用,引起人们的广泛关注。本文以超顺磁性四氧化三铁（Fe₃O₄）为磁源,设计了核壳结构的水滑石基磁性纳米复合缓蚀剂、磁性壳聚糖负载型缓蚀剂以及核壳一体结构的中空介孔Fe₃O₄微球负载型缓蚀剂。将磁性与纳米容器的特点相结合制备了多功能复合缓蚀剂以期实现缓蚀剂的磁控释放、循环利用以及高效缓蚀。（1）采用离子交换法合成了核壳结构的超顺磁性复合缓蚀剂Fe₃O₄@Mo O₄-LDHs和Fe₃O₄@MBT-LDHs,采用共沉淀法制备核壳结构的复合缓蚀剂Fe₃O₄@Zn Al Ce-Mo O₄-LDHs。制备的复合缓蚀剂具有磁控释放性能,在磁场下释放速率减慢,同时缓蚀作用时间延长。在无磁场模式下,释放机制主要是LDHs层间扩散和壳层LDHs颗粒间扩散。施加磁场模式下,复合缓蚀剂的释放机制为LDHs层间扩散、LDHs粒子间扩散和磁性纳米粒子间的扩散。三种复合缓蚀剂对碳钢的缓蚀效率分别为78.9%、93.6%和89.1%,多次循环后仍具有良好的缓蚀性能。（2）采用离子凝胶法制备了核壳结构的超顺磁性Fe₃O₄/CS/inhibitors复合缓蚀剂,提高了缓蚀剂负载量和缓蚀效率。当壳聚糖浓度为2.0 mg/m L、壳聚糖与三聚磷酸钠质量比为6以及三聚磷酸钠浓度为1.50 mg/m L时缓蚀剂负载量最高,其中缓蚀剂Mo O₄^2-和苯甲酸根（C₆H₅COO^-）负载量分别达到34.8%和22.1%。复合缓蚀剂具有磁控释放性能,外加磁场可以延缓两种缓蚀剂的释放,使其释放时间延长至48 h。在无磁场模式下,Fe₃O₄/CS/inhibitors的释放主要受离子交换和Fickian扩散控制,而在磁场作用下,缓蚀剂的释放机制为离子交换、菲克（Fickian）扩散和磁性纳米颗粒之间的扩散。复合缓蚀剂Fe₃O₄/CS/inhibitors对碳钢的缓蚀效率高达95.6%。此外,制备过程中的壳聚糖浓度、壳聚糖与三聚磷酸钠质量比以及三聚磷酸钠浓度三个制备条件主要通过影响释放路径影响复合物的释放行为。（3）采用溶剂热法制备中空磁性Fe₃O₄微球,并利用浸渍法负载二巯基苯并噻唑（MBT）缓蚀剂,合成超顺磁性核壳一体结构的Fe₃O₄/MBT复合缓蚀剂,实现了复合缓蚀剂的多功能化。该复合缓蚀剂中MBT负载量为55.4%,且具有磁控释放性能,在1350 Gs磁场强度下释放37.66 h时释放量仅为10%。在无磁场模式下,释放机制主要是Fickian扩散,而施加磁场模式下释放机制主要是Fickian扩散和磁性纳米粒子之间扩散。复合缓蚀剂对碳钢缓蚀效率高达95.7%,且具有良好的循环利用性能,五次循环后缓蚀剂负载量为45.1%,缓蚀效率为78.8%。（4）为了进一步提高中空Fe₃O₄微球的负载量,利用草酸溶液对其进行刻蚀,并采用浸渍法负载MBT缓蚀剂。随刻蚀剂草酸浓度的增高,微球空腔和孔径变大。当草酸浓度为7.0 mg/m L时微球缓蚀剂负载量最高,可达到77.6%。此外,缓蚀剂的释放速率随刻蚀剂草酸浓度增大而提高,且释放行为具有磁控释放性能。制备的中空Fe₃O₄微球可以负载多种缓蚀剂如铈离子(Ce³⁺)、苯并三氮唑（BTA）和Mo O₄^2-,且皆具有磁控释放性能和良好的缓蚀性能。更多还原

【Abstract】 Seawater circulating cooling technology has attracted people’s attention for its advantages of rich resources,reducing environmental pollution and saving fresh water resources.The corrosion of common metal equipment carbon steel in circulating cooling seawater is a serious problem that can not be ignored.At present,the multi-functional supported corrosion inhibitors have aroused more attention because it can realize the continuous release of corrosion inhibitor and prolong the protection of carbon steel.In this paper,superparamagnetic ferric oxide（Fe₃O₄）was introduced as magnetic source,and the core-shell structural layered double hydroxides（LDHs）-based magnetic nanocomposite inhibitor,magnetic chitosan（CS）supported inhibitor and hollow mesoporous Fe₃O₄ microspheres supported inhibitor were designed.The composite inhibitor prepared combined the magnetic property and characteristics of nanocontainer,in order to achieve the effect of magnetic controlled release,recycling and efficient corrosion inhibition.（1）Superparamagnetic composite inhibitors Fe₃O₄@Mo O₄-LDHs and Fe₃O₄@MBT-LDHs with core-shell structure were synthesized by ion exchange method.The core-shell structural Fe₃O₄@Zn Al Ce-Mo O₄-LDHs composite inhibitor was prepared by coprecipitation method.The results show that the composite inhibitor has magnetic controlled release property,and the magnetic field slows down the release rate and prolongs the inhibition time.Without magnetic field,the release mechanism is mainly interlayer diffusion of LDHs and the inter particle diffusion of LDHs layer.While under magnetic field,the release mechanism includes the interlayer diffusion of LDHs,the inter particle diffusion of LDHs layer and the diffusion among magnetic nanoparticles.The corrosion inhibition efficiency of the three kinds of composite inhibitors for carbon steel is 78.9%,93.6%and 89.1%respectively,and they still have good corrosion inhibition performance after repeated cycles.（2）Superparamagnetic Fe₃O₄/CS/inhibitors composite corrosion inhibitor with core-shell structure was prepared by ionic gel method,which improves the loading capacity and inhibition efficiency of corrosion inhibitor.When the concentration of chitosan was 2.0 mg/m L,the mass ratio of chitosan to sodium tripolyphosphate was 6and the concentration of sodium tripolyphosphate was 1.50 mg/m L,the loading capacity of Mo O₄^2-and C₆H₅COO^-reached maximum,which was 34.8%and 22.1%,respectively.The composite inhibitor has magnetic controlled release property and the external magnetic field could delay the release behavior of the two kings of inhibitors,which prolonged the release time to 48 h.Without magnetic field,the release of Fe₃O₄/CS/inhibitors is mainly controlled by ion exchange and Fick’s law of diffusion,while the release mechanism under magnetic field mainly includes ion exchange,Fickian diffusion and diffusion among magnetic nanoparticles.The inhibition efficiency of the prepared composite inhibitor Fe₃O₄/CS/inhibitors for carbon steel is up to 95.59%.In addition,three preparation conditions including the concentration of chitosan,the mass ratio of chitosan to sodium tripolyphosphate and the concentration of sodium tripolyphosphate during the fabrication process mainly affect the release behavior of the composite by affecting the release path.（3）Hollow magnetic Fe₃O₄ nanospheres were prepared by solvothermal method,and the superparamagnetic Fe₃O₄/MBT composite inhibitor with core-shell integrated structure was synthesized by loading 2-Mercaptobenzothiazole（MBT）inhibitor into the prepared Fe₃O₄ microspheres via impregnation method,which realizes the multifunctionality of the composite inhibitor.The MBT loading capacity of the composite inhibitor is 55.4%and the composite inhibitor presents the magnetic controlled release performance,when the magnetic field strength is 1350 GS,the release amount was only 10%at release time of 37.66 h.Without magnetic field,the release mechanism is mainly Fick’s law of diffusion and the release mechanism of the inhibitor under magnetic field mode was mainly Fickian diffusion and diffusion among magnetic nanoparticles.The composite inhibitor shows good corrosion inhibition for carbon steel,up to 95.7%and it also has good recycling performance.After five cycles,the inhibitor loading capacity was 45.1%,and the inhibition efficiency was 78.8%.（4）To further improve the loading capacity of hollow Fe₃O₄ microspheres,the obtained Fe₃O₄ microspheres was etched with oxalic acid solution and MBT inhibitor was loaded into the nanospheres by impregnation method.It shows that with the increase of oxalic acid concentration,the cavity and pore size of the nanospheres become larger.When the concentration of oxalic acid was 7.0 mg/m L,the obtained microsphere has the maximal inhibitor loading capacity,which is up to 77.6%.In addition,the release rate of inhibitor from the nanospheres increases with the increase of oxalic acid concentration and the release behaviour shows magnetic controlled release performance.The prepared hollow Fe₃O₄ microspheres can load a variety of inhibitors,such as cerium ion(Ce³⁺),benzotriazole（BTA）and Mo O₄^2-,which all present magnetic controlled release performance and good corrosion inhibition.更多还原