Application Research Of Metal-Organic Frameworks In Marine Corrosion Detection And Protection

Corrosion has been a major problem that occurred in the whole world and needs to be solved urgently.Especially,the problem of marine corrosion is more serious,which brings enormous economic losses and security threats to the whole world.Therefore,the vigorous development of new materials or technologies for marine corrosion detection and protection is of great significance for the purpose of ensuring the safe use of marine engineering equipment or marine structures,reducing the economic losses of the country and the world,and protecting the lives and safety of the people of the world.Metal-organic frameworks?MOFs?,as a new class of multifunctional materials,have shown excellent application prospects in various fields such as gas storage,adsorption and separation,catalysis,sensing,drug delivery and so on in recent years.MOFs materials have many advantages,such as large specific surface area,highly ordered pores,controllable size and shape,adjustable structure and function,therefore,it is feasible and innovative to develop its application in marine corrosion detection and protection.In this dissertation,MOF materials have been prepared for the application research of corrosion detection and protection,including the sensing detection of the traditional corrosion inhibitor,nitrite,based on MOF-based electrochemical sensor and the fabrications of MOF-based superhydrophobic coatings for the corrosion protection against carbon steel and copper.It is of great significance to study the action mechanism of corrosion inhibitors and the analysis of their effective life as well as the monitoring and detection of corrosion inhibitors that are harmful to the environment.By fabricating MOFs-based superhydrophobic coatings or surfaces,study the influences of material structure,composition,topography and other factors on the properties of superhydrophobic surface,such as anticorrosion,stability,durability,self-cleaning,anti-icing and others,and summarizes the law of the anticorrosion performance and key factors,and provides new methods and techniques for marine corrosion protection theory and application research.The main research contents and results are as follows:?1?An electrochemical sensing platform based on Cu-based metal-organic framework?Cu-MOF?decorated with gold nanoparticles?AuNPs?is constructed for the sensitive detection of the traditional corrosion inhibitor nitrite.Cu-MOF was synthesized by a simple wet chemical synthesis at room temperature.AuNPs were electrodeposited on Cu-MOF modified glass carbon electrode?Cu-MOF/GCE?using potentiostatic method.The AuNPs decorated Cu-MOF?Cu-MOF/Au?displays synergetic catalytic effect for the oxidation of nitrite due to the large surface area and porosity of Cu-MOF,which could prevent the aggregation of AuNPs and increase the adsorption of nitrite,combining with the high conductivity and excellent catalytic activity of AuNPs.A nitrite sensing platform was constructed based on Cu-MOF/Au/GCE,and amperometric technique was adopted for quantitative determination of nitrite.The prepared electrochemical sensing platform demonstrates high sensitivity,selectivity and good stability for the detection of nitrite.It shows two wide linear ranges of 0.1–4000 and 4000–10000?mol L^-1,and the low detection limit of 82 nmol L^-1.Moreover,the sensing platform can also be used for the nitrite detection in real samples.This work would broaden the application of MOFs material in constructing more novel electrochemical sensing platforms.?2?A very facile method that combining nano-sized zeolitic imidazolate framework-8?ZIF-8?particles with low surface energy perfluorooctyltriethoxysilane?POTS?was used to fabricate superhydrophobic paint,which can be facilely and discretionarily coated on various substrate surfaces by spraying to form superhydrophobic coating.Furthermore,epoxy resin?EP?coating was used as adhesion agent to improve the mechanical robustness and durability of the superhydrophobic coating.The as-prepared ZIF-8/POTS/EP superhydrophobic coating shows not only excellent water-repellency?water contact angle=168.2°?,self-cleaning,abrasion resistance,anti-icing,loading-increasing and drag-reducing,but also fantastic corrosion resistance and stability:the impedance modulus value of the ZIF-8/POTS/EP superhydrophobic coating at low frequency?0.01 Hz?was improved by 7 orders of magnitude than Q235 steel;and it maintained its superhydrophobic property after weathering in air for 300 days or immersing in 3.5wt.%NaCl aqueous solution for 60 days.We believe that the facile method we proposed for fabrication of MOF-based superhydrophobic coating can not only promote the effortless and large-scale preparation of superhydrophobic surface and their practical applications in future,but also provide a novel way for applying MOF materials into more fields.?3?Cu-BTC/Cu₂O film was prepared on the copper surface by in-situ synthesis method,and it was further hydrophobically modified by POTS with low surface energy to give Cu-based MOF superhydrophobic film for the corrosion protection performance investigation in simulated seawater.One advantage of this experiment is that the synthesis method Cu-BTC film is green and environmentally friendly,in which Cu matrix is directly used to replace Cu salt in the reaction to reduce the threat of environmental pollution.CuO/Cu₂O bilayer film was prepared by heat treatment of copper substrate in air atmosphere,and then it further hydrothermally reacted with1,3,5-benzenetricarboxylic acid?H₃BTC?in water/ethanol solution to obtain Cu-BTC film.Scanning electron microscope?SEM?,X-ray diffraction?XRD?,X-ray electron spectroscopy?XPS?and Fourier infrared transform spectroscopy?FTIR?etc.were used to characterize the prepared surfaces,which proved the successful preparation of Cu-BTC MOF film.The surface wettability of copper substrate before and after treatment was compared by water contact angle test,and the optimized superhydrophobic surface showed a high water contact angle of 165.2°.The self-cleaning and anti-corrosion properties of the prepared superhydrophobic surface were tested,and the results showed that the in-situ prepared MOF superhydrophobic film possessed not only satisfactory self-cleaning property,but also good protection against copper corrosion.This work could provide new ideas and some guidance for the development of more green and environment-friendly superhydrophobic anti-corrosion surfaces.In summary,this dissertation expands the application scope of MOFs,especially in the field of marine science,provides a new thought for the preparation of high sensitivity to detect corrosion electrochemical sensing platform,extends new materials and new technologies for preparing superhydrophobic surfaces and coatings.It demonstrates the promising application potential of the stable superhydrophobic coating in the field of marine corrosion protection,and has important value to deepen the MOFs application in the wider research fields.