Hong Kong is one of the few places in the world which uses seawater for flushing. Due to the presence of more complex ions and diverse microorganisms in seawater, corrosion and biofouling are the major deterioration problems that the seawater pipelines of Hong Kong have been currently facing. The pipe failure rate of seawater pipes in the region also remained high in the past decades. One of the most cost-effective ways to prevent these is to apply a coating to the internal lining of pipes. However, industrial coatings in the market still have an opportunity to improve their anti-corrosion and anti-biofouling property for long-term use. This study aims to determine the feasibility of incorporating ionic liquids (IL) into ceramic epoxy coatings to enhance their anti-corrosion and anti-...[ Read more ]

Hong Kong is one of the few places in the world which uses seawater for flushing. Due to the presence of more complex ions and diverse microorganisms in seawater, corrosion and biofouling are the major deterioration problems that the seawater pipelines of Hong Kong have been currently facing. The pipe failure rate of seawater pipes in the region also remained high in the past decades. One of the most cost-effective ways to prevent these is to apply a coating to the internal lining of pipes. However, industrial coatings in the market still have an opportunity to improve their anti-corrosion and anti-biofouling property for long-term use. This study aims to determine the feasibility of incorporating ionic liquids (IL) into ceramic epoxy coatings to enhance their anti-corrosion and anti-biofouling property. 1-butyl-3-methylimidazolium iodide (BMIM-I) was used as a candidate ionic liquid, while CP 232 and CN 200 were the ceramic epoxy coatings used for this study.

The first part focuses on the effect of incorporating BMIM-I on the thermomechanical properties of ceramic epoxy coating. The addition of BMIM-I did not affect the adhesion of the coating, decreased their hardness, and made both coatings more hydrophilic. Furthermore, coatings were cured after one (1) hour at 55^oC, and their FTIR spectra showed no degradation. CP 232 and CN 200 with different IL concentrations were thermally stable below 100^oC. BMIM-I did not alter the surface morphology of the ceramic epoxy coatings and was successfully detected on the surface via EDS and XPS. The second part investigated the ILs effect on the curing progress of ceramic epoxy coatings via in-situ Raman spectroscopy. It was found that adding IL helped hasten the curing progress of CP 232 at room temperature and CN 200 at elevated temperature. Thus, the interaction of BMIM-I varies from one epoxy monomer to another and needs a specific high temperature at which it will interact with the epoxy. The third part tackles the effect of BMIM-I on the anti-corrosion property of ceramic epoxy coatings. Results showed that it did not help achieve higher corrosion inhibition efficiency (CIE), and due to the coatings’ hydrophilicity, it allowed water to enter the epoxy matrix. This section also showed that CN 200 has better anti-corrosion properties than CP 232, owing to its ability to post-cure or self-heal when immersed in water.

The fourth part deals with the effect of BMIM-I on the anti-biofouling property of ceramic epoxy coatings. Bactericidal test and Crystal Violet assay consistently showed that S. aureus had a higher %reduction than E. coli, suggesting that adding BMIM-I has more impact on Gram-positive bacteria. CLSM images confirmed the presence of E. coli biofilm cells and EPS after 48h in the biofilm reactor. Although CN 200 with BMIM-I had a visible reduction in biofilm density compared to the control, the biofilm cells are still scattered almost entirely in the substrate. BMIM+ was also found to leach out of the epoxy matrix at different rates, depending on the type of ceramic epoxy and the amount of added BMIM-I.

The last chapter summarizes the results obtained in the previous chapters, and suggestions were given for possible routes or next steps in this research study.