The effect of different chemicals (H 2 SO 4 , NaOH and H 2 O 2 ) pretreatments at various concentrations and microwaveassisted chemical (NaOH, H 2 SO 4 + NaOH and H 2 SO 4 + NaOH + H 2 O 2 ) pretreatments on conversion of lignocelluloses in kitchen waste for maximum glucose yield were comparatively investigated. Overall, pretreatment by dilute H 2 SO 4 (2%) achieved the highest glucose yield of 39.43 g/L with glucose recovery of 98.86%. Alkali pretreatment using NaOH at different concentration shows no significant effect on the glucose generation (0.61-1.13 g/L) when NaOH concentration was increased. However, the combination of alkali pretreatment with microwave treatment resulted in a drastic increase of glucose yield in kitchen waste sample. Meanwhile, H 2 O 2 pretreatment seems to have little effect on the glucose yield (1.53-3.05 /L) when the concentration of H 2 O 2 was increased. But when this oxidizing agent was added to H 2 SO 4 and NaOH -microwave treatment, it increases the glucose yield from 10.36 to 13.31 g/L. With respect to glucose recovery, all microwave-assisted chemical pretreatment achieved the value of more than 90% glucose recovery.
No abstract
Often in the water injector (WI) system with liners, the "unseen" damage such as micro scratch is very difficult to be detected, and these micro scratches, when not detected will eventually become a major damage. Employing self-healing technology in the liner will ensure that the minor damage will be healed autonomously during operation, subsequently preventing further major damage. The in-situ healing of the damages is one of the amazing criteria offered by this technology. The integrity of the WI system is eventually assured, prolonging the service life of the materials and avoiding unnecessary expensive inspection and maintenance. In this present work, self-healing technology has been developed for the epoxy-based materials used in glass-reinforced (GRE) liner system for WI tubing. The novel self-healing additives were synthesized using a facile synthesis method and have been proven to be able to potentially replace the expensive rare-earth based catalyst, hence making the commercial step viable. The metal-organic frameworks (MOFs) microcapsules self-healing in the epoxy-based liner system demonstrated successful autonomous healing efficiency at elevated temperatures as examined using a 3D-profilometer, with a healing efficiency of more than 80%. The system with the self-healing additives was able to recover the barrier performance of the liner, up to 98% efficiency as shown by the electrochemical impedance spectroscopy (EIS) assessment. In addition to that, within 2 hours of healing activation by temperature, the samples with the self-healing additives were able to autonomously heal, reaching more than 50% healing efficiency. Moreover, this self-healing system was able to heal a damage width of up to 700µm, for more than 80% healing efficiency. It is worth mentioning that the healing ability remained functional even though the samples had been exposed to harsh conditions for 1000 hours. The healing agent particularly contained in the microcapsules remains intact and stable throughout the stability study, hence suggesting a robust self-healing system. This finding shows the possibility of this technology to provide a sustainable production of self-healing additives for a liner in water injector's well, hence potentially improving the integrity of the materials.
Polymer coatings, especially epoxy and polyurethane paint systems, have been widely used to prevent corrosion of metallic components and structures. However, due to environmental and mechanical effects, the barrier efficiency of the coatings may be substantially compromised during transportation and service, as demonstrated by localized scratches, delamination, or stress-related microcracks. Application of a self-healing coating that can restore damages and recover its performance with minimal external intervention could prevent corrosion at the damaged coating. In this present work, the healing efficiency and long-term durability of Boronic Ester (BE) blended with Polyurethane (PU) as a self-healing system for top side coating of offshore platform structures was investigated. The BE was mixed at a ratio of 50:50 with PU resin and applied as a top layer on a PU coated steel plate with a thickness of approximately 300-350 μm. The healing efficiency, mechanical performance, and durability under simulated environmental conditions such as salt spray and UV were investigated according to the related ASTM standards. As a first step, the electrical impedance spectroscopy (EIS) and 3D profilemeter microscope were used to assess the healing ability of the scratched coating at room temperature and humidity level of 85 %. The mechanical performance of the self-healing coating layer was evaluated using a pull off adhesion test to investigate the compatibility of the self-healing system with the existing commercial PU topcoat system, while a long term 3000 hours salt spray and 4200 hours cyclic UV test were performed to evaluate the self-healing coating's durability in harsh conditions. Preliminary assessment using EIS and 3D profilemeter microscopes on the scratched PU/BE self-healing coating revealed significant healing efficiency of more than 80% for healing condition at ambient temperature and humidity level of 85%. The self-healing coating layer also demonstrated excellent adhesion efficiency, with adhesion greater than 300 psi suggesting good compatibility of the BE-PU layer with commercial PU coating. The salt spray and cyclic UV tests that were performed to determine the durability of the self-healing coating revealed that the 50BE/50PU layer remained intact and exhibited good healing performance with more than 80% efficiency even after exposure to harsh conditions. The findings from the study demonstrated that the BE/PU material has the potential to be used as a self-healing system for topside coating of offshore platforms structures, thereby lowering maintenance costs.
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