MIL-101(Cr)/epoxy composite coating for enhanced corrosion resistance in concrete sewer infrastructure

Concrete sewer systems are essential to urban infrastructure but are highly susceptible to microbial-induced corrosion (MIC), leading to severe structural degradation and substantial maintenance costs. This study develops a MIL-101(Cr)/epoxy composite coating to mitigate MIC and enhance concrete durability in aggressive environments. MIL-101(Cr) nanoparticles were synthesized via a scalable hydrothermal process and incorporated into epoxy matrices at varying concentrations (0.5 %, 1.0 %, and 1.5 % by weight). The optimized 1 wt% MIL-101(Cr)/epoxy composite exhibited remarkable corrosion resistance, reducing weight loss to 5.2 % after 65 days of sulfuric acid exposure, improving performance by 78.3 % over uncoated concrete and 70.6 % over pure epoxy coatings. Water absorption was minimized to 0.12 %, ensuring superior moisture resistance and long-term durability. The composite coating achieved a pull-off strength of 6.12 MPa, a 48.5 % enhancement over conventional epoxy coatings, highlighting its strong adhesion and structural integrity. Thermogravimetric analysis showed improved thermal stability, with dehydration peaking at 173.6 °C. Density Functional Theory (DFT) calculations further validated the experimental findings, demonstrating enhanced electron-donating and electron-accepting properties that contribute to the composite’s outstanding anti-corrosive performance. This study demonstrates that MIL-101(Cr)/epoxy composites are a promising and sustainable solution for extending the service life of concrete sewer infrastructure in corrosive environments.