Utilization of Tuna Fish Skin Waste: Synthesis and Application of Nanocarbon Dots for Corrosion Resistance in Epoxy Polymers

Abstract

World fishery production and its processing generate huge volumes of fish waste which cause significant challenge to public health and urban planning. The objective of this study is to prepare nanocarbon dots using tuna skin waste and to assess their effectiveness as an additive in three epoxy polymer coatings. These coatings will be applied to BIS 2062 boat building steel to study corrosion in marine environments. Fish skin-derived nanocarbon dots (FSCD) were synthesized through hydrothermal carbonization. Spectroscopic evaluation confirmed the presence of multiple fluorophores in FSCD, which suggest that molecule’s structure includes a cyclic conjugated carbon core with dangling functional groups such as COOH, C=O, −OH and C–NH at the edges, resulting in blue–green fluorescence. Electrochemical characteristics of FSCD-reinforced commercial epoxy polymer (3 types)-coated BIS 2062 steel demonstrated excellent corrosion resistance in marine environment. The optimum concentrations of FSCD were determined to be 0.05% in bisphenol A and Dobeckot epoxy polymers, and 0.02% in Araldite epoxy polymer, as evidenced by the highest polarization resistance, lowest corrosion current density and capacitance. The nano-FSCD exerted a synergistic influence on pore-free polymerization due to the presence of dangling functional groups such as amines, in addition to the amine-based hardener. Therefore, fish waste-derived carbon dots offer great potential as a cost-effective and eco-friendly anticorrosive additive for epoxy polymers, meeting the majority of requirements in the anticorrosive coating industry.