Synthesis of agricultural biomass‐derived biochar‐based epoxy coatings with corrosion resistance and surface protection properties

Abstract The growing emphasis on sustainable materials has sparked interest in biochar as an eco‐friendly coating material. Biochar, a carbon‐rich material derived from the pyrolysis of various agricultural residues, exhibits excellent structural stability, high porosity, and surface functionality, making it a suitable coating material when combined with appropriate binding agents. This study focused on the production of biochar from agricultural crop residues, including sugarcane bagasse, corn stover, and coconut shell, through slow pyrolysis at 550°C with a heating rate of 5°C min −1 for 1 h. Furthermore, the physicochemical characterization of biochar was conducted to assess its compatibility with various binding agents and its suitability as a coating additive. The formulated biochar coatings were evaluated for their adhesion strength, moisture resistance, durability, and mechanical stability. The results demonstrated that a triple‐layered biochar‐based epoxy coating on a metallic surface enhanced adhesion strength and reduced corrosion rate compared to the uncoated substrate when exposed to a 5 wt.% NaCl solution for 60 days. The triple‐layer coating showed less pitting or delamination even after prolonged immersion under NaCl solution, confirming its superior barrier properties and surface protection. The coating delayed chloride‐ion penetration, but once compromised, the underlying mild steel began to corrode. Furthermore, the study highlights the role of biochar in reducing the dependency on synthetic fillers, promoting waste valorization, and contributing to carbon sequestration. The findings emphasize the potential of biochar‐based coatings in various industrial applications, including industrial equipment, construction, packaging, and protective surface treatments, aligning with the principles of green and circular economy.