Incorporation of Agro-industrial Waste Coconut Fiber in Anti-corrosive Coatings as Environmentally Friendly Pigment

Ecological pigments represent an innovative class of materials suitable for incorporation into epoxy primers. This study outlines a methodology for integrating coconut microfibers as environmentally friendly pigments in epoxy organic coatings. Two types of microfibers were utilized: untreated (UM) and treated (TM) coconut fibers, incorporated into coatings at PVC levels of 2.5 and 5.0%. Electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), and adherence tests using the pull-off method were conducted. EIS measurements indicated that coatings incorporating untreated coconut fibers exhibited superior performance in initial immersion stages. Impedance modulus at low frequencies for samples with untreated fiber incorporation (UMP50 and UMP25) initially demonstrated the highest values up to 24 h of immersion (|Z|_0.01Hz-UMP50 = 2.82 × 109 Ω cm²; |Z|_0.01Hz-UMP25 = 2.03 × 109 Ω cm²; |Z|_0.01Hz-MP00 = 6.09 × 108 Ω cm²), but over time, samples without fiber incorporation exhibited better results. After 720 h, the sample with treated fibers at PVC = 5.0% showed higher impedance values. Adherence tests confirmed that fiber addition did not compromise coating adhesion. In conclusion, incorporating microfibers as pigments in epoxy-based organic coatings successfully enhanced their anti-corrosive properties.