Protection of mild steel in acidic and saline media using a novel surface coat developed with Pueraria phaseoloides seed extract and epoxy resin

Abstract

Pueraria phaseoloides (PP), commonly known as tropical kudzu or puero, stands as an invasive leguminous vine native to Southeast Asia; yet recent studies unveil its promising potential in myriad applications beyond its weed-like reputation. Pueraria phaseoloides seed was extracted into powder form (PPS) was followed by a comprehensive characterization employing CHNS-O, UV-Visible, FTIR, SS NMR, and TGA analysis, while surface analysis via XPS and SEM unveiled the presence of polysaccharides and proteins, encompassing S-containing protein amino acids like cysteine. The corrosion studies of epoxy coatings formulated with PPS (PPE) in acidic and saline media tagged PPS as a laudable bio-filler. Pursuant to the gravimetric analysis, the optimum concentration for superior corrosion inhibition is found to be 0.3 wt% PPE. Tafel plots confirm the viable anticorrosive characteristics of 0.3 wt% PPE coating (97.62 % and 98.08 % in acidic and saline media respectively), which are validated by electrochemical impedance spectroscopy (98.75 % and 95.00 % in acidic and saline media respectively) employing the L(R(C(R(Q(R(LR)(CR))))) equivalent circuit model, with constant protection efficiency values across all techniques. Assessing the corrosion studies of PPE composite coating, turned the table of the invasive weed into a powerful corrosion deterrent.

Keywords

• Pueraria phaseoloides
• Polarization
• EIS
• Surface coating