Weight loss and electrochemical measurements of aluminum corrosion in diesel fuel and biodiesel prepared via transesterification of waste cooking oil

Abstract

Recent studies have found potentials in the utilization of biodiesel from renewable energy sources to tackle environmental pollution associated with the release of exhausts from fossil diesel fuel engines. However, it's imperative to investigate the corrosion rate and nature of the engine components fuelled with the biodiesel. This study examines the corrosion rate and nature of aluminum coupon (AC) in fossil diesel fuel (DF) and biodiesel produced from waste cooking oil via transesterification reaction (WCOB) using weight loss and electrochemical measurements. Taguchi Orthogonal Array was used to study the influence of temperature, immersion time, agitation and WCOD/DF volume. Weight loss method revealed highest corrosion rates to be 0.0052 mm y−1 and 0.0381 mm y−1 for AC in DF and WCOB respectively. Corrosion rate increased with increase in immersion time and temperature. A shift in the corrosion potential from -0.192 V to -0.574 V; and -0.178 V to -0.516 V was revealed by potentiodynamic polarization curve for AC in WCOB and DF respectively. Nyquist plots exhibited relatively perfect semicircles of different diameters and similar shape. The developed mathematical models were effective for corrosion rate prediction. Minimum corrosion rates of 1.222 × 10−3 mm y−1 and 1.822 × 10−3 mm y−1 for AC in DF and WCOB are respectively feasible at optimum point. Presence of carbon and oxygen on AC surface; pits formation; and loss of Al ion into WCOB and DF after corrosion were noticed. In conclusion, the corrosion rate of AC in WCOB was higher than the DF counterpart.

Keywords

• Electrochemical measurements
• Taguchi orthogonal array
• Weight loss method
• Renewable energy
• Waste cooking oil biodiesel