Corrosive characteristics of bioethanol and gasoline blends for metals Saravana Kannan Thangavelu 1,2 , Abu Saleh Ahmed 3 and Farid Nasir Ani 1, * ,† 1 Department of Thermo Fluids, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia 2 Faculty of Engineering, Computing and Science, Swinburne University of Technology, 93350 Kuching, Sarawak, Malaysia 3 Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia SUMMARY Corrosive characteristics of lignocellulosic bioethanol on metals, such as mild steel, copper, and aluminum were studied by static immersion test at room temperature. Effect of metals on degradation of fuel properties, such as pHe, total acid num- ber, acidity, density, viscosity, calorific value, flash point, and color changes were evaluated. Moreover, the transformation of water content and oxidation products in the fuel were investigated. Effect of fuel blends on corrosion rate, chemical structure of metals, and morphology of corrosion product were also examined. Results showed that the corrosion of metals in E50 (50% bioethanol and 50% gasoline) is high compared with E25 and E0. Moreover, degradation of fuel properties and compositional changes in E25 and E50 were high compared with E0. The corrosion rate of aluminum in E50 (0.216 mpy) was lower than copper (0.441 mpy) and mild steel (0.487 mpy). Moreover, the corrosion rate of aluminum in E25 (0.096 mpy) was also lower than copper (0.285 mpy) and mild steel (0.297 mpy). It was discovered that corrosion of materials and degradation of fuel properties were 2.4 times high in higher ethanol blends (above E25) compared with lower ethanol blends (up to E25). Copyright © 2016 John Wiley & Sons, Ltd. KEY WORDS aluminum; bioethanol; copper; corrosion; gasoline; mild steel Correspondence *Farid Nasir Ani, Department of Thermo Fluids, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia. † E-mail: farid@fkm.utm.my Received 9 December 2015; Revised 7 March 2016; Accepted 14 April 2016 1. INTRODUCTION In recent years, the increasing demands for petroleum fuels and the environmental pollution issues have motivated the explorations for new alternative fuels. Biofuels, especially bioethanol and biodiesel have gained progressive impor- tance as alternative fuels for automotive engines [1]. Bioethanol produced from biomass and bioenergy crops is considered as potential alternative to gasoline, because of its high octane number, high heat of vaporization, and low vapor pressure [2]. The usage of up to 10% bioethanol in gasoline (E10) has been implemented in many countries. Globally, there is a growing pressure to rise the ethanol content in the transportation fuel up to 25% (E25) for the future vehicles and flex-fuel vehicle capable of up to 85% ethanol (E85) [3]. Bioethanol, although a clean and sustainable fuel, normally creates corrosion and degrada- tion of automotive fuel system materials when added to gasoline [4–6]. The presence of water and oxygen molecules in bioethanol contributes to corrosion and deg- radation of automotive materials [5]. The petrol engine parts made from mild steel, such as fuel tank, fuel lines, and fuel tube outlet; copper, such as bearing, washer, and bushing; and aluminum, such as fuel filters and fuel feed pump are mostly affected by the fuels [7]. Several researchers studied the corrosion behavior of metals in ethanol and gasoline blends [3–6,8–15]. Most of the researchers investigated the corrosion behavior of metals, such as ferrous (low and medium carbon steel, chromium carbon steel and stainless steel) [4,5,8– 11,14,16], copper [4,5,15], aluminum, and aluminum al- loys [3,5,6,8,12,14] in ethanol and gasoline blends through electrochemical properties. Moreover, ethanol and gasoline blends, such as E0 (100% gasoline), E5, E10, E15, E20, E22, E85, and E100 (100% ethanol) have been tested in most of the studies at temperature ranging from 18 to 100 °C [3–6,8–15]. None of these studies analyzed the stability and corrosive properties of bioethanol fuel for INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. (2016) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/er.3555 Copyright © 2016 John Wiley & Sons, Ltd.