Physico-chemical Characteristics and Fatty Acids Composition of Some Selected Nigerian Vegetable Oils for Quenching Medium

Abstract

Four vegetable oils (cotton seed oil, palm kernel oil, neem seed oil and palm oil) were characterized with respect to their physicochemical properties and fatty acids profiles with the aim of investigating their suitability as quenching media for medium carbon steels. The physicochemical properties were determined by using appropriate ASTM methods. The fatty acid ester compositions were determined by a gas chromatographic analysis procedure. The results obtained showed that the different vegetable oils exhibited different viscosity and viscosity-temperature behaviour corresponding to their varying molecular structures and level of saturation. The following values were obtained for the various physicochemical parameters measured in cotton seed oil, palm kernel oil, neem seed oil and palm oil: viscosity value at 40ºC were (34.8, 41.69, 32.41 and 39.7) cSt; viscosity value at 100°C were (6.9, 8.94, 7.89 and 8.2) cSt; the Iodine values were (115.09, 19.59, 120.16 and 35.90) g I2/100 g while the acid values were (1.80, 0.22, 12.97 and 1.23) mgKOH/g respectively. The level of saturation of the fatty acids followed the decreasing order of palm kernel oil (0.25), palm oil (0.92), cotton seed oil (1.35) and neem seed oil (1.39). The results obtained showed that the vegetable oils under study are suitable as potential quenching media for carbon steels with palm kernel oil being the most suitable followed by cotton seed oil and neem seed oil. The least suitable among the oils is palm oil.