Effects of Extracting Solvents on the Physicochemical Properties of Alchornea cordiforlia, Hura crepitans, Irvingia gabonensis and Pycnanthus angollensis Oils

Aims and Objectives: To determine the effect of extracting solvents on the physicochemical properties of oils extracted from four locally available plant seeds in Nigeria namely: Alchornea cordiforlia, Hura crepitans, Irvingia gabonensis and Pycnanthus angollensis using three different solvents namely; n-Hexane, Petroleum ether and Dichloromethane.

Place and Duration of Study: Department of Chemistry Laboratory, University of Calabar, Nigeria. The study was carried out between August 2019 and December 2019, (5 months).

Methodology: Each plant seed was ground into a paste and extracted for its oil using a Soxhlet extractor and three different solvents namely; n-Hexane, Petroleum ether and Dichloromethane. The physicochemical properties of the oils were then analysed.

Results: The results revealed the mean values of the physicochemical properties of A. cordifolia oil extracted using Hexane, Petroleum ether and Dichloromethane respectively were % yield (36.50, 34.50 and 32.00), specific gravity (0.91, 0.91 and 0.92), flash point (156.00, 155.00 and 191.00°C), Acid value (23.76, 25.10 and 26.80 mEqk-1), % free fatty acid (11.88, 12.55 and 13.40), Peroxide value (6.56, 6.38 and 6.90 mEqK-1), Saponification value (163.20, 156.40 and 165.50 mgKOHg-1) and iodine value (25.40, 48.60 and 46.50 g/100 g). The mean values of the properties of H. crepitans oil across the 3 solvents respectively were % yield (32.20, 31.50 and 29.00), specific gravity (0.92, 0.93 and 0.94), flash point (271.00, 259.00 and 240.00°C), Acid value (21.00, 21.80 and 22.20 mEqk-1), % free fatty acid (10.50, 10.90 and 11.10), Peroxide value (5.85, 6.26 and 7.10 mEqK-1), Saponification value (172.50, 190.40 and 185.60 mgKOHg-1) and Iodine value (43.60, 34.50 and 26.90 g/100 g). Properties of the I. gabonensis oil were % yield (33.20, 34.00 and 32.50), Specific gravity (0.92, 0.94 and 0.94), flash point (230.00, 236.00 and 260.00°C), Acid value (3.72, 3.70 and 3.90 mEqk-1), % free fatty acid (1.86, 1.85 and 1.95), Peroxide value (2.98, 4.26 and 3.63), Saponification value (239.50, 252.40 and 245.80) and Iodine value (25.30, 11.70 and 44.20). Mean values of P. angollensis oil properties were % yield (34.10, 36.20 and 33.00), Specific gravity (0.92, 0.92 and 0.93), flash point (260.00, 258.00 and 256.00°C), Acid value (23.68, 25.00 and 26.00 mEqk-1), % free fatty acid (11.84, 12.50 and 13.00), Peroxide value (4.25, 5.30 and 5.96), Saponification value (25.30, 52.50 and 57.30) and Iodine value (25.20, 11.68 and 44.40). The odour, colour and physical state of all the oils at room temperature was the same across the 3 solvents.

Conclusion: The results indicate that the physicochemical properties of the oils vary with the extracting solvent and its polarity. Their properties revealed that some of them can be used for many domestic and industrial purposes especially for the making of paints, soap, cosmetics, lubricants and varnishes.