Winterization of Vegetable Oil Blends for Biodiesel Fuels and Correlation Based on Initial Saturated Fatty Acid Constituents

Winterization is a simple method to remove saturated fatty acid contents in biodiesel fuels for improving their cold flow properties. In-this work, biodiesel fuels with different initial long-chain (C16 and above) saturated fatty acid constituents (S-i) were prepared from blends of palm, canola, and corn oils. The prepared biodiesels were treated at various winterization temperatures (T-w) to investigate the effect of T-w, and S-i on the final saturated fatty acid constituents (S-w) of the winterized biodiesel fuel. Optical microscopy showed that ball-like crystals formed with fluid regions at moderate cooling rates (-6 degrees C/h) could allow solid-liquid separation by filtration. A saturated fatty acid reduction ratio, R-s, defined as (S-i - S-w)/S-i X 100, was used with the experimental results on large samples (ca. 600 mL) to develop a correlation for winterization temperature as T-w (degrees C) = 0.659 S-i (wt%) - 0.104 R-s (wt%) - 10.197. The correlation can provide estimation of the required winterization temperature for reducing a specified ratio of fatty acids in a biodiesel fuel that mainly contains long-chain fatty acids from the initial saturated fatty acid constituents. When used with literature relationships for cold filter plugging point (CFPP) and S-w, estimation of the CFPP of winterized biodiesel fuels is possible without requiring-actual winterization treatment.