Reactive extraction of castor seeds and storage stability characteristics of produced biodiesel

In the present study, oil was extracted from a single castor seed by eppendorf vial method, and the oil yield was compared with the yield obtained from Soxhlet method. The oil yield from both methods was about 55% and comparable. Free Fatty Acid (FFA) content of extracted castor oil was found to be lower (<1 mg KOH/g oil). Therefore, single step transesterification (reactive extraction) was carried out to study the effect of various reaction variables on the conversion of castor oil biodiesel. The optimum biodiesel conversion of similar to 93% was achieved under following conditions: 4h, 1:250 oil to MeOH molar ratio, 1 wt.% NaOH, 40 degrees C, 0.75 mm particle size, 20 g seed, 600 rpm and 10 (vol.%) co-solvent. The estimated fuel properties of biodiesel obtained with NaOH, KOH and NaOH (with co-solvent) were found to be similar and within the limits of ASTM standards. Similarly, storage stability of prepared biodiesel was evaluated over a six-month storage period (180 days) under three different storage conditions. The results showed a sharp decrease in fuel stability over time in terms of increase in density from 0.878 to 0.984 g/cm(3), kinematic viscosity (10.59-16.18 cSt), acid value (0.52-5.15 mg KOH/g) respectively. While, iodine value significantly decreased from 82.5 to 54.57 g I-2/100 g oil over time. Biodiesel sample stored in the open air degraded faster than samples stored in other storage conditions. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.