Pre-Treatment of High Free Fatty Acids Oils by Chemical Re-Esterification for Biodiesel Production—A Review

Abstract

Non edible oil sources have the potential to lower the cost of biodiesel. However, they usually contain significant high amounts of free fatty acids (FFA) that make them inadequate for direct base catalyzed transesterification reaction (where the FFA content should be lower than 3%). The present work reviews chemical re-esterification as a possible method for the pre-treatment of high FFA feedstock for biodiesel production. The effects of temperature, amount of glycerol, type and amount of catalyst have been discussed. Chemical re-esterification lowers FFA to acceptable levels for transesterification at the same time utilizing the glycerol by product from the same process. Further researches have been proposed as a way forward to improve the process kinetics and optimization so as to make it more economical.

Rubber seed oil: A potential renewable source of biodiesel for sustainable development in sub-Saharan Africa

“…The use of non-edible oils from seeds of rubber, jatropha, castor, linseed, moringa oleifera, cotton, karanja, neem and tobacco plants are being proposed to avert any impending fuel-food crisis [1,2,[13][14][15][16][17][18][19]. Raw material accounts for about 60-90% of the production cost of biodiesel and producing biodiesel from these feedstock will ultimately reduce its consumer's price [1,14,[20][21][22]. In consideration of nature of all these plants, rubber tree had less investigation on its potentials and in many sub-Saharan Africa (SSA) countries, it stands to be only a source of latex.…”

Influence of the inclusion of co-products of the soy oil industry in poultry diets on nutrient digestibility, growth performance, and production

“…Therefore, the yield, quality and characteristics of the resulting re-esetrified oil relies on the reaction temperature, the amount of glycerol, the source of FFA, and the type and quantity of the catalyst if used (reviewed by Kombe et al, 2013). The amount of FFA of the resulting re-esterified oil depends on the temperature and the time for the reaction.…”

“…The amount of FFA of the resulting re-esterified oil depends on the temperature and the time for the reaction. According to the literature soapstocks containing from 37 to 50% of FFA can be reduced to less than 5% after 3 to 6 hours of a reaction at 200ºC, showing lower yields at lower temperatures (Kombe et al, 2013). A higher yield of the reaction can be achieved with the use of catalyst reducing the final FFA concentration and the time for the reaction.…”

“…A higher yield of the reaction can be achieved with the use of catalyst reducing the final FFA concentration and the time for the reaction. Also, the use of glycerol in excess of the theoretical amount required can reduce the final FFA concentration and affect the kinetics of the reaction reducing the time needed to achieve the maximum yield (Kombe et al, 2013). Moreover, the excess of glycerol in the reaction can be used to increase the yield of MAG in the resulting oil (Blanco et al 2004).…”

“…The process yields a blend of neutral lipids including FFA, MAG, diacylglycerols (DAG) and TAG in variable proportions, depending on the temperature, the catalyst used and the amount of glycerol added (Kombe et al, 2013).…”