Waste from biodiesel production by transesterification using sulfuric acid and potassium hydroxide as catalysts

Abstract

Waste from biodiesel production process by transesterification reaction of palm oils and methanol was investigated in this study. The experiments were conducted in a batch system at atmospheric pressure. Reaction temperature of 60-65°C and two hours of reaction time were used for each experiment. Potassium hydroxide and sulfuric acid were used as catalysts and the amount of catalysts were 0.5% and 1.0% weight of palm oil. The reaction was carried out at a molar ratio of methanol to oil of 6:1. The reaction products were allowed to separate into two phases after each experiment. Samples were taken from both phases and were kept for analysis to determine the amount of residue catalysts, soaps, and methanol. Biodiesel phase was further washed with water to remove its contamination. Washed water is also analyzed. Experimental results show that unreacted methanol were dissolved in both phases of reaction products. It is found that unreacted methanol, residue catalyst, and soap dissolved in crude glycerol phase more than in crude biodiesel phase. Soap is found that in reaction products only when potassium hydroxide is used a catalyst. Different amount of free fatty acids in each type of palm oils affected with amount of soap. Amounts of waste components and washing water increase with an increase in amount of catalysts. The scale of process does not have any effect in the distribution of waste in each phase of reaction products.