The aim of the work was to determine the effect of oils quality and transesterification method on the degree of conversion of the fatty acids. Material consisted of 4 samples of oil: rapeseed oil obtained by the laboratory hot pressing of rape seeds oils in approx. 80 °C, waste rapeseed and palm oils and one refined rapeseed oil. Oils used in the one-stage transesterification were characterized by a lower hydrolysis and oxidation degree than the oils used in two-stage transesterification (double-base and base-acid method). The quality of the obtained crude methyl esters was determined in terms of acid number, peroxide value, the lipid composition by thin layer chromatography. Quantitative testing of the degree of transesterification and the share of individual esters of fatty acids was conducted by gas chromatography. Studies have shown that that degree of conversion of the fatty acid methyl esters is dependent on both the quality of the oil and the method of transesterification. If oils are characterized by a good quality, then a method of transesterification is less important. However, if oils are heavily contaminated, then the right technology for their transesterification should be chosen, e.g. oil with high content of FFA should be subjected to base-acid transesterification. Studies have shown. If oils are characterized by a good quality, then a method of transesterification is less important. However, if oils are heavily contaminated, then the right technology for their transesterification should be chosen, e.g. oil with high content of FFA should be subjected to base-acid transesterification.
The interest in biodiesel production from low cost feedstocks is still increasing. Such feedstocks usually contain large amounts of free fatty acids, which make the currently employed base catalysts inefficient, thereby promoting the use of acid catalysts. Due to the high activity and low cost, sulfuric acid could become the most widely used acid catalyst for biodiesel production. Research undertaken so far using sulfuric acid for esterifi cation of fatty acids has shown that the products obtained fail to meet the requirements of the standard EN 14214. This paper describes a systematic study of rapeseed oil fatty acids esterification in order to obtain a product complying with the standard EN 14214. The influence of sulfuric acid concentrations (0.1-3.0%), methanol molar ratios (1:1-20:1) and reaction time (0-360 min) was evaluated. Finally, a two-stage esterification process was developed, where in optimal conditions esterification yield of 97.8% and ester content of 99.6% were achieved.
Post-coagulation sludge was added to fish hydrolyzates (silage). Silage was prepared using whole sprats (Spratus sprains). Technology of the process has been modified and sulphuric acid was replaced with phosphoric acid. The objective was to evaluate the quality of produced silage during storage, particularly the changes of peroxide value and amount of free fatty acids in silage fat.
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