Rational conditions of fatty acids obtaining by soapstock treatment with sulfuric acid

Abstract

As a result of alkaline neutralization of oils, a significant amount of soapstock is formed, the utilization of which creates an environmental and economic problem. The production of fatty acids from soapstock using sulfuric acid decomposition is investigated in this work. The peculiarity of the work is the determination of regression dependences of the yield and neutralization number of fatty acids on the soapstock processing conditions: temperature and duration. Soapstock obtained after neutralization of sunflower oil was used as raw material. Soapstock indicators: mass fraction of moisture – 15.4 %, total fat – 71.9 %, fatty acids – 64.5 %, neutral fat – 7.4 %. Rational conditions of soapstock processing are determined: temperature (90–95) °С, duration 40 min. Under these conditions, the fatty acid yield is 79.0 %, the neutralization number is 180.0 mg KOH/g. Quality indicators of the obtained fatty acids: mass fraction of moisture and volatile substances – 1.8 %, mass fraction of total fat – 97.0 %, cleavage depth – 64.5 % of oleic acid, the presence of mineral acids – no. Fatty acids correspond to fatty acids of the first grade according to DSTU 4860 (CAS 61788-66-7). An increase in the temperature and duration of soapstock contact with sulfuric acid increases the yield and neutralization number of fatty acids. This is due to a decrease in the viscosity of the reaction medium, an increase in the depth of cleavage of soapstock soaps with sulfuric acid, an increase in the intensity and duration of mass transfer. The developed rational conditions allow obtaining fatty acids from soapstock, which correspond in composition to fatty acids from refined deodorized sunflower oil. The results allow solving a number of economic and environmental problems associated with soapstock utilization and can be implemented in oil refineries and fatty acid production

Technology development of fatty acids obtaining from soapstok using saponification

“…In comparison with the data [16], the use of two-stage soapstock processing technology using saponification led to the increase in the neutralization number of acids by 4 %, yield -by 16.2 % under rational conditions. Table 4 presents the quality indicators of fatty acids obtained without saponification [16] and by two-stage technology with saponification (under rational conditions). According to Table 4, it was found that the fatty acids obtained with soapstock saponification are of high quality.…”

“…A comparative analysis of the composition of fatty acids obtained with saponification, without soapstock saponification and fatty acid composition of sunflower oil was performed (Table 5). The composition of fatty acids obtained without saponification and sunflower oil is presented according to [16]. Therefore, the composition of fatty acids obtained with saponification is closer to the fatty acid composition of sunflower oil than the composition of fatty acids obtained without soapstock saponification.…”

“…According to Table 5, it was found that the composition of fatty acids obtained by the two-stage method is closer to the fatty acid composition of sunflower oil. The work differs from the existing [11,[16][17][18] scientific developments in the extraction of fatty acids from soapstocks by studying the conditions of the two-stage technology of soapstock processing. This technology makes it possible to obtain fatty acids with improved quality and yield.…”

“…The method of fatty acids obtaining from soapstock was investigated, which includes two stages: preliminary soapstock saponification with sodium hydroxide solution; treatment of saponified soapstock with sulfuric acid solution. Treatment of saponified soapstock with sulfuric acid solution was performed under rational conditions, previously determined in [16]: temperature (90-95) °C, duration 40 min. The influence of soapstock pre-saponification conditions on the yield and neutralization number of fatty acids: duration of saponification and concentration of sodium hydroxide solution was determined.…”

“…In [16], rational conditions for fatty acids obtaining from soapstock by decomposition with sulfuric acid were determined: temperature (90-95) °С, duration 40 min. Under these conditions, the yield of fatty acids was 79.0 %, the neutralization number -180.0 mg KOH/g.…”