Technology development of fatty acids obtaining from soapstok using saponification

Natalia Sytnik,Dmytro Saveliev,Viktoriia Kalyna,Volodymyr Ishchuk,Oleg Kostyrkin,Olena Petukhova,Olena Petrova,Tetiana Kovalova,Kostiantyn Ostapov,Ekaterina Kunitsia

doi:10.15587/1729-4061.2021.241942

Abstract

The processing of oil refining waste is essential from economic and environmental points of view. An important issue is the processing of soapstock to extract fatty acids, which are raw materials for various industries. The two-stage method of fatty acids obtaining from soapstock using saponification with sodium hydroxide solution and decomposition with sulfuric acid is investigated. The peculiarity of the work is the study of the influence of soapstock saponification conditions on the key efficiency indicators of fatty acid extraction: yield and neutralization number. A sample of soapstock was obtained as a result of alkaline neutralization of sunflower oil. Soapstock quality corresponds to DSTU 5033 (CAS 68952-95-4): mass fraction of total fat – 68.5 %, fatty acids – 62.6 %, neutral fat – 5.9 %. Rational saponification conditions were determined: duration (85 min.) and concentration of sodium hydroxide solution (45 %). After saponification, the soapstock was subjected to decomposition with sulfuric acid under the following conditions: temperature 90 °C, duration 40 min. Under the rational saponification conditions, the yield of fatty acids (91.8 %) and the neutralization number (187.1 mg KOH/g) were determined. The obtained fatty acids correspond to the first-grade fatty acids according to DSTU 4860 (CAS 61788-66-7). Acid indicators: mass fraction of moisture and volatile substances – 1.5 %, mass fraction of total fat – 98.0 %, cleavage depth – 69.2 % oleic acid. The use of the soapstock saponification stage before decomposition leads to an improvement in the quality indicators and an increase in the neutralization number of fatty acids by 4 %, yield – by 16.2 %. The results of the study make it possible to produce fatty acids from soapstock by two-stage technology with high yield and neutralization number

Highlights

The main components of soapstock are fats, fatty acids and their sodium soaps, phospholipids, unsaponifiable and waxy substances, dyes
Depending on the fatty acid composition of the raw material and the concentration of the alkali solution used in the neutralization technology, the composition and Technology organic and inorganic substances properties of soapstock, its structure and viscosity change
Fatty components of soapstock are capable of oxidation and pose a fire hazard [2]

Summary

Introduction

The main components of soapstock (waste of alkaline oil refining) are fats (up to 70 %), fatty acids (up to 30 %) and their sodium soaps, phospholipids, unsaponifiable and waxy substances, dyes. Depending on the fatty acid composition of the raw material and the concentration of the alkali solution used in the neutralization technology, the composition and Technology organic and inorganic substances properties of soapstock, its structure and viscosity change. Disposal of this waste without recycling leads to environmental pollution [1]. It is important to develop new methods for the rapid detection of dangerous air pollution Such methods allow to promptly detect overt and covert dangerous air pollution and increase the effectiveness and timeliness of measures to prevent air pollution in order to protect people and the environment [4]. The construction of industrial facilities requires strict compliance with regulatory requirements, the implementation of constructive calculations, taking into account the impact of possible hazards during the operation of an enterprise [5]

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