POTENTIAL OF PURIFICATION USED TURBINE OILS WITH BENTONITE AND OBTAINING BASE OIL FROM IT

УДК 66.01

ABSTRACT

The article examines the possibilities of cleaning used turbine oils and their recycling as base oils. Used turbine oil of the Shell Turbo S4 GX46 brand, which was cleaned in laboratory conditions using activated bentonite adsorbent, was selected as the object of the research. After the cleaning process, the main physicochemical parameters of the oil were studied based on GOST standards, which showed that the physicochemical properties of the cleaned oil improved. In particular, a sharp decrease in the acid number, an improvement in the color index, the complete disappearance of mechanical impurities and water content demonstrates a deep cleaning of the oil. During the research, turbine oil cleaned using activated bentonite was compared with TP-30 base oil, as well as IGP-30 industrial oils. The results of the comparison showed that the main physicochemical properties of the cleaned oil were characterized by high oxidation stability, low acidity, and improved low-temperature properties compared to TP-30 and IGP-30 oils. The results obtained confirm the possibility of effective purification of used turbine oils based on the adsorption method and their recycling as base oils in industry.

АННОТАЦИЯ

В статье рассматриваются возможности очистки отработанных турбинных масел и их вторичного использования в качестве базовых масел. В качестве объекта исследования выбрано отработанное турбинное масло марки Shell Turbo S4 GX46, которое очищалось в лабораторных условиях с использованием активированного бентонитового адсорбента. После процесса очистки были изучены основные физико-химические показатели масла в соответствии со стандартами ГОСТ, что показало улучшение физико-химических свойств очищенного масла. В частности, резкое снижение кислотного числа, улучшение цветового показателя, полное исчезновение механических примесей и содержания воды свидетельствуют о глубокой очистке масла. В ходе исследования турбинное масло, очищенное с использованием активированного бентонита, сравнивалось с базовым маслом ТП-30, а также с индустриальными маслами ИГП-30. Результаты сравнения показали, что основные физико-химические свойства очищенного масла характеризуются высокой стабильностью к окислению, низкой кислотностью и улучшенными низкотемпературными свойствами по сравнению с маслами ТП-30 и ИГП-30. Полученные результаты подтверждают возможность эффективной очистки отработанных турбинных масел на основе адсорбционного метода и их вторичного использования в качестве базовых масел в промышленности.

Keywords: base oil, bentonite adsorbent, adsorption process, kinematic viscosity, viscosity index, acid number, sulfated ash content, sulfur content, oxidation products, TP-30, IGP-30, industrial oils.

Ключевые слова: базовое масло, бентонитовый адсорбент, адсорбционный процесс, кинематическая вязкость, индекс вязкости, кислотное число, сульфатная зольность, содержание серы, продукты окисления, ТП-30, ИГП-30, индустриальные масла.

Introduction: Turbine oils are essential for the efficient operation of equipment of power engineering, aviation and industries. They provide resistance to temperature, load, and corrosive effects. Nevertheless, over time, used oils become contaminated with oxidation products, aromatic compounds, and mechanical impurities, which degrade their quality and shorten the service life of the equipment. With the increasing demand for hydrocarbon resources worldwide, the recycling of used turbine oils and their use as base oils is not only economically but also environmentally important. The recycling process effectively utilizes existing hydrocarbon resources, reduces the need for new raw materials, and contributes to the development of sustainable energy and the petrochemical industry. The purification of turbine oils using adsorbents such as bentonite is currently one of the most effective technological methods. This process reduces aromatic and oxidized fractions, improves viscosity and pour point [1-2], and optimizes acid number and color properties. In recent years, in order to effectively use oil resources and reduce the environmental burden, the purification of used turbine oils and their recycling into industry as base oils has become one of the important scientific and practical directions[3-4]. This process creates the opportunity to recycle existing hydrocarbon resources and significantly reduces the need for new raw materials. This research examines the issue of directing used turbine oils to meet the requirements of industrial base oils such as TP-30 and IGP-30 by purifying them[5-6]. The purification process using adsorbents such as bentonite plays a key role in this. This method reduces oxidation products and aromatic fractions, improves the color of the oil, reduces the acid number, and optimizes its viscosity and low-temperature properties. The main task of the research is to assess the possibility of purifying used turbine oils to bring them closer to the standards of industrial base oils such as TP-30 and IGP-30, and to analyze the economic and environmental efficiency of their reuse in industry [7-8].

Derived results and analyses. The following physicochemical properties of the used oil (Shell Turbo S4 GX 46) selected as the object of the research were analyzed at Chilon Lubricants LLC at room temperature of 22°C, relative humidity of 58% and atmospheric pressure of 720.059 mmHg.

Our study determined some important physical parameters of oil purified with bentonite in laboratory conditions based on GOST requirements. The results of the research are presented in Table 1.

Table 1.

Experimental parameters of bentonite-treated turbine oil

This oil is characterized by a high viscosity index, stable operation over a wide temperature range, high thermal stability, good corrosion protection properties and chemical purity[9]. It is suitable for use in mechanisms operating under high loads, as well as in cold and hot climates. The absence of mechanical impurities and water content extends its service life.

Materials and methods. The physicochemical characteristics of Shell Turbo S4 GX46 turbine oil purified with bentonite and TP-30 mineral base oil are compared in Table 2.

Table 2.

Physicochemical characteristics of Shell Turbo S4 GX46 turbine oil purified with bentonite and TP-30 mineral base oil

The analysis of the physicochemical parameters in Table 2 shows that Shell Turbo S4 GX46 is a much higher quality and more highly refined turbine oil than TP-30. This difference is especially evident in terms of oxidation stability, purity and low-temperature properties.

One of the most important parameters, the viscosity index, is 139 for Shell Turbo S4 GX46, which is significantly higher than for TP-30 (≥95). This increases its stability to temperature changes and reliability under operational conditions. The acid number (0.0025 mg KOH) and ash content (0.0014%) are very low in Shell Turbo S4 GX46, which indicates a high degree of refinement of the oil and the almost complete absence of oxidation products. In TP-30, these parameters are significantly higher. The pour point (-44°C) of Shell Turbo S4 GX46 is much lower, allowing it to maintain high fluidity even in cold conditions. The TP-30 has a lower pour point of -10°C, which limits its low temperature properties. The sulfur content (0.0092%), density, and color index (0) also confirm that Shell Turbo S4 GX46 is a cleaner, less contaminated, and more highly refined oil[10].

The physicochemical properties of Shell Turbo S4 GX46 turbine oil refined with bentonite and IGP-30 mineral oil are compared in Table 3 [11].

Table 3.

Physicochemical properties of Shell Turbo S4 GX46 turbine oil refined with bentonite and IGP-30 mineral oil

Analysis of Table 3 shows that Shell Turbo S4 GX46 oil is a much more refined and stable product in terms of physicochemical properties than IGP-30. This difference is especially evident in the indicators related to the degree of oxidation, low-temperature properties and chemical purity. In terms of kinematic viscosity, both oils are located in almost the same range (IGP-30: 39–50 mm²/s, Shell: 42.78 mm²/s), which indicates their belonging to the same viscosity class. Therefore, from a hydrodynamic point of view, they are compatible oils. However, the low-temperature properties differ sharply: the pour point of Shell Turbo S4 GX46 is -44°C, which is significantly lower than that of IGP-30 (-15°C). This indicates that Shell oil has a higher ability to work in cold conditions. The difference in acid number is very large: while IGP-30 has ≤1 mg KOH, Shell oil has only 0.0025 mg KOH. This indicates that Shell Turbo S4 GX46 oil is almost free from oxidation products and has a high level of stability. Also, the sulfur content (≤1% in IGP-30, 0.0092% in Shell Turbo S4 GX46) and the color index (0 compared to 3.5) confirm that Shell oil is much more thoroughly refined[12-13]. This increases its environmental and operational advantages.

Conclusion. As a result of the conducted studies, it was scientifically confirmed that used Shell Turbo S4 GX46 turbine oil can be effectively purified using bentonite adsorbent. The purification process carried out in laboratory conditions led to a significant reduction in oxidation products, resinous compounds, mechanical impurities and other harmful components in the oil. The determined physicochemical indicators show that as a result of cleaning, the oil is brought into a state that meets industrial requirements. In particular, a sharp decrease in the acid number and a complete improvement in color indicate the high efficiency of the adsorption process. Based on comparative analyses, it was established that the main indicators of the cleaned oil fully comply with the standards of the TP-30 base oil, and surpasses in some parameters. It was also noted that it differs from IGP-30 industrial oils in terms of its high degree of purification, low acidity level and improved operational properties. The results show that the technology of processing used turbine oils using bentonite is economically efficient, technologically simple and environmentally friendly. This approach can help reuse waste oils, reduce the need for new base oils, and reduce the negative impact on the environment.

References:

1. ASTM D445. Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity).
2. ASTM D2270. Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 °C and 100 °C.
3. ASTM D92. Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester.
4. ASTM D97. Standard Test Method for Pour Point of Petroleum Products.
5. ASTM D974. Standard Test Method for Acid and Base Number by Color-Indicator Titration.
6. ASTM D4310. Standard Test Method for Determination of Sludging and Corrosion Tendencies of Inhibited Mineral Oils.
7. Shell Turbo S4 GX 46 Technical Data Sheet. Shell Global Solutions.
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11. Salomatov Bekhruz Tўymurodovich, Panoev Nodir Shavkatovich, & Safarov Zhasur Alizhon Ugli (2025). Study of the composition and physicochemical properties of waste oils generated in the polypropylene production shop of UZ-KOR GAS CHEMICAL JV LLC. Universum: technical sciences, 6 (2 (131)), 41–46. doi: 10.32743/UniTech.2025.131.2.19424Salomatov, B., Panoev, N., & Safarov, J. (2025). POTENTIAL OF CLEANING SPENT TURBINE OILS USING LOCAL BENTONITE SORBENTS. Austrian Journal of Technical and Natural Sciences, (3-4), 130-135.
12. Salomatov B.T., Panoev N.S., Safarov J.A., Tilloeva D.M. Regeneration Of Used Turbine Oils And Recovery Of Their Quality Parameters Using Activated Bentonite. Journal of Chemistry and Technologies, 2025