Investigation of the effects of ultrasound processing on the characteristics of lubricating emulsions

Аннотация

This study examines the potential application of used vegetable oil for the production of lubricating emulsions. It has been determined that for the bleaching of used vegetable oil with an acid value (AV) of 4.0 mg KOH/g, a 4% clay-based adsorbent is sufficient. The maximum emulsion stability, achieved after 8 minutes of ultrasonic treatment, corresponds to a formulation containing 20% vegetable oil, 3% emulsifier, and 0.2% NaHCO3. Further increasing the amount of vegetable oil improves the emulsion quality; however, it also raises production costs. The American Journal of Applied Sciences 6 https://www.theamericanjournals.com/index.php/tajas The American Journal of Applied Sciences According to Bancroft's rule, the dispersion medium is the liquid in which the emulsifier dissolves or is better Keywords: Vegetable oils, emulsions, droplet size, wetted. To enhance emulsion stability, emulsifiers and ultrasonic treatment, used oils, emulsion stability. stabilizers are frequently employed. Emulsifiers often include surface-active agents (surfactants), colloidal Introduction: Emulsions are microheterogeneous electrolytes, high-molecular-weight compounds systems formed from two immiscible liquids. The size (HMWCs), and highly dispersed powders. In O/W of the globules ranges from 0.1 to 50 µm. Emulsions emulsions, hydrophilic substances such as alkali metal are classified into direct emulsions, i.e., "oil-in-water" soaps, gelatin, albumin, tannin, protein, chalk, gypsum, (O/W), where the dispersion medium is water, and and clay are used, whereas for W/O emulsions, inverse emulsions, "water-in-oil" (W/O), where the hydrophobic substances such as multivalent metal dispersion medium is oil, a non-polar liquid. Emulsions soaps, lanolin, rubber, ceresin, paraffin, and carbon are further categorized into three types based on the black are utilized [7,8]. relative content of the dispersed phase: dilute The emulsifying mechanism of surfactants is based on emulsions (where the dispersed phase constitutes up the adsorption of molecules at the phase boundary, to 0.1%), concentrated emulsions (0.1%–74%), and forming solvation shells around the droplets. Figure 1a highly concentrated emulsions (above 74%) [1-3]. illustrates an O/W emulsion globule obtained by When two liquids of different polarities are vigorously intensive mixing of toluene and water with the mixed, an emulsion forms due to an increase in addition of the emulsifier sodium oleate. In this case, interfacial surface area, leading to enhanced excess emulsion stability is ensured by the reduction of surface energy (σS). This excess energy causes the interfacial surface tension and the formation of a coalescence of dispersed phase droplets (globules), hydration shell. The electric charge of the droplet is resulting in rapid emulsion breakdown. Therefore, induced by the ionic dissociation of the polar -COONa stabilizers or emulsifiers are commonly used in group, which enhances emulsion stability. Figure 1b practical applications to produce stable emulsions, presents a W/O emulsion globule obtained in the chosen based on the type of emulsion being formed [4- presence of calcium oleate [9]. 6]. Figure 1. Orientation of Emulsifier Molecules at the Phase Interface The structure of the stabilizing interfacial layer is are oriented toward the aqueous phase, while the non- complex. The polar groups in the colloidal electrolyte polar groups are directed toward the non-polar phase. The American Journal of Applied Sciences 7 https://www.theamericanjournals.com/index.php/tajas The American Journal of Applied Sciences As a result, two surfaces are formed with different being imported. Therefore, for the production of surface tensions (σA) and (σB). The emulsifier wraps lubricating materials, it is necessary to find an around the droplets to prevent coalescence. When the alternative to vegetable oils or explore other less surface tension between the emulsifier and oil (σA) is commonly consumed vegetable oils. One such greater than that between the emulsifier and water alternative is used cooking oils from public catering (σB), an O/W emulsion is formed. In this case, for the services. oil phase with a high (σA) value, the formation of a This study investigates the feasibility of using used minimal spherical surface is more likely compared to vegetable oils collected from public catering services to the aqueous phase. However, if (σA) is lower than (σB), produce food-grade lubricating emulsions. a W/O emulsion is formed (see Figure 1b). The ratio METHODS between the hydrophilic and lipophilic (hydrophobic) parts of the emulsifier molecule plays a key role in its Used vegetable oils exhibit a color index of 18 red emulsifying ability. This ratio is commonly referred to units, 6 blue units at 35 yellow, with an acid value (AV) as the hydrophilic-lipophilic balance (HLB) [10]. of 3.8 mg KOH/g, and a peroxide value (PV) measured in mmol of active oxygen per kg. Food-grade lubricating