The development of new environmentally-friendly cutting fluids is an important technological advancement. The aim of this study was to assess the tribological behavior of microemulsions (W/O) developed with epoxidized soybean oil and nonionic surfactants with different degrees of ethoxylation (NP4EO, NP6EO and NP9.5EO). The tribological performance of the microemulsion systems was assessed in a High Frequency Reciprocating Rig (HFRR) tribometer. Microemulsions showed Newtonian fluid behavior, with viscosities compatible with conventional cutting fluids. In addition, contact angle values above 90º indicate spherical-shaped drops on the surface on which they are deposited, due to their hydrophobic nature. The microemulsions formulated using surfactants with lower ethoxylation numbers and 20% concentration exhibited greater stability, lower viscosity and better friction reduction during tribological contact between surfaces, given that the average wear scar diameter was 118 µm with smooth surfaces exhibiting slight slippage wear caused by abrasion, as identified by SEM/EDS analyses.
Coconut shell powder (CP) and diatomite (Di) were modified with microemulsion (μE), producing low‐cost adsorbents for copper (II) removal from aqueous solutions. The μE was prepared using as active phase an anionic surfactant sodium octanoate (SO), obtained from the saponification of octanoic acid. The effect of modification on the adsorption capacity of Cu+2 was evaluated taking into consideration the solution pH, equilibrium time, temperature, and initial concentration of metal in solution. The adsorbents were analyzed by characterization techniques of X‐Ray Fluorescence, scanning electron microscope and Fourier Transform Infrared Spectroscopy. The obtained experimental data were analyzed using the equations of Langmuir, Freundlich, Temkin, and Dubinin Radushkevich models. The initial concentration of 50 mg Cu+2/L solution and 0.2 g of adsorbent materials modified with the μE presented a Cu+2 removal efficiency of 86.81% and 96.3% for CP and Di, respectively. The kinetic models of pseudo first‐order, pseudo second‐order, Elovich, and intraparticle diffusion were used in this study to describe the adsorption rate. The presence of sodium octanoate functional (OS) group provided ion exchange sites suitable to Cu+2 adsorption. The stability of the OS impregnation using microemulsion was evaluated based on a desorption study.
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