The effect of liquid-phase oxidation impurities on the solubility of water in hydrocarbon fuels was studied.The results show that the concentration of polar surfactant molecules in the first region increases (true solution)during fuel oxidation,and since the oxidation groups (-COOH,-O=O,-OH,etc.) have similar dipole moment μ,the dielectric loss tangent tan δ increases linearly in this region with surfactant concentration.Upon further oxidation,micelle structures begin to form at a certain point.Micelle formation leads to a sharp decrease in the dipole moment attributable to the monomer unit μ/n,where n is the number of molecules in a micelle.A several-fold decrease in the dipole moment leads to a sharp drop in tan δ.Upon further increase in the number and size of micelles,the dipole moment remains practically unchanged,and the dielectric loss tangent begins to increase linearly again with surfactant concentration.If the critical concentration for micelle formation is achieved upon further oxidation of hydrocarbon liquids,micelle formation processes occur spontaneously in the solution,and the true solution becomes a colloidal system (sol).The resulting micelles are structured with hydrocarbon radicals of molecules toward the outside and hydrophilic (polar) groups toward the inside.Water molecules are located inside micelles and held so securely that water molecules do not aggregate as temperature decreases.The reason for significant differences in the equilibrium solubility of water in hydrocarbon fuels is the different oxidation factors of product samples,resulting from the accumulation of various concentrations of oxidation products,which are natural surfactants,in hydrocarbon fuels.
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