The critical crossover at the n-hexane-water interface

Abstract

According to estimates of the parameters of the critical crossover in monolayers of long-chain alcohol molecules adsorbed at the n-hexane -water interface, all systems in which this phenomenon is observed are characterized by the same value of the critical exponent ν ≈ 1.8.Atoms or molecules adsorbed on the surface of a liquid or crystal frequently form a spatially inhomogeneous structure in which domains of two homogeneous phases coexist [1][2][3][4]. Both of these phases tend to intermixing, since the formation of one-dimensional interphase boundaries leads to a significant decrease in the system energy [5]. An evident consequence of this is the impossibility of a two-dimensional (2D) first-order phase transition in this system; instead, an infinite sequence of phase transitions (critical crossover) must take place [6].This article presents the results of an analysis of experimental data obtained earlier [7,8], which allowed a critical parameter of the crossover at the n-hexanewater interface to be established.A macroscopically flat interphase boundary (interface) between n-hexane (a nonpolar organic solvent) and water (see Fig. 1) offers an example of the system, featuring the phenomenon of critical crossover. Under normal conditions, n-hexane (saturated hydrocarbon with the formula C 6 H 14 , a density of ∼ 0.65 g/cm 3 at T = 298 K, and a boiling temperature of about 342 K) and water exhibit virtually no mutual solubility. * tikhonov@kapitza.ras.ru 1

Application of Alkyletanolamide Surfactants Based on Nyamplung (Callophylum Inophylum L.) Seed Oil in Cream Base

“…The density of nhexane is 0.66 g/cm 3 which is smaller than the density of water 0.997 g/cm 3 . This can affect the position of the formed phase layers (Tikhonov, 2010). After the reactants began to react in the waterbath shaker, the mixture became cloudier compared to the colour of the reactants before being reacted.…”

Optimization of Lipase-Catalyzed Synthesis of Fatty Hydroxamic Acids from Terminalia Catappa L. Kernel Oil

“…24,25 The density of water is greater when compared to n-hexane, so the aqueous phase is below hexane phase. The density of water is (ρ=0.997 g/cm 3 ), while n-hexane is (ρ=0.66g/cm 3 ) at a temperature of 298 K. 26 Then after the reactants are added with lipase enzyme, it appears that the enzyme is in the aqueous phase. This is because the enzyme lipase is polar.…”

Thermotropic phase transition in an adsorbed melissic acid film at the n-hexane–water interface

“…This system can be isotropic or anisotropic even in the case of isotropic bulk phases [1][2][3][4]. It was reported earlier that melissic acid (C30-acid) is adsorbed at the interface between nhexane and an aqueous solution of sulfuric acid (pH ≈ 2) as a protonated multilayer in which there exist three thermotropic mesophases [5].…”