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The density ρ of coexisting phases of the ternary system water+1,4-dioxane+potassium chloride was investigated along the liquid–liquid–solid coexistence curve near the critical end-point using a vibrating tube densimeter. By visual determination, this lower critical end-point was located at 311.026±0.010 K with a mole ratio dioxane (D) to water (W) rc=nD/nW=0.418±0.004. Density measurements were carried out in the range 0.01 K<(T−Tc)<31.5 K (i.e., 3×10−5<t=(T−Tc)/Tc<0.1). The obtained coexistence curve displays an apparent sharp crossover at reduced temperatures t≃10−2 from a nonclassical (Ising) to a classical (mean field) exponent. In ancillary experiments, the critical salt concentration was determined. Reduced critical values were calculated and compared with those predicted by the simplest ionic model (RPM, Restricted Primitive Model). The relation between critical behavior and reduced critical parameters in the present and other non-Coulombic systems is discussed.

An aerosol-based process was used to prepare mesoporous TiO(2) microspheres (MTM) with an average diameter in the range of 0.5-1 microm. The structural characteristics and photocatalytic properties of the synthesized materials were determined. As-prepared MTM materials and those heated in air from 400 to 600 degrees C exhibited mesoporous texture with a narrow size distribution and an inorganic framework that consisted of 4-13 nm anatase crystallites. Pore volumes for the MTM materials were in the range of 0.17-0.34 cm(3) g(-1). Microspheres heated to 400 degrees C presented a locally ordered mesopore structure and possessed X-ray diffraction d spacings between 9.8 and 17.3 nm. Heating above 400 degrees C resulted in a loss of the mesoscopic order, a decrease of the surface area, retention of the porosity, and an increase of the anatase nanoparticle size to 13 nm. The accessibility of the pore volume was measured by monitoring the uptake of gallic acid (GA) using Fourier transform IR. The MTM materials made excellent catalysts for the photodegradation of GA, with the performance being higher than that of an equivalent sample of Degussa P25. The present MTM materials are advantageous in terms of their ease of separation from the aqueous phase, and hence a novel photocatalytic process is proposed based on separate adsorption and photocatalytic decomposition steps with an improved and more rational use of both catalyst and sunlight.