Solubility of 3‑Aminobenzoic Acid in Supercritical Carbon Dioxide Modified by Ethanol

The solubilities of 3-aminobenzoic acid with different concentrations of ethanol cosolvent in supercritical carbon dioxide were measured by using flow-type equipment at pressures from 10.0 MPa to 21.0 MPa and temperature 308 K to 328 K. The effects on solubility of 3-aminobenzoic acid in SCCO₂ with ethanol mole concentration of 1.0 % were investigated at temperatures of 308 K, 318 K, and 328 K; then, the study was also carried out with ethanol mole concentrations of 2.0 % and 4.0 % at 318 K, respectively. The experimental results revealed that the equilibrium solubility of 3-aminobenzoic acid was effectively increased in the presence of ethanol. The measured solubility data were correlated using the modified Sovova model, the modified Chrastil model, and the modified MST model, and the best agreement was obtained applying the modified Sovova model

Tuning Morphology of Nanostructured ZIF‑8 on Silica Microspheres and Applications in Liquid Chromatography and Dye Degradation

Zeolitic imidazolate framework-8 (ZIF-8) is one type of metal–organic framework (MOF) with excellent thermal and solvent stability and has been used extensively in separation, catalysis, and gas storage. Supported ZIF-8 structures can offer additional advantages beyond the MOF-only materials. Here, spheres-on-spheres (SOS) silica microspheres are used as support for the nucleation and growth of ZIF-8 nanocrystals. The surface functionalities (−SH, −COOH, and −NH₂) of silica and reaction conditions are investigated for their effects on the ZIF-8 morphology. The use of SOS microspheres results in the formation of highly crystalline ZIF-8 nanostructured shell with varied sizes and shapes, ranging from spherical to cubic and to needle crystals. The SOS@ZIF-8 microspheres are packed into a column and utilized for separation of aromatic molecules on the basis of π–π interaction in high-performance liquid chromatography (HPLC). Furthermore, by thermal treatment in air, ZIF-8 nanocrystals can be transformed into ZnO coating on SOS silica microspheres. The SOS@ZnO microspheres show excellent photocatalytic activity, as measured by degradation of methyl orange in water, when compared to ZnO nanoparticles. This study has demonstrated the facile way of using SOS microspheres to prepare core–shell microspheres and their applications