Separation of Light Gases from Xenon over Porous Organic Cage Membranes

Herein, we demonstrate the successful synthesis and separation ability of CC3 porous organic cage membranes grown on tubular supports for light gases He, CO₂, CH₄, and Kr over xenon. CC3 membranes were synthesized using secondary seeded growth and displayed different separation performances depending on the crystal size, size distribution of the seeds, and membrane thickness. CC3 membranes as thin as ∼2.5 μm resulted in high single gas permeances of 2114, 1962, 1705, 773, and 162 GPU, for He, CH₄, CO₂, Kr, and Xe, respectively. The highest ideal selectivities for He/Xe, CH₄/Xe, CO₂/Xe, and Kr/Xe gas pairs were 13, 12, 10.5, and 4.8, respectively. Mechanistically, the membranes separated He, CO₂, Kr, and CH₄ from Xe mainly via gas diffusivity differences. Therefore, the separation was kinetically driven.

Recent developments of monolithic and open-tubular capillary electrochromatography (2017-2019)

Capillary electrochromatography, which combined the high selectivity of high-performance liquid chromatography and the high separation efficiency of capillary electrophoresis, is an attractive separation tool. In this review, the developments on monolithic and open tubular capillary electrochromatography during 2017 to August 2019 are summarized. Considering the development of novel stationary phases is the most active research field in capillary electrochromatography, monolithic capillary electrochromatography is classified according to the polymer-based and hybrid monolithic columns, while open-tubular capillary electrochromatography is categorized by cyclodextrin, silica, polymer, nanomaterials, microporous materials, and biomaterials-based open tubular columns.