Development of novel methods for chiral discrimination remains a challenging and important area due to the structure similarity but significantly different roles of enantiomers in biological and environmental systems. Here we report a 3D chiral porous Zn-organic framework (Zn 2 (bdc)(L-lac)(dmf)•DMF) coated quartz crystal microbalance (QCM) sensor for chiral discrimination of four pairs of enantiomers. The adsorption isotherms of the enantiomers on Zn 2 (bdc)(L-lac)(dmf)•DMF follow the Dubinin-Astakhov equation. The QCM sensor shows excellent sensitivity and enantioselectivity. The chiral recognition ability of Zn 2 (bdc)(Llac)(dmf)•DMF sensor was temperature and concentration dependent. The chiral selectivity factor ranged from 1.36 (S/R-1-(1-naphthyl)ethylamine) to 2.20 (S/R-1-phenylethylamine) at 25 o C. The good chiral recognition capacities to enantiomers make Zn 2 (bdc)(L-lac)(dmf)•DMF potential for the discrimination of enantiomers.
To strengthen the particles radial
movement and mixing, the longitudinal
vortex generator of a sphere was adopted in the spouted bed in this
study. To find the influence of the longitudinal vortex and particle
properties on axial and radial velocities of particles in a 152 mm-diametered
spouted bed, particle image velocimetry (PIV) was employed. The experimental
results show that the addition of the longitudinal vortex generator
caused the vortex movement of high-speed gas and induced a considerable
secondary fine vortex in the cross section of the spouted bed, and
the existence of longitudinal vortex significantly improved the radial
velocity of particles, compared with that of the conventional spouted
bed. Due to the effect of longitudinal vortex on particles, the phenomenon
of early dropping of particles was increasingly obvious with the rise
in bed height, and the value of axial velocity of particle phase was
negative. With the decrease in the particle diameter, the longitudinal
vortex effect of gas-driven particle movement would be enhanced. The
longitudinal vortex could enhance particle velocity under a wide range
of particle diameters, and the enhancement factor η decreased
with the rise in the particle diameter and gradually approaches to
1.
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