Separations Technology最新文献

In the field of food technology the main applications of pervaporation through hydrophilic membranes are the removal or extraction of water from aroma azeotropic aqueous mixtures. In this study, experiments for removal of water containing aroma compounds of ethanol, propanol, butanol, hexanol, ethyl acetate and acetic acid were performed through a composite, plate and frame type hydrophilic PVA (poly vinyl alcohol) membrane in a 0.5 m² plane module at constant feed temperature and permeate Vacuum pressure. The analysis is presented in terms of variations in permeation flux and separation factor. The results show the decrease in separation factor as well as permeation flux with the increase of alcohol in feed. Hexanol does not permeate through PVA membrane. Activity coefficient of water is higher than that of organic. Pervaporation selectivity differ from Liquid-vapor thermodynamic equilibrium.

Lithium-incorporated zeolite Ys (Li-NaYs) were directly synthesized under a hydrothermal condition from a gel mixture of Li₂O·Na₂O·SiO₂·Al₂O₃·H₂O. It was confirmed by XRD, NMR and elementary analysis, that lithium ions could be introduced onto the ion sites of zeolite Y during the course of crystallization. Usage of lithium citrate as the lithium source is the indispensable factor to achieve the synthesis. In adsorption of mixtures of 2,6-dimethylnaphthalene and its isomers, Li-NaYs exhibited greater adsorptive capacities and higher adsorption selectivities to 2,6-dimethyl naphthalene than NaY. Direct hydrothermal synthesis of Li-incorporated zeolite Y prevents the blockage of pore openings and/or channels during lithium ion-exchange. Furthermore, the difference in adsorptive properties between Li-NaY and Li ion-exchanged NaY is due to Li ions being introduced onto the S₁ ion sites, which can hardly be ion-exchanged, during the hydrothermal synthesis.

The solubilization of ortho and para isomers of substituted phenols such as nitro phenols, chlorophenols, cresols and isopropylphenols in anionic micelles is reported. A comparison of the free energy of micellar solubilization provides an insight into the effect of the nature and position of the substituent. The solubilization of the ortho substituted phenols was found to be energetically more favourable than that of corresponding para isomers when the substituent was polar in nature (nitropheols and chlorophenols). Conversely, phenols with nonpolar substituents (cresols and isopropylphenols) resulted in the para isomer being more favourably solubilized by the micelles.

A methodology to fractionate suspended particles according to size and/or acoustic properties is reported. This fractionation is accomplished by simultaneously subjecting the particles to a resonant acoustic field and a laminar flow field propagating in an orthogonal direction. The acoustic field induces a redistribution of the particles within the cross-section of a narrow separator channel while the laminar flow transports the particles along the separator channel towards the exit. By altering the strength of the flow relative to the strength of the acoustic field, the desired fractionation can be controlled. Proof-of-principle experiments conducted with binary mixtures of polystyrene particles are reported. The performance of the experimental device was analyzed using a model based on calculations of the trajectory of particles through the chamber. The acoustic method has potential to rapidly and selectively factionate suspended solids with very low specific power consumption.