G.S. Luo

Oxidative desulfurization of DBT with H2O2 catalysed by TiO2/porous glass

Aimed at ultra-deep oxidative desulfurization (ODS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to control air pollution, we specially designed and prepared porous glass supported with TiO2 nanoparticles acting as an amphiphilic catalyst. Hydrogen peroxide which is considered as the “green” oxidant was used, and for the extreme liquid–liquid phase ratio (usually larger than 1500) reaction system, a pore volume of 0.19 mL g−1 of the catalyst provides enough space for the storage of hydrogen peroxide. The as-prepared catalyst offers a high interfacial surface area of 116.9 m2 g−1 and enhances the reaction by facilitating the mass transfer. The mono-dispersed TiO2 exhibited good crystallinity. The mean diameter varied from 2.1 to 7.8 nm with the loading amount increasing from 1.27 wt% to 9.85 wt%. The catalyst showed high activity and good stability for producing ultra-clean fuels: 100% conversion was obtained within 2 min and the conversion just decreased from 100.0 ± 1.0% to 94.3 ± 0.6% after 5 cycles. Overall, this new reusable catalyst provided an alternative for highly efficient ultra-deep desulfurization in a green way.

Pervaporation separation of ethyl tert-butyl ether and ethanol mixtures with a blended membrane

A new kind of membrane was prepared by blending cellulose acetate butyrate with cellulose acetate propionate. The properties of this membrane were evaluated by the pervaporation separation of ethyl tert-butyl ether and ethanol mixtures. The experimental results showed that the selectivity and the fluxes of this membrane depend on the blend and on that of processed feed mixtures. With respect to temperature, the overall and the ethanol fluxes obey the Arrhenius equation. The total and the ethanol fluxes increase with the increase of the cellulose acetate butyrate content in the blended membrane, the ethanol concentration in the feed and the experimental temperature. But the selectivity decreases as the cellulose acetate butyrate content in the membrane and the experimental temperature are raised. When the feed composition is varied, the lowest selectivity is observed in the vicinity of the azeotropic composition. The swelling and the sorption experiments also gave the same results.

Preparation of coiled hollow-fiber membrane and mass transfer performance in membrane extraction

Abstract Based on the swelling action of organic solvents on hollow-fiber membranes, a new technique of solvent-swelling and dry-shaping for preparing coiled hollow fibers from straight hollow fibers was introduced. The mass transfer performance of these coiled fibers was tested with 30% TBP (in kerosene)–phenol–water as a working system in a membrane extraction process, and compared with the results obtained from the straight fibers. After long time test, it was proved that the coiled fibers were stable when they contacted with the organic solvent in the membrane extraction process. As to the mass transfer performance, it was found that the presence of vortices in the coiled fibers provided better mass transfer performance than the straight fibers. The improvement factor was in the range of 2–4. With an increase of the phase velocity inside the tube, the mass transfer coefficient and energy input in the coiled fibers grew up much more quickly than that in the straight fibers. An empirical correlation for predicting the mass transfer coefficients and an equation for pressure drop in the coiled fibers were suggested.

Aqueous two-phase electrophoresis for separation of amino acids

Two-phase electrophoresis, coupling traditional solvent extraction with electrophoresis, is a novel separation technique. Being bio-compatible, aqueous two-phase electrophoresis provides a successful method for separating mixtures of biomolecules. In this work, the separation of amino acids by aqueous two-phase electrophoresis was examined with dextran-polyethylene glycol-water as a working system. The influences of separation time, field strength, initial solute concentration and two-phase contact area were studied in intermittent separation equipment. The experiment results show that aqueous two-phase electrophoresis is an effective separation technique for amino acids. With time, field strength, and contact area increasing, mass fluxes across the interface are increased quickly.

Selective recovery of amino acids by aqueous two-phase electrophoresis

Abstract Aqueous two-phase systems (ATPSs) formed by spontaneous phase separation of different water-soluble polymers are bio-compatible. Aqueous two-phase electrophoresis, coupling traditional solvent extraction with electrophoresis, is a novel separation technique and provides a successful method for separating mixtures of biomolecules. In this work, the selective recovery of amino acids by aqueous two-phase electrophoresis was examined with dextran–polyethylene glycol–water as a working system. The experiment results show that glutamic acid can be separated from phenylalanine and tryptophan successfully. The influences of the electrophoresis time, field strength, and phase volume ratio were studied in an intermittent separation equipment.

Development of Cellulose Acetate Propionate Membrane for Separation of Ethanol and Ethyl tert-Butyl Ether Mixtures

Abstract For pervaporation separation of ethanol and ethyl tert-butyl ether mixtures, a cellulose acetate propionate membrane was chosen as the experimental membrane because of its high selectivity and good mass fluxes. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the permeates depend on the ethanol concentration in the feed and the experimental temperature. With increases of the ethanol weight fraction in the feed and the temperature, the total and partial mass fluxes increased. With respect to the temperature, ethanol mass flux obeys the Arrhenius equation. The selectivity of this membrane decreases as the temperature and the ethanol concentration in the feed increase. This membrane shows special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, minimum values of ethanol concentration in the permeate a...

Separation of Ethyl Tert-Butyl Ether-Ethanol by Combined Pervaporation and Distillation

Abstract A cellulose derivative membrane (30 wt.% cellulose acetate butyrate (CAB) combined with 70 wt.% cellulose acetate propionate (CAP)) was prepared, and its properties were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether (ETBE) and ethanol. The experimental results showed that the selectivity and permeability of the membrane were dependent on the blend composition, the processed feed and the experimental temperature. With respect to the temperature, the fluxes obeyed the Arrhenius equation. On the basis of these results, a separation process for the production of ETBE was developed by combining pervaporation and distillation. The distillation column was designed with the software ASPEN PLUS, and the liquid-vapour equilibria were predicted by the UNIFAC method. The area of the membrane was calculated according to the production capacity. It may be concluded that the combined process for the separation of mixtures of ETBE and ethanol is simple with high recovery of the ETBE product.

LIQUID-LIQUID PHASE EQUILIBRIUM UNDER EXTERNAL ELECTRIC FIELDS

With the development of novel combined-field separation techniques, the influence of external fields on the thermodynamic properties of working systems is an important area of study. A study on the phase equilibrium of n-butanol/citric acid/water under an electric field was carried out. The effects of field strength, temperature, and solute concentration in the aqueous phase on the distribution coefficients were investigated, and the results were analyzed through chemical potential equations. The experimental results show that, if enough time is allowed, an equilibrium state will be reached for the working system under the action of an electric field. Increased voltages and temperatures resulted in higher distribution coefficients between butanol and water. If the solute concentration in the aqueous phase is lowered, the distribution coefficient is strongly increased with an increase of the field strength. However, at unchanged field strength, a higher solute concentration will cause a decrease in the distribution coefficient. Also, the logarithm of the ratio defined by the distribution coefficient under an electric field to the distribution coefficient without an electric field is directly proportional to the voltage applied to the system.

Concentration of Formic Acid Solution by Electro-electrodialysis

The traditional production process for formic acid is a high-energy-consumption process. To save energy when concentrating formic acid solutions, anion-exchange membranes 3362W and AM-203 were evaluated for facilitating the concentration of formic acid solution by electro-electrodialysis. The effects of concentration, temperature, electric current, and time on the electro-electrodialysis process were studied. Experimental results indicated that electro-electrodialysis was an effective method for concentrating formic acid solutions at 30°C. Higher efficiencies were not obtained at higher temperatures. If the concentration of a working system was greater than 10 wt%, the overall current efficiency was greater than 100%. The overall current efficiency was 80–95% when the concentration of a system was less than 10 wt%. In general, the overall current efficiency was increased with an increase of low current density. After a certain value, the overall current efficiency would begin to drop. The performance of the AM-203 membrane was better than the 3362W membrane. With the AM-203 membrane it was found that the overall current efficiency was decreased if the concentration difference between the cathodic and anodic compartments was increased.

Sorption and pervaporation separation of ethyl tert—butyl ether and ethanol mixtures through a blended membrane

A new kind of membrane was prepared by blending poly( acrylic acid ) with cellulose acetate propionate for the separation of ethyl tert-butyl ether and ethanol mixtures. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the fluxes of this membrane depend on the blend composition and on that of processed feed mixtures. With respect to temperature, the ethanol fluxes obey the Arrhenius equation. The fluxes increase with the increase of the poly(acrylic acid) content in the blended membrane, the ethanol concentration in the feed, and the experimental temperature. But the selectivity decreases as the poly( acrylic acid) content and the experimental temperature are raised up. When the feed composition is varied, this membrane shows the special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, the minimum values of ethanol concentration in the permeate and in sorption solution are obtained. The swelling ratios increase with an increase in the temperature and the ethanol concentration. The ethanol concentration in the sorption solution is also influenced by the temperature and composition of the mixtures. When the temperature increases, the sorption selectivity of the membrane decreases.