Separation of azeotropic mixtures using air microbubbles generated by fluidic oscillation

Abstract

The feasibility of separating the azeotropic mixture of ethanol-water using microbubble-mediated batch distillation is presented. The effects of the depth of the liquid mixture in the bubble tank and of the inlet air microbubble temperature on the process efficiency were investigated. The enrichment of ethanol in the vapor phase was higher than that achieved at equilibrium conditions for all liquid ethanol mole fractions considered, including the azeotrope. On decreasing the depth of the liquid mixture and increasing the temperature of the air microbubbles, the separation efficiency of ethanol was improved. Ethanol with purity of about 98.2 vol % was obtained using the lowest liquid level (3 mm) in conjunction with the highest air microbubble temperature (908C). Separation was achieved with a small rise in the temperature of the liquid mixture (48C) at a depth of 3 mm and evaporation time of 90 min making this system suitable for treating thermally sensitive mixtures.

Membrane defouling using microbubbles generated by fluidic oscillation

“…There are many advantages using the fluidic oscillator in term of cost-effectiveness, robustness, reliability, immobile parts and no requirement of electricity (Zimmerman et al, 2011). The bubbles generated by fluidic oscillation have low energy consumption that distinguish the method from other method such as ultrasonic and rotary disk which require a significant supply energy (Abdulrazzaq et al, 2015). Zimmerman et al, (2008) explained this device acted as a fluidic amplifier with a potential to pinch off hemispherical cap bubble.…”

“…This early break off of bubble formation at the diffuser aperture offers smallest possible bubble size. Fig.2 and Eq.1 illustrates the relationship of the smaller microbubble to have higher surface area to volume ratio which lead to momentum transfer rates, especially for scrubbing the surface of membrane (Abdulrazzaq et al, 2015;Agarwal et al, 2012). A fluidic oscillator mainly consists of 3 parts: one inlet for air supply, two mid ports for the feedback loop, and two exit ports as the oscillation channel outlet.…”

Continuous removal of ethanol from dilute ethanol-water mixtures using hot microbubbles

“…Recently, hot microbubble clouds generated by fluidic oscillation in shallow liquids (liquid height approximately a few bubble diameters) were shown to be effective in stripping ethanol from concentrated ethanol–water mixtures (90% (mol/mol) [17] , 50% (mol/mol) [18] and 40% (wt/wt) 19 ) due to high interfacial area for mass transfer, improved mixing in both phases and non-equilibrium mass transfer [17] , [18] , [19] . In our previous work [20] , with a batch stripping system containing dilute ethanol–water mixtures (~4% (v/v)), it was demonstrated that short bubble residence times in the liquid phase are beneficial for ethanol separation, as non-equilibrium mass transfer leads to supersaturated vapour at the point at which the bubbles escape the liquid.…”

Esterification for biodiesel production with a phantom catalyst: Bubble mediated reactive distillation

“…Abdulrazzaq et al [18] describe the strongly non-equilibrium preference for ethanol vaporisation in ethanol-water mixtures by hot microbubble injection. Subsequent modelling by Abdulrazzaq et al [19] clarifies that the non-equilibrium driving force is kinetically much more rapid at vaporising ethanol in all liquid proportions.…”