Effect of ultrasound on liquid phase adsorption equilibria of azeotrophic and non-azeotrophic mixtures
Adsorption process is a well-established technology in chemical Industries. Adsorption technology is becoming more popular for many important processes such as purification, catalysis reaction and bulk separation. This is due to its high adsorption efficiency and mild operating conditions. However,...
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| Format: | Thesis |
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2009
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| Summary: | Adsorption process is a well-established technology in chemical Industries. Adsorption technology is becoming more popular for many important processes such as purification, catalysis reaction and bulk separation. This is due to its high adsorption efficiency and mild operating conditions. However, the difficulty of azeotrophic adsorption and low-mass transfer rate limit adsorption development and applications. Conventional adsorption showed a low selectivity particurlary for azeotrophic mixture. Ultrasound was proven as an alternative method to the conventional adsorption process. Ultrasound is a very useful tool in intensifying the mass transfer process and breaking the affinity between adsorbate and adsorbent. mTherefore, the aim of this work is to investigate the effect of ultrasound on liquid phase adsorption equilibria on azetrophic and non-azeotrophic mixtures. In order to study the adsorption process, the accurate measurement and interpretation of
adsorption is the most important initial step In any analysis of any adsorption process. Therefore, the equilibrium isotherms of azeotrophic and non-azeotrophic
mixtures with and without ultrasound were determined using conventional method.
This work was restricted to measure azeotrophic (acetone-ethanol) and nonazeotrophic
(methanol-ethanol) mixtures. The adsorption systems for azeotrophic and non-azeotrophic mixtures were studied at 30ºC onto two different properties of porous adsorbent namely activated carbon and silicalite ZSM-5. In the case of
adsorption under ultrasound effect, the ultrasound wave was applied at a frequency of 21 kHz with 25% amplitude at atmospheric pressure. Two different models were used to analyse the liquid phase adsorption equilibria of azeotrophic and nonazeotrophic mixtures. Pseudo-ideal adsorption model and Gibbs dividing plane model were used for azeotrophic and non-azeotrophic mixtures by correlating with
the experimental data. The results showed that both isotherms of azeotrophic and non-azeotrophic mixtures on activated carbon and silicalite zsm-5 using conventional method were obtained at entire concentration range (mole fraction between 0 to 1). In the case of isotherms of azeotrophic mixture, the result obtained showed that the azeotrophic point of excess adsorption was noticeably
moved due to the ultrasound effect. The excess isotherms of non-azeotrophic (methanol-ethanol) mixture onto activated carbon and silicalite ZSM-5 with and without ultrasound, were well correlated by Pseudo-ideal adsorption model.
According to this model, the adsorptive capacities of azeotrophic and nonazeotrophic
mixtures on activated carbon and silicalite zsm-5 were found to decrease but the selectivity was increased. However, the azeotrophic mixture was analyzed using Pseudo-ideal adsorption model and it at lower liquid concentration
follow Langmuir type of equation. Meanwhile, the Gibbs dividing plane model was found correlated well for both Isotherms of azeotrophic and non-azeotrophic mixtures. According to this model, the adsorption of azeotrophic and nonazeotrophic mixtures on activated carbon and silica lite zsm-5 were lower compared In the absence of ultrasound.
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