How to determine the equilibrium concentration in a fixed bed(column) of adsorbent? Is it possible to determine the equilibrium curve (isotherm) with the data obtained from the bed(column)?
Yes you can determine isotherms by frontal analysis. Feed a solution having the desired solute until the outlet concentration is equal to the inlet concentration. A mass balance will tell the amount of adsorbed solute, this will be an equilibrium value. Repeat the process using solutions with different concentrations of solute.
Hi Masoume Az
isotherm plots are resulted from the bach adsorption experiments not the dynamic ones. In a fixed-bed column study, concentration varies with time and you can not say any of your effluent samples are in equilibrium condition, because a fixed-bed column may not reach to the equilibrium state based on the amount of flowrate. A mass balance on breakthrough curves gives you the whole amount of adsorbed contiminant during the whole process, in other words, bed adsorption capacity is obtained by fixed-bed studies which is different from the adsorption capacity obtained by batch experiments and isotherm plots.
remind that isotherm plots are obtained by plotting the equilibrium adsorption capacity (qe) vs equilibrim concentration (ce) from batch experiments.
best regards
Interesting Mahdi Askari you should write a book explaining what equilibrium is.
Dear Dr. Omar Gonzalez-Ortega
I will kindly appreciate you for your comment. But I feel rather confused that my answer is correct or not. If no, I was wondering if I could learn something valuable from you. My answer was based on my studies about batch and dynamic adsorption in the articles and all the results obtained from these two types of adsorption experiments.
I will appreciate if you guide me.
Best regards.
Omar Gonzalez-Ortega & Mahdi Askari
thanks for your reply. If we want to save time with recirculated feed in a fixed bed, How we can determine balance(equilibrium concentration) in it??? We can say that if the concentration of input and output is equal, is it balanced? Is it possible that the dose of selective adsorbent which in that the input and output concentrations were equal ,passed from the equilibrium point and it is maximum adsorption ( not the maximum actual capacity) ???
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