Please explain I am so confused between in these two value in my experiment.
Dear Dr. Rupa Chakraborty,
experimental adsorbed quantity (qe exp) is the obtained value in adsorption experiments at equilibrium, while the calculated quantity (qe cal) is the predicted value by using the equation of studied isotherm.
At first, run couple of experiments at different initial concentration of the analyte and then plot the isotherm (qe exp vs Ce). Subsequently fit an adsorption model (e.g. Langmuir); nonlinear form of the model is recommended. At any concentrations (preferably at high concentrations in order to calculate the maximum adsorption capacity) you can obtain the highest qe. exp or insert the value of the equilibrium concentration of the adsorbate (Ce) into the isotherm model and obtained the qe cal.
For more details, please see at: https://www.asee.org/file_server/papers/attachment/file/0002/2184/ASEE_Paper.pdf
Best regards, Pierluigi Traverso
Experimental qe=(Ci-Cf)V/m
Calculated qe is obtained from an isotherm such as the Langmuir model as qe=kCe/(1+kCe), or any other models.
The difference shows to what extent the experimental data follow a model.
Thank you so much Ali Nematollahzadeh. It is really very helpful information for me.
They have all answered well and correctly@Rupa Chakraborty
Qe experimental is the qe that you get when you use the formula (Co-Ce)V/M directly after the experiment while qe calc is the one you get from formula like pseudo-1st and pseudo-2nd order model
The value qe (experimental) is the value of adsorption capacity by your experiment. On the other hand qe (cal) is the adsorption capacity calculated using different kinetics model. These two value are quite similar only in one kinetic model which has best linear fitting.
Dear Colleague!
Experimental adsorbed quantity (qe exp) is the obtained value in sorption experiments at equilibrium, while the calculated quantity (qe cal) is the predicted value by using the equation of studied isotherm.
First, run a couple of experiments at different initial concentrations of the adsorbate, then plot the isotherm (qe exp. vs Ce).
Finally, fit an adsorption model (e.g. Langmuir). The nonlinear form of the model is recommended.
At any concentrations (preferably at high concentrations, to calculate the maximum adsorption capacity) you can either read the highest qe exp. or insert the value of the concentration into the isotherm model and calculate the qe (called qe cal.) qe=kCe/(1+kCe),
Please, I got all through negative values of Langmuir separation factors (RL). Normally, the curve usually used to be concave up, decreasing. Now my question is how would the curve look like in the case of negative RL values against Co (initial concentration). That is, plotting the RL versus Co. ???
the experimental qe can be calculated from the experimental data, while the calculated qe can be estimated from the kinetic models. Below paper can help you to understand that.
The experimental value is calculated from the formula, q=(int. conc-eq. conc)*volume/mass. The theoretical value is calculated from the kinetic model equation by plotting the graph and finding the slope and intercept. Generally the value of theoretical value will be higher than the experimental value. If the value of adsorption capacity calculated from second order kinetic model is matching with the experimental value, then we can say that experimental data fits better to the second order kinetic model.
Rupa Chakraborty What do you really mean. Is it about the physical meaning of both quantities, or about the possible differences in the values related to the experimental method and the method of determining the upper limit of the approximating function. To determine a reliable qeexp value, the kinetic experiment must last long enough. How long? - it depends on the rate of the process, so it is necessary to use increasing sampling time and monitor the changes in the concentration of the solution. As for qecal, not only the approximating function is important, but also the calculation method. I would avoid here graphical methods related to the change of the coordinate system and implicit functions with respect to q.
This video indoduces how to compare experimental and calculated equilibrium adsorption capacity, qe value in adsorption kinetic study easily! #aminulcheminnovation #AminulSir
https://youtu.be/kRn8PTdFAJ4
Q obtained at certain time and concentration is experimental and the Q obtained from the equation of kinetic study is calculated. More closer value of experimental Q with calculated Q, the data fits well the particular kinetic plot.
C R Girish Is this the main criterion to be fit into PSO if calculated Qe is closer to experimental Qe? In my case, R2 is higher for PSO than PFO but calculated Qe is more closer to experimental Qe in case of PFO, how can I justify these data?