If the dye solution mixed with photocatalyst sample is kept under dark for maintaining the adsorption-desorption equilibrium for 20 min.
Then, for calculating the degradation efficiency (according to given formula below), whether to consider initial concentration (C0) of dye before light illumination (at t= -20 min) or concentration (C0) of dye after reaching adsorption equilibrium before light illumination (at t=0 min) ?
Degradation Efficiency (%) = (1-C/C0)*100
Some of the research papers have considered C0 in the calculation, the degradation efiiciency after setting the adsorption equilibrium ?
Article Degradation effect of temperature variation and dye loading ...
The degradation (or decomposition ) means the complete loss of the molecule structure. The spectrum of products might overlap with the spectrum of the initial material. Therefore, the formula
Degradation Efficiency (%) = (1-C/C0)*100
might be correct or not. The adsorption/desorption are reversible processes and does not result in the degradation, I would suggest to use the formula:
Degradation Efficiency (%) = (1-N/N0)*100,
where N and N0 are the total number of molecules left after reaction and the initial number of molecules in the system.
The initial concentration of dye was considered before the adsorption-desorption equilibrium.
Dear Surbhi,
I agree with prof. Yurii.
In my opinion, We must establish adsorption desorption equilibrium prior to illuminate the solution in the presence of catalyst. Once the adsorption of dye molecules gets saturated on the surface of catalyst then we illuminate the system to understand the photon induced adsorption-desorption process. And, here onwards we calculate the reduction of solute concentration (w.r.t. irradiation time) with the help of the above mentioned formula. If we consider the initial solute concentration then we won't be able to differentiate the effect of adsorption or photo-decomposition.
All the best.
-Aayush
Dye molecules degradation efficiency (%)= (Dye molecules degraded during reaction/Dye molecules initially added to the reaction system)*100
Surbhi Sharma your reaction immediately starts at light illumination, in my opinion C0 should be taken just before light illumination.
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MS Bashir
Surbhi Sharma, The process is in two stages. In the first, the adsorbate concentration decreases due to adsorption. In the second, it may increase temporarily due to desorption, but generally decrease due to photocatalytic decomposition. Thus, it is only possible to determine the final value of the degradation degree by relating it to the initial concentration of the adsorbate/substrate (before adsorption). However, it should be borne in mind that for a given final time, some portion of the substrate/adsorbate may not desorb.
I would like to add that, of course, one can try to measure the current concentration and determine the instantaneous values of the degree of degradation. However, these data cannot be interpreted because we do not know the actual adsorbed mass during the photocatalysis.
Surbhi Sharma
Degradation efficiency= (C0-Ct/C0)* 100 (%)
where Co and Ct are the initial dye concentration and concentration at a time ‘t’ respectively.
I hope you will find it suitable for your question.
Thank you.
Best luck with your research !!
Is C0 is the initial concentration of pollutants or the concentration after the equilbrium adsorption desorption is established?