In adsorption process, at different time 0min (0.5Abs ), 15min (0.3Abs.) and 32 minutes (0.78Abs.). Commonly absorbance (Abs) peaks should be decreasing in nature. But in my case the final 32min peak shows higher abs. values than others. Can you suggest why it happens in peak value?
UV irradiation may decompose what you adsorb into other compounds, also able to absorb UV light. Maybe. Without further information about adsorbent and adsorbate, it is difficult to be more precise.
It may also be a simple technical problem, did your repeat the experiment ?
Alain
your adsorbate adsorbed on adsorbent at 0 min to 15 min. Then after 15 min its take desorption process.
Desorption will not take place spontaneously, unlike the temperature changed under the effect of irradiation. Was the tempoerature strictly controlled ? Was the liquid stirred at the same time for temperature homogeneisation ? Isotherms should be obtained at strictly constant temperature, hence their name.
Alain
Thanks for your valuable contribution, In doping/adsorption process using UV - light, Metal complex Cu surrounded with 4amine group and 2ClO4 doped into TiO2 , Here room temperature reactions with continuous stirring. finally it shows Cu doped into TiO2 semiconductors with proper decreasing intensity in Raman spectra with increasing in time (0m,15m,30m). After repeated reactions also shows same results
To Dr. A.S.G,
If it so means then what happening in Raman spectrum shows systematic decreasing counts with increasing in time?
To Prof. Alain,
Is there any disturbance of lamp temperature ? Is there any other probability of problem?
If photo-chemical reaction means your complex was decompose after 15 min, and that wavelength for pi-pi transition state means your ligand come out from your central metal coordination environment, if d-d transition means Cu2+ ia come out from ligand environment.
For Raman intensity decrease due to increase cu content in tiO2 surface some structural defect or oygen vacancy created in your cu-TiO2 particle.
My first time answer only for adsorption process no photo-chemical process.
@ Raj
The lamp may produce heating of the solution, which is in favour of desorption, hence the need of a strict temperature control. UV light may also produce photodegradation of other compounds which may be present in the system.
Alain
UV irradiation is producing heat on one hand and on other hand quantum electronic atomic rearrangement. All together producing desorption, chemical decomposition, diffusion and atomic rearrangement. This will strongly depends on UV wave length, power, pulsed mode and duty cycle, and of thermal conductivity and temperature of the substrate.
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