hello every body
i have synthesized titanium dioxide and titanium dioxide doped with gadolinium via Sol gel method.
in DRX analysis for both catalysts i have anatase phase for Gd-TiO2 and TiO2 in different intensity.
in the literature we found that titanium dioxide is very active in anatase form.... but when i tested them, the activity is very low the initial concentration is 20 ppm and final concentration is 12 ppm for 4 hours of reaction.
the polutant is rhodamine 6G
i joined the pictures for DRX analysis for both TiO2 and Gd-TiO2 and you can confirm that both of catalyst the presence of anatase form.
why they are not active ? is there any problem in method of synthetisation
If titanium dioxide is not active in the presence of gadolinium, then gadolinium deactivates your catalyst. Catalysts can have substances that degrade their properties. The mechanism can be different. There can be a decrease in the adsorption of rhodamine or a decrease in active sites on the catalyst or a change in the state of the activated complex. Additional research is needed to find out why.
the activity of titania decreases with loaded Gd, because the ionic radius of Gd is very high compared with ionic radius of Ti......
regards
Hello, in order to choose a suitable metal doped on Titania must notice the ionic radius so, Ti ionic radius is 0.74 A, but Gd is 1.075 A, so the last metal is big , that depress the incorporated between TiO2 and Gd in crystal lattice.
Best regards,
Dr. Luma
thanks
i choose molar ratio for doping 0.5% of Gd and i think it is not very important quantity for doping. should i decrease this ratio ??
and for titanium dioxide i think the activity is low but the for is anatase always ???
Please note the followings:
1- Based on the XRD of TiO2, you got impure anatase phase as the peaks of the rutile phase are also present which has less photo-catalytic activity.
2- The XRD of the (TiO2+Gd) indicates that the crystallinity of the phases is reduced due to the addition of Gd. This can also affect the activity.
3- As you know, the activity of any material is a function for many variables, rather than its phase identity, such as the surface area, the pore type, the pore distribution, etc..
4- During the catalytic reaction, your material may got poisoned or fouled due to the quality of the chemicals.
Dear Imad
Thé presence of little rutile phase in titanium dioxide can increase the activity (degussa p25 is the best example).
Do you recommend to characterize those catalyst for the distribution of pores ??
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