hello
i hope synthesis TiO2 nanoparticles for photocatalysis of pollutants via Sol-Gel route by hydrolysis of titaniumtetraisopropoxide (TTIP) and other product.
i use this molar ratio (TTIP: Ethanol: water: HCl,,,, 1: 4: 10: 0.5) respectively i have problem when i drop water to the solution of TTIP dissolved in ethanol and HCl and .. the gel formed rapidly and i cant stir ?? why i can not obtain transparent sol ?
thanks
Dear Allouche,
You need to add the TTIP solution (in ethanol) slowly/dropwise into the distilled water and keep stirring the solution for around an hour. Initially the solution will be like a white/ milky solution and then turn into transparent gel.
Remember, the gel is a weak structure and sometimes it breaks down (after becoming transparent) back into milky solution (if you don't have the right ratios, stirring speed and time and have any impurities or so on).
See the protocol given in one of our published paper as below;
"Gel preparation
TiO2 nanoparticles were produced by the hydrothermal treatment of the sol–gel.16 In this work, a 0.5 M solution of titanium butoxide (Ti(OBu)4) in 2-propanol was slowly added into distilled water at 1 : 4 volume ratio with continuous stirring for 45 minutes. The obtained suspension was filtered to receive the hydrolyzed Ti precipitate.
The Ti precipitate was then added in dilute solutions of HNO3 and TBA and heated around 70 C for about 1 hour with continuous stirring to produce the acidic and alkaline peptized gels respectively. The gels prepared were treated hydrothermally to produce nanoparticles for further investigation."
You may like to read couple of our recently published papers on synthesis of TiO2 nanoparticles by sol-gel hydrothermal process.
https://www.researchgate.net/publication/255748536_Hydrothermal_synthesis_of_titanium_dioxide_nanoparticles_studied_employing_in_situ_energy_dispersive_X-ray_diffraction?ev=prf_pub
https://www.researchgate.net/publication/270914836_In_situ_EDXRD_kinetic_and_mechanistic_study_of_the_hydrothermal_crystallization_of_TiO2_nanoparticles_from_nitric_acid_peptized_sol-gel
Note:
Many factors affect the formation of gel structure and features (such as particle size, shape, crystallographic phase etc.) of final TiO2 products including TTIP to solvent to water ratios, solution stirring speed and time, solvent used, acid type and conc used and so on.
Wish you all the best.
Rehan
Article Hydrothermal synthesis of titanium dioxide nanoparticles stu...
Article An in situ EDXRD kinetic and mechanistic study of the hydrot...
Adding on to dear Enrico's answer, yes some researcher may add the stabilizer however you don't need to add it and most researchers reported synthesizing the sol-gel without having to add any stabilizer. From our experience, my PhD research and some of my students' work, we never added any stabilizer for sol-gel formation.
All the best
Salam
I change the proportions l'île this TTIP.ETOH.H2O.HCL (1:10:6:0.5)
FIRST i prepared solution 1 (TTIP, ETOH) UNDER STTIRING AND WHITE SOLUTION IS OBTAINED THEN I ADDED HCL AND THE SOLUTION COMES LIMPIDE THEN I ADDED WATER DROPWISE UNDER VIGOROUS STTIRING I OBTAINED SOL BUT I LEFT THE SOL 4 DAYS I DO NOT OBTAINED GEL?????
Why thé gel is not formed
Hi,
Add TTIP drop wisely to acidic mixture of ethanol and water. Stir for 3 hours.
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