This is the method I am following adding 0.305 g of ammonium metavanadate (NH4VO3, Sigma-Aldrich, 99.99%), 0.119 g of sodium hydroxide (NaOH, Sigma-Aldrich, ≥97.0%, pellet), 0.205 mL of phosphoric acid (H3PO4, Sigma-Aldrich, 85 wt% in H2O) to 100 mL of 0.02 M aqueous citric acid solution (HOC(COOH)(CH2COOH)2, Sigma-Aldrich, ≥99.5%) while the solution was continuously stirred. Next, ammonium hydroxide (NH4OH, Aldrich, 28.0 ∼ 30.0% NH3 basis) was slowly added to the solution to adjust its pH to 9 at which metal ions can be chelated by citric acid. Then, water was evaporated at 80°C to transform the solution from sol to gel.
However, its not forming a gel even though water is evaporating, what should I do?
Hi Abu Faizal
I'm not familiar with the compound you are trying to make, but if the formula you've written is correct this is a trivalent vanadium (V(3+)) salt. I don't see in your procedure anything obvious that would reduce vanadate (V(5+)) to trivalent vanadium. Citrate is unlikely to do it, although it may reduce V(5+) to V(4+).
By the way, the concentrations seem low for gel formation - not impossible, but just an extra incentive to double-check that you got your procedure right.
Best regards,
Emanuel Cooper
Если гель не образовлся на стадии смешивания реагентов, то при выпаривании его тоже не будет. Прикрепите фото.
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