In the experiment of chemical actinometry using ferrioxalate, at low concentration, the iron tris phenanthroline complex has a fixed absorbance and no problem.
At high concentration, there is no fixed value of absorbance, what should I do, and what is the optimum condition (pH, amount of fluoride, etc) that should be done to obtain good results ?
thanks for your reply doctor.
it;s not the problem!, ferrioxalate 0.15 M irradiated to LED with wavelength 530nm, Fe3+ photo-reduced to Fe2+, i take portion of the solution and add it to o-phenanthroline in the presence of fluoride as masking agent for Fe3+, but the absorbance value still increase, i want to know the optimum condition to prevent Fe3+ from photoreduction during the measurement.
The best for LED would be to buy a power meter and forget a chemical actinometry. That's what we do in our lab. In your case keep all samples wrapped in Aluminum foil, stir the solution in optical cell during taking the spectrum. Acidify your sample solution to pH 1-2. Try HCl, chloride may work similarly to fluoride
Thanks :)
i think the problem not only in the pH value, but also the amount of masking agent like fluoride and its addition time to prevent the photoreduction of ferric ion.
i solve the problem. thanks :)
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