First of all you have to dissolve palladium from your catalys /coated active carbon or some kind of silicate.../. Follow these steps:
1. weigh an oven dry sample of spent catalyst into the baker,
2. add a mixture of conc. HNO3 and 37 % HCL /1:3 vol./
3. let the reaction proceed for a few hours.
4. neutralise carefully the acids with a hydroxide solution /NH4OH or NaOH/. In the case of NH4OH add a slight excess of it so that you can smell ammonia.
5. Filter the suspension using high density cellulose filter, and wash the solids and filter with small amount of hot water. A centrifuge may be used , too.
Then you can transfer the filtrate into volumetric flask and submit to an instrumental analysis /ICA, AAS.....
You can also determine Pd content in your sample using gravimetry.
1.add an excess of 80% formic acid /reducing agent/ to the sample . Heat the final solution of paladium salts for short time. Palladium will precipitate in the form of fine powder. Filter or centifuge the suspension, vash Pd with H2O and ethanol, dry and weig-ht.
2. express amount of Pd in per-cent of weight of owen dry spent catalyst.
R.S.
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