Letter 4072

Analysis of Sodium Sulphate in Nickle Baths. 

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Hello all,

Does anyone have the analytical procedure to analyse a Watts Nickel plating bath for Sodium Sulphate content ? Thanks in advance,

Khozema Vahanwala Automaxx   Bangalore, Karnataka, India

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What you really want to test for is sodium - the bath is full of sulfate ion from the nickel sulfate.

There is a selective ion probe for sodium. Special techniques may need to be used because the solution has a lot of dissolved material and some of the components may be interferences.

The other applicable method is flame photometry, where the yellow sodium emission is measured and used to quantitate the Na.

I'm sorry, but there's no simple titration or color method, to the best of my knowledge.

Dave Wichern - Bronx, NY, USA

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Hello K Vahanwala,

To find the Sulfate: take a 10 ml sample of the bath and (to be added in the order listed) about 100 ml DI water, 5 ml 50% HCl, 25 ml Ba(NO3)2 solution (about 15 grams of reagent grade barium nitrate in about 70 ml of DI water)the sulfate will precipitate continue adding drop wise more barium nitrate until no more precipitate is formed, allow solution to stand 4 hours, filter in tared Gooch crucible, wash precipitate with DI water, dry in oven at 110 degrees C., cooling in desiccator (dry to constant weight), and weigh. SO4 (oz/gal) = (weight in grams of precipitate) X 5.488

Now, find the Nickel content and Chloride content. In order to find the Nickel AS Chloride then Nickel AS Sulfate, the balance of the Sulfate would be present as the Sodium salt.

Regards,

Fred Mueller, CEF
- Royersford, PA

Dear Mr Fred and Mr David.

Thanks for the immediate response. Much appreciated.

Pardon my ignorance but is it possible to briefly explain Flame Photometry ? I am also lost as to " tared Gooch Crucible" . Is there any other colloquial name or description for it?

Thanks again,

Khozema Vahanwala Automaxx  Bangalore, Karnataka, India

Flame photometry is done with a special instrument, a photometer. The sample is sprayed into an oxygen/hydrogen flame, and the light resulting from the emission of the sodium ions in the flame (in this case yellow) is measured with a photosensor. The intensity of the emission is proportional to the sodium concentration.

It's an expensive instrument - an outside lab would likely have one though.

Dave Wichern
- Bronx, NY, USA

Hey K. Vahanwala,

A Gooch Crucible is a small porcelain filter that (can be used with a paper or glass filter disc) retains the precipitate so that is can be weighed. It is used with a vacuum flask (pulling a vacuum speeds the filtration) and rubber gasket to make a seal. It can be reused after cleaning with the right acids and bases (safety first, lots of concerns, like were the vacuum pump exhausts). After cleaning the Gooch Crucible is dried in an oven at 110 degrees C. (this drives off the water and brings the crucible to its constant weight or lowest weight). Cooling and storing the crucible in a desiccator prevents the reabsorption of water moisture. We have weighed the crucible (tared) and will substract out the crucible to find the weight of the precipitate. Lab products can be found on-line.

Regards,

Fred Mueller, CEF
- Royersford, PA

You are interested in Sodium and not in sulfate. Well the easiest way to check sodium is by Atomic Absorption.

Sara Michaeli     chemical process supplier Israel

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