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Alternative acid for nickel plating

2005

I am a plating engineer working in Malaysia.

My company is currently using boric acid for our nickel electro-plating line. However our current effluent plant does not removes boron (from boric acid usage).

Is there any other alternative acid that can be used? How about H2SO4?

Eric Chong
plating shop - KL, Selangor , Malaysia

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Boric acid is a buffer, so sulfuric acid will not be suitable. I am intrigued, as you seem to infer that boric acid is the only acid you are using in the bath, so what type of nickel bath are you operating? You can remove boric acid by ion exchange, but why not consider a closed loop system if you are having a problem with waste boric acid.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2005

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Hi Eric, please take a look in a basic electroplating book. Look for the function of boric acid. You will see, that it is used for buffering the electrolyte in the cathodic film. Without using boric acid the pH would increase in the cathode film during electroplating so much that Ni-hydroxide would precipitate. This would cause rough layers. Resume: No, you can't substitute boric acid with sulfuric acid. Sulfuric acid has no buffer function, it's a strong acid.

Best regards,

Michael Hekli
Switzerland
2005

Hi, boric acid is used as an buffer agent. With sulfuric acid and/or hydrochlorid acid you adjust the pH (depending on your chloride and/or sulphate content in the bath). You should not have so much boric acid (30-45g/l in electrolyte) that you will get problems in your waste water plant. Hope I could help you, Regards, Dominik Michalek

Dominik Michalek
- Mexico City, Mexico
2005

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Dear Trevor,

The boron presence in our effluent not only come from the nickel bath as well, but also from the rinse step. We have experimented with a closed loop system, however after some time the bath become too contaminated, and affects our product.

Eric Chong
- KL Selangor, Malaysia
2005

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Mr Eric Chong.

While you are right in infering the Boron comes from the Boric acid , you are now clear that Bright Nickel needs boric to remain stable and plate acceptably. Your problem is with effluent.There is Boron in the effluent. Please increase the dragouts to three or four. Recycle the dragout and prevent Nickel solution from reaching the effluent stream. Use evaporative recovery when Nickel metal crosses 6 GPl in Dragout one. Recycle the remaining dragouts backwards . Keep the Nickel as metal below 1 GPL in dragout 4. Below 3 gpl in dragout 3 and below 4 gpl in Dragout 2. Use DI water to top up dragouts. This is one way of saving some money and keeping Boron where it belongs..in your bath buffering the pH.

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016
2005

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Eric, what does the bath become contaminated with? The whole principle of closed loop is that the only thing that goes into it is clean water and the rinses are used to top up the relevent tanks. Obviously you do not mix rinses from different process tanks.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2005