| Search our quarter-million Q&As |
Home of the finishing HOTLINE since 1989
-----Treatment of electroless nickel waste
2000
Can anybody suggest an effective technique for treating spent bath (electroless nickel plating) from our process bath. We use nickel sulphate, sodium hypophosphite, wetting agents and ammonia ⇦ on eBay or Amazon [affil link] for pH adjustment in the process. Currently, for our waste water treatment we use CaCl2, NaBH4 and adjust the pH to 9.0, precipitate settles and then filter press. We still have 50 to 100 ppm nickel.
Could anybody please suggest any more effective treatment techniques or precipitating agents that might be more effective to remove nickel. Your suggestions are highly appreciated. Thanks in advance. Josephine
Josephine C. Lee- Taipei, Taiwan
Here in the U.S. the problem has largely gone away for plating shops since many vendors take back the exhausted solutions for recycling. But two non-chemical methods you might wish to consider are:
1). Electrolytic plate-out (in practice this is often used in combination with ion-exchange; ion-exchange removes nickel to very low ppm, then the resin is regenerated and the regenerant and backwash solutions are what is actually electrolytically treated).
2). Spontaneous plate-out onto steel wool ⇦ on eBay or Amazon [affil link] . letter 4492 covers this idea in additional detail.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Hello Josephine, I believe that electroplating is the method of choice. There is, however, some things to consider. The effectiveness, where most of the energy is used to plate metal is greatest in a very narrow pH-range. Between 8.5-9.
You must use "large area, steel wool" cathodes. When this solution gets electroplated some kind of organic is formed as a result of anodic oxidation. It smells almost like formaldehyde. I put in carbon filters in the plating equipment and let the solution go through these. After plating is done, there is a question of the hypophosphate. If it is possible to discharge then ok. Otherwise you have to treat it with ferric chloride ⇦ on eBay or Amazon [affil link] or your carbonate and filter press it. Sven
Sven- Sweden
This is a meeting place for camaraderie & sharing, not a free consultancy. So some readers don't engage with anonymous posters.
A. You can use vacuum distillation for your plating wastes coupled with IX and other technologies you can recover and reuse much of your electroless nickel plating process chemistry
David Delasanta- Worcester, Masssachusetts
July 28, 2008
Q. Hello, I'm in the process of starting an electroless nickel plant. The last plant I worked in had very dubious quality standards, and little or no waste treatment, so I have no idea what waste treatment involves.
I have been reading up on the net and have found that most methods of effluent treatment are only for heavy metals.There is no mentions of how to treat phosphates and other such no metallic biproducts. I would be most grateful to any one who can suggest a method or atleast point me in the right direction.
Thank you for your time.
Ravi Patel
to be plating shop owner - Gujarat, India
June 2, 2008
Try plating out as much of the nickel as possible, electrolytically. Then, adjust the pH to 8.5 - 9, and drop the rest of the Ni with sodium sulfide, DTC, or a similar precipitant. Plain hydroxide precipitation is quite incapable of removing the metal from EN solutions or rinses, because of the complexants used in formulating them.
Dave Wichern
Consultant - The Bronx, New York
June 5, 2008
Would it be possible to reuse some of the nickel present in the effluent? how effective are methods like electrowinning and electrodialysis.
Ravi Patel- Anand, Gujarat, India
June 7, 2008
On Precipitating Nickel from Wastewater
I have a problem regarding precipitating Nickel from wastewater due to the presence of ammonia. Is there any way I can remove ammonia without having to add too much of hazardous chemicals such as strong bases and the like so that I can precipitate nickel?
Joe Nerystudent limnologist - Quezon City, Philippines
September 22, 2008
September 25, 2008
Hi, Joe. ammonia is easily boiled off, but this may change a water pollution problem into an air pollution problem :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Use a sulfur based precipitant, at a pH of something like 8. At that value, enough of the ammonia will be present as NH4+, instead of NH3, which is the active complexant.
Dave Wichern
Consultant - The Bronx, New York
First of two simultaneous responses --
Thank you for the answers! :p But actually I was looking for environment-friendly precipitants of Nickel. I have to keep the pH to about 6.5-9 and I should not add potentially hazardous components. It's really hard to precipitate nickel and copper when there's ammonia.
Joe Nerystudent limnologist - Quezon City, Philippines
September 26, 2008
October 5, 2008
Second of two simultaneous responses --
Joe, you can use a precipitant product at a neutral pH to precipitate out the nickel. There are many precipitants available, but because the ammonia is a very tough complexing agent I would recommend a DTC (dimethyldithio carbamate or a diethyldithio carbamate)Either of these two should work, but the diethyl is much more effective on nickel complexes although significantly more expensive than the regular DTC.
The nickel should precipitate out as a nickel carbamate (or whatever precipitant it is that you use), but the ammonia will still be in solution. You have not done anything to get rid of the ammonia.
- Greenville, South Carolina
October 6, 2008
Sorry! Finishing.com is temporarily Read-Only.
Ted Mooney is retiring but I have several offers to take it over.
We're working hard to make sure we find it the best new home.