Disposal of Electroless Nickel(2000)
I am trying to dispose of Electroless Nickel in the environmentally friendliest manner possible. Plating out the metal does not seem to work. Has anybody done it? What did you have to add to break the complexes? Has anybody got a better idea as to how to dispose of it.
Thanks for your help!
Chemserve Trio - Durban, South Africa
Here in the U.S. this is not a big problem anymore because many of the vendors take the solutions back for disposal or recycling when exhausted. But to plate out the nickel, what you need is 0000 steel wool [linked by editor to product info at Rockler] because of its very large surface area.
Ted Mooney, P.E.
Pine Beach, New Jersey
First of two simultaneous responses-- (2000)
Assuming that it is a normal EN, elevate the temp to the top limit, put in some steel wool and raise the pH with NH4OH to about 0.5 ph higher than the recommended top limit. The bath will literally self destruct. It will plate like mad on the tank also, so have an old junker tank to do it in.
I never did it, but I would guess that a SS cathode, bagged carbon anode, top of the recommended temp and pH, great agitation and about 6 volts should give a very rapid plate on the cathode. If it was passivated, you should be able to peel the nickel plate off.James Watts
- Navarre, Florida
Second of two simultaneous responses-- (2000)
As Ted said, steel wool is a good process to decompose an EN bath ,just be very carefull as you will get a lot of hydrogen and it might explode. Make sure that you are able to control the EN decomposition.
chemical process supplier
Plating out spent Electroless Ni on steel wool will only work while there is an excess of reducing agent, so you may need to add additional hypophosphite to get a low residual nickel concentration.
Sodium borohydride has also been used for this purpose, but still results in 10-30 mg/l of soluble and difficult to treat Nickel.
Electrowinning is difficult unless you have an extremely high surface area cell, heat and pH control.
Alot of people use the steel wool method and treat the residual with carbamates.
Good Luck!Lyle Kirman
consultant - Cleveland, Ohio
Can the process of plating out the nickel from an EN bath using SS anodes, etc. (as described by James Watts) be also used to plate out nickel from a Bright Watts formula? How clean would the resulting liquid be, and what else would be required to render the solution harmless?Ian Wallace
I need a little help. Having exhausted chemical precipitation of electroless nickel, I'm conducting a little R&D on plating out the nickel.
I took a 1,000 milliliter beaker of electroless nickel and dropped in some steel wool. I raised the pH to 9.0 with a strong spent ammonia solution. I did not seen an any visible plating out of nickel. I then added some sodium hypophosphite solution in varying concentrations to assist in the reduction of the nickel. I am not noticing any plating out of the nickel. Any further guidance your readers can offer would be appreciated.Jim Sullivan
- Paterson, New Jersey
I use the steelwool process and add some extra hypophosphite, then plate out at operating temp. It usually plates out down to 15-30ppm Ni. Then I remove to batch tank ,Raise Ph to 9.0 ( min.) I then add 800ml of 30% hydrogen peroxide to oxidize excess hypo , mix for 2 hrs. add DTC to precipitate the rest. I get .5-1.0ppm Ni. With out the peroxide I could only get 5-10ppm Ni. It would also efect the conversion of Cr+6 in my flowthru system when running the clean water off of the top of the batch thru the system for discharge. I have 200 gal EN tanks I have had good success with this process , you will have to play around with the amount of peroxide to use so you don't get floating of your sludge when discharging to your system. let me know how this works for you...EKEric King
metal finishing - Tualatin, Oregon, USA
Forgot to add that I use caustic soda beads to raise ph NOT ammonium hyroxide...MAKES BIG DIFFERENCE EKEric King
metal finishing - Tualatin, Oregon, USA
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