How to remove nickel ions from a solution?

Have you tried membrane separation technology?

Try adding alkali; it will produce nickel hydroxide precipitate. Ammonia can also be added to form a precipitate

It depends on the circumstances. If it contains only sodium ions and no other cations, it can be concentrated using reverse osmosis or nanofiltration membrane processes. However, **the control on nickel ion emissions is very strict, with requirements generally set at below 0.5 mg/L. Therefore, the permeate from reverse osmosis or nanofiltration still requires EDI or chelating resin ion exchange to meet the standards. If it contains nickel ions, as well as cations with high solubility in hydroxides such as sodium and potassium ions, and no ammonium ions, then nickel hydroxide can certainly be precipitated by using sodium hydroxide. A pH of around 8.7–9.0 is generally required for the nickel ions to precipitate sufficiently. If it contains calcium, magnesium, and iron ions but no ammonium ions, the situation becomes more complex; whether sodium hydroxide or calcium hydroxide is added, the precipitate may be a mixture. However, the situation becomes complicated if the aqueous solution contains nickel ions along with ammonium ions or ammonia. Under alkaline conditions, free ammonia forms various complexes with nickel ions, which in turn prevents the nickel ions from precipitating and even causes nickel oxide to dissolve again. Please check out my post on the theoretical forum: Interesting chemical engineering exam questions – 4: Why do precipitates form and then disappear repeatedly when an alkali is added to some salt solutions? The situation is also more complicated in the presence of cyanides. So, you need to provide more detailed information – what ions or compounds are present in the wastewater or solution, and what is the concentration of nickel ions? How much are you planning to remove? A large proportion of the wastewater treated by membrane methods at present is wastewater that contains both ammonia nitrogen and heavy metals. This is the difficulty, as well as the technical barrier.

How much water is there? What is the pH value? Are there any other ions?

1. Potentially present high-valent nickel ions reduced by sodium bisulfite； 2. Sodium sulfide precipitates nickel ions.

Nickel can be removed and recovered using chelating resins~

No, it’s just a drug for which renny nickel is used as a catalyst. This involves an organic reaction, and the final step is acid-catalyzed hydrogenation; the nickel catalyst dissolves into the product. How can one remove the nickel ions from the product?

Trace amounts of water, with organic solvents used as reaction solvents. It’s just a catalyst in the form of nickel ions; later on, we only added a salt, acid, and ammonia water

The presence of nickel ions is due to nickel being dissolved using salts and acids during the reaction process; the substances we produce dissolve under acidic conditions but not under alkaline conditions. I would like to ask how to remove nickel ions. The main issue is that the residues produced so far do not meet the standards; it is suspected that nickel ions and their complexes are the cause. Or in other words, the aluminum ions in Reney nickel

When performing catalytic hydrogenation without adding salt or acid, you can remove the nickel catalyst completely before adding salt or acid