What removal method is applicable for nickel in water treatment?

The method of removal for nickel in water treatment that is applicable is precipitation or cation exchange. This approach is effective because nickel ions can be precipitated out of solution by adding specific reagents that form insoluble compounds with nickel. Common precipitating agents include sodium sulfide or lime, which react with nickel ions and form nickel sulfide or nickel hydroxide precipitates, respectively. These precipitates can then be separated from the water through processes like sedimentation and filtration.

Cation exchange is another effective technique for removing nickel from water. In this process, nickel ions in the water are exchanged for other cations, commonly sodium or hydrogen ions, which are held on a resin. This method is particularly useful for water with lower concentrations of nickel and can achieve very low levels of nickel in the final treated water.

Membrane filtration can be useful in certain contexts for separating contaminants based on size but is not the primary method for effective removal of dissolved nickel from water. Ozonation is more suited for oxidizing organic contaminants and may not specifically target nickel ions. Activated carbon adsorption can effectively remove various organic compounds and some metals to a lesser extent, but it typically lacks the specificity and efficiency that precipitation and cation exchange methods provide for nickel removal.