Removal of Cu²⁺ and Ni²⁺ Ions from Industrial Wastewater Using a Hierarchically Structured Carbon Film Synthesized In Situ in a Chloride Melt

The removal of nickel and copper ions from 0.1 M nickel and copper sulfate solutions in a neutral medium in the temperature range 20–80°C by hierarchically structured carbon films (HSCFs) synthesized on the surface of molten magnesium in a chloride melt is investigated. An increase in the holding temperature of HSCFs in nickel and copper sulfate solutions to 80°C is shown to increase in the extraction of nickel and copper from solutions by 3–3.5 times. The products of holding HSCFs in nickel and copper salt solutions are studied by scanning electron microscopy, electron probe microanalysis, X-ray photoelectron spectroscopy, and Raman spectroscopy. Copper is shown to be adsorbed by the HSCF surface without the formation of solid interaction products in the form of stable aquacomplexes of divalent copper ions, and holding of HSCF in a nickel sulfate solution leads to the formation of fine nickel hydroxide crystals on the HSCF surface. HSCF can be recommended as an effective carbon filter for purification of industrial wastewater from divalent nickel and copper ions in a neutral medium.