Effect of background electrolytes and pH on electroflotation efficiency for heavy metal removal

The growing issue of heavy metal contamination in water threatens ecosystems and human health due to their toxicity, bioaccumulation, and carcinogenicity. This study examines how background electrolytes and pH affect the efficiency of electroflotation in removing heavy metals from wastewater. The highest removal efficiency (>99%) was observed at pH 10.0 in chloride-containing electrolytes. Sulfate, nitrate, and carbonate anions slightly reduced efficiency (by 1–3%), while phosphate anions nearly halted the process due to less soluble compounds and reduced bubble adhesion. Electroflotation of metal mixtures (Cu-Ni, Ni-Zn, Cu-Zn) with organic additives showed varied results: solvents significantly improved Cu-Ni removal, while purifying liquids reduced it. For Ni-Zn, penetrants boosted efficiency by 300%. In the Cu-Zn system, varnish and purifying liquids increased removal by 200%, but penetrants decreased it by 400%. The resulting metal-rich sludge is suitable for further processing, and treated water can be reused in industrial cycles.