WASTE TREATMENT OF TWO ELECTROPLATING SOLUTIONS OF CU AND ZN BY MIXING AND PRECIPITATION

Abstract

Our studies suggest a cheap and simple way to decontaminate two ligand-containing rinsing waters of metal finishing. Both copper diphosphate and acidic zinc ammonium containing rinsing wastewater may be decontaminated by mixing, which results in precipitation of solid solution of potassium, ammonium, copper, and zinc diphosphates. About 80–99.5% of environmentally hazardous substances, viz. zinc, copper, and diphosphate are removed from the solution. Chemical and phase composition of the precipitate was examined. We have also suggested several possible ways to utilize the precipitate. This way of decontamination requires no expensive reagents since only a small amount of H₂SO₄ is required for pH adjustment.

Keywords:

• Diphosphate
• Copper
• Zinc
• Ammonium
• Electroplating
• Rinsing water
• Decontamination
• Precipitation
• X-ray diffraction
• Phase composition

ACKNOWLEDGMENTS

The authors thank Lithuanian State Science and Studies Foundation for the financial support.