Removal and Recovery of Fluoborates and Metal Ions from Electroplating Wastewater

摘要

Two separate methods for the treatment of fluoborate wastewater from the electroplating of tin, solder, copper and nickel stripping were investigated. These involved specific ion flotation and electrodialysis to treat dilute waste streams from single tank rinsing or concentrated wastewaters from counter-current or series rinsing, respectively. The fluoborate ion was found to bind with an alkylamine acetate by displacement of the acetate group and can be removed from dilute waste stream either by air flotation or ultrafiltration. Ultrafiltration provided greater rates of removal than air flotation. The surfactant can be recovered for reuse by electrolysis. A new high density low porosity graphite anode that is resistant to the corrosive properties of fluoboric acid electrolyte was developed for electrodialysis treatment of the tin, solder and copper fluoborate containing wastewaters. Fluoboric acid electrolyte was used to prevent contamination of the products with sulfate ion. Recoveries of the metal ions were in excess of 90 percent with the stannous ion being preferentially concentrated in the product and with the stannic ion remaining preferentially in the feed. In general, recoveries of the fluoborate ions were in excess of 80 percent.