Removal of Ni(II) in aqueous solutions by foam fractionation

The electroplating industry uses a lot of water in many of its processes. Because of the rapidly decreasing availability of water in many areas and the need of pollution control, efficient and economical methods for treating electroplating wastewater are urgently studied. Foam fractionation was used to remove divalent ions Ni(II) from its aqueous solutions with two surfactants. The optimum values influencing the separation effect of these ions were studied. The optimum separation conditions for Ni(II) were initial Ni(II) concentration 5mg/L, liquid loading volume 200mL, gas velocity 70mL/min, the initial pH and temperature 30 degrees C, providing an enrichment ratio 12, and a recovery 98%. Enrichment ratio was found to increase with an increase in the feed flow rate. With a concentration decrease in the bulk solution, the separation factor was found to increase. The study indicates the foam separation is a feasible and promising way for treating electroplating effluents.