Polyelectrolyte-Enhanced Ultrafiltration of Copper from a Waste Stream

Abstract

The concentration of copper in a simulated wastewater was successfully reduced from 100 ppm to less than 1 ppm by polyelectrolyte-enhanced ultrafiltration. In polyelectrolyte-enhanced ultrafiltration, copper is ionically bound to the polymeric chain of an anionic polyelectrolyte. Ultrafiltration then filters out this large copperpolyelectrolyte complex. At the same polyelectrolyte-to-copper ratio in the 1:1 to 3:1 (weight basis) range and a feed temperature in the 15 to 40°C range, sodium carboxymethyl cellulose was more efficient for copper removal and exhibited higher flux values than sodium polystyrene sulfonate. The experiments showed that transmembrane pressure has a minimal effect on removal of copper whereas the polyelectrolyte-to-copper ratio has considerable influence. It was also seen that the permeate copper concentration decreased with a decrease in feed temperature. Decreasing the feed temperature also caused a reduction in flux because of an increase in the viscosity of the feed solution.