Separation of Cu(II) by foam fractionation

Abstract

An apparatus was constructed and used to investigate the separation of copper (II) from very dilute solutions of cupric sulfate by foam fractionation. Two agents, SARKOSYL NL-30 and AEROSOL 22 were used, with emphasis on the latter. Both are commercial purity amides: SARKOSYL NL-30 is lauroyl-N-methyl, N-acetic acid, sodium salt while AEROSOL 22 is tetrasodium N-octadecyl, N-(l,2-dicarboxyethyl) sulfosuccinamate.

Spectrophotometric methods using ^-quinolinol-5-sulfonic, acid (HQSA) and cyclohexene-l, 2-dinitrilotetraacetic acid (CDTA) were investigated and used to analyze for one to two hundred mg/l Cu(II). HQSA is sensitive to an excess of AEROSOL 22, while CDTA is not, due to the much larger instability constant of CuCDTA (pK « 21.30 compared to 11.53 for the HQSA complex). A reasonably large instability constant for Cu-AEROSOL 22 is indicated.

Good recoveries of copper were obtained. It was found that SARKOSYL NL-30 precipitates copper from solutions containing as little as 5 mg/l, while cupric AEROSOL 22 was almost completely miscible with water. The latter was precipitated from 1.0 M KCl containing 12 mg/l copper, however.