COPPER(II) REMOVAL FROM AQUEOUS-SOLUTIONS BY CHELATION IN SUPERCRITICAL CARBON-DIOXIDE USING FLUORINATED BETA-DIKETONES

Copper removal from aqueous solutions by chelation in supercritical ca rbon dioxide was investigated. The chelating agents were 1,1,1-trifluo roacetylacetone (TFA) and dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octan edione (FOD). Extraction efficiencies were determined for a single equ ilibrium stage in the temperature range 308-328 K and the pressure ran ge 9.9-24.0 MPa and ranged from 4% to 84%. The extraction efficiencies increased with increasing the initial amount of chelating agent and w ith decreasing the initial copper concentration. No significant change s in extraction efficiencies were observed with temperature and pressu re at a fixed initial amount of chelating agent. A thermodynamic model based on combined reaction and phase equilibria was also developed fo r prediction of extraction efficiencies.