Title : Electrorecovery of high purity Cu from the electrotronic wastewater
Abstract:
Due to the simple equipment and uses of minimal chemicals of electrodeposition, the high purity copper recovered from the wastewater containing copper ions is investigated by the cathodic depostion. Using Cu plate as the working electrode, the onset potential for cathodic reduction of 5000 ppm Cu2+ is 0.07 V (vs. Ag/AgCl/3 M NaCl(aq)). The electrodeposition of Cu2+ is located in the kinetic, mixed and mass transfer control regions for the potential ranges of 0.07 ~ 0.04, 0.04 ~ -0.15 and less than -0.15 V, respectively. Increasing the current density from 0.375 to 1.0 mA cm-2 the current efficiency for electrorecovery of cupper in 5000 ppm Cu2+ stagnant aqueous solution is increased from 87.17 to 96.46 %. Based on the SEM images, a compact Cu deposit composed with 1 ~ 5 ?m particles is obtained from the cathodic deposition of 5000 ppm Cu2+ in the 0.1 M H2SO4 aqueous solution with the current density of 0.5 mA cm-2. The surface morphologies and the XRD spectra of Cu deposit is not affected by the presence of 20 ppm Ni2+ and 10 ppm Zn2+ in the aqueous solution. In the presence of 20 ppm Ni2+ and 10 ppm Zn2+, the high purity cupper deposit can be electrorecovered, because Ni and Zn are undetectable in ICP analysis.
Audience Take Away:
- Using Cu and graphite plates as working and counter electrodes, Cu ion can be reduced for potential less than 0 V based on the results from CV and polarization curve experiments. The electrorecovery of Cu ion from 0.1 M H2SO4 aqueous solution is controlled by the kinetic of electrode surface, mixed kinetic and mass transfer control and mass transfer from bulk solution to electrode surface for the potentials of 0 ~ -0.1, -0.1 ~ -0.3 and less than -0.3 V, respectively.
- When the electrorecovery of Cu ion is set at kinetic controlled region, increasing the current density from 0.375 to 1.0 mA cm-2 the current efficiency increases from 87.17 to 96.46 %.
- The current efficiency is slightly decreased for the solution agitated by introducing N2 gas into the solution.
- A compact Cu deposit composed with 1 ~ 5 ?m particles is found in the SEM images for recovering Cu2+ from the solution.
- Based on the XRD, EDS and ICP-OES analysis, the co-deposited Ni and Zn is not found when the electrorecovery of Cu2+ from the solution in the presence of 20 ppm Ni2+ and 10 ppm Zn2+.
