Recovery of germanium from waste solar panels using ion-exchange membrane and solvent extraction

• Germanium was recovered from the wasted solar panel against silicate.
• Concentration of germanium was conducted with catechol complexation, membrane permeation and solvent extraction.
• The proposed system enhanced germanium purity at 39 times.

Germanium was recovered from the waste solar panels using the processes of selective catechol complexation, membrane adsorption and elution, and solvent extraction. Because the solar panels included a high concentration of germanium, the key technique used was high selectivity against silicate ion using hydrometallurgy. Due to the selective complexation of germanium ions with catechol, the operation at low pH enhanced the selectivity. 0.1 M hydrochloric acid was used to elute the germanium ions. To remove the catechol from the germanium containing solution, solvent extraction using trioctylphosphine oxide was performed, demonstrating that 81% of catechol was removed. Compared with the initial percentage of germanium to silica, the concentration of silicate was 39 times higher in the germanium-concentrated solution, indicating that the proposed sequential process was very a powerful technique for the recovering germanium.