An improvement for enrichment and purification of germanium using carbonyl acid extractants

Germanium is a strategic metal that is challenging to enrich and purify without any side effects, especially stability and selectivity. Here the role of carbonyl acid in selective separation of germanium from complex industrial liquids was highlighted. Integrating theoretical and experimental analyses, carbonyl acids exhibit strong binding ability and high selectivity to germanium was demonstrated. The first set of carbonyl acid extractant (CAE) for germanium extraction was successfully synthesized with a solubility of less than 50 mg/L at pH = 0. The process analysis exhibits the extraction rate of germanium in a single stage by CAEs exceeds 99.9 %, while the separation factor surpasses 10³, far beyond 10¹ of hydroxamic acids. Furthermore, the stripping rate for germanium in a single stage exceeds 83.0 %, with germanium accounting for over 99.9 % of the total metal content in the stripping solution. The CAE extraction process is straightforward and characterized by high germanium separation efficiency. The development of CAE not only realises the stable, green, low-carbon, and high-efficiency purification of germanium, but also the universality and inspiration of CAE make it highly significant and valuable in both theoretical research and practical applications.