Selective recovery of metals of technological and environmental importance from complex aqueous matrices of industrial origin

Global energy consumption, a critical driver of economic growth, reached 620 exajoules in 2024, with fossil fuels contributing 81.29% of the total, according to BP's "Statistical Review of World Energy." However, the reliance on fossil fuels has significantly exacerbated CO2 emissions, intensifying global warming and its associated environmental challenges, including severe weather events, rising sea levels, and ecosystem disruptions. In response, nations have prioritized climate action, with 195 countries committing to the Paris Agreement's goal of limiting global warming to 2°C above pre industrial levels. To address these challenges, advancements in e-mobility and clean energy technologies have emerged as pivotal solutions. The adoption of EVs has accelerated due to declining battery costs. However, the environmental benefits of e-mobility depend on the sustainability of electricity sources, EV manufacturing processes, and battery disposal. Moreover, the increasing demand for CRMs like cobalt and lithium, essential for LIBs, highlights supply chain vulnerabilities. Over half of the world’s cobalt is mined in the Democratic Republic of Congo, raising ethical and environmental concerns, while lithium reserves are concentrated in regions like the "lithium triangle" of South America. REEs, crucial for renewable energy, advanced electronics, and national security, face similar supply challenges. China dominates global REE production and processing, prompting diversification efforts by other nations. The recycling of materials is a very important topic, especially for CRMs, as it promotes sustainability by reducing the environmental impact of raw material mining, conserving finite resources, and ensuring a steady supply for technological and industrial applications. Ionic Liquids (ILs) are known for their customizable properties, have shown promise in the extraction and recycling of CRMs. In this thesis, it will be demonstrated that phosphonium based IL [P66614][Dec] is able to efficiently and selectively recover, Co(II) from concentrated HCl solutions. However, the high acid concentrations required for these processes pose environmental concerns, emphasizing the need for greener alternatives. Environmentally friendly leaching agents, such as acetic and citric acids, offer potential alternatives but face limitations in metal recovery and selectivity. HCl-based leaching processes, while less sustainable, demonstrate superior separation of transition metals from REEs, followed by precipitation of metals as hydroxides and oxalates. Further research is needed to improve the kinetics, reduce acid dependency, and enhance REE separation processes.