Graphene Oxide Membranes for Critical Raw Materials Recovery and Water Purification: From Cleanroom Wastewater to Fluorite

The European Union has identified fluorite (CaF 2 ) as a critical raw material (CRM) due to its economic importance, negligible recycling, and high import dependency. This study investigates a functionalized graphene oxide (fGO) membrane for purifying wastewater containing dissolved fluorides below the solubility limit of CaF 2 and the subsequent CRM recovery. While the fundamental interaction is known in batch systems, closed‐loop recovery processes using this kind of membrane remain unexplored. Utilizing fGO synthesized via a scalable, green approach, we transition beyond conventional adsorption to a dynamic membrane‐stripping cycle. Comprehensive material characterization is provided. The fGO membranes were tested in a real‐case scenario using cleanroom facility wastewater. Fluorine concentration was successfully reduced from 21 down to 1.4 mg L −1 , meeting the EU/USA discharge and drinking water standards. High‐purity CaF 2 powder was recovered. This work establishes a viable, non‐conventional membrane‐based approach for waste valorization, advancing circular economy principles in the semiconductor and microelectronics industries by transforming a hazardous waste into a strategic resource.