Ion Imprinted Polymers for the Extraction and Recovery of Rare Earth Elements from Geothermal Fluids

Innumerable technological advancements have been spurred by the unique and irreplaceable properties of the rare earth elements REE). This widespread application has made the REE absolute necessities for sustaining healthy technological, scientific, and economic growth. Rare earth elements are used in many industrial sectors, including green energy, aerospace, computing, lighting, automobile, and chemical catalysis. There are currently no viable alternatives to the REE with equivalent performance in applications ranging from computers and displays, to renewable energy generation and energy storage, driving significant global demand for these elements. Mining, which is expensive and laborious with a significant environmental burden, is currently the only way of extracting and harvesting these elements. Additionally, domestic sources of REE cannot keep pace with the increasing demand of U.S. manufacturing. Similarly, global demand outstrips production, and previously mined stocks currently cover the difference. The U.S. has relied on imports for the past 15 years, and China, the worlds leading source of REE, has indicated partial control of exports, or punitive tariffs, in the near future. Extracting and recovering REE from geothermal fluids is a viable alternative source for these elements. An environmentally-benign capture and recovery technology is proposed, which will: benefit the geothermal electricity industry by creating new revenue streams to reduce the overall cost of electricity production; diversify domestic REE sources; and create a new market, that of REE harvesting from different types of water. The proposed technology entails the use of a series of selective and reusable polymers for the extraction of each, individual REE. These novel materials are based on inexpensive polymers, selectively imprinted for capture of individual elements, and represents a new approach to rare earth ion separation from aqueous media. The technology leverages the availability of geothermal fluids and the naturally occurring, dissolved REE loads therein to produce REE in significant quantities. The proposed technology circumvents energy-intensive mining and separation of the REE from ores by capturing the dissolved REE ions from aqueous geothermal streams and recovering a pure product in an automated, modular system. Phase I will enable development of the technology by optimizing polymer production, expanding synthesis of selective polymers to critical materials of national interest, testing the performance of those polymers under a range of conditions, and conceptualizing system designs for Phase II. In the next phase, model systems will be built, and the prototype will be tested in pilot-scale to demonstrate feasibility beyond the lab. The proposed technology will create a new revenue stream for geothermal power plants and will diversify domestic critical material resources, which is in line with U.S. DOE goals.