Microbe Encapsulation for Selective Rare-Earth Recovery from Electronic Waste Leachates

Abstract

Rare earth elements (REEs) are indispensable components of many green technologies and of increasing demand globally. However, refining REEs from raw materials using current technologies is energy intensive and enviromentally damaging. Here, we describe the development of a novel biosorption-based flow-through process for selective REE recovery from electronic wastes. An Escherichia coli strain previously engineered to display lanthanide-binding tags on the cell surface was encapsulated within a permeable polyethylene glycol diacrylate (PEGDA) hydrogel at high cell density using an emulsion process. This microbe bead adsorbent contained a homogenous distribution of cells whose surface functional groups remained accessible and effective for selective REE adsorption. The microbe beads were packed into fixed-bed columns, and breakthrough experiments demonstrated effective Nd extraction at a flow velocity of up to 3 m/h at pH 4–6. The microbe bead columns were stable for reuse, retaining 85% of the adsorption capacity after nine consecutive adsorption/desorption cycles. A bench-scale breakthrough curve with a NdFeB magnet leachate revealed a two-bed volume increase in breakthrough points for REEs compared to non-REE impurities and 97% REE purity of the adsorbed fraction upon breakthrough. These results demonstrate that the microbe beads are capable of repeatedly separating REEs from non-REE metals in a column system, paving the way for a biomass-based REE recovery system.

U.S. Industrial and Commercial Motor System Market Assessment Report Volume 2: Advanced Motors and Drives Supply Chain Review

“…The European Union (EU) funded a variety of efforts around rare-earth element recycling, including a multifaceted Fraunhofer Institutes project ("Substitution, Efficiency, Recycling: Fraunhofer IMWS" 2018). The U.S. DOE funded efforts at universities and national labs (Brewer et al 2019). While challenging, these pathways are technically feasible and could serve as a path toward increased recycling above current levels (near zero) "if recycling became mandated or very high prices of rare-earth elements made recycling [economical]" (Goonan 2011).…”

Retrospective on Recent DOE-Funded Studies Concerning the Extraction of Rare Earth Elements & Lithium from Geothermal Brines (Final Report)

“…The objectives of the project were to genetically modify E. coli to express LBT on cell surfaces and demonstrate that LBT-modified cells could bind REE. LBT-modified bacteria were then imbedded in a solid support resin and used in flow-through ion-exchange columns to demonstrate the use of REE-binding bacteria as ion-exchange sorbents (Brewer et al, 2019b;Jiao, 2020). In addition, the project developed a simple cell surface complexation model to simulate REE separation under column flow (Chang et al, 2020;Jiao, 2020).…”

“…LBT-engineered E. coli were encapsulated in beads and tested for REE sorption on both batch and flow-through experiments (Chang et al, 2020;Jiao, 2020). Bacteria were encapsulated within a permeable polyethylene glycol diacrylate (PEGDA) hydrogel at high cell density, using an emulsion process (Brewer et al, 2019b;Jiao, 2020). Cell densities and PEGDA concentrations were varied to determine the optimal microbe bead formulation (Jiao, 2020).…”

Recovery of rare earth elements by nanometric CeO2 embedded into electrospun PVA nanofibres

“…7,18,23,24 The nal step of the process features the separation, purication, and concentration of REEs by using solvent extraction, 25,26 chemical precipitation, 27,28 ion exchange, 29 electrochemical methods 30 or biosorption. 31 Among these methods, adsorption emerged as a simple, cost-effective, non-toxic, waste-free approach to separate and concentrate REEs. 32 A variety of adsorptive materials have been used, such as polymers, 51 clays, 33 MOFs, 34 carbonbased materials, 35,36 natural-derived bres 37,38 and metal oxide particles.…”