ETH Zurich's Breakthrough: Gold from Electronic WasteSustainable Gold Recovery Revolutionizes E-Waste

Professor Raffaele Mezzenga and his team at ETH Zurich have pioneered a method reminiscent of alchemy, transforming electronic waste into precious gold by employing a byproduct from cheese production.

The method addresses the extraction of valuable metals such as gold from electronic waste, a process traditionally marred by high costs and environmental hazards due to the use of toxic chemicals and substantial energy.

Introducing an innovative and sustainable technique, Mezzenga's group uses a sponge made from protein matrix to efficiently and eco-friendly extract gold, significantly minimizing the environmental footprint.

Efficient Gold Recovery Using Protein Matrix Sponge

The groundbreaking sponge is produced by denaturing whey proteins under specific conditions, resulting in a gel of protein nanofibrils. Upon drying, this gel forms a sponge with a remarkable affinity for gold ions present in solutions of dissolved electronic components.

The procedure initiates with dismantling old computer motherboards to retrieve metal components. These components are dissolved in an acid bath to ionize the metals, preparing them for absorption by the protein sponge.

This method stands out for its selective absorption of gold ions. Despite the sponge's capacity to bind various metals, gold ions exhibit a significantly higher affinity, a fact substantiated in their research published in Advanced Materials.

Subsequent heating of the sponge laden with gold ions facilitates their reduction back to metal, culminating in the production of a gold nugget. From a batch of 20 motherboards, the team successfully recovered a 450-milligram nugget of gold, boasting a purity of 91% or 22 carats.

Path to Commercialization and Beyond

The economic feasibility of this method is underscored by the low material and energy costs relative to the value of recoverable gold. The team is now focused on advancing this technology for commercial application, exploring additional sources of gold beyond electronic waste.

Future endeavors include examining alternative sources of gold, such as industrial waste from microchip production or gold-plating operations, and investigating other protein-rich byproducts for sponge manufacturing, aiming to further enhance the sustainability of their method.

Professor Mezzenga expresses enthusiasm for the project's sustainability, highlighting the dual waste-to-resource transformation. "Utilizing a byproduct of the food industry to reclaim gold from electronic waste not only addresses waste management challenges but does so with remarkable environmental stewardship," he notes, showcasing the project's alignment with principles of sustainability and resource recovery.

David Lamy
David Lamy Author
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