Nature’s nanocavity can save billions of dollars in lost metal from old electronics

The smartphones and laptops we discarded contain billions of dollars worth of key metals, namely cobalt, nickel and lithium, that can power our digital lives.

However, the current recycling method recovers only 15% of these valuable materials, leaving $7 billion in metals each year. Now, researchers at the University of Pittsburgh have found that naturally occurring proteins can selectively draw these metals from e-waste using a milder process than traditional stimulating chemical extraction.

The protein is called ferritin, like a microscopic cage, with an appetite for a specific metal. When added to a solution containing mixed metals that recycle electrons, the ferritin nanocontent concentrates cobalt and nickel, while largely neglecting lithium – this selectivity can revolutionize how we recover critical materials from electronic waste.

Metal magnets of nature

Ferritin evolved to safely store iron in living cells, assembling itself into a hollow spherical structure about 10 nanometers wide. But Meng Wang, assistant professor of environmental and civil engineering at Swanson Institute of Engineering in Pittsburgh, wondered if these natural nano contents might also work for other metals.

His team’s experiments revealed significant selectivity of ferritin. The protein nano content concentrates cobalt ions to levels thousands of times in its cavity. “That’s why selectivity is key,” Wang explained. “You want the protein to selectively separate or restore metals.”

The inner surface of the ferritin nanometers has dense negative charges, which can attract positively charged metal ions through electrostatic forces. But the protein showed a clear preference: cobalt gained the strongest appeal, followed by nickel, while lithium was barely registered.

Cleaning Chemistry

Current metal recycling relies on irritating solvents and high-energy processes that stimulate hazardous waste. Ferritin operates under what Wang calls “benign, neutral conditions” without the need for dangerous chemicals.

The metal concentration capability of this protein can achieve a clever two-step process. First, ferritin selectively captures the target metal from the mixed solution. Then, since the trapped metals reach such high concentrations in the nanometer range, they can be precipitated as pure solid compounds and have simple additions such as sodium bicarbonate.

Key performance indicators of the study:

• Cobalt recovers to reach 95% purity from cobalt lithium mixture
• Each nanometer amount may capture about 7,162 cobalt ions
• Metal separation occurs within minutes, not hours
• The process works at room temperature under neutral pH conditions

Charge factor

The selective part of the protein is derived from the charge. Cobalt and nickel ions carry +2 charges, while lithium only has +1, which makes the first two more attractive inside the negative charges to ferritin. But the separate fees don’t explain everything.

“Even if both cobalt and nickel are +2, we still observe a significant adsorption difference between the two,” Wang noted. “The part we don’t understand yet.” This mystery can have the key to engineering a more selective nanorange.

Wang envisions a future system with three tanks: one that captures nickel using modified ferritin and the other for cobalt, leaving behind a pure lithium solution ready for further processing. This accuracy will greatly improve recovery rates while reducing environmental impacts.

From the laboratory to reality

The research focuses on metals from lithium-ion batteries, but the principle can be extended to other electronic components. In the United States alone, the global generation of e-waste is close to 7 million tons per year, and even a modest increase in recovery rates could release billions of materials.

The next challenge involves understanding exactly why ferritin prefers certain metals over others. “If recyclable, critical metals can be used to supplement the supply chain.” In the future, discarded electronics become the future of the materials needed to build their replacement.

For now, ferritin provides evidence that sometimes the most complex solutions are wrapped in nature’s packages – the same-sized cages that have perfected the metal handling capacity for millions of years.

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