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Tiny Robots Take on Heavy Metals in Wastewater

One of the challenges facing developing nations is balancing industrialization and environmental responsibility. There's enormous pressure from developed nations for these countries to be mindful of pollutants and toxins. Many of those pollutants, like heavy metals, end up in industrial wastewater. Manufacturing facilities that make batteries and electronics produce this type of water, which can pollute ecosystems or even enter the general water supply. Fortunately, a collection of scientists have a potential solution: tiny robots.

These robots are smaller than the width of a human hair and incredibly simple with no moving parts. Each is a tube with three layers. The outermost layer is graphene oxide, which can adsorb — or hold on to — lead in industrial wastewater.

The middle layer of the tube is nickel, which is ferromagnetic. This allows the scientists to move the tiny robots through a magnetic field. The researchers use this method when it's time to collect all the microbots.

The innermost layer of the robot is made of platinum. This becomes the motor for the microbots — you just need to add hydrogen peroxide to the wastewater. The platinum decomposes the hydrogen peroxide into water and oxygen. The oxygen then forms into tiny bubbles that pop out the back of the tube and create propulsion. This causes the tiny robots to “swim” in wastewater, soaking up lead.

After about an hour, the microbots can remove 95 percent of the lead ions. Once scientists remove the microbots from the wastewater, they can place the robots inside a special acidic solution. This strips the adsorbed lead ions, which can be reclaimed and used in other applications.

The scientists hope to extend the usefulness of the microbots by increasing the number of heavy metals they can adsorb, such as arsenic or mercury. They also want to improve the manufacturing process to lower the cost of production, making the robots more easily available.

With this solution, developing nations could continue to industrialize, improving local economies and the welfare of citizens. At the same time, they can treat wastewater to prevent it from polluting the environment and creating a health hazard. On top of that, they will be able to put heavy metals to other uses, increasing the overall efficiency of operations. We may owe it all to tiny, simple robots.

Watch the video above to learn more about these waste-removing robots.

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