Gold is recovered from the ore after a process of crushing and screening. Photo: IC

Chinese scientists have developed a universal green, high-efficiency membrane separation method to selectively extract a range of heavy metal resources critical to new energy technologies. This offers a potential solution to long-standing challenges in traditional extraction techniques, such as high pollution, low efficiency, and high energy consumption, while also supporting critical metal recovery and recycling, Chinese Academy of Sciences (CAS) announced on Monday. 

The accelerated advancement of China’s dual carbon goals has fueled rapid growth in clean energy technologies such as wind power, photovoltaics, electric vehicles, and nuclear energy. This growth has driven up demand for specific heavy metal elements, some of which face heavy import dependence and potential supply shortages, according to an article released by the CAS on its official WeChat account. 

A joint research team made up of scientists from the State Key Laboratory of Photoelectric Conversion and Utilization of Solar Energy at Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT), CAS, and the Technical Institute of Physics and Chemistry, CAS, has developed a method for heavy metal extraction inspired by biological calcium ion channels. They published the research results in the international academic journal Nature Nanotechnology, according to a statement released by the QIBEBT. 

According to reports, solvent extraction and adsorption methods are predominantly used to extract heavy metal ions by binding them selectively. However, these methods require excessive chemical use and cause environmental problems. 

While membranes offer a cleaner, chemical-free alternative, they have historically failed at this specific task because heavy metal ions are often so similar in size and charge that standard filtration cannot tell them apart. To solve this, the scientists looked to a master of microscopic sorting: the biological cell. 

The scientists found that in nature, biological voltage-gated calcium channels act like an exclusive VIP club. They feature a narrow, one-dimensional hallway lined with highly specific binding sites. When the “VIP” calcium ions enter in a single file, they effectively block the door for all other competing ions – a phenomenon scientists call an “anomalous mole fraction effect,” Gao Jun, corresponding author of the study and researcher at QIBEBT, told the Global Times on Monday. 

Inspired by this natural design, the research team engineered a new separation mechanism. They created microscopic channels just wide enough, at about 1.4 nanometers, to force target heavy metal ions to line up in a single file, Gao said. 

When the researchers coated the insides of these artificial channels with specific chemical designed to attract uranium, the system successfully mimicked the biological anomalous mole fraction effect. Once uranium entered the channel, it blocked out competing elements like vanadium. And because the trapped uranium ions repelled one another, they shuttled through the barrier smoothly and rapidly, bypassing the usual gridlock. 

In a continuous test using natural seawater over 22 days, the process efficiently pulled out uranium while rejecting a sea of other background metals. 

This technology can be extended to the extraction of various metals such as copper and gold by modifying functional groups, the small surface chemical units that modify material properties without changing the underlying structure. It is expected to offer a greener, more efficient approach to critical metal recovery and strengthen domestic mineral supply chain resilience, China Central Television reported. 

Ultimately, this microscopic sorting mechanism could one day lead to a much greener, more sustainable global mining and recycling industry, Gao said.