Plastic Polymer Recovers Precious Etals

Related Vendors

Universität Ulm

Wuxi InfiMotion Technology Co., Ltd.

Researchers at Ulm University have developed an organic material with extraordinary properties: The novel polymer can recover precious metals such as gold or palladium from solutions, separate toxic semi-metals and also make batteries more environmentally friendly.

The special feature of the white, flaky material developed by the research group led by Professor Max von Delius from the Institute of Organic Chemistry at the University of Ulm is its exceptionally high sulphur content of around 50 percent and its highly fissured surface.

"Our material is based on a reaction class not previously used in polymer chemistry—so-called thioorthoester chemistry," explains von Delius. "This involves the use of molecules that are made up of one carbon and three sulphur atoms, like a tripod. This composition naturally gives the material an extremely high sulphur content and leads to strong cross-linking within the polymer. This ensures high stability, insolubility in water and an extremely fragmented surface structure." While the high sulphur content was one of the researchers' goals, the porous structure, which is comparable to a natural sponge, was created more by chance during the synthesis process and turned out to be a fortunate side effect. "This large contact surface means that the sulphur atoms can bind metal ions particularly effectively," says von Delius.

Twice the Palladium Binding Capacity of Commercial Scavengers

One possible application is the targeted separation of so-called coinage metals such as palladium, gold and silver from solutions. In the case of palladium, which is widely used in the pharmaceutical industry and is similarly expensive to gold, the material achieves better results than the existing so-called scavengers. These are metal scavenging substances used by pharmaceutical companies, for example, to remove palladium residues from medicinal raw materials. Metal binding analyses carried out by a team led by Professor Kerstin Leopold at the Institute of Analytical and Bioanalytical Chemistry revealed a maximum palladium binding capacity of 41.2 milligrams per gram for the thioorthoester polymer. This is almost twice as much as that of an established commercial scavenger.

The polymer is also suitable for environmental applications; for example, to remove problematic substances such as the toxic semi-metal antimony from slag in waste incineration plants. In tests, the new material absorbed up to 2.23 milligrams of antimony per gram of polymer—several times over. Up to 83 percent of the bound substances could be released from the material again, with only a slight loss of performance after several uses. "The ability to selectively separate certain metals is a major advantage," says Leopold.

We have observed a stable capacity of around 100 mAh per gram over 1000 charging and discharging cycles. And unlike conventional cathode materials, the new polymer contains no critical metals and has a significantly lower environmental impact.

Professor Max von Delius

Environmentally Friendly Battery With Sulphur Instead of Metal

The new polymer also shows promising properties as a component of modern energy storage systems. As part of the Cluster of Excellence POLiS ("Post Lithium Storage"), the researchers tested the material as a metal-free cathode in lithium-ion batteries. "We observed a stable capacity of around 100 mAh per gram over 1000 charge and discharge cycles. And unlike conventional cathode materials, the new polymer does not contain any critical metals and has a significantly lower environmental impact," reports von Delius. The work of the Ulm researchers was not only accepted by the renowned journal Angewandte Chemie International Edition, but was also upgraded to the new journal Angewandte Chemie Novit after receiving top marks in the peer review process—the first published study in this format, which only publishes articles with exceptional novelty value.

Further Development Planned With Industry Partners

A patent application has already been filed for the newly developed material, primarily due to its outstanding properties as a selective binder for metals such as palladium and antimony. Its use as a metal-free, organic cathode in lithium batteries is also part of the patent application. The research team is currently preparing talks with potential industrial partners to further develop the process towards market maturity in various areas—from chemical product preparation to water purification and energy storage.

Secure and Compliant Authentication in Laboratories

Secure & Contactless User Authentication at GMP/GLP