Extracting Precious Metals from Discarded Electronics

Scientists at the University of York have worked out an innovative technology to recover precious metals like gold, silver and others from electronic gadgets that users have disposed. The technique involves the use of a gel to draw the metals from the waste and change them into nanoparticles that are conducting in nature. Eventually, these are transformed to make up a hybrid nanomaterial, which can be adapted for use in various new electronic applications.

Many of the electronic gadgets that are thrust aside by users when they are not suitable for usage contain small amounts of gold, silver and several other expensive metals. Though these metals are present in minute quantities in each of the devices, the abundance of electronics cast off every year makes for a significant amount that can be collected by efficient extraction techniques.

Self-assembling gels derived from simple sugars

Professor David Smith of the university teamed up with a PhD student Babatunde Okesola to derive a gel from sorbitol, a type of sugar alcohol that is popular as a low calorie sweetener in food and pharmaceutical industries. Being hygroscopic or water absorbing nature, sorbitol finds use in certain other applications, too. Hydrogenation of glucose can produce sorbitol commercially, as it is present in several fruits.

Sindhu Suravaram and Dr. Alison Parker of the Department of Chemistry assisted in the research, the results of which they published in Angewandte Chemie.

Selective removal

Sorbitol’s hygroscopic property allows it to form a gel easily on contact with the water vapor in the atmospheric air. The gel structure allows the precious metals to adhere to the surface so that they can be removed with ease. Furthermore, the stable nature and anti crystallizing properties of the gel makes it an ideal material for extracting the metals. The scientists found that the sorbitol-based gel could draw out these elements from intricate structures deep within the gadgets. Amazingly enough, the researchers found that the gel appeared to have an affinity for these metals, which allowed for the extraction of these valuable elements from among various other substances. This selective separation makes the extraction process cost effective.

Additional benefits

The researchers discovered that apart from recovering the precious metals from the electronic devices, the Nano fibers within the gel convert the metals into nanoparticles over a period. These minute particles implanted within the gel make it electrically conducting.

Okesola explains that since gels add in the properties of both liquids and solids, they can be used to bridge the gap between hard word of electronics and the soft world of biology. This interface could be exploited in future electronics and other technologies. In fact, the researchers are currently working on techniques to produce renewable energy from bacteria using the conducting gel nanoparticles.

The researchers also hope to utilize these conducting sorbitol gels in more ambitious projects involving the integration of biological organisms and electronics through the concept of cybernetics. One can loosely define cybernetics as the science of communication and control between animal and machine worlds. Cybernetics can throw light on various puzzling facts in nature.