An innovative way to recover gold from electronic waste using whey
An innovative way to recover gold from electronic waste using whey
Researchers at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) were able to extract gold metal fromelectronic waste. Their new method, which they describe as “highly sustainable”; On a fibrous protein sponge, scientists derive it from whey, which is the remaining liquid (separated) from milk or yogurt, and is considered one of the byproducts of the cheese and dairy products industries.
For many centuries in ancient times, humanity was obsessed with finding ways to transform basic materials into gold, which resulted in the myth of the “Philosopher’s Stone,” which was said to be able to transform cheap materials such as lead into the precious metal. But, what if we told you that this myth has become, in one way or another, a reality today?! Of course, not by converting lead into gold, but by extracting the yellow metal from electronic waste.
E-waste contains a variety of precious metals, including copper, cobalt, and even large amounts of gold; Therefore, recovering these metals from the waste of various electronic devices makes sense. Given the increasing demand for these minerals on the one hand, and on the other hand, ridding the environment of hundreds of thousands of tons of these wastes, which can cause many severe environmental impacts.
Converting waste into resource
With terms such as “Circular Economy” and “sustainable development” gaining great momentum in recent years, all industries have become required to find green solutions that take into account reducing the carbon footprint to the minimum, while maximizing recycling and reuse processes, and minimizing production processes from virgin raw materials.
As a result, many recycling methods have emerged in various industries, including the electronics industry, which is the industry responsible for meeting the continuous and growing needs of users, in light of a digital age witnessing unprecedented consumption rates, which has drawn attention to electronic waste, which can be exploited to achieve a number of Sustainable Development Goals (SDGs), most notably the twelfth goal: responsible consumption and production.
However, the methods that have been invented and developed so far to recover metals from electronic waste consume a lot of energy and often require the use of highly toxic chemicals, which may make the process of recycling this waste economically and environmentally infeasible. The previous problem prompted a group of researchers at the Swiss Federal Institute of Technology – led by Professor Rafael Mezenga – to find a sustainable solution to it.
The research team made it its top priority to find a cost-effective method that, at the same time, avoids the use of toxic chemicals. With the aim of finding an effective way to recycle electronic waste. They succeeded in achieving this through an innovative method that uses a sponge made of a protein matrix, which we will discuss in the following lines.
Selective adsorption of gold
To manufacture the sponge we referred to, “Muhammad Bidayish,” one of the senior scientists in the research group, reshaped whey proteins under acidic conditions and high temperatures, to obtain a gelatinous mass of protein nanofibers, and then dried this mass to obtain the required sponge.
But, what is the role of this sponge in recovering gold from electronic waste? The sponge provides the appropriate surface for gold atoms to adsorb. For those who do not know, adsorption represents a phenomenon in which atoms or molecules of a fluid (gas or liquid), called the adsorbent, accumulate on the surface of another solid substance known as the adsorbent. By applying the above to the research in question, the gold atoms are the adsorbed material, and the sponge is the adsorbed material.
First, the research team dissolved the metal parts found in 20 motherboards from old computers in an acidic solution. This is with the aim of converting various metal molecules into ions (ionization process). After that, they placed the sponge made of protein fibers in the previous solution. To adsorption of gold ions, as gold ions have greater efficiency in adhering to protein fibers, compared to other metals.
In the next step, the researchers heated the sponge, for the purpose of converting gold ions into small flakes. They then melt these flakes, forming a solid mass containing 91% gold and 9% copper, which is equivalent to 22 carat gold. It is worth noting that the recovered amount of gold from 20 motherboards was 450 milligrams.
Attractive economic feasibility
From an economic standpoint, Mezinga’s calculations show that this new technology can be applied on a commercial scale, as the cost of purchasing the necessary materials in addition to the cost of the energy used in all stages of the process does not exceed 50% of the value of the gold that can be recovered. Which means that the new method is economically feasible.
Although recycling electronic waste is the primary goal of this process, researchers are looking at other sources to recover gold, including industrial waste resulting from the manufacture of microchips, or from gold plating processes. In addition, the scientists plan to check whether they can make protein fibrous sponges (adsorption media) from other protein-rich byproducts, by looking at food industry waste.
The ingenuity of this new method of recovering gold from electronic waste lies in its reliance on a by-product of the food industry; Which means that waste from two different industries is converted into gold, a process that represents the spirit of the circular economy and achieves many Sustainable Development Goals (SDGs).
Moreover, this method will contribute to reducing the demand for virgin metals, especially gold. Thus reducing the carbon footprint of electronic industries, and reducing dependence on mining operations – which are stressful for the environment – fundamentally.
