Scientists develop Sponge to extract gold from E-Waste

An innovative new sponge made of graphene oxide and chitosan has been created by a team of scientists. This is an excellent invention, as this sponge can be used to extract gold from electronic waste, which is a major breakthrough for the e-waste industry.

Before this method was created, previous research proved that removing gold or silver or any other metals from electronic equipment, which was deemed no longer useful, is a difficult and quite often, dirty business. However, it was also clear that removing these materials from the e-waste was an important process, as it allows the materials to be recycled.

Once it became common knowledge that discarded electronics, more often referred to as e-waste, contained copious amounts of gold, along with other heavy metals, scientists began creating methods which would allow facilities to recover the valuable metals. However, often these processes would rely on the use of synthetic chemicals, which would have a damaging effect on the environment.

It was recently at the National University of Singapore, when chemists and materials scientists, who were working with colleagues from Manchester University in the UK, as well as, Guangdong University of Technology in China, came up with this excellent sponge method and published a paper about it. This paper was published in the National Academy of Sciences and it spoke about how the team made their sponge, as well as how well it worked throughout the testing period.

This new study portrayed how the research team had found a forward-thinking new method which allowed them to remove the gold in a cheap and clean way. Not only is this new method cheaper and cleaner than previous methods, but it is evidently better than conventional methods and it is also much more convenient.

During their process, the research team selected specific materials, ensuring that the chosen ones had both been used to extract gold from other materials. On top of this, another benefit to choosing graphene, is that this particular material has previously demonstrated the ability to absorb ions, as well as chitosan, a natural biopolymer, which is a reducing agent. The purpose of using a reducing agent within this case, was so that it could catalytically convert gold ions into their solid form.

From there, the two materials were manufactured into a composite and this was done through allowing the chitosan to go through the process of self-assembling on two-dimensional graphene flakes. Performing this process also resulted in the formation of sites on the material that were able to bind to gold ions. Once the gold ions has been effectively absorbed into the graphene, the chitosan then converted them into their solid gold state. Doing this allowed for easy collection and this became a process that the research team deemed as ‘highly efficient.’

Once this process was complete, the team tested their sponge and they did this with the use of real e-waste which was provided by a recycling company. This e-waste was provided in the form of a solution mixture, which consequently meant that first it had to go through the process of being ground up along with other materials present in the electronic equipment and then mixed into a liquid. The team took a measurement prior to treatment and this showed that the mixture had a gold concentration of 3 ppm.

When the test was complete, the team received results, stating that the new sponge had the ability to extract an estimated 17g of Au3+ ions, along with slightly more than 6 g of Au+. The team stated that these amounts, ‘approximately 10 times that of any other known extraction process.’