Recycling metal, another use of Prussian blue

Release time:2022-06-20 16:06:28

The new method recovers gold from e-waste more efficiently than from ore. Source: Shinta Watanabe et al

In the art world, Prussian blue was first used as a pigment and dye, and painters such as Picasso, Van Gogh and gezhabezhai also used it because of its deep blue. In the chemical field, scientists have found that this pigment has another interesting feature and special use. Relevant papers were published in the scientific report a few days ago.

A big problem of nuclear waste and electronic waste is that gold and platinum group metals, which are the key metals in computer chips, will be wasted in the process of treatment. Jun onoe and Shinta Watanabe of Nagoya University in Japan cooperated with Takeshita Kenji of Tokyo University of technology to find that the solution to this urgent environmental and technical problem may lie in Prussian blue.

Prussian blue has a climbing rack like lattice in the nanospace. Previous experiments have found that it can absorb platinum group metals. However, it is not clear how this works.

Researchers used inductively coupled plasma atomic emission spectrometry, ultraviolet visible near-infrared spectrophotometer, etc. to learn more about this process.

"The experiment of adsorption of platinum group metals by Prussian blue nanoparticles found that it absorbed platinum group metals through iron ion substitution while maintaining the structure of the climbing frame." Onoe explained that this mechanism allows Prussian blue nanoparticles to absorb more gold and platinum group metals than traditional bio based adsorbents.

This study shows a way to solve the problem of nuclear waste disposal - recycling platinum group metals. In the post-treatment process of high-level radioactive waste liquid, platinum group metals often precipitate on the side wall surface of the melter, which affects the stability and increases the disposal space and cost.

The study found that 0.13 g ruthenium, 0.16 g rhodium, 0.30 g palladium and 0.107 g molybdenum could be recovered by using 1 g Prussian blue nanoparticles. Recently, Prussian blue was used to remove radioactive cesium-134 and 137 elements from the contaminated soil caused by the Fukushima nuclear power plant accident.

The gold content in a ton of mobile phones is 300~400 grams, which is 10~80 times higher than that in natural ores. Prussian blue nanoparticles have heat resistance, nitric acid resistance and γ Because of the radiation, the team's technology can be used not only in the disposal process of nuclear waste, but also in the recycling process of electronic waste.

"Our results show that Prussian blue or its analogues are a strong candidate for improving the recycling of precious metals in nuclear and electronic waste, especially compared with traditional bio based adsorbents / activated carbon," onoe said

In the current situation of increasingly limited natural resources, the loss of valuable metals in waste treatment is a serious problem. By improving metal recovery efficiency, Prussian blue or similar materials are expected to make production more environmentally friendly and economical.