Green Chemistry and Biomimicry: A More Sustainable Process for Metal Extraction

A team of chemists from McGill University in Montreal, Quebec, Canada, and Western University in London, Ontario, Canada, have developed a way to process metals without toxic solvents and reagents. Their innovation could help reduce negative environmental impacts of metal extraction from raw materials and electronic scrap.

As reported by McGill, “The system, which also consumes far less energy than conventional techniques, could greatly shrink the environmental impact of producing metals from raw materials or from post-consumer electronics…In an article published recently in Science Advances, the researchers outline an approach that uses organic molecules, instead of chlorine and hydrochloric acid, to help purify germanium, a metal used widely in electronic devices. Laboratory experiments by the researchers have shown that the same technique can be used with other metals, including zinc, copper, manganese and cobalt.”

The development is an interesting example of biomimicry. Germanium is a semiconductor not found in substantial quantities in any one type of ore, so a series of processes are used to reduce mined materials with small quantities of the metal to a mixture of germanium and zinc. Isolation of germanium from the zinc in this resulting mixture involves what one of the researchers called “nasty processes.” For an alternative less dependent upon toxic materials and energy use, the researchers found inspiration in melanin, the pigment molecule present in skin, hair, and irises of humans and other animals. Besides contribution to coloration, melanin can bind to metals. The researchers synthesized a molecule that mimics some of melanin’s metal-binding qualities. Using it they were able to isolate germanium from zinc at room temperature, without solvents.

Image of a shiny, silver-grey metallic rock
Image of germanium by W. Oelen, CC BY 3.0

As the McGill article states, “The next step in developing the technology will be to show that it can be deployed economically on industrial scales, for a range of metals.”

Read the full story, published June 7, 2017 by the McGill Newsroom at https://www.mcgill.ca/newsroom/channels/news/more-sustainable-way-refine-metals-268517.

See also “A chlorine-free protocol for processing germanium,” Martin Glavinović et al., Science Advances, 5 May 2017. DOI: 10.1126/sciadv.1700149 http://advances.sciencemag.org/content/3/5/e1700149

To learn more about germanium and its applications (including fiber-optics, infrared optics, solar electric applications, and LEDs), see the Wikipedia article on germanium at https://en.wikipedia.org/wiki/Germanium.

NASA Invests in Innovative Concepts, Including Electronic-recycling Microbes

The National Aeronautics and Space Administration (NASA) recently announced that 13 proposals had been selected for funding as part of the NASA Innovative Advanced Concepts (NIAC) program, which “invests in transformative architectures through the development of pioneering technologies.” According to the press release, “NIAC Phase I awards are valued at approximately $100,000 for nine months, to support initial definition and analysis of their concepts. If these basic feasibility studies are successful, awardees can apply for Phase II awards, valued up to $500,000 for two additional years of concept development.” Read the full press release on the NASA web site.

Among the funded proposals is a concept entitled Urban bio-mining meets printable electronics: end-to-end at destination biological recycling and reprinting,” submitted by Lynn Rothschild, NASA’s Ames Research Center in Moffett Field, California. The project description states:

“Space missions rely utterly on metallic components, from the spacecraft to electronics. Yet, metals add mass, and electronics have the additional problem of a limited lifespan. Thus, current mission architectures must compensate for replacement. In space, spent electronics are discarded; on earth, there is some recycling but current processes are toxic and environmentally hazardous. Imagine instead an end-to-end recycling of spent electronics at low mass, low cost, room temperature, and in a non-toxic manner. Here, we propose a solution that will not only enhance mission success by decreasing upmass and providing a fresh supply of electronics, but in addition has immediate applications to a serious environmental issue on the Earth. Spent electronics will be used as feedstock to make fresh electronic components, a process we will accomplish with so-called ‘urban biomining’ using synthetically enhanced microbes to bind metals with elemental specificity. To create new electronics, the microbes will be used as ‘bioink’ to print a new IC chip, using plasma jet electronics printing. The plasma jet electronics printing technology will have the potential to use martian atmospheric gas to print and to tailor the electronic and chemical properties of the materials. Our preliminary results have suggested that this process also serves as a purification step to enhance the proportion of metals in the ‘bioink’. The presence of electric field and plasma can ensure printing in microgravity environment while also providing material morphology and electronic structure tunabiity and thus optimization. Here we propose to increase the TRL level of the concept by engineering microbes to dissolve the siliceous matrix in the IC, extract copper from a mixture of metals, and use the microbes as feedstock to print interconnects using mars gas simulant. To assess the ability of this concept to influence mission architecture, we will do an analysis of the infrastructure required to execute this concept on Mars, and additional opportunities it could offer mission design from the biological and printing technologies. In addition, we will do an analysis of the impact of this technology for terrestrial applications addressing in particular environmental concerns and availability of metals.”

Note that “TRL” refers to “Technology Readiness Level,” a measure of the technological maturity of a concept, indicative of the degree to which it has developed beyond the initial faults and unforeseen problems that inevitably arise when something theoretical is brought into practice. NASA TRL definitions help characterize whether a concept is ready for use in space flight during missions or has been “flight proven” as part of successful missions.

Printable Electronics
Graphic depiction of printable electronics, from concept description on NASA web site.

Though the idea is geared toward making missions to Mars more practical in terms of the weight of materials needed to pack for missions and dealing with the lack of a local repair shop in the event of a device breakdown, the concept–if successful–could have obvious positive impacts on sustainable electronic product design and responsible management of the ever-growing stream of discarded electronics here on Earth. This could end up becoming one more example of how technology developed to enable space exploration could have benefits to humans in their everyday terrestrial lives. NASA has published an annual accounting of such technologies called “Spinoff” since 1976.

For more information on the NIAC program, visit https://www.nasa.gov/directorates/spacetech/niac/index.html. For more information on technological “spinoffs”  from space exploration which improve life on Earth, see the press release for the 2016 edition of Spinoff, and the official NASA Spinoff web site.