In a remarkable feat of ingenuity, Chinese scientists have found a way to transform contaminated wastewater into valuable semiconductor materials. Researchers are hopeful the novel, environmentally friendly production method could boost innovation in China’s chip manufacturing sector.
Semiconductors and microchips play a vital role in the functioning of modern society and can be found in everything from electronics, motor vehicles, airplanes, medical equipment, credit cards, hi-tech weapons systems and satellites.
Chip production is often a process of several months, involving hundreds of steps in some of the cleanest and most controlled environments.
Now studies conducted by researchers from the Chinese Academy of Sciences’ (CAS) Shenzhen Institute of Synthetic Biology and the Harbin Institute of Technology, and published in the peer-reviewed scientific journal, Nature Sustainability, describe a cost-effective method that utilises bacteria to remove organic pollutants and heavy metals from water, creating chemicals relevant to the production of semiconductors in the process.
Team leads, professors Gao Xiang and Lu Lu, set about converting wastewater into what they called ‘biohybrids’ – a combination of both biological and synthetic semiconductor components.
They selected a waterborne microorganism known as Vibrio natriegens as their bacterium for the study. Gao explained that the salt water-friendly bacteria is one of the fastest-proliferating industrial microbes known to the scientific community, capable of multiplying twice as fast as E. coli.
The tiny organisms thrive in salty water and have been found to be highly tolerant of a variety of inhospitable conditions, including wastewater. Vibrio natriegens use sugars, alcohols, amino acids and roughly 200 other organic materials as a source of nutrients, making them a perfect candidate for their study, according to the research unit.
Gao and his colleagues trained the bacteria to absorb sulphates from the contaminated water, producing hydrogen sulphide gas as a by-product. The gas interacts with metallic ions present in the water, creating nanoparticle semiconductor materials in a chemical reaction.
The method is versatile and highly effective, capable of being applied to several metallic ions, creating useful compounds such as lead sulphide, mercury sulphide and cadmium sulphide, all of which have industrial applications, according to the team’s research paper.
The resultant nanoparticles were then applied to a bacterial surface, creating semiconductor hybrids. When exposed to solar radiation, the hybrid material transformed the ultraviolet and infrared light into electrons, providing additional energy to the bacteria.
Lab tests found the biohybrids could extract 99 per cent of cadmium ions present in a wastewater solution, transforming the ions into cadmium sulphide. After the process is complete, the semiconductor nanoparticles can be extracted from the solution via filtration, Gao explained.
The team’s breakthrough may not just have applications in the semiconductor sector. An October report by the South China Morning Post revealed that as the biohybrid grows in the wastewater, it reacts with organic pollutants in the solution, creating a substance called 2,3-Butanediol, a transparent liquid used in a variety of industries, including agriculture, cosmetics and medicine.
The team is now seeking to scale up their tests and is investigating methods to recreate the process on wastewater with a greater surface area, maximising the amount of light the microbes are exposed to and thus creating usable amounts of semiconductor nanoparticles, according to Professor Gao.