A new electrochemical device produces high-purity oxygen in situ, and researchers hope it could help alleviate oxygen scarcity.
Two years into the COVID-19 pandemic, access to oxygen remains a major issue in low- and middle-income countries.
While a majority of patients with COVID-19 have mild or moderate symptoms, as COVID-19 is a respiratory disease, damage to the lungs means they are less efficient at getting oxygen through to the blood circulation.
“Acute shortage of medical oxygen with ≥99.5% purity directly led to the death of an alarming number of critically ill patients who could have been cured,” said Changming Zhao, a researcher at Anhui Entropy Technology Co., Ltd, China, in an email. “This painful fact prompted us to start researching how to improve oxygen supply devices in hospitals.”
In a study Posted in Advanced Energy MaterialsZhao and his collaborators Sen Lin of Fuzhou University and Yuen Wu of the University of Science and Technology of China have developed a device that generates its own oxygen supply using electrochemistry.
“Current oxygen supply devices, such as oxygen tanks and commercial pressure swing adsorption (PSA) oxygen generation devices, cannot produce oxygen. on the spot and with high purity (≥99.5%),” Zhao said. “The limitations of existing oxygen supply devices may be one of the reasons for oxygen shortages in many countries. Therefore, we sought to develop a device to overcome the limitations of conventional oxygen supplies and help to fill in the gaps.
Solving oxygen shortage with new technology
In hospitals, oxygen is stored in liquid form in large tanks connected to the rooms. With intensive care units overrun with critically ill patients, the oxygen supply could not keep up due to storage and transportation issues. An alternative generator called a PSA device can be used in such cases as it provides rapid and continuous production of oxygen. However, it only produces oxygen with a purity of about 93%, which does not meet WHO Pharmacopeia standards for high purity medical oxygen (≥99.5%) .
“In some emergency cases, such as patients with severe heart and brain tissue hypoxia, supplying them with the oxygen generated by the PSA device may not achieve the optimal therapeutic effect,” Zhao said. Even with this limited performance, many healthcare providers have had to make concessions due to a lack of equipment and supplies.
The team therefore developed a new device based on electrochemistry, which provides ≥ 99.9% pure oxygen. “The most important difference between our electrochemical oxygen generation device and existing oxygen supply devices is the oxygen source,” Zhao explained. “For liquid oxygen stored in tanks, oxygen is obtained from the separation of liquefied air under very low temperature. This method requires cumbersome and complex production equipment, as well as energy consumption important, is therefore difficult to achieve on the spot production for hospitals.
“For PSA oxygen generation devices, oxygen is obtained from the physical separation of oxygen from air, and the separation efficiency is difficult to reach 100%, so the purity of oxygen is limited,” he continued.
The new device produces oxygen through an electrochemical reaction that takes place under a specific voltage. The oxygen in the air is selectively reduced at the cathode of the device to a protonated species. This compound is then passed to the anode where it is oxidized to oxygen, largely free of the other air elements. The result is an easy-to-access, pure oxygen supply.
If these results from the prototype are promising, to implement the device on a large scale, optimization is still necessary.
“Although the device can work steadily for several hundred hours, it is still far less than the actual application requirements, which would require tens of thousands of hours,” Zhao said. “In further studies, we will improve the reaction system by replacing the alkaline solution with pure water to slow down the aging of the core components, thus extending the service life. At the same time, we are also focusing on the development of plates thin, inexpensive bipolars to further reduce cost and weight.”
The team established a company called Anhui Entropy Energy Technology Co., Ltd dedicated to accelerating its commercial availability.
Reference: Changming Zhao, Sen Lin, Yuen Wu, et al., Electrochemical oxygen generator with 99.9% oxygen purity and high energy efficiency, Advanced Energetic Materials (2022). DOI: 10.1002/aenm.202201027