New Membrane Technology May Aid Biofuel Production
(Argonne National Laboratory/Biomass Magazine) Named for the mythical god with two faces, Janus membranes –double-sided membranes that serve as gatekeepers between two substances—have emerged as a material with potential industrial uses. Creating two distinct “faces” on these delicate surfaces, however, is a process fraught with challenges.
By applying a common high-tech manufacturing technique in an uncommon way, researchers at the U.S. Department of Energy’s Argonne National Laboratory have discovered a new way to chemically deposit a second face, resulting in Janus membranes that are more robust and precisely structured than previous incarnations. Recently described in an article in Advanced Materials Interfaces, the patent pending technology could help optimize or enable a wide range of industrial processes, from treating wastewater to making biofuels.
According to Argonne’s Seth Darling, Janus is also the Roman god of passages, making the name even more apt for these membranes that mark the boundary between substances—conveying gas bubbles into liquids, for example, or separating oil and water.
According to Darling, the Janus membrane research is part of a broader effort at Argonne to advance a “new water cycle” for society, in which water would be treated and reused as many times as possible before being released back into the environment.
Argonne researchers turned to atomic layer deposition (ALD), a technique commonly used in microelectronics and semiconductor fabrication, to improve the process. Using ALD, they deposited a water-attracting layer of aluminum oxide onto a water-repellent polypropylene membrane, creating a stable Janus membrane that could be used, for example, in fine-bubble aeration of water.
The technique emerged from what initially appeared to be an unsuccessful experiment conducted by Ruben Waldman, a graduate student at the University of Chicago’s Institute for Molecular Engineering. Darling is advising Waldman on his doctoral degree.
Waldman was investigating how ALD would affect membranes and noticed that the aluminum oxide was not fully coating the membrane’s bottom side. After consulting with Hao-Cheng Yang, an expert on Janus membranes and a postdoctoral appointee working with Darling at the CNM, Waldman decided to see whether this one-sided deposition could be optimized to achieve the partial layering needed for Janus membranes. READ MORE Abstract (Advanced Materials Interfaces)