Rhea Verbeke: Epoxide-based membranes for sustainable desalination

Finding solutions to overcome water scarcity is a key challenge of the 21st century, given that half of the global population will live in water-stressed regions by 2050 (including Belgium).

While the most obvious way to alleviate the global water crisis is to decrease our water footprint, technology can help increase fresh water supply.  For example, membranes can desalinate sea water to produce fresh water. Acting as semipermeable barriers, desalination membranes allow water to pass while salts and other dissolved compounds are rejected. Current desalination membranes achieve excellent water fluxes and salt rejections thanks to their polyamide-based top layer. However, this layer is also a major source of concern in industrial water treatment plants as it is highly reactive towards chlorine, a disinfectant added upstream to kill microorganisms.

Even though actively removed from the water, chlorine often accidentally reaches the membrane surface. Chlorine attack then leads to membrane performance losses, premature membrane module replacement and disposal, plant productivity losses, and increased overall costs.

To overcome these large economic losses (up to 30%) and improve the sustainability of current desalination plants, tremendous research has been focused on developping a chlorine-resistant membrane. Motivated to help put an end to this 40 years quest, I started a PhD in 2016 at the KU Leuven Membrane Technology Group under supervision of Prof. Vankelecom. And so I embarked on a research journey that brought me all around the world, from the DuPont Water Solutions industrial facilities in Spain, to the labs of Yale University in the United States, with an overlay in a nuclear reactor in Germany. The  knowledge obtained in these contrasting environments has allowed me to establish a better understanding of the chlorine-sensitivity of commercial polyamide membranes, both at the nano- and the macroscale. However, the breakthrough occurred when we developed the first chlorine-resistant desalination membrane by using epoxide instead of polyamide chemistry.

We chose to work with epoxides for their impressive chemical, thermal and mechanical robustness, as demonstrated by their wide use in the automotive and flooring industry. We transferred the knowledge of the well-known monophasic bulk epoxide polymerization to the interfacial synthesis of thin, yet cross-linked poly(epoxyether) films. Owing to their intrinsic high chemical stability, our newly synthesized epoxide-based membranes are not only chlorine-resistant, but also acid- and caustic-resistant. This novel generation of epoxide-based membranes may therefore pave the way for their successful and sustainable implementation in applications under harsh conditions, such as acid mine leachates or pharmaceutical waste streams.

After demonstrating the technology as a proof of concept, we filed a patent and are now exploring the synthesis of epoxide-based membranes at pilot-scale to meet the pressing market demand.

For my postdoc, I recently obtained financial support from FWO to continue exploring this exciting research line. Most of all, I see this as an opportunity to help find holistic solutions for today’s complex and intertwined challenges (e.g., water-energy-food nexus) through collaborations with people of diverse fields and backgrounds.