In a significant stride towards more energy-efficient industrial processes, researchers at the University of Twente have developed advanced solvent-resistant nanofiltration (SRNF) membranes that could revolutionize the way industries handle liquid waste and solvent recovery. The study, led by Harpreet Sondhi from the Inorganic Membranes group, explores the potential of molecular layer deposition (MLD) technology to create highly stable and efficient membranes for nanofiltration.
The research, published in the journal ‘Applied Surface Science Advances’ (translated as ‘Advances in Surface Science Applications’), focuses on the development of metalcone hybrid layers, which exhibit remarkable chemical stability in various solvents and water-solvent mixtures. These membranes, with pore diameters of less than 2 nanometers, can reject over 90% of polyethylene glycol molecules larger than 390 Daltons, making them highly effective for separating and recovering valuable solutes from industrial process streams.
One of the key innovations in this study is the use of surface-silanization to enhance the hydrophobicity of the MLD layers. “By increasing the hydrophobicity, we were able to significantly improve the permeance of n-hexane through the membranes,” explains Sondhi. “For surface-silanized titanicone layers, the n-hexane permeance was tripled, and for alucone layers, it was doubled compared to the unsilanized layers.” This enhancement in permeance, coupled with the membranes’ high chemical stability, makes them an attractive prospect for industries looking to reduce their energy consumption and improve their sustainability credentials.
The membranes were deposited using vapor-phase titanium tetra-chloride and trimethyl-aluminum as precursors, with ethylene glycol as a co-reactant for nanopore fabrication. The researchers also employed methyltrimethoxysilane for surface-silanization, which was carried out after the MLD layers were deposited at temperatures of 125°C and 150°C. The membranes were then annealed in air and nitrogen at 250°C and 350°C to further enhance their properties.
The results of this study demonstrate the versatility of MLD as a technology for developing advanced membranes for large-scale industrial applications. “The membranes maintained their permeation rates after 48 hours of continuous exposure to various solvents, which is a clear indication of their high chemical stability,” says Sondhi. This stability, combined with the membranes’ high rejection rates and enhanced permeance, could make them a game-changer for industries such as pharmaceuticals, petrochemicals, and chemicals, where solvent recovery and waste treatment are major challenges.
As the world grapples with the need to reduce its carbon footprint and transition to a more sustainable future, innovations like these advanced SRNF membranes could play a crucial role in helping industries to become more energy-efficient and environmentally friendly. By providing a more efficient and cost-effective alternative to conventional distillation methods, these membranes could help to reduce the energy consumption and greenhouse gas emissions associated with industrial processes, paving the way for a cleaner, greener future.
The research conducted by Sondhi and their team at the University of Twente is a testament to the power of innovation and the potential of advanced materials to transform industries and drive progress towards a more sustainable future. As the world continues to search for solutions to the challenges posed by climate change and resource depletion, the development of advanced SRNF membranes offers a glimmer of hope and a promising path forward.