Scientists proposed the “solid solvent method” to prepare a mixed matrix membrane

Professor Jin Wanqin’s team of Nanjing University of Technology has made new progress in the field of separation membranes and proposed the “solid solvent method” to prepare ultra-thin and ultra-high doped mixed matrix membranes. On September 22, the research results were published online in Science.

Schematic diagram of membrane preparation. Photo courtesy of the research group

Membrane structure and separation performance. Photo courtesy of the research group

According to reports, membrane technology has the advantages of low separation energy consumption, but its development is generally limited by the permeability and selectivity, and the preparation of mixed matrix membranes by doping high-performance inorganic fillers in polymers is expected to break through this bottleneck and become the frontier of international research in recent years. However, faced with the major challenges of packing agglomeration and interface defects, mixed matrix membranes are still not used on a large scale. Jin Wanqin’s team is one of the earliest teams in the world to carry out hybrid matrix membrane research, and has been committed to solving these two problems for a long time.

“We propose to use the polymer as a solid solvent, dissolve the precursors of the filler and coat it on the surface of the porous carrier to form an ultra-thin film layer, and then convert the precursors in the polymer into fillers in situ. Chen Guining, the first author of the paper and Ph.D. of Nanjing University of Technology, introduced that different from the traditional complex process of “synthetic filler-dispersed filler-packing and polymer mixing” to prepare a mixed matrix membrane, this method only needs to dissolve the high-content precursor in the polymer to achieve uniform ultra-thin doping of high-content filler, and the new hybrid matrix membrane structure with the filler as the main phase is conducive to the formation of penetrating pores between the fillers and provides ultrafast transport channels for molecules.

Experiments show that the thickness of the mixed matrix film prepared by the “solid solvent method” is only 50 nanometers, and the filler doping amount is as high as 80%, which realizes the improvement of membrane permeability and selectivity. Based on the ultra-thin film layer and the filled through-sieve pores, the mixed matrix membrane exhibits excellent separation performance of inorganic membranes (pure filled phase), and the hydrogen/carbon dioxide separation performance is high, and the polymer membrane and mixed matrix membrane are 1~2 orders of magnitude.

“The ‘solid solvent method’ mainly relies on the processing and preparation technology of polymer membranes, so it is easy to scale up and prepare ultra-thin flat plate and hollow fiber hybrid matrix membranes. Liu Fair, co-corresponding author of the paper and professor of Nanjing University of Technology, said that the method is suitable for different types of fillers and polymer matrices, showing good prospects for large-scale preparation and universality of membrane materials.

“This study proves the feasibility of ultra-thin and ultra-high doped mixed matrix membranes for the first time, and also provides a new idea and theoretical technical basis for the development of ultra-thin separation membranes and functional coatings based on nanomaterials.” Jin Wanqin, the corresponding author of the paper, introduced that the hybrid matrix membrane has great application potential in carbon capture and other processes, which is expected to help the implementation of China’s dual carbon strategic goals. With the funding of the National Key R&D Project, the team is carrying out research on the scale-up preparation and application technology of mixed matrix membrane. (Source: China Science News, Wen Caifei, Zhu Lin)

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