Semi-permeable cell membranes in nature serve as barriers and gatekeepers, allowing some molecules to pass through and to prevent others from doing so. Artificial membranes are used to separate gasses or liquids to remove wastes or in biotechnology, food technology, and pharmaceutical industries. Membrane-based separation offers a scalable, green, and energy-efficient tool for numerous applications,
About half of the membrane market is in medical applications such as use in artificial kidneys to remove toxic substances by hemodialysis and as artificial lung for bubble-free supply of oxygen in the blood.
Another important technical application of membranes includes the production of drinking water by reverse osmosis; a huge reverse osmosis plant is located in Israel’s Sorek Valley and has an output of 624,000 cubic meters a day. Using membranes enables separations to take place that would be impossible using thermal separation methods.
Inspired by nature, numerous research groups have attempted to develop similar membrane channels that enable precise filtration of various materials for diverse industrial applications. But synthetic fabrication of such membranes, with high levels of well-ordered pores, and high uniformity and selectivity, poses a complex engineering challenge, made even more complex when the membranes are intended for extremely small nanoparticle separation.
Now, researchers from the Technion-Israel Institute of Technology in Haifa and the Helmholz-Zentrum Hereon Center in Germany have developed a new concept for fabricating membranes for on-demand nanoparticle separation with high selectivity. These membranes are relevant for diverse applications that include pharmaceutical processing, materials separation, water purification and wastewater treatment.
Published in Advanced Materials under the title “Hybrid Organic–Inorganic–Organic Isoporous Membranes with Tunable Pore Sizes and Functionalities for Molecular Separation,” the research study was led by assistant Prof. Tamar Segal-Peretz and doctoral student Assaf Simon at the Technion’s Wolfson Faculty of Chemical Engineering, together with Dr. Zhenzhen Zhang and Prof. Volker Abetz at the German institution. .
The team succeeded in fabricating such membranes using block copolymers – spontaneously self-assembled polymer molecules, in combination with metal oxide growth on and within the block copolymer pores. The process developed by the researchers provides an excellent method for precisely tuning the pore size as well as other properties of the membrane. In addition, the metal oxide is an ideal base for incorporating functional groups on the membrane surface, granting it unique properties, such as electric charge and hydrophobicity (water repellency). These membranes exhibited superior performance in the separation of nanoparticles based on size, charge, and/or hydrophobicity.
The researchers believe their breakthrough will provide various industries with a new, versatile and accurate tool for the filtration of molecules, pollutants, and other particles.