These tiny holes could change how the world cleans water

A team of researchers from the CSIR-Central Salt and Marine Chemicals Research Institute (CSMCRI), the Indian Institute of Technology Gandhinagar (IITGN), Nanyang Technological University in Singapore, and the S N Bose National Centre for Basic Sciences has developed a new type of highly precise filtration membrane. The study, published in the Journal of the American Chemical Society, describes a technology that could help industries cut energy use and dramatically increase water reuse.

Many industrial activities depend on separating different substances from one another. These separation processes are essential for tasks such as drug purification, textile dye treatment, and food production. Yet they are also among the most energy-intensive operations in manufacturing, accounting for roughly 40% to 50% of global industrial energy consumption.

Most facilities still rely on traditional approaches such as distillation and evaporation. While effective, these methods require large amounts of energy and contribute significantly to carbon emissions. Membrane-based filtration is generally considered a cleaner alternative, but conventional polymer membranes often contain pores of uneven size. Over time, those pores can change shape or degrade, reducing performance and limiting their usefulness in demanding industrial environments.

"To address these limitations, we engineered a new class of ultra-selective, crystalline membranes called "POMbranes," which contain pores that are about one nanometer wide, thousands of times thinner than a human hair," said Dr. Shilpi Kushwaha, Senior Scientist at CSMCRI.

The new membranes draw inspiration from biological systems such as aquaporins, which regulate the movement of molecules through precisely sized channels. To achieve this level of control, the researchers used polyoxometalate (POM) clusters. Each cluster contains a naturally occurring opening that is exactly 1 nanometer wide and remains permanently stable.

According to Ms Priyanka Dobariya, a CSMCRI research scholar and co-first author of the article, "These POMs are tiny, crown-shaped metal clusters that have a permanent, perfect hole in their centre that does not change or lose shape, which is the biggest hurdle with traditional plastic filters."

Creating a practical membrane required arranging billions of these tiny ring-like structures into a continuous, defect-free layer. To accomplish this, the researchers attached flexible chemical chains to the POM clusters.

When the modified clusters were placed on water, they naturally spread out and organized themsel