• A
  • A
  • A
  • ABC
  • ABC
  • ABC
  • А
  • А
  • А
  • А
  • А
Regular version of the site

Russian Scientists Improve Water Purification Membranes Using Metal Ions

Russian Scientists Improve Water Purification Membranes Using Metal Ions

© HSE University

Researchers have proposed using polymer membranes modified with copper, zinc, and chromium metal ions for water purification. These polymers were used for the first time in water purification via electrodialysis. Copper-based membranes demonstrated record selectivity for monovalent ions, opening new possibilities for sustainable water recycling. The study has been published in the Journal of Membrane Science

Electrodialysis is a water purification method that removes contaminants without chemical reagents by moving ions through a membrane under an electric field. The efficiency of purification depends on the membrane’s properties, particularly its selectivity—the ability to allow certain ions to pass while blocking others. Polymer membranes typically allow multivalent ions, such as sulphates, to pass through more easily than monovalent ions like nitrates. This results in precipitate forming on the membrane surface, which block ion transfer and can lead to system failure. Therefore, scientists are developing ways to enhance membrane selectivity for monovalent ion transport.

Electrodialysis membranes are usually made of polymers containing channels with charged walls that selectively permit ions to pass. A conventional polymer consists of a chain of carbon atoms with charged functional groups attached via strong covalent bonds. These groups are part of the polymer’s structure because they are fixed to its side chain.

HSE scientists have demonstrated how a simple modification can enhance the selectivity of polymer membranes. They used polybenzimidazole (PBI)-based membranes embedded with metal ions—copper, zinc, and chromium. In this structure, metals bonded with nitrogen atoms from the polymer through coordination bonds, which are easier to form and break compared to strong covalent bonds. This property allows the material’s structure to be modified and adapted for specific applications. 

Andrey Manin
© HSE University

‘A typical polymer can be imagined as a string of lights, where the main chain is the wire and the functional groups are bulbs attached to it. In regular membranes, the bulbs remain fixed in place, whereas in our case, they appear to levitate. We can adjust their number by adding more or fewer metal ions during synthesis, thus regulating the membrane’s properties,’ explains study author Andrey Manin, a master's student in the Chemistry of Molecular Systems and Materials programme at the HSE Faculty of Chemistry and a researcher at the Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences (IGIC RAS).

Copper-ion-enhanced membranes demonstrated record-breaking selectivity in separating nitrates from sulphates. Scientists suggest two possible explanations. Firstly, the ion channel size within the membrane structure is ideally suited for nitrate transport, while larger sulphate ions get trapped. Secondly, nitrate ions may interact with metal ions in the coordination sphere, facilitating their passage through the membrane.

Experiments confirmed that copper-infused membranes are not only effective but also stable, retaining their properties over extended use. This is a significant advantage over zinc-based membranes, where zinc ions leached from the polymer matrix, contaminating water with heavy metals. Scientists are exploring several ways to scale the technology for industrial application.

‘In our experiment, we used substituted polybenzimidazole synthesised by our colleagues at INEOS RAS. However, for industrial production, a more accessible and widely manufactured polymer, such as unsubstituted polybenzimidazole, could be used. Another option is to apply a thin layer of the synthesised polymer with metal ions onto commercially available electrodialysis membranes. This approach would enhance selectivity while maintaining conductivity due to the base material. Since these membranes are already produced using well-established processes, adding one more stage would not significantly impact production costs but could greatly improve membrane efficiency,’ says Andrey Manin.

See also:

Low-Carbon Exports Reduce CO2 Emissions

Researchers at the HSE Faculty of Economic Sciences and the Federal Research Centre of Coal and Coal Chemistry have found that exporting low-carbon goods contributes to a better environment in Russian regions and helps them reduce greenhouse gas emissions. The study results have been published in R-Economy.

Russian Scientists Assess Dangers of Internal Waves During Underwater Volcanic Eruptions

Mathematicians at HSE University in Nizhny Novgorod and the A.V. Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences studied internal waves generated in the ocean after the explosive eruption of an underwater volcano. The researchers calculated how the waves vary depending on ocean depth and the radius of the explosion source. It turns out that the strongest wave in the first group does not arrive immediately, but after a significant delay. This data can help predict the consequences of eruptions and enable advance preparation for potential threats. The article has been published in Natural Hazards. The research was carried out with support from the Russian Science Foundation (link in Russian).

Centre for Language and Brain Begins Cooperation with Academy of Sciences of Sakha Republic

HSE University's Centre for Language and Brain and the Academy of Sciences of the Republic of Sakha (Yakutia) have signed a partnership agreement, opening up new opportunities for research on the region's understudied languages and bilingualism. Thanks to modern methods, such as eye tracking and neuroimaging, scientists will be able to answer questions about how bilingualism works at the brain level.

How the Brain Responds to Prices: Scientists Discover Neural Marker for Price Perception

Russian scientists have discovered how the brain makes purchasing decisions. Using electroencephalography (EEG) and magnetoencephalography (MEG), researchers found that the brain responds almost instantly when a product's price deviates from expectations. This response engages brain regions involved in evaluating rewards and learning from past decisions. Thus, perceiving a product's value is not merely a conscious choice but also a function of automatic cognitive mechanisms. The results have been published in Frontiers in Human Neuroscience.

AI Predicts Behaviour of Quantum Systems

Scientists from HSE University, in collaboration with researchers from the University of Southern California, have developed an algorithm that rapidly and accurately predicts the behaviour of quantum systems, from quantum computers to solar panels. This methodology enabled the simulation of processes in the MoS₂ semiconductor and revealed that the movement of charged particles is influenced not only by the number of defects but also by their location. These defects can either slow down or accelerate charge transport, leading to effects that were previously difficult to account for with standard methods. The study has been published in Proceedings of the National Academy of Sciences (PNAS).

Electrical Brain Stimulation Helps Memorise New Words

A team of researchers at HSE University, in collaboration with scientists from Russian and foreign universities, has investigated the impact of electrical brain stimulation on learning new words. The experiment shows that direct current stimulation of language centres—Broca's and Wernicke's areas—can improve and speed up the memorisation of new words. The findings have been published in Neurobiology of Learning and Memory.

Artificial Intelligence Improves Risk Prediction of Complex Diseases

Neural network models developed at the HSE AI Research Centre have significantly improved the prediction of risks for obesity, type 1 diabetes, psoriasis, and other complex diseases. A joint study with Genotek Ltd showed that deep learning algorithms outperform traditional methods, particularly in cases involving complex gene interactions (epistasis). The findings have been published in Frontiers in Medicine.

Cerium Glows Yellow: Chemists Discover How to Control Luminescence of Rare Earth Elements

Researchers at HSE University and the Institute of Petrochemical Synthesis of the Russian Academy of Sciences have discovered a way to control both the colour and brightness of the glow emitted by rare earth elements. Their luminescence is generally predictable—for example, cerium typically emits light in the ultraviolet range. However, the scientists have demonstrated that this can be altered. They created a chemical environment in which a cerium ion began to emit a yellow glow. The findings could contribute to the development of new light sources, displays, and lasers. The study has been published in Optical Materials.

Genetic Prediction of Cancer Recurrence: Scientists Verify Reliability of Computer Models

In biomedical research, machine learning algorithms are often used to analyse data—for instance, to predict cancer recurrence. However, it is not always clear whether these algorithms are detecting meaningful patterns or merely fitting random noise in the data. Scientists from HSE University, IBCh RAS, and Moscow State University have developed a test that makes it possible to determine this distinction. It could become an important tool for verifying the reliability of algorithms in medicine and biology. The study has been published on arXiv.

Habits Stem from Childhood: School Years Found to Shape Leisure Preferences in Adulthood

Moving to a big city does not necessarily lead to dramatic changes in daily habits. A study conducted at HSE University found that leisure preferences in adulthood are largely shaped during childhood and are influenced by where individuals spent their school years. This conclusion was drawn by Sergey Korotaev, Research Fellow at the HSE Faculty of Economic Sciences, from analysing the leisure habits of more than 5,000 Russians.