Chemists from St Petersburg University create zinc nanosheets for wastewater treatment
Scientists from St Petersburg University have developed a method for producing uniquely shaped zinc oxide nanoparticles — nanosheets — that can be utilised in water purification systems to remove toxic organic compounds, including dyes and antibiotics.
Organic compounds — such as dyes and antibiotics — are toxic and must be properly disposed of when used at home to minimise their impact on the environment.
Specialised services and facilities are available for this purpose, but not everyone has access to them. As a result, harmful substances are often discharged into the sewage system along with wastewater from industrial plants and livestock farms.
The results of the research supported by a grant from the Russian Science Foundation are published in the top-rated Q1 scholarly journal Ceramics International.
Olga Osmolovskaya is the leader of the group for synthesis and investigation of nanoparticles and nanostructured materials at St Petersburg University and Associate Professor in the Department of General and Inorganic Chemistry. She explained that one of the most promising modern approaches to addressing water pollution is photocatalysis. Photocatalysis is a process in which semiconductor particles break down pollutant molecules under light exposure through a chemical reaction.
However, to develop an effective photocatalyst, it is essential to understand the specifics of its functionality. To this end, the chemists from St Petersburg University synthesised a series of nanoparticles through chemical precipitation and examined the properties of the resulting materials to uncover the true mechanism of their action, which is critical for their practical application.
Scientists are well aware that nanoparticle properties are highly dependent on their size and shape. In this study, the synthesised particles are approximately 20 nanometres thick and take the form of plates, which is why they are called nanosheets. As part of the study, the chemists tested an approach where, in addition to varying the synthesis conditions — the primary factors influencing the outcome — substances providing interfering ions were introduced into the reaction medium. These interfering ions helped arrange the forming crystals in a specific order, ultimately resulting in the production of nanosheets.
To visualise the results, one can imagine an ordinary tree leaf. Its large surface area collects dew droplets, analogous to the surface of nanosheets where contact with pollutants and their subsequent destruction occurs. However, like a leaf, nanosheets also have lateral surfaces, which, although thinner, play a crucial role. We have demonstrated that in nanosheets, it is the lateral surface that is responsible for generating radicals — special forms of water molecules and dissolved oxygen that break down harmful molecules.
Ksenia Meshina, a co-author of the study, Research Laboratory Assistant in the Department of General and Inorganic Chemistry at St Petersburg University
Mikhail Voznesenskiy, another author of the study, Associate Professor in the Department of Physical Chemistry at St Petersburg University, highlighted that the research is unique in that it uses quantum chemical calculations. Such a detailed level of analysis allows for the consideration of defects in the crystal structure of nanoparticles and provides valuable insights into the processes of adsorption and photocatalysis.
The approaches developed by the research team at St Petersburg University make it possible to explain the efficiency of the photocatalyst for each specific pollutant. An additional advantage of the approach is that zinc oxide, the material used in the study, is non-toxic and possesses antibacterial properties, making it both environmentally friendly and biocompatible.
The interdisciplinary research, which integrated methods from physical, inorganic, computational, and analytical chemistry as well as materials science, was conducted at the St Petersburg University Research Park. The research was conducted using the equipment of the following resource centres: the Centre for X-ray Diffraction Studies; the Centre for Innovative Technologies of Composite Nanomaterials; the Chemical Analysis and Materials Research Centre; the Computing Centre; the Centre for Optical and Laser Materials Research; the Centre for Physical Methods of Surface Investigation; the Cryogenic Department; and the Interdisciplinary Resource Centre for Nanotechnology.
The research project under which this study was conducted was supported by a grant from the Russian Science Foundation. St Petersburg University is the leader in the number of grants from the Russian Science Foundation: in 2022, St Petersburg University researchers received 112 grants, which is 5.5% of the total number of winning projects and the largest number of grants for one organisation. In 2023, the University maintained its leadership in this contest of the Russian Science Foundation: scholars from St Petersburg University received 70 grants, which is 5% of the total number of winning projects. This November, specialists from St Petersburg University, using the equipment at the Interdisciplinary Resource Centre for Nanotechnology at the St Petersburg University Research Park, created a congratulatory inscription on the University’s badge to mark the 10th anniversary of the Russian Science Foundation.
"Experiments on dye decomposition using light and computational chemistry methods have led to the development of a material capable of removing more than 90% of certain pollutants from water. At the same time, it is important to acknowledge that there is no universal photocatalyst: a material effective for one pollutant may not work for another. This makes it essential to fine-tune the parameters of the photocatalyst for efficient wastewater treatment tailored to specific pollutants. The results of our work enable us to achieve this much more quickly by reducing the number of experiments needed through the use of computer calculations," said Mikhail Osmolowsky, Associate Professor in the Department of General and Inorganic Chemistry at St Petersburg University.
Previously, scientists in this research group developed a method for synthesising magnetite nanoparticles coated with a zinc oxide shell.
St Petersburg University, the oldest university in Russia, was founded on 28 January (8 February) 1724. This is the day when Peter the Great issued a decree establishing the University and the Russian Academy of Sciences. Today, St Petersburg University is an internationally recognised centre for education, research and culture. In 2024, St Petersburg University celebrates its 300th anniversary.
The plan of events during the celebration of the anniversary of the University was approved at the meeting of the Organising Committee for the celebration of St Petersburg University’s 300th anniversary. The meeting was chaired by Dmitry Chernyshenko, Deputy Prime Minister of the Russian Federation. Among the events are: the naming of a minor planet in honour of St Petersburg University; the issuance of bank cards with a special design; and the branding of the aircraft of the Rossiya Airlines to name just a few. To mark the 300th anniversary of St Petersburg University, a postage stamp depicting the Twelve Collegia building and the monument to Count Sergey Uvarov was issued. Also, a Soyuz rocket bearing the symbols of the University was launched from the Baikonur Cosmodrome.
By the decision of the Governor of St Petersburg Alexander Beglov, 2024 is a year of the 300th anniversary of St Petersburg University in St Petersburg. On the day of the University’s 300th anniversary torches were lit on the Rostral Columns on the Spit of Vasilyevsky Island. St Petersburg University flags were raised on the Palace Bridge. The city public transport was decorated with the University’s symbols. During St Petersburg’s City Day celebrations in May 2024, St Petersburg University acted as a participating venue. Additionally, the University has launched a website dedicated to the anniversary. The website contains information about outstanding University staff, students, and alumni; scientific achievements; and details of events held as part of the celebration of the 300th anniversary of the University.