Chemists from St Petersburg University develop a new photocatalyst for water purification from organic compounds

In recent years, the content of organic pollutants in wastewater has surged due to the rapid global expansion of the chemical industry. Scientists are now focusing on the development and implementation of environmentally friendly technologies to mitigate the adverse effects on the environment.

The findings of the research supported by a grant from the Russian Science Foundation are published in the Q1 scientific journals: ACS Applied Nano Materials and Chemospher.

Among the various organic pollutants, two major classes stand out: dyes and antibiotics, which are particularly toxic at high concentrations. Dyes are widely used in the textile industry and the production of household chemicals, plastics, paints, and varnishes. Antibiotics, meanwhile, are extensively employed to treat human diseases, prevent infections in agriculture, and occasionally in fertiliser production.

These substances can enter wastewater during both production and use. For instance, non-persistent dyes are washed out of fabrics during laundering, while antibiotics are partially excreted with biological waste, entering wastewater and exerting long-term effects on natural biological processes. Consequently, slightly elevated concentrations of these pollutants are now present in most of the world’s major rivers. However, these levels currently have no significant adverse impact on the environment.

The chemists from St Petersburg University are actively researching and developing technologies to address this issue. Their innovations include a sorbent for removing antibiotics from contaminated water, a purification method involving nanoparticles, and zinc nanosheets for advanced water treatment systems.

As part of a new project supported by a grant from the Russian Science Foundation, the scientists from St Petersburg University have proposed using photocatalysis to eliminate organic pollutants, such as dyes and antibiotics. According to Evgenii Skripkin, a student at St Petersburg University and one of the researchers, photocatalytic material in water generates active radicals, also known as reactive oxygen species, under the influence of a light source. These reactive species effectively break down pollutants.

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. At the same time, 25% of the funded projects are led by early-career researchers. 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. St Petersburg University submitted 214 applications for the 2023 contest, and almost one in three of them was supported.

Different substances can serve as photocatalytic materials. To identify the most effective option, it is essential to systematically study the synthesis process, explore the relationship between synthesis conditions and the resulting nanoparticle parameters for each material, and develop an optimal production algorithm. Additionally, the efficiency of the purification process depends on the specific pollutant: a photocatalyst effective for one type of contaminant may be ineffective against another. 

"Even slight variations in synthesis conditions can significantly alter a material’s properties, either diminishing or markedly enhancing its effectiveness. For instance, the smallest nanoparticles may agglomerate into larger ones under certain conditions. By adjusting synthesis parameters, we can control this process and tailor the material’s properties to our needs," explained Olga Osmolovskaya, Associate Professor at the University, the leader of the group for synthesis and investigation of nanoparticles and nanostructured materials at St Petersburg University.

The chemists from St Petersburg University have developed tin dioxide-based photocatalysts and tested their efficiency. The materials demonstrated the ability to remove mixtures of antibiotics — sulphapyridine, sulphadimidine, and sulphamethoxazole — from water. 

The photocatalyst developed by the scientists achieved over 95% decomposition of antibiotics in 35 minutes and completely broke down a mixture of three dyes — methylene blue, methyl violet, and rhodamine 6G — within 20 minutes.

According to Mikhail Voznesenskiy, Associate Professor in the Department of Physical Chemistry at St Petersburg University, the primary advantages of this method are its waste-free nature and ease of implementation, as it does not require complex equipment or significant time and financial resources. The researchers’ development enables the replication of similar experiments for purifying water from other organic compounds. This project paves the way for the creation of composite materials that can be integrated into water treatment systems. The next phase of the scientists’ work at the University will focus on designing a prototype for such a system.

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 celebrated its 300^th 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 300^th 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 300^th 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 was a year of the 300^th anniversary of St Petersburg University in St Petersburg. On the day of the University’s 300^th 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 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 300^th anniversary of the University.