A study published in the Chemical Engineering Journal proposes a new approach to environmental remediation of pharmaceutical pollutants in water flows. This approach is based on a phenomenon known as “sparks,” which refers to the sparks that appear on the surface of a metal when it is subjected to plasma electrolytic oxidation (PEO).
During PEO, a metal part (in this case, aluminum) is immersed in a liquid to which an electrical voltage is applied. This results in the growth of an oxide coating. During the process, micro-electrical discharges, or sparks, appear. These sparks last for fractions of a second and cover a small area. However, they lead to very high temperatures, which is why they are nicknamed the “second sun.” This treatment is used on aluminum, magnesium, titanium, and other metal parts in the aerospace, automotive, medical, and electronics industries to create an oxide coating that improves the resistance of the material to corrosion and heat.
Materials produced with PEO are also used for water and wastewater treatment to degrade organic waste. Recently, a team led by Professor Ernesto Chaves Pereira from the Chemistry Department at the Federal University of São Carlos (UFSCar) in the state of São Paulo, Brazil, demonstrated that using the sparks themselves rather than the material can lead to much better results than those achieved with conventional methods. This work was supported by FAPESP (projects 19/27029-5 , 21/11630-1 , 21/12394-0 , 22/06219-3 , 22/05195-3 , and 24/07206-8 ).
The research aimed to develop a more efficient method of eliminating contaminants, a primary concern for scientists, managers, and public policymakers and regulators, as even low concentrations can cause adverse effects.
Once released into the environment, contaminants can affect living organisms and alter the ecological balance. In the case of antibiotics, they can favor the selection of resistant bacteria. Additionally, they are persistent, making them difficult to eliminate.
“Drugs are designed to be long-lasting and thus persist in the environment. Their degradation in nature is very complicated; they’re complex molecules, and in existing processes, the reaction doesn’t reach complete carbonization, that is, the transformation of the organic molecule into CO2 and water. The reaction is partial and stops at what we call reaction intermediates, organic byproducts that are sometimes even more toxic than the original molecule,” Pereira explains.
“About four years ago, the arrival of a postdoctoral researcher at our laboratory inaugurated work on environmental remediation, and given the complexity of the problem, we decided to try using sparks,” recalls the research coordinator. “Right from the first attempts, everything went very well,” he celebrates. The study involved researchers from the Center for Development of Functional Materials ( CDMF ) and the Center for Innovation in New Energies ( CINE ). The CDMF is a FAPESP Research, Innovation, and Dissemination Center ( RIDC ) based at UFSCar. The CINE is an Applied Research Center ( ARC ) established by FAPESP and Shell in 2018. It is based at the State University of Campinas (UNICAMP), the University of São Paulo (USP), and UFSCar, with the participation of eight other Brazilian institutions.
Experiments
The tests were performed on three pharmaceutical substances: the antibiotic ofloxacin, the anti-inflammatory diclofenac sodium, and the antidepressant fluoxetine. The substances were tested separately and in combination. High and low concentrations of the drugs were also considered. “In this case, environmental concentrations are low, which increases the difficulty of remediation. Thus, the results obtained at these low concentrations indicate the potential for application in real situations,” Pereira explains.
Another piece of data indicating this proximity to real-world situations is that the best results were obtained for the mixture of contaminants, the most common situation found in rivers and other waterways.
Unlike conventional methods, such as advanced catalysts using different materials, photocatalysis, biological treatments, and physical methods like adsorption, the use of sparks led to the carbonization of contaminants. In samples exposed to the procedure for 60 minutes, 58% of the diclofenac, 60% of the ofloxacin, and 93% of the fluoxetine were destroyed. In addition to these positive results, the method is much cheaper in terms of energy consumption.
“The study establishes the plasma generated during the PEO process as an innovative, efficient, and environmentally friendly platform for the remediation of pharmaceutical pollutants, filling a critical gap in current technologies by ensuring complete mineralization and eliminating risks associated with secondary pollution,” the UFSCar researcher says. “Along with this work published at the end of 2025, we also have promising results for bacteria and petroleum derivatives, and the patent has already been applied for, allowing the solution to move on to the next steps necessary for application,” he adds.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe .
Chemical Engineering Journal
An innovative method for environmental remediation using sparks formed during plasma electrolytic oxidation on aluminum foils
28-Nov-2025