Low-speed magnetic stirring activation of peroxymonosulfate with TiO2 nanoparticles as tribocatalyst for degradation of organic pollutants

Persistent organic pollutants represented by dyes and phenolics possess high chemical stability, strong toxicity, and considerable environmental persistence. Advanced oxidation processes (AOPs), which enable the in situ generation of diverse reactive oxygen species, have emerged as indispensable strategies for the efficient elimination of refractory organic contaminants. As a prominent oxidant, peroxymonosulfate (PMS) can be activated to generate sulfate radicals (SO₄•^-). Relative to conventional hydroxyl radicals, SO₄•^- exhibits a longer half-life, higher oxidation potential, and stronger degradation capacity, thereby rendering PMS-based AOPs highly attractive for the advanced remediation of organic wastewater.

Nevertheless, the efficient activation of PMS remains a prerequisite for the sustained production of SO₄•^-. Traditional activation routes, such as thermal activation, photo-irradiation, and ultrasonication, suffer from inherent drawbacks including excessive energy consumption, poor scalability, and strict requirements on the light transmittance of wastewater. On the other hand, tribocatalysis, a recently developed mechanical energy-driven catalytic paradigm, demonstrates exceptional merits including environmental friendliness, low energy consumption, and simple device configuration, making it a promising candidate for practical wastewater decontamination.

Recently, a team led by Wanping Chen from Wuhan University, China first explored low-speed (400 rpm) magnetic stirring activation of PMS with TiO₂ nanoparticles as tribocatalyst for degradation of organic pollutants. This work not only clearly reveals the potential of PMS in environmental remediation but also demonstrates a route to effectively convert low-intensity mechanical energy into chemical energy.

The team published their work in Journal of Advanced Ceramics on February 9, 2026.

“In this report, we conducted the investigation under conditions specifically modified for tribocatalysis, such as home-made PTFE magnetic rotary disks were driven to rotate at 400 rpm through magnetic stirring in which PTFE magnetic rods are usually used, and PTFE disks were coated on the bottoms of glass beakers in which the solutions were contained. These rather simple modifications are vital for achieving surprising tribcatalytic results,”said Wanping Chen, a professor at School of Physics and Technology at Wuhan University (China), who published his first paper on tribcatalytic degradation of organic dyes in 2019.

“Commercial TiO₂ nanoparticles have been adopted in this study to demonstrate the process for tribocatalytic activation of PMS. As a material with well-studied tribocatalytic performance, those effects from PMS addition can be clearly revealed.” said Wanping Chen.

Under the modified conditions, solutions of 50 mg/L RhB, MB, MO and 20 mg/L BPA all can be readily degraded by magnetic stirring-stimulated TiO₂ nanoparticles, except that no noticeable degradation happened to 20 mg/L phenol. With the addition of 200 mg/L PMS, the tribocatalytic degradation was greatly enhanced and all solutions, including 20 mg/L phenol, were degraded rather thoroughly in quite short periods of time, and their total organic carbon removals were substantially improved.

In accordance with the greatly enhanced tribocatalytic degradation, the formation of SO₄•^- and increased amounts of ·OH, O₂·⁻ , and ¹O₂ all were observed through electron paramagnetic resonance spectroscopy analyses for the PMS addition. “The tribocatalytic activation of PMS can be well explained in terms of the reaction between PMS and electrons from electron–hole pairs excited in TiO₂ nanoparticles by mechanical energy absorbed through friction. This result actually provides an evidence to the rather abstract tribocatalytic mechanism based on excitation of electron–hole pairs in semiconductors by mechanical energy in some sense.” said Wanping Chen.

Obviously, this is just a beginning for low-frequency mechanical energy tribocatalytic activation of PMS/PDS and many more investigations are highly desirable. In this regard, Chen put forward two kinds of investigations that deserve to be conducted immediately, namely characterizing tribocatalytic activation of PMS/PDS for more kinds of semiconductor materials, and exploring tribocatalytic degradation of more kinds of organic pollutants, especially those in real wastewater with the addition of PMS/PDS. It will be highly interesting if Co and Fe-containing materials that have been especially effective for photocatalytic activation of PMS/PDS can be proven to be similarly outstanding for tribocatalytic activation of PMS/PDS.

About Author

Wanping Chen holds a BSc and a Ph D in ceramics from Tsinghua University. He was a scientist at the Institute for Materials Research, Tohoku University, Japan from 1998 to 2001, and a post doc at Hong Kong Polytechnic University from 2001 to 2004. He has been a professor at School of Physics and Technology, Wuhan University, China since 2005.

Chen has conducted investigations on preparation and properties of various metal oxides-based functional materials for more than 30 years. His research interest began to cover the tribocatalytic behavior of metal oxide semiconductors in 2018 and a series of papers on tribocatalysis have been published subsequently from his laboratory.

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2024 IF is 16.6, ranking in Top 1 (1/34, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508