In sharp contrast to photocatalysis and other prevalent catalytic technologies, tribocatalysis has emerged as a promising technology to degrade high-concentration organic dyes in recent years. In this study, BaTiO₃ (BTO) nanoparticles were challenged to degrade methyl orange (MO) solutions with unprecedentedly high concentrations through magnetic stirring. With BTO nanoparticles and home-made PTFE magnetic rotary disks in 50 mg/L MO solutions, 10 h of magnetic stirring resulted in 91.4% and 98.1% degradations in an as-received glass beaker and in a beaker with a PTFE disk coated on its bottom, respectively. Even for 100 mg/L MO solutions, nearly complete degradation was achieved by magnetic-stirring-stimulated BTO nanoparticles in beakers with the following four kinds of bottom: 97.3% degradation in 30 h for a glass bottom, 97.4% degradation in 20 h for a PTFE coating, 97.9% degradation in 42 h for a Ti coating, and 97.4% degradation in 74 h for an Al₂O₃ coating. Electron paramagnetic resonance (EPR) analyses revealed that the generation of reactive oxygen species (ROS) by magnetic-stirring-stimulated BTO nanoparticles is dramatically affected by the bottom material of beakers. These findings suggest an appealing prospect for BTO nanoparticles to utilize mechanical energy for sustainable water remediation.

This study presents a waste-valorization strategy by developing calcined natural shell particles (CNSP) derived from waste oyster shells as an efficient tribocatalyst for degrading high-concentration organic pollutants, a challenge for which conventional photocatalytic approaches are hindered by light shielding. The CNSP catalyst, confirmed as calcite CaCO₃ with low surface area and stable crystalline structure, demonstrated exceptional efficacy in degrading Rhodamine B (RhB) solutions across a wide concentration range (50–300 mg/L) under mechanical friction, achieving 99% removal of 50 mg/L RhB in 1 h and 300 mg/L RhB in 18 h with a 0.5 g catalyst. This catalyst maintained a degradation efficiency of over 95% in a continuous six-cycle process. Mechanistic studies revealed that the tribocatalytic process generates reactive oxygen species (ROS), primarily hydroxyl ($•\mathrm{O}\mathrm{H}$) and superoxide ($•{{\mathrm{O}}_2}^{-}$) radicals, which drive the decomposition of dye molecules. Electron paramagnetic resonance (EPR) spectroscopy directly confirmed the generation of these radicals. These findings establish CNSP as a promising, low-cost, and environmentally benign catalyst for wastewater treatment. This work not only provides a novel strategy for high-concentration dye removal but also reduces the environmental burden of aquaculture shell disposal. Further work is needed to evaluate its performance in real industrial effluents and with mixed pollutants.