Preparation Of Ba_1-xSr_xTiO₃（x=0-0.3） Nanoparticles And Their Tribocatalytic Performance

The complex composition,high organic content,and difficult biochemical degradation of dye wastewater make it more challenging to treat it.However,the increasing emissions of dye wastewater can damage the environment and endanger human health.In recent years,tribocatalysis has shown great potential in degrading organic dyes.In tribocatalysis,the catalyst converts the collected mechanical energy into chemical energy by simply stirring and rubbing,followed by a redox reaction to produce active species to degrade organic dyes.Since the application of tribocatalysis for the degradation of organic dyes has been developed recently,the research on tribocatalysis is still in its infancy.Therefore,more investigations on tribocatalysis are needed.In this paper,the degradation performance of Ba_1-xSr_xTi O₃（x=0-0.3）nanoparticles with different strontium content on organic dyes under the action of friction was investigated.The effects of catalyst preparation methods,substitution doping,and friction devices on the tribocatalytic performance were investigated.The main conclusions are as follows:（1）To investigate the effect of catalyst preparation methods on tribocatalytic performance.The BaTi O₃ catalysts were prepared by solid-state,sol-gel,and hydrothermal assisted sol-gel methods,and the prepared catalysts were used for tribocatalytic degradation of rhodamine B dye.The dyes were degraded using a magnetic stirring device,and the three catalysts exhibited different degradation performance of the dyes after rubbing with the magnetic stirrer for 8 h.The results showed that the BaTi O₃catalyst prepared by the hydrothermal assisted sol-gel method achieved 53.1%degradation of the dye.The solid-state and sol-gel methods prepared catalysts degraded the dye by only 14.4%and 37.6%.The smaller particle size of the BaTi O₃ catalysts synthesized by the hydrothermal assisted sol-gel method indicates that the catalysts have a larger specific surface area,which is conducive to the exposure of more active sites,and then the redox reaction on the surface of the catalysts to generate active species to degrade dye.（2）To investigate the effect of substitution doping on tribocatalytic performance.The hydrothermal assisted sol-gel method was used as a catalyst preparation method,and Ba_1-xSr_xTi O₃（x=0-0.3）catalysts with different strontium contents were prepared by this method.The effect of strontium doping on the tribocatalytic degradation of rhodamine B by BaTi O₃ was investigated at room temperature and under shaded conditions.The results showed that strontium doping improved the degradation efficiency of the dye by BaTi O₃,and the degradation efficiency of the dye by Ba_0.8Sr_0.2Ti O₃ catalyst was 88%after 8 h of stirring and rubbing.In comparison,the dye degradation efficiency by the BaTi O₃ catalyst was only 53.1%.Electrochemical impedance spectroscopy analysis showed that the strontium doping improved the tribocatalytic performance of BaTi O₃ due to the enhancement of charge transfer efficiency.In tribocatalysis,the catalyst and the frictional effect it is subjected to are very critical for dye degradation.Active species detection experiments showed that there are hydroxyl radicals（·OH）,superoxide radicals（·O₂^-）,and holes（h⁺）generated in the tribocatalysis process.Combined with a series of tribocatalysis experiments,the mechanism of tribocatalysis degradation of dyes may be the effect of frictional charge transfer and internal electric field.（3）To investigate the effect of friction devices on tribocatalytic performance.Based on the characteristics of tribocatalysis,which requires friction between catalyst and friction pair,a ball mill degradation device and an electric stirring device were designed for dye degradation and compared with the magnetic stirring device for dye degradation.The degradation performance of the three friction devices for dye degradation was tested by varying experimental factors such as friction force,the material of the friction pair,or friction contact area.The results showed that the improvement of tribocatalytic performance could be achieved by increasing the friction force,increasing the friction contact area,and changing the material of the friction pair.In the study of the effect of the material of the friction pair on the dye degradation,the friction pair composed of polytetrafluoroethylene（PTFE）exhibited higher dye degradation performance.Notably,the electric stirring device showed super high dye degradation performance compared to the magnetic stirring device and the ball mill degradation device when the same material of the friction pair was used,and increasing the friction could accelerate the dye degradation,degrading more than 99%of rhodamine B in only 40 min.The active species detection experiments showed that the ball mill degradation device and the electric stirring device produced active species during the dye degradation process.