Catalytic ozone oxidation of m-cresol by spirulina biochar-modified perovskite: Catalyst deactivation and in situ regeneration

In this study, a LaFe0.26Mn0.74O3-δ perovskite catalyst modified using spirulina biochar (LFMO-xBiochar) was used to compare the effects of water flushing on the ozonation performance on a pilot scale. The results showed that timely water flushing operation could effectively extend the service life of LFMO-xBiochar and maintain the chemical oxygen demand (COD) removal rate above 60% for nearly 40 h during the reaction. Density functional theory (DFT) calculations showed that the protonated Fe, Mn, and oxygen vacancies on the catalyst surface were the main active sites. Combined with SEM/EDS mapping, BET, FTIR and XPS measurements, the results showed that organic pollutants and deposits hindered the ozone decomposition at the active sites on the catalyst surface, leading to its final deactivation. However, timely water flushing could effectively remove the organic pollutants and inorganic salts adsorbed onto the catalyst surface during the initial deactivation stage. Additionally, water flushing loosened or removed surface deposits, re-exposing the active sites and restoring some pores, thereby promoting the catalyst regeneration and prolonging its service life. This study provides new insights into the deactivation and regeneration of ozonation catalysts, which can support practical industrial applications of this process.