Ozonation Catalyzed by CoxFe1 Layered Double Hydroxide for the Degradation of P-toluenesulfonic Acid

Catalyst of Fe–Co-layered double hydroxide (LDH) prepared by co-precipitation could effectively improve the degradation of pharmaceutical intermediate – p-toluenesulfonic acid (p-TSA) in the water during ozonation. The experimental results showed that under the condition of pH 7.9, catalyst dosage 0.1 g/L and aqueous ozone concentration 6.2 mg/L, 20 mg/L of p-TSA obtained a TOC removal percentage of 85%. To search for the mechanism of Fe–Co LDH catalytic ozonation and degradation of organic pollutants, hydroxyl radicals were measured with dimethyl sulfoxide (DMSO) and high-performance liquid chromatography (HPLC). The existence of hydroxyl radicals in catalytic ozonation system was also indirectly detected by observing the influence of quenching agents of HCO3− and PO43- on the p-TSA removal. Furthermore, we used electron paramagnetic resonance (EPR) to directly detect the hydroxyl radicals generated during the catalytic ozonation of p-TSA. The experiment results fundamentally revealed the mechanism of catalytic ozonation to degrade organic pollutants.