Enhancing acid orange II degradation in ozonation processes with CaFeO nanoparticles as a heterogeneous catalyst.

This study used CaFeO nanoparticles as a catalyst for ozonation processes to degrade Acid Orange II (AOII) in aqueous solution. The study compared heterogeneous catalytic ozonation (CaFeO/O) with ozone treatment alone (O) at different pH values (3-11), catalyst dosages (0.25-2.0 g L), and initial AOII concentrations (100-500 mg L). The O alone and CaFeO/O systems nearly completely removed AOII's color. In the first 5 min, O alone had a color removal efficiency of 75.66%, rising to 92% in 10 min, whereas the CaFeO/O system had 81.49%, 94%, and 98% after 5, 10, and 20 min, respectively. The O and CaFeO/O systems degrade TOC most efficiently at pH 9 and better with 1.0 g per L CaFeO. TOC removal effectiveness reduced from 85% to 62% when the initial AOII concentration increased from 100 to 500 mg L. The study of degradation kinetics reveals a pseudo-first-order reaction mechanism significantly as the solution pH increased from 3 to 9. Compared to the O alone system, the CaFeO/O system has higher values. At pH 9, the value for the CaFeO/O system is 1.83 times higher than that of the O alone system. Moreover, increasing AOII concentration from 100 mg L to 500 mg L subsequently caused a decline in the values. The experimental data match pseudo-first-order kinetics, as shown by values of 0.95-0.99. AOII degradation involves absorption, ozone activation, and reactive species production based on the existence of CaO and FeO in the CaFeO nanocatalyst. This catalyst can be effectively recycled multiple times.