Cobalt species immobilized on nitrogen-doped ordered mesoporous carbon for highly efficient catalytic ozonation of atrazine

The strategy of coupling transition metal and N-doped carbon catalysts have garnered great attention in catalytic ozonation. To overcome the inferior mass transfer of O3, we prepared a hetero-structure catalyst (Co3O4@Co-N-CMK3), which was composed of Co3O4 nanoparticles (NPs) and cobalt-nitrogen doped ordered mesoporous carbon. Co3O4@Co-N-CMK3 displayed a uniformly arranged long-range mesoporous channel structure with large surface area (537.24 m2/g). The adsorption efficiency of ATZ (10 mu M) was 55% at 15 min in presence of 0.05 g/L catalyst. After aeration of 3.5 mg/L O3 gas (50 mL min-1), the ATZ removal increased to 99.6% with rate constant of 0.354 min -1 in Co3O4@Co-N-CMK3/O3, 35.4-fold that in ozonation. The turnover frequency (TOF) value of Co3O4@Co-N-CMK3 reached 7.08 min-1 g-1, which was 2.2-93.2 folds higher than the reported ozonation catalysts. Co3O4@Co-N-CMK3 displayed the adsorption performance for ATZ and could activate O3 into center dot O2- and center dot OH effectively. The equivalent to Co2+ and equivalent to Co-Nx were main active sites. The synergy between Co3O4 and Co-N-CMK3 accelerated interface electron transfer, which was conducive to the redox of equivalent to Co2+/equivalent to Co3+. The degradation pathway and intermediates toxicity were speculated using HPLC-MS measurement and Toxicity Estimation Software Tool simulation. The stability of Co3O4@Co-N-CMK3 for ATZ removal was certified by five consecutive experiments in catalytic ozonation. Moreover, the Co3O4@Co-N-CMK3/O3 process had good applicability to common anions and humic acid, real water and different pollutants.