Enhanced catalytic ozonation performance of highly stabilized mesoporous ZnO doped g-C3N4 composite for efficient water decontamination

A series of functional organic-metal zinc oxide (ZnO) doped graphitic carbon nitride (g-C3N4) denoted as ZnO-CN composites were fabricated via a facile mixing and calcination approach. The composition, structure, and morphology of the as-prepared ZnO-CN composites were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, fourier transform infrared (FT-IR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. When loading amount of ZnO is 0.1 and calcination temperature is 650 degrees C (denoted as ZnO-CN0.1-650), the kinetic constant of atrazine (ATZ) degradation was 2.73 min(-)1, which was almost 10.5 times higher than that of ozone alone, exhibiting the highest catalytic ozonation activity. The results of the characterization indicated that ZnO-CN0.1-650 presents the mesoporous structure in laminated g-C3N4 and Zn(II) are strongly coordinated and stabilized within the electron-rich g-C3N4 framework. The feasibility of ZnO-CN0.1-650 for practical application was further evaluated at different catalyst dosages, initial ATZ concentrations, solution pHs, and natural organic matters. Radical scavengers experiments demonstrated that O-2(center dot-), OH, and O-1(2) are the dominant reactive radical species. In addition, the composite showed excellent stability for pollutants removal over multiple reaction cycles. A possible mechanism of the enhanced catalytic ozonation activity is attributed to the host-guest interaction between ZnO and g-C3N4, as well as the improved meso-porosity, increased surface area, and intensive mass and electron transfer ability ascribed to the electronic and surface properties modification. Overall, the ZnO-CN0.1-650 composite is demonstrated to be a highly efficient, stable, and recoverable catalyst, which provided a promising alternative in catalytic ozonation.