Efficient enhancement of ozonation performance via ZVZ immobilized g-CN towards superior oxidation of micropollutants.

A functional organic-metal composite material zero-valent zinc immobilized graphitic carbon nitride (ZVZ-g-CN) was prepared by a fast and facile two-step synthetic approach with an optimal ZVZ content of 5.4 wt%. The structure, surface morphology and chemical composition of the as-synthesized ZVZ-g-CN were characterized by BET surface area, XRD, FT-IR, SEM, TEM, and XPS, respectively. ZVZ-g-CN composite exhibited superior catalytic ozonation activity with an improvement of 61.2% on atrazine (ATZ) degradation efficiency in 1.5 min reaction, more than 12 times of the pseudo-first-order rate constant, and almost 16-fold of the R value obtained in O/ZVZ-g-CN process compared to O alone. Meanwhile, the ATZ degradation efficiency was gradually enhanced with increasing ZVZ-g-CN dosage and initial solution pH in the range from 3.0 to 9.0, and a higher amount of ATZ was degraded when the initial concentration of ATZ rose from 1 to 10 mg L. The enhanced catalytic ozonation activity of ZVZ-g-CN is attributed to the synergistic effects among ZVZ, ZnO and g-CN, as well as the improved dispersibility, increased surface area, and intensive electron-transfer ascribed to the electronic and surface properties modification. The radical scavengers experiments demonstrated that O, OH, and O were the dominant reactive radical species in the multifunctional processes. Moreover, an empirical kinetic model was proposed to predict ATZ degradation. The results indicated that the ZVZ-g-CN composite was a highly efficient, recoverable, and durable catalyst, which would provide a promising alternative in catalytic ozonation.