Ozonation inactivation of Escherichia coli in aqueous solution over MgO nanocrystals: modelling and mechanism

Abstract

BACKGROUND This study aims to reveal the potential of using heterogeneous catalytic ozonation processes (HCOP) in water disinfection and provide a direction to tailor the catalytic activity by crystal facet engineering. Four kinds of MgO nanocrystals individually with exposure of (111), (200), (110) and (100) facets were prepared and used. RESULTS It is found that MgO functions as a bactericide as well as a catalyst for ozonation. The catalytic activity of MgO nanocrystals decreases in the order MgO(111) > MgO(200) > MgO(110) > MgO(100). The apparent first‐order inactivation rate (kap) fitted by the Hom model of MgO(111)/O3 is 2.56 min‐1, which is 32.0 and 3.5 times that of single ozonation and classic MgO(100)/O3. It is confirmed by scavenger studies that •OH mainly works in MgO(111)/O3 while more direct ozonation occurs in other cases. Some O2•− are also detected in the presence of MgO. With the attack of these reactive oxidation species, cell membranes were damaged and intracellular components were released, leading to the death of Escherichia coli. CONCLUSION These results indicate that HCOP is a promising technology for water disinfection, and crystal facet engineering is an effective strategy to enhance the catalytic performance. © 2017 Society of Chemical Industry

Advanced Ozonation Processes for Water and Wastewater Treatment

“…Several MgO nanocrystals with different crystal facets of (111), ( 110), (100) and ( 200) have been synthesized and applied to investigate their reactivity in the catalytic ozonation of Escherichia coli. 64 Their catalytic capabilities follow the order of MgO(111)4MgO(200)4MgO(110)4MgO(100), indicating that the crystal facets play a crucial role in catalytic activity. This is also evidenced by scavenger experiments in which OH detected in the heterogeneous catalytic ozonation was the main ROS in the MgO(111)/O 3 system, while more direct ozonation and a portion of O 2 À can be observed in other catalytic ozonation processes.…”