Production of Reactive Oxygen Species by the Reaction of Periodate and Hydroxylamine for Rapid Removal of Organic Pollutants and Waterborne Bacteria

Periodate (PI, IO4-) can be activated by hydroxylamine (HA), resulting in the rapid removal of organic pollutants within seconds. While the previous studies on PI-based advanced oxidation processes (AOPs) have proposed iodate radical ((IO3)-I-center dot) as the major reactive species, no evidence of (IO3)-I-center dot production was found in the present PI/HA system. Reactive oxygen species (ROS) including (OH)-O-center dot, HO2 center dot, and O-1(2) are proposed to be the main oxidants of the PI/HA system, which is supported by various tests employing the scavengers, chemical probes, and spin-trapping electron paramagnetic resonance (EPR) technique. To minimize the risk of toxic iodinated byproduct formation caused by reactive iodine species such as HOI and I-2, the molar ratio of HA/PI was optimized at 0.6 to achieve the stoichiometric conversion of IO4- to iodate (IO3-), a preferred nontoxic sink of iodine species. The PI/HA system also efficiently inactivated both Gram-positive and -negative bacteria with producing O-1(2) as the dominant disinfectant. The mechanism of ROS production was also investigated and is discussed in detail. This work offers a simple and highly efficient option for PI activation and ROS production which might find useful applications where urgent and rapid removal of toxic pollutants is needed.