Transient Chemiluminescence Assay for Real-Time Monitoring of the Processes of SO32--Based Advanced Oxidation Reactions

The hydroxyl radical (center dot OH) is a strong oxidizing agent in situ generated in advanced oxidation processes (AOPs) and crucial for assessing the performances of AOPs toward organic contaminants' degradation. Herein, we developed a specific luminescent probe, APDI (N' N'-di(propylethylenediamine)-perylene-3,4,9,10-tetracarboxylic diimide), to selectively detect center dot OH among diverse reactive oxygen species and other radicals. Based on the transient chemiluminescence (TCL) spectra, the in situ concentration profile of center dot OH within 0.01 s interval time in classical Fenton reactions and four kinds of SO32--based AOPs was obtained, which provides insights into the high dynamic processes of the whole center dot OH generation and consumption processes. Besides, compared with acidic conditions, reduced degradation efficiencies in Fe2+-SO32- and Fe2+-SO32--H2O2 systems were found under neutral conditions. The complete depletion of active free radicals due to SO2- radicals generated from Fe2+ and SO32- should account most for decreased degradation efficiencies evidenced by a new SO2* TCL signal discovered in the TCL spectra. In addition, similar phenomena have also been found in other M(n-1)+-SO32--related AOPs. As SO32- and HSO3- often exist naturally in wastewater, more efforts are needed to improve the performance of Fe2+-H2O2 systems. This discovery has important significance for organic contaminant degradation in a natural environment.

Automated summary

A specific luminescent probe was developed to selectively detect hydroxyl radicals, providing insights into the dynamic processes of hydroxyl radical generation and consumption.