Chemiluminescence of 3-aminophthalic acid anion-hydrogen peroxide-cobalt (II)

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

The hydroxyl radical (·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 ·OH among diverse reactive oxygen species and other radicals. Based on the transient chemiluminescence (TCL) spectra, the in situ concentration profile of ·OH within 0.01 s interval time in classical Fenton reactions and four kinds of SO₃^2--based AOPs was obtained, which provides insights into the high dynamic processes of the whole ·OH generation and consumption processes. Besides, compared with acidic conditions, reduced degradation efficiencies in Fe²⁺-SO₃^2- and Fe²⁺-SO₃^2--H₂O₂ systems were found under neutral conditions. The complete depletion of active free radicals due to SO₂^-̇ radicals generated from Fe²⁺ and SO₃^2- 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)+-SO₃^2--related AOPs. As SO₃^2- 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.

Use of an Artificial Miniaturized Enzyme in Hydrogen Peroxide Detection by Chemiluminescence

Advanced oxidation processes represent a viable alternative in water reclamation for potable reuse. Sensing methods of hydrogen peroxide are, therefore, needed to test both process progress and final quality of the produced water. Several bio-based assays have been developed so far, mainly relying on peroxidase enzymes, which have the advantage of being fast, efficient, reusable, and environmentally safe. However, their production/purification and, most of all, batch-to-batch consistency may inherently prevent their standardization. Here, we provide evidence that a synthetic de novo miniaturized designed heme-enzyme, namely Mimochrome VI*a, can be proficiently used in hydrogen peroxide assays. Furthermore, a fast and automated assay has been developed by using a lab-bench microplate reader. Under the best working conditions, the assay showed a linear response in the 10.0-120 μM range, together with a second linearity range between 120 and 500 μM for higher hydrogen peroxide concentrations. The detection limit was 4.6 μM and quantitation limits for the two datasets were 15.5 and 186 μM, respectively. In perspective, Mimochrome VI*a could be used as an active biological sensing unit in different sensor configurations.