Engineering a simple multisignal-output probe for measuring residual peroxymonosulfate in advanced oxidation reactions

Abstract

The extensive applications of peroxymonosulfate (PMS) in the field of environmental pollutant treatment based on advanced oxidation processes (AOPs) have prompted a high demand for advances in the probe ranging from improving their performances to strengthening their practicalities. Here, a multisignal-output probe of PMS was achieved by the unconventional application of traditional chromogenic system, 3,3′,5,5′-tetramethylbenzidine with Co2+ ions (Co2+-TMB). It works on the trace Co2+-catalyzed specific conversion of a colorless TMB into a blue oxidation product (oxTMB) with PMS as the oxidizing agent, accompanied by the enhanced absorption value of oxTMB at 652 nm and decreased fluorescence intensity of TMB at 405 nm. The change of color was directly observed. The combination of a hydrogel with a colorimetric platform favors the real-time and convenient sensing of PMS in the concentration range of 0.98 to 130.29 μM. A good linear relationship between the PMS concentration and both the absorption and fluorescence intensity was obtained with an r2 value of 0.999, and a detection limit of 0.03 μM for fluorescence and 0.11 μM for spectrometry. Such a multisignal output probe with the advantages of simplicity, convenience, high sensitivity and stability improves the reliability and practical adaptability. This study successfully applied a valuable strategy for sensing PMS, and verified its availability in detecting the residual quantity of PMS in pollutant water treated by AOPs and PMS concentrations in actual water samples with peroxydisulfate (PDS).