Naproxen as a Turn-On Chemiluminescent Probe for Real-Time Quantification of Sulfate Radicals

Current techniques for identifying and quantifying sulfate radicals (SO4·–) in SO4·–-based advanced oxidation processes (SR-AOPs) are unsatisfactory due to their low selectivity, poor reliability, and limited feasibility for real-time quantification. In this study, naproxen (NAP) was employed as a turn-on luminescent probe for real-time quantification of SO4·– in SR-AOPs. The chemiluminescence(CL) yield (ΦCL) of the reaction of NAP with SO4·– was first determined to be 1.49 × 10–5 E mol–1 with the bisulfite activation by cerium(IV) [Ce(IV)/BS] process. Then, the maximum peak concentrations of SO4·– in the Ce(IV)/BS-NAP process was quantified to be ∼10–11 M based on the derived equation. Since ΦCL of the reaction of NAP with SO4·– was much greater than that with other reactive oxidizing species (ROS), the developed CL method worked well in selective quantification of SO4·– in various SR-AOPs (e.g., the activation of peroxymonosulfate and persulfate by iron processes). Finally, the electron transfer from NAP to SO4·– was proposed to be the critical step for CL production. This work provides a novel CL method for real-time quantification of SO4·–, which facilitates the development of SR-AOPs and their application in water and wastewater treatment.