Rational design of porphyrin-based ionophores for enhanced perchlorate selectivity in ion selective electrodes: application to fireworks wastewater analysis

The high-concentration perchlorate (ClO4−) wastewater discharged by the firework and firecracker industry poses a significant threat to the ecological security of the receiving water bodies and drinking water sources. In the context of the Internet of Things (IoT), monitoring high-concentration perchlorate wastewater necessitates intelligent control and management. This study introduces a liquid-contact ion-selective electrode (ISE) featuring novel porphyrin-based ionophores for the rapid, sensitive, and selective determination of perchlorate determination. The electrode features a poly(vinyl chloride) (PVC)-based membrane, typically called an ion-selective membrane (ISM), optimized with iron(III) meso-tetraphenylporphine chloride (Fe[III]TPPCl) as the ionophore, ortho-nitrophenyloctyl ether (NPOE) as the plasticizer, and tridodecylmethylammonium chloride (TDMACl) as the ionic additive. Systematic screening revealed Fe(III)TPPCl's superior performance over other metalloporphyrins, exhibiting a near-Nernstian slope (–68.42 ± 0.91 mV·decade–1), a low detection limit (LOD = 10−5 M), and strong anti-interference capability, particularly against sulfate (logKijSSM = –4.45). Optimization of membrane composition (1.1 wt% Fe[III]TPPCl, 65.6 wt% NPOE, 32.8 wt% PVC, 0.5 wt% TDMACl) enabled a wide linear range (10−5–10−1 M), fast response time (< 5 s), and stability across pH 2–10. The ISE was validated for real-sample analysis, achieving a mean recovery of 104.3% in spiked surface water and 96.4% in firework wastewater without pretreatment. Results correlated well with ion chromatography, confirming the electrode's accuracy. This work demonstrates a cost-effective, field-deployable sensor for ClO4− monitoring in complex environmental matrices, addressing critical regulatory compliance needs.