Catalytic degradation of sulfaquinoxalinum by polyester/poly-4-vinylpyridine nanofibers-supported iron phthalocyanine

Abstract

Iron (II) phthalocyanine (FePc) supported on electrospun polyester/poly-4-vinylpyridine nanofibers (PET/P4VP NFs) was prepared by stirring in tetrahydrofuran. The resulting product was confirmed and characterized by ultraviolet-visible diffuse reflectance spectroscopy, attenuated total reflection Fourier transform infrared spectra, X-ray photoelectron spectroscopy, gas chromatography/mass spectrometry, and ultra-performance liquid chromatography. More than 95% of sulfaquinoxalinum (SQX) could be removed by the activation of hydrogen peroxide in the presence of FePc-P4VP/PET with a PET and P4VP mass ratio of 1:1. This system exhibited a high catalytic activity across a wide pH and temperature range. The degradation rates of SQX achieved 100, 95, and 78% at a pH of 3, 7, and 9, respectively, and the degradation rates of SQX are more than 80% at the temperature ranging from 35 to 65 °C. DMSO₂ could be detected by gas chromatography/mass spectrometry after the addition of DMSO, suggesting the formation of the high-valent iron intermediates in this catalytic system. In addition, the electron paramagnetic resonance experiments proved that free radicals did not dominate the reaction in our system. Therefore, the high-valent iron intermediates were proposed to the main active species in the FePc-P4VP/PET/hydrogen peroxide system. In summary, the heterogeneous catalytic processes with non-radical catalytic mechanism might have better catalytic performance for the removal of organic pollutants, which can potentially be used in wastewater treatment.