Hydroxylamine Promoted Goethite Surface Fenton Degradation of Organic Pollutants.

In this study, we construct a surface Fenton system with hydroxylamine (NHOH), goethite (α-FeOOH), and HO (α-FeOOH-HA/HO) to degrade various organic pollutants including dyes (methyl orange, methylene blue, and rhodamine B), pesticides (pentachlorophenol, alachlor, and atrazine), and antibiotics (tetracycline, chloramphenicol, and lincomycin) at pH 5.0. In this surface Fenton system, the presence of NHOH could greatly promote the HO decomposition on the α-FeOOH surface to produce ·OH without releasing any detectable iron ions during the alachlor degradation, which was different from some previously reported heterogeneous Fenton counterparts. Moreover, the ·OH generation rate constant of this surface Fenton system was 10-10 times those of previous heterogeneous Fenton processes. The interaction between α-FeOOH and NHOH was investigated with using attenuated total reflectance Fourier transform infrared spectroscopy and density functional theory calculations. The effective degradation of organic pollutants in this surface Fenton system was ascribed to the efficient Fe(III)/Fe(II) cycle on the α-FeOOH surface promoted by NHOH, which was confirmed by X-ray photoelectron spectroscopy analysis. The degradation intermediates and mineralization of alachlor in this surface Fenton system were then systematically investigated using total organic carbon and ion chromatography, liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry. This study offers a new strategy to degrade organic pollutants and also sheds light on the environmental effects of goethite.