Rapid removal of flutriafol in water by zero-valent iron powder

Abstract

A study of the effect of zero-valent iron (ZVI) powder is carried out for the first time on the degradation of flutriafol (( RS)-2,4′-difluoro-α-(1 H-1,2,4-triazol-1-ylmethyl)-benzhydryl alcohol, C 16H 13F 2N 3O), a bifluorinated soil and water persistent triazole pesticide using a laboratory scale device consisting of a 20 ml pyrex serum vials fixed to a Vortex agitator. Different amounts of ZVI powder (10–50 g l −1) at pH 6.6 and room temperature were investigated. Experiments showed an observed degradation rate k obs directly proportional to the surface of contact of flutriafol with ZVI. Flutriafol degradation reactions demonstrated first order kinetic with a half-live of about 10.8 ± 0.5 min and 3.6 ± 0.2 min when experiments were conducted at [ZVI] = 10 g l −1 into oxygenated and anoxic solutions, respectively. Three analytical techniques were employed to monitor flutriafol degradation and to understand solution and by-products behaviors: (1) A UV–Vis spectrophotometer; (2) a high performance liquid chromatography (HPLC) coupled with a photo diode array (PDA) and fluorescence detectors; (3) a similar HPLC coupled with a PDA and a mass spectrometer detectors equipped with an atmospheric pressure photoionization source. Results showed a complete disappearance of flutriafol after 20 min of contact with ZVI, the loss of fluorescence properties of the final by-products, the defluorination of the triazole pesticide via hydroxylation reaction and finally the hydrogenation of the triazole ring.