Abstract
A new Fe-based metallic glass with composition Fe76B12Si9Y3 (at. %) is found to have extraordinary degradation efficiency towards methyl orange (MO, C14H14N3SO3) in strong acidic and near neutral environments compared to crystalline zero-valent iron (ZVI) powders and other Fe-based metallic glasses. The influence of temperature (294–328 K) on the degradation reaction rate was measured using ball-milled metallic glass powders revealing a low thermal activation energy barrier of 22.6 kJ/mol. The excellent properties are mainly attributed to the heterogeneous structure consisting of local Fe-rich and Fe-poor atomic clusters, rather than the large specific surface and strong residual stress in the powders. The metallic glass powders can sustain almost unchanged degradation efficiency after 13 cycles at room temperature, while a drop in degradation efficiency with further cycles is attributed to visible surface oxidation. Triple quadrupole mass spectrometry analysis conducted during the reaction was used to elucidate the underlying degradation mechanism. The present findings may provide a new, highly efficient and low cost commercial method for azo dye wastewater treatment.
Highlights
Azo dyes represent about one-half of the dyes used in the textile industry
X-ray diffraction (XRD) results show the amorphous nature of the as prepared amorphous ribbons and the G-zero-valent iron (ZVI) powders ball-milled from R-ZVI (Fig. 1b)
The results show that both types of powders have a narrow particle size distribution ranging from a few to tens of micrometers and the average diameters for G-ZVI and crystalline ZVI powder (C-ZVI) are 21.9 and 26.5 μ m, respectively
Summary
Azo dyes represent about one-half of the dyes used in the textile industry. It has been reported that about 20% of dyestuff is discharged directly into the environment by textile factories[1,2]. Fe-based amorphous powders and metallic glass composites have been developed that demonstrate higher efficiency in the degradation of azo dyes and other organic contaminants compared to conventional iron powders[10,11,12]. Some Fe-based metallic glasses have been found to have high efficiency in degrading organic chemicals[10,11,12], many issues are still poorly understood and require further investigation This includes understanding the underlying mechanism of the degradation process, how it is influenced by the degradation environment and by the atomic and electronic configurations of the glass structure, and how to develop optimized Fe-based glass systems with higher degradation efficiency and service life. The effects of 1) annealing the G-ZVI powder, 2) changing the glass form (powder versus ribbon), and 3) changing the degrading environment were studied to elucidate the possible degradation mechanism
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