Tris (?-Chloroethyl) Phosphate Degradation Effects And Mechanisms By Two MIL-101(Fe)/Light/Oxidant Systems

Metal–organic frameworks?MOFs?are novel porous materials which have broad application prospects due to their diverse structures and easy customization.Yet,there are still various challenges in the application of heterogeneous photocatalysis for organic contaminants removal based on MOFs.Especially,it is still necessary to develop effective reaction systems and methods.In this study,to evaluate the degradation effectiveness of organophosphorus flame retardant,tris??-chloroethyl?phosphate?TCEP?,in aqueous matrixes,MIL-101?Fe?was prepared,and two photocatalytic systems were developed:MIL-101?Fe?/light/H₂O₂ and MIL-101?Fe?/light/S₂O₈^2-.The main results are as follows:1.TCEP removal efficiency in these two systems were explored by changing the light wavelength,reaction temperature,catalyst/oxidant ratio and other factors.Visible light at 420nm was the optimal wavelength,and acidic condition was benefit.Low temperature,high catalyst/oxidant ratio and anions inhibited the degradation of TCEP.2.Degradation pattern of TCEP in these two systems both showed S-shape curves,including a slow induction period and a rapid free radical oxidation process.The induction period involved the adsorption of reactants and the activation of photocatalysts,while the radical oxidation process of both systems conformed to follow pseudo-first-order kinetics.The reaction rate and removal rate are highly dependent on the reaction conditions.3.Based on high resolution mass spectrometry analysis,MIL-101?Fe?/420nm/H₂O₂ system found eleven degradation products.The mineralization rate of TCEP reached 80%under acidic conditions in 60 min.The MIL-101?Fe?/420 nm/S₂O₈^2-system had five degradation products and only 45%mineralization rate after 240 min degradation.The structural analysis of the proposed degradation products showed that the degradation pathways of TCEP included cleavage,hydroxylation,carbonylation and carboxylation.4.In the recyclability and stability degradation experiments,MIL-101?Fe?mass loss in these two systems were lower than 1%under acidic conditions?p H=3?.In the actual aqueous matrixes degradation experiment,both systems showed high performance on the TCEP degradation.Therefore,the MOF/photo/oxidant system can be a potential technology for eliminating organic pollutants in water.