Rapid degradation of metamitron and highly complex mixture of pollutants using MIL-53(Al) integrated combustion synthesized TiO2

In the present work, we report a new approach for the synthesis of TiO₂-MIL-53(Al) (MIL: Matériaux de l′Institut Lavoisier) nano-composite. The integration of microwave synthesized metal organic framework (MOF) with combustion synthesized metal oxide is reported for the first time. The synthesized materials were characterized using an X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscope, energy dispersive X-ray spectroscope, energy dispersive X-ray fluorescence, porosimeter, and UV–visible diffuse reflectance spectroscope. The diffraction pattern of the composite indicated the presence of TiO₂ as well as MIL-53(Al). Furthermore, the presence of anatase–rutile mixed phase of TiO₂ in the synthesized material was observed. The Fourier transform infrared spectrum was in support of XRD observations. A significantly low surface area and porosity of the composite material, compared to its parent components, was observed. The surface micrograph image of the composite depicted its nano-sheet type morphology. The energy dispersive X-ray analysis confirmed the presence of Ti, Al, C and O in the composite material. The composite material exhibited a narrow band-gap compared to the pristine MIL and TiO₂.As an application, the photocatalytic activity of synthesized material was determined by the degradation of metamitron. The application part is also one of the novelties of the present work. The effect of catalyst loading, initial concentration of metamitron and presence of inorganic ions on the photocatalytic degradation was investigated. The reusability of the composite material was evaluated. A plausible mechanism of photocatalytic degradation is proposed based on radical scavenging experiments. To the best of our knowledge, to date, there is no study on the application of TiO₂-MOF composite for the photocatalytic degradation of herbicide. Further, the synthesized material was successfully used for the photocatalytic degradation of a complex mixture of pollutants comprising metamitron, methylene blue, rhodamine B and 2, 4-dichlorophenol. This is a first of its kind study to demonstrate the application of TiO₂-MOF composite for photocatalytic degradation of a highly complex mixed pollutant.     

A study of the photocatalytic degradation of metamitron in ZnO water suspensions

The photocatalytic degradation of the herbicide metamitron in water using ZnO under Osram ULTRA-VITALUX® lamp light was studied. The effect of the operational parameters such as initial concentration of catalyst, initial metamitron concentration, initial salt concentration (NaCl, Na₂CO₃ and Na₂SO₄) and pH was studied. The optimal concentration of catalyst was found to be 2.0 g/l. First-order rate constants were calculated for the uncatalysed reactions. On the base of the Langmuir-Hinshelwood mechanism, a pseudo first-order kinetic model was illustrated and the adsorption equilibrium constant and the rate constant of the surface reaction were calculated (0.119 l mg^− 1 and 0.836 mg l^− 1 min^− 1, respectively). The photodegradation rate was higher in acidic than in alkaline conditions. When salt effect was studied, it was found that sodium carbonate was the most powerful inhibitor used, while sodium chloride was the weakest one. A negligible inhibition was observed when the concentration of sodium chloride was 20 mM.The rate of photodecomposition of metamitron was measured using UV spectroscopy and HPLC, while its mineralization was followed using ion chromatography (IC), as well as total organic carbon (TOC) and total nitrogen (TN) analysis.Under the employed conditions, almost complete disappearance of 9 mg/ml of herbicide, 56% TOC and 34% TN removal, occurred within 4 h. The ion chromatography results showed that the mineralization led to ammonium, nitrite and nitrate ions during the process.     

除草剂苯嗪草酮的合成研究进展

苯嗪草酮是一种专利保护期已过,低毒、高效的除草剂,在国内有着较好的市场前景,概要地叙述了其性状、毒性、合成路线和展望。     

化工中间体苯乙酮酸的合成初探

概述化工中间体苯乙酮酸的合成方法及用途,介绍由苯乙酮经扁桃酸合成苯乙酮酸的情况。