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Photocatalytic reduction of Cr(VI) onto the spinel CaFe2O4 nanoparticles
Optik ( IF 3.1 ) Pub Date : 2020-09-16 , DOI: 10.1016/j.ijleo.2020.165610
H. Kenfoud , N. Nasrallah , O. Baaloudj , D. Meziani , T. Chaabane , M. Trari

The nanoparticles of the spinel CaFe2O4 (CFO) with a crystalline size of 34 nm were synthetized by nitrate route. The phase was identified by X-ray diffraction (XRD) and confirmed by the Fourier transform infrared (FTIR); the lattice constants were refined by the Rietveld method. The optical properties were measured by diffuse reflectance and a direct forbidden band of 1.93 eV was determined. Also, the photo-electrochemical properties were investigated to build the potential diagram of the junction CFO/HCrO4 solution in order to predict the interfacial phenomena. Curiously, CFO is n-type semiconductor with a flat band potential of -0.24 VSCE enough cathodic to be involved in an electronic exchange with the chromate species. Indeed, the thermal variation of the conductivity follows an experimental law with an activation energy of 0.17 eV. The oxide is stable against photo-corrosion in presence of oxalic acid which captures the photoholes and enhances the photoactivity through the separation of electron/hole pairs. The photo reduction of Cr (VI) under visible-light irradiation is improved on CFO nanocomposite. Herein, the effect of pH, CFO dose and Cr(VI) initial concentration (Co) on the photo reduction of Cr(VI) was investigated. An abatement of 86 % of HCrO4 was achieved under optimal conditions (pH ∼ 3, CFO dose 0.6 g/L, Co 30 ppm) upon illumination (16 mW cm-2). The photoactivity reached 100 % under solar light (98 mW cm-2).



中文翻译:

尖晶石CaFe 2 O 4纳米粒子上光催化还原Cr(VI)

尖晶石CaFe 2 O 4(CFO)的纳米粒子具有34 nm的晶体大小通过硝酸盐路线合成。通过X射线衍射(XRD)鉴定相,并通过傅立叶变换红外(FTIR)证实。晶格常数通过Rietveld方法精制。通过漫反射测量光学性质,并确定1.93eV的直接禁带。此外,光电化学性能进行了研究来构建结CFO / HCRO的电势图4 -溶液中,以预测界面现象。奇怪的是,CFO是平带电势为-0.24 V SCE的n型半导体足够的阴极参与与铬酸盐物质的电子交换。实际上,电导率的热变化遵循实验定律,其活化能为0.17 eV。该氧化物在草酸的存在下对光腐蚀是稳定的,草酸会捕获光孔并通过电子/空穴对的分离增强光活性。在CFO纳米复合材料上,可见光照射下Cr(VI)的光还原得到了改善。在此,研究了pH,CFO剂量和Cr(VI)初始浓度(C o)对Cr(VI)光还原的影响。的HCRO的86%消减4 -最佳条件(pH〜3,CFO剂量为0.6g / L,C下达到ö 30ppm的)照射时(16毫瓦厘米-2)。在太阳光(98 mW cm -2)下,光活性达到100%。

更新日期:2020-09-16
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