Photocatalytic mineralization of disperse red 167.1 by cubic Cu2O nanoparticles: Experimental and theoretical approach

The monoazo dye Disperse Red 167.1 (DR167.1) is known as a carcinogenic pollutant in industrial textile wastewater. In the present study, cubic Cu2O morphology was synthesized and characterized by FESEM, XRD, BET/BJH, FTIR, and DRS techniques. We found the crystallite size was 24.96 nm by the Williamson-Hall. Also, the band gap energy was equal to 1.8 eV by Kubelka-Munk. To further understand the general structure and electron properties, theoretical density calculations were performed using DOML3, CASTEP and FHI- aims codes. The direct band gap was 1.298eV by (CASTEP) code and 1.886 eV by (FHI aims) code, which was calculated using Principle Density Function (DFT) calculations. We found that based on the selection rule (Delta L= +/- 1), two types of electronic transitions are possible: Electron transition from 3dCu to 3pCu orbitals and 2pO to 3dCu orbitals. Physicochemical parameters were calculated in photocatalytic degradation of DR167.1 by Cu2O nanoparticles. The oxidation results indicated that at pH equal to 6.44 without the presence of H2O2, 0.75 mg.L-1 of Cu2O, and color concentration of 210 mg.L-1 during 2 min, a considerable efficiency as large as 84.40 % was obtained. Removal under the visible light irradiation rose to 93.25% upon increasing the time to 40 min. The kinetics of this process obeyed from pseudo-second order model. From an isothermic point of view, the highest correlations and minimum error values belonged to the Fritz Schlunder, Koble Corrigan, and Tempkin isotherms respectively.