Preparation and characterization of Cu2O–ZnO immobilized on diatomite for photocatalytic treatment of red water produced from manufacturing of TNT

Cuprous oxide and zinc oxide composites have been successfully immobilized on natural diatomite by two-step deposition. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), ultraviolet–visible diffuse reflection absorptive spectroscopy (UV–vis/DRS), and Raman spectroscopy were used to characterize the materials. Gas Chromatography/Mass Spectroscopy (GC/MS) was employed to analyze the organic compositions of red water from TNT manufacturing. The zinc oxide content and the carrier affect the optical properties of the composites and the photocatalytic activity of the composites determined by visible-light-induced degradation of red water. The results show that when the molar ratio of ZnO versus Cu2O is 4:2.5, the Cu2O–ZnO/diatomite composite exhibits optimal optical properties and photocatalytic activity and can degrade 72.8% of red water under the irradiation of the visible light for 4 h, while Cu2O/diatomite and the non-immobilized Cu2O–ZnO can only degrade 33.3% and 39.5% of red water, respectively. Most of the organics except 1,3,5-trinitrobenzene can be effectively photocatalytically degraded.