Magnetic photocatalytic nano-semiconductors prepared from carbon quantum dots compounded with copper ferrate and their application in dye wastewater treatment

Abstract

To investigate new and potent photocatalytic materials for organic pollutants, in this work, copper ferrate (CuFe2O4) nanoparticles were synthesized by sol-gel combustion method and then combined with the microwave synthesis method to prepare CQDs/CuFe2O4, which was used for the degradation of methylene blue (MB) dye. Firstly, scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and electrochemistry were employed to validate the composite effect of CQDs/CuFe2O4. The MB removal (99.86%) was maximized under the optimal conditions (1.5% CQDs/CuFe2O4, 10 mg/L, pH 7.0). Meanwhile, the recycling performance after magnet adsorption and recovery and the effects of carbon quantum dots (CQDs) dosing (0.5% ∼ 3%), dye concentration (10 mg/L ∼ 30 mg/L), and pH (3.0 ∼ 11.0) on the degradation of MB dye by the CQDs/CuFe2O4 system were comprehensively investigated. Finally, based on the findings of the free radical scavenging experiments, the photocatalytic mechanism is proposed that the high catalytic activity of CQDs/CuFe2O4 is owed to its high specific surface area, narrow bandgap, and multiple active sites. On account of the introduction of the CQDs, the rate of electron mobility is improved and carrier complexation is reduced. In conclusion, the present work provides an effective photocatalytic system for removing organic pollutants by CQDs/CuFe2O4 composites at room temperature under neutral conditions.