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In this work, nano-sized mixed oxides of Mn3O4 and CuO were successfully prepared by a simple hydrothermal method and used as an effective heterogeneous sono-Fenton catalyst for p-nitrophenol (PNP) degradation at the neutral condition. The prepared nanocomposite was characterised by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and N2 adsorption–desorption analysis. The results showed that the Mn3O4.CuO nanocomposite can catalyze efficiently the decomposition of PNP under ultrasonic irradiation in comparison with pristine Mn3O4 and CuO. The almost complete degradation of PNP was achieved within 20 min at pH 8.0 by using 0.1 mol/L of H2O2 and 0.01 g of the catalyst. Also, the stability and reusability test showed that the prepared nanocomposite had good stability during the Fenton process. Finally, the main oxidative species involved in the sono-Fenton process based on the results of radical species trapping experiments were identified. [ABSTRACT FROM AUTHOR]

Release of dyes without performing adequate treatment into the water can lead to environmental risk and serious health problems. The development of effective and economic adsorbent materials for the removal of dyes from industrial wastewaters has gained great consideration in recent years. In the present study, a novel bio-based nanocomposite has been developed for ultrasoundassisted adsorption of malachite green (MG) from aqueous solutions. The synthesized adsorbent consisting of both hydrophobic surface and hydrophilic polar functional groups was prepared by covalent binding of epoxidized sunflower oil (ESFO) on the surface of silica-coated magnetite nanoparticles. The synthesized sorbent was characterized by FE-SEM, EDS, FT-IR, XRD, VSM and thermal analysis. The effects of experimental parameters including pH, amount of sorbent, temperature and uptake time were investigated for MG adsorption on Fe3O4@SiO2-ESFO sorbent using Box-Behnken design. At the optimized conditions, the adsorption capacity of the magnetic nanocomposite for MG was found to be 4.97 mg g1 according to the removal yield of 90.0%, while 88% of the adsorption occurred at the first 1 min, and the adsorption equilibrium was achieved in few minutes. The results showed that the proposed Fe3O4@SiO2-ESFO sorbent exhibits a strong adsorption affinity to MG, and the adsorption isotherms are well described by Freundlich model. A thermodynamic study of the adsorption indicated that MG adsorption on sorbent was an endothermic and spontaneous phenomena. [ABSTRACT FROM AUTHOR]

In the present study, a novel nanocomposite based on CuCo2O4 and N-doped graphene quantum dots (N-GQDs) as an iron-free heterogeneous Fenton-like catalyst was prepared by a two-step solvothermal method. The surface morphology, chemical structure, crystal phase, surface area and pore size distribution of the synthesized nanocomposite were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), Fourier Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmittance electron microscopy (HRTEM) and N2 adsorption–desorption analysis. The results showed that the N-GQDs play a significant role in the enhancement of the catalytic degradation of methylene blue (MB) as a model contaminant. The CuCo2O4/N-GQD nanocomposite exhibited a higher degradation rate of about 47 times higher than that of pristine CuCo2O4. This promotion can be attributed to the higher surface area of the CuCo2O4/N-GQD nanocomposite compared to pristine CuCo2O4 as well as the synergistic effects between the N-GQDs and CuCo2O4. The effects of pH, catalyst mass and the initial concentration of H2O2 on the catalytic degradation of MB were investigated using Box–Behnken design. Finally, the dominant reactive oxygen species generated in the degradation process were identified and the possible mechanism of the catalytic degradation of MB was proposed. [ABSTRACT FROM AUTHOR]

In the present study, a novel nanocomposite based on CuCo2O4 and N-doped graphene quantum dots (N-GQDs) as an iron-free heterogeneous Fenton-like catalyst was prepared by a two-step solvothermal method. The surface morphology, chemical structure, crystal phase, surface area and pore size distribution of the synthesized nanocomposite were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), Fourier Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmittance electron microscopy (HRTEM) and N2 adsorption–desorption analysis. The results showed that the N-GQDs play a significant role in the enhancement of the catalytic degradation of methylene blue (MB) as a model contaminant. The CuCo2O4/N-GQD nanocomposite exhibited a higher degradation rate of about 47 times higher than that of pristine CuCo2O4. This promotion can be attributed to the higher surface area of the CuCo2O4/N-GQD nanocomposite compared to pristine CuCo2O4 as well as the synergistic effects between the N-GQDs and CuCo2O4. The effects of pH, catalyst mass and the initial concentration of H2O2 on the catalytic degradation of MB were investigated using Box–Behnken design. Finally, the dominant reactive oxygen species generated in the degradation process were identified and the possible mechanism of the catalytic degradation of MB was proposed. [ABSTRACT FROM AUTHOR]

In this study, optimisation of the photocatalytic behaviour of crystal violet (CV) by thiourea (Tu)-codoped TiO2 thin film in fixed bed photoreactor was investigated by central composite designs (CCDs). The effective variables were pH, the concentration of CV dye, flow rate and reaction time. The results of the CCD model showed a good agreement with experimental results, with R² = 0.9680 (p < 0.0001) and maximum degradation efficiency was obtained at the optimum conditions: dye concentration 8.5 mg/L, pH 9, flow rate 6 mL/min and reaction time 80 min. Subsequently, three absorbing chemical compounds presented in the degradation reaction were obtained by using singular value decomposition (SVD) method and evolving factor analysis (EFA). Then a multivariate curve resolution with alternating least squares (MCR-ALS) was performed to achieve the concentration and spectral profiles for each component. Finally, a hard modelling method was applied to determine the kinetic constants of distinct reactions occurred in the photocatalytic degradation process. The reaction rate constants were calculated for the first and second steps as k1 = 0.08327 (SD = ±0.0015)/min and k2 = 0.045 (SD = ±0.0006)/min, respectively. [ABSTRACT FROM AUTHOR]