L. Khezami

Adsorption and photocatalytic degradation of malachite green by vanadium doped zinc oxide nanoparticles

Herein the degradation of malachite green (MG) dye from aqueous medium by vanadium doped zinc oxide (ZnO:V3%) nanopowder was investigated. The specific surface area and pore volume of the nanopowder was characterized by nitrogen adsorption method. Batch experimental procedures were conducted to investigate the adsorption and photocatalytic degradation of MG dye. Adsorption kinetics investigations were performed by varying the amount of the catalyst and the initial dye concentrations. Adsorption and photocatalytic degradation data were modeled using the Lagergren pseudo-first-order and second-order kinetic equation. The results showed that the ZnO:V3% nanopowder was particularly effective for the removal of MG and data were found to comply with Lagergreen pseudo-first-order kinetic model.

Nanoporous activated carbon for fast uptake of heavy metals from aqueous solution

AbstractA novel nanoporous activated carbon (NAC), based on organic xerogel compounds, was prepared at 650°C pyrolysis temperature by sol–gel method from pyrogallol and formaldehyde (PF-650) mixtures in water using perchloric acid as catalyst. The performance of NAC was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and nitrogen porosimetry. The metal uptake characteristics were explored using well-established and effective parameters including pH, contact time, initial metal ion concentration, and temperature. Optimum adsorptions of Co2+ and Cd2+ were observed at pH 6.0 and 7.0, respectively. Langmuir model gave a better fit than the other models, and kinetic studies revealed that the adsorption is fast and its data are well fitted by the pseudo-second-order kinetic model and thermodynamic properties, i.e. ΔG°, ΔH°, and ΔS°, showed that adsorption of Co2+ and Cd2+ onto NAC was endothermic, spontaneous, and feasible in the temperature range of 300–328 K.

Efficient Removal of Cobalt from Aqueous Solution by Zinc Oxide Nanoparticles: Kinetic and Thermodynamic Studies

Abstract This article deals with the removal of cobalt ions using zinc oxide nanopowder. The nanomaterial was prepared via the sol–gel method under supercritical drying. The nanomaterial was characterised via XRD, SEM, EDX, FTIR, and BET surface area techniques. The kinetics, equilibrium, and thermodynamic studies of the metal ions adsorption on the nanomaterial were conducted in batch mode experiments by varying some parameters such as pH, contact time, initial ion concentrations, nanoparticles dose, and temperature. The data revealed significant dependence of the adsorption process on concentration, and the temperature was found to enhance the adsorption rate indicating an endothermic nature of the adsorption. The adsorption complied well with the pseudo-second-order kinetics model. The adsorption process was found to match the Langmuir adsorption isotherm. The ZnO nanoparticles could successfully remove up to 125 mg·g−1 of Co(II) ions at elevated temperature. The metal ions adsorption could be described as an endothermic, spontaneous physisorption process. A mechanism for the metal ions adsorption was proposed.

Flower Buds Like MgO Nanoparticles: From Characterisation to Indigo Carmine Elimination

Abstract Here, we demonstrate a pyrolysis route for the synthesis of flower buds like magnesium oxide nanoparticles using a magnesium carbonate precursor without additional chemicals. The effect of heating at different time intervals upon the structure and morphology of the acquired nanostructures were investigated via X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and Fourier transformation infrared spectroscopy. Nitrogen adsorption was employed to study its porosity. The obtained data confirmed the formation of target nanoparticles that exhibited increasing sizes as pyrolysis time was lengthened. As a consequence a high surface area up to 27 m2 g−1 was recorded for the sample heated for 1 h duration. Furthermore, Indigo Carmine dye adsorption was carried out using the largest surface area species which showed an adsorption capacity of 158 mg g−1. The adsorption was found to comply with the Langmuir isotherm and it follows the pseudo-second-order kinetics. The diffusion process showed intra-particle along with film diffusion mode.