Study of the Interaction of Heavy Metals (Cu(II), Zn(II)) Ions with a Clay Soil of the Region of Naima-Tiaret-Algeria

The RM (RM stands for the pristine clay) collected from sites in the Naima-Tiaret-Algeria and its purified phase TM (TM stands for the treated clay) were characterized using XRF, XRD, FT−IR, SEM−EDX, and DC electrical conductivity techniques. The as-prepared clays were used as potential adsorbents for the removal of Cu2+ and Zn2+ metals ions. Highly purified clay TM, exhibiting a basal, spacing of 25.83 Å and CEC of 51 meq/100 g, was obtained. The type of interstratified I/M in the studied sites is S=1, based on the calculation method of Watanabe. The percentage of illite type S=1 is between 80−85% illite. The adsorption equilibrium was established in 60 min with the capacities of 28.57 and 24.39 mg/g for Cu2+ onto RM, 32.25 and 4.95 mg/g for Zn2+ in the presence of TM. D-R isotherm model was more suitable with the adsorption process than Freundlich and Langmuir models suggesting the ion exchange nature of the retention mechanism in most cases (E > 8 kJ/mol). Pseudo second-order model best described the kinetics of adsorption process. The adsorption mechanism was mainly monitored by ion exchange mechanism between exchangeable interlayer cations (Na) in the interstratified I/M and Cu2+ or Zn2+ metals from aqueous matrix. Further, the release of H+ ions from the edge of the layer structure in acidic environments promote the adsorption of heavy metals onto the surfaces interstratified I/M clay soils via electrostatic attraction. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

NZF Nanoscale Particles: Synthesis, Characterization and its Effective Adsorption of Bromophenol Blue

The ferrospinels NixZn1_xFe2O4 (x = 0.0 and 0.6) nanoparticles (NPs) were successfully prepared by a sol-gel method and analyzed by TGA/DTA, XRD, SEM-EDS, UV-Vis-DRS, and pHIEP. The adsorption potential of NZF NPs towards the Bromophenol blue (BPB) dye was investigated. The batch adsorption efficiency parameters were studied including contact time, pH, initial dye concentrations and catalyst dosage. Results indicated that NZF crystallized in single-phase and exhibited smaller crystallite size (49 nm vs. 59.24 nm) than that of the pristine (ZF). The SEM analysis showed that the materials are elongated-like shape. NZF catalyst showed a red-shift of absorption bands and a more narrowed band gap (2.30 eV vs. 1.65 eV) as compared to ZF. The adsorption process was found to be highly dependent to the pH of the solution, dye concentration and adsorbent dose. Under optimum conditions of 5 mg.L–1 BPB, 0.5 g.L–1 NZF catalyst, pH = 6, and 25 °C, up to ≈ 86.30%  removal efficiency could be achieved after 60 min. Pseudo-second-order kinetic model gave the best fit with highest correlation coefficients (R2 ≥ 0.99). A high specific surface area, a stabilized dispersion state of NZF NPs and the electrostatic interaction between the BPB-2 anions and the NZF-H3O+active sites on NZF surface were believed to be the main factors that can be responsible for the high adsorption efficiency. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Urea-Assisted Synthesis of Mesoporous TiO(2) Photocatalysts for the Efficient Removal of Clofibric Acid from Water

International audienceMesoporous TiO(2) photocatalysts intended for the advanced removal of clofibric acid (CA) from water were synthesized by the sol-gel method in a medium containing cetyl-trimethyl-ammonium bromide (CTAB) and urea, using either ethanol or isopropanol to dilute the TiO(2) precursor. The activation of the samples was undertaken at 550, 650 and 750 °C. The XRD revealed that the nature of the solvent resulted in significant differences in the anatase-to-rutile ratios obtained at different temperatures. The specific surface area values were situated between 9 and 43 m(2)·g(-1) and the band gap values were similar for all the samples. The photocatalytic activity of the prepared samples was examined for the degradation of CA, an emergent water contaminant. The photocatalytic tests performed under UV-A irradiation revealed that the photo-reactivity of these materials depends on the calcination temperature. The best results were obtained for the samples calcined at 750 °C, which showed high yields of CA elimination, as well as almost complete mineralization (over 95%) after 180 min of reaction. Good results in terms of catalyst reusability in the reaction were found for the catalyst showing the highest photo-reactivity. Therefore, the samples can be considered good candidates for future water remediation applications

Preparation and characterization of p–n heterojunction CuBi2O4/CeO2 and its photocatalytic activities under UVA light irradiation

CuBi2O4/CeO2 nanocomposites were synthesized by the solid state method and were characterized by a number of techniques such as X-ray diffraction, scanning electron microscopy and UV–Vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was investigated under UVA light and assessed using Congo red (CR) dye as probe reaction. The efficiency of the coupled CuBi2O4/CeO2 photocatalyst was found to be related to the amount of added CuBi2O4 and to the pH medium. The CuBi2O4/CeO2 photocatalyst exhibited the high efficiency as a result of 83.05% of degradation of CR under UVA light for 100 min of irradiation time with 30 wt% of CuBi2O4 at 25 °C and pH 7, which is about 6 times higher than that of CeO2. The photodegradation reactions satisfactorily correlated with the pseudo-first-order kinetic model. The mechanism of the enhanced photocatalytic efficiency was explained by the heterojunction model

Synthesis, characterization, and optical properties of visible light-driven Bi2S3 nanorod photocatalysts

We report a simple and large-scale one-pot method for the synthesis of Bi2S3 nanorods by using the complexation of Bi(NO3)3??5H2O and Na2S??9H2O precursors. The as-synthesized photocatalyst was characterized by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, high-resolution X-ray photoelectron spectroscopy, UV-vis spectroscopy, N2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric and differential thermal analysis measurements. The photocatalytic performance of the Bi2S3 nanorods was evaluated for the photodegradation of phenol red under visible light irradiation. The orthorhombic Bi2S3 photocatalyst exhibited a 99% photocatalytic efficiency at 100 min under visible light irradiation, which is ascribed to the high specific surface area and crystallinity. The active sites on the Bi2S3 photocatalyst diminished the unwanted recombination of charge carriers within the photocatalyst