Publications Internationales

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Subject: search.filters.subject.Congo Red

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    Co-Precipitation Synthesis of NiFe2O4 Using NH4HCO3 as Precipitant: Characterization and Photocatalytic Degradation of Organic Pollutant
    (Pleiades Publishing, 2024) Saadi S.; Kezzim A.; Irekti, Amar; Nas, Mehmet Salih; Guettaf, M.
    Structural properties and the photocatalytic activity of the synthesized NiFe2O4 via co-precipitation process using NH4HCO3 as a precipitating agent were studied. The resulting sample was calcined at 550°C and the formation of pure ferrite phase with spinel structure was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy methods. The morphology of this spinel was investigated using a scanning electron microscopy (SEM). The optical absorption spectroscopy obtained the optical band gap (Eg = 1.81 eV). This material was applied as a photocatalyst for the photodegradation under UV light of Congo Red (CR) a persistent and recalcitrant dye. The effect of catalyst dose, initial concentration, and pH on photocatalytic degradation was investigated. Degradation efficiency of 82% was achieved for 3 h with a catalyst dose of 0.5 g/L. Furthermore, the material exhibited better photocatalytic activity in an alkaline medium, and the degradation kinetics followed a pseudo-first-order reaction.
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    Synthesis, characterization and application of tetragonal BaTiO3-δ in adsorption and photocatalysis of congo red
    (Elsevier, 2023) Merrad, S.; Abbas, Moussa; Brahimi, R.; Bellal, B.; Trari, M.
    The synthesis by a simple approach of the deficient Barium Titanate BaTiO3-δ (BTO) crystallizing in a perovskite structure is reported along with the physicochemical properties. Thermal analysis (TG/DSC) was performed to elucidate the synthesis process. The X-ray diffraction (XRD), BET analysis, scanning electron microscopy (SEM-EDS) and electrochemistry were investigated. The catalyst revealed a single phase with a tetragonal symmetry obtained by treatment at 650 °C. The direct band gap (3.34 eV), obtained from diffuse reflectance spectroscopy (DRS), is assigned to the charge transfer O2-: 2p-Ti4+: 3d. The electrical characterization indicated a non-degenerate conductivity due to oxygen vacancies with an activation energy of 0.33 eV. The capacitance measurements indicated n-type behavior with a flat band potential (Efb) of − 0.43 V and a carrier concentration (ND) of 3.90 1018 cm−3. The photocatalytic process was elucidated by the electrical impedance spectroscopy (EIS). The performance of BTO was assessed by a combination of the adsorption of Congo Red (CR) followed by its degradation under UV light. The photodegradation kinetic was well fitted by a pseudo-first-order model with an abatement of 50% and 91% under UV and solar lights respectively. Different scavengers were used to evaluate the reaction mechanism and the radicals O2•- are the main reactive species of the CR oxidation. Four regeneration cycles demonstrated the catalyst stability. A degradation mechanism was established based on the scavengers effect
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    Study of Congo Red removal from aqueous solution by using the deficient perovskite SrTiO3-δ under solar light
    (Elsevier, 2022) Merrad, S.; Abbas, Moussa; Brahimi, R.; Trari, M.
    The deficient perovskite SrTiO3-δ (STO) synthesized by nitrate route was identified by X-ray diffraction (XRD) and characterised by BET analysis, Attenuated Total Reflectance (ATR) and X-ray photoelectron spectroscopy (XPS). The latter enables us to determine the valence states of Sr2+, Ti4+ and O2−. A band gap of 3.32 eV was determined from the diffuse reflectance, assigned to the charge transfer O2−: 2p → Ti4+: 4s and white coloration of STO. The conduction band (−0.60 VSCE) and the valence band (2.72 VSCE) derived respectively from O2−: 2p and Ti4+: 4s orbitals are within the gap region of STO, thus generating O2·− and ·OH radicals responsible for the photo oxidation of Congo Red (CR), a hazardous dye. The photo-catalytic efficiency of STO was confirmed by the CR adsorption and degradation under solar light. Various physical parameters like the catalyst dose, dye concentration, initial pH, irradiation source and inhibitory effect of anions were studied. The synergetic effect of the electron injection from Congo Red into the STO-conduction band was confirmed by the electrochemical measurements through the photocurrent-potential plots and contribute to the photoactivity. An abatement of 62% and 97% are obtained under UV light and solar irradiation respectively
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