Synthesis and Characterisation of Novel Catalyst Ag-TiO 2 Loaded on Magnetic Algerian Halloysite Clay (fe 3 O 4 -HKDD3) for the Photocatalytic Activity of Methylene Blue Dye in an Aqueous Medium

This work aimed to synthesise a magnetic photocatalyst based on Ag-TiO2 nanoparticles supported on Algerian Halloysite clay (HKDD3) loaded with magnetite Fe3O4 through a solvothermal method. The prepared catalyst was characterised by X-ray diffraction (XRD), high-resolution transmission electronic microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis, UV-vis-DRS Diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). Structural and morphological characterisation exhibited that magnetite (Fe3O4) and (TiO2) particles were on a nanometre scale and their sizes were estimated around 50 nm and 30 nm, respectively. DRS results demonstrated that the bandgap has shifted from 3 to 1.75 eV. The photocatalytic performance was evaluated under visible light by changing different operating parameters including photocatalyst loading, initial dye concentration, pH, and scavenger's effect. The methylene blue discoloration was 92% with mineralisation of 87%, which was achieved at pH 6.7 after 3 hours of irradiation visible light with a dosage of 0.937 g/l of catalyst. The photocatalyst can be easily separated due to the action of an external magnetic field. The O-center dot(2)- and (OH)-O-center dot species are the main ones responsible for the photodegradation of methylene blue dye.