New-route synthesis of N-doped TiO2 via exposing the TiCl3 precursor to non-thermal quenched plasma at various times

The exposure of TiCl3 to the plasma electric discharge burned in moisten air lead to the formation of TiO2 nanopowder for short exposure time (<30 min). However, as expected for longer exposure time, the N-doped TiO2 was formed. The synthesized powder for three exposure times was characterized by X-ray diffraction (XRD), FTIR spectroscopy, and nitrogen physisorption. The nitrogen loading was confirmed by X-ray photoelectron spectroscopy (XPS) analysis and the redshift response of doped photocatalyst was evaluated through the discoloration of aqueous Remazol Brilliant Blue-R dye under daylight. As a result, the textural analysis revealed the mesoporous materials with a specific surface area of 157 m2 g−1. The chemical states of nitrogen have been assigned to N–Ti–O and O–N–O in the TiO2 lattice. The photo-degradation rates of RBB-R dye were 62; 76 and 81%, respectively, for the sample exposed during 20, 30 and 60 min. The observed enhanced photocatalytic activity is mainly attributed to the increasing amount of Nitrogen loaded that shift the photocatalytic response in the visible region of light

New-route synthesis of N-doped TiO2 via exposing the TiCl3 precursor to non-thermal quenched plasma at various times

International audienc

Gliding Arc Plasma Synthesis of MnO2 Nanorods for the Plasma-Catalytic Bleaching of Azoïc Amaranth Red Dye

Manganese (IV) oxide (MnO2) nanoparticles were synthesized, via a plasma-chemical route by using a gliding arc discharge at atmospheric pressure. α-MnO2 nanorods were obtained from the chemical reduction of KMnO4. The synthesis yield was 96.8% after 4.5 min of exposure of the solution to the plasma. Further increase of the exposure time induced a decrease of MnO2 yield because of its reductive transformation into Mn2+ ions. Particles were characterized by X-ray powder diffraction, scanning electron microscopy, Fourier Transform Infrared spectroscopy, and nitrogen physisorption. The plasma-catalytic properties of the synthesized material were tested in the bleaching of amaranth red (AR). AR bleaching efficiencies of 17 and 44% were respectively obtained when the plasma and plasma-catalyst processes were applied for 30 min with initial pH 10. The influence of the initial pH, and catalyst concentration were investigated: the AR bleaching efficiency increased linearly with the catalyst concentration and increased markedly when the pH of the solution decreased

Plasma chemical functionalisation of a Cameroonian kaolinite clay for a greater hydrophilicity

A Cameroonian kaolinite powder was treated with gliding arc plasma in order to increase the amount of hydroxyl functional groups present on its external surfaces. The functional changes that occurred were monitored by Fourier transform infrared spectroscopy. The crystalline changes were followed by the X-ray diffraction. The ionisation effect, acid effect, and water solubility of the treated samples were also evaluated. Results showed that there is breaking of the bonds in the Si–O–Si and Si–O–Al groups, followed by the formation of new aluminol (Al–OH) and silanol (Si–OH) groups at the external surface of kaolinite after exposing the clay to the gliding arc plasma. The increase in hydroxyl groups on the surface of kaolinite leads to the increase of its hydrophilicity. Moreover, new charges appear on its surfaces and no significant change in crystallinity has occurred. This study shows that clays in powder form being can effectively be functionalised by gliding arc plasma in spatial post discharge processing mode. Knowing that the treatment in spatial post discharge offers the possibility to process large amounts of clay, this work is of great interest to the industry