Photocatalytic dye-degradation activity of nano-crystalline Ti_1−xM_xO_2−δ (M =Ag, Pd, Fe, Ni and x = 0, 0.01) for water pollution abatement

Abstract

Redox-pair stabilization in TiO2 lattice by doping of Ag+ and Pd2+ ions play a defining role in enhancing the photocatalytic activity of the catalyst by scavenging electrons generated through UV-irradiation on the catalyst.

Synthesis of titanates for photomineralization of industrial wastewater and organic pollutants

“…The VB (valence band) of tunnel-type titanates consists mostly of O 2p-orbitals, whereas the CB (conduction band) mainly involves Ti3d-orbitals. [32][33][34] Na + ions are sandwiched in between these layers and can be replaced with ions and/or neutral molecules, as shown in Fig. S1a.…”

“…Emission spectroscopy was utilized to investigate the transfer of charge carriers and to measure the probability of hole-electron pair development in titanates. [32][33][34] In general, if the emission intensity is higher, the recombination of electron and hole pairs is also high and vice versa. [32][33][34] The intensity of emission for Ag/PdTO was much lower when compared 33 with that of the parent NaTO and PdTO, as revealed in Fig.…”

“…[32][33][34] In general, if the emission intensity is higher, the recombination of electron and hole pairs is also high and vice versa. [32][33][34] The intensity of emission for Ag/PdTO was much lower when compared 33 with that of the parent NaTO and PdTO, as revealed in Fig. 7.…”

“…45 The first two processes have some drawbacks, such as leaving behind partly degraded impurities and/or colourless by-products in the pollutant solution. [32][33][34] Therefore, the current study is focused on the mineralization process. The photodegradation performance of the synthesized NaTO, PdTO, and Ag/PdTO photocatalysts under visible light (300 watts, 40 V, tungsten halogen lamp with a photon flux of 12 000 lumens and a light intensity of 1, 36 000 lux) was examined for the mineralization of dyes, such as methyl red (MR), 46 reactive X3B (X3B), 47 cotton blue (CB), 48 methylene blue (MB), 49 methyl violet (MV), 50 and rhodamine B (RhB), 51 in aqueous solution.…”

“…54,55 We previously reported a modified system (Fig. S18 †) for the mineralization and degradation of IWW effluents, [32][33][34] where the photoreactor involves three stages of unscrambling solid waste and degradation processes, with the first two stages occurring under visible-light and the final stage under UV-visible light irradiation. The dark coloured IWW test solutions were checked at different time intervals by UV-vis absorption and LC-MS.…”