Catalytic degradation of Acid Orange 7 by H₂O₂as promoted by either bare or V-loaded titania under UV light, in dark conditions, and after incubating the catalysts in ascorbic acid

Abstract

Bonelli (2015) Catalytic degradation of Acid Orange 7 by H 2 O 2 as promoted by either bare or V-loaded titania under UV light, in dark conditions, and after incubating the catalysts in ascorbic acid,

Visible Light-Driven Photocatalytic Activity and Kinetics of Fe-Doped TiO2 Prepared by a Three-Block Copolymer Templating Approach

“…Concerning the NPs morphology, Figure 3 shows the TEM micrographs of two selected samples, namely, the undoped TiO 2 ( Figure 3 a) and the sample at the intermediate Fe content, i.e., Fe(2.5)-TiO 2 ( Figure 3 b): in agreement with previous studies showing that this synthesis leads to the formation of elongated particles with rather uniform shape and dimension, forming agglomerates with interparticle mesoporosity [ 45 , 51 ] and that Fe-doping does not alter the NPs shape [ 45 , 51 ], the TEM analysis showed the occurrence of agglomerated NPs of rather uniform shape and size with both samples.…”

Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

“…The sample of mesoporous titania (MT) was obtained by soft-template synthesis as reported in [20] and [23]. Two solutions were prepared: to obtain solution A, 5.0 g Ti(OBut) 4 (titanium tert-butoxide) were added dropwise to 30.0 mL acetic acid solution (20%, v/v) and the mixture was then vigorously stirred for about 4 h; to obtain solution B, 3.0 g Pluronic P123 and ca.…”

“…Though the measurement of the initial rate (within the first 20 min of the reaction) was more affected by error than the final conversion, the positive effect of excess H 2 O 2 on the initial conversion rate was less evident. This was likely due to the fact that a high concentration of H 2 O 2 can scavenge HO· radicals with formation of HO 2 · radicals [Equation (1)] with a lower oxidation power, which may slow down AO7 degradation: [20,23]. The formation of such surface Ti-OOH species was already revealed by XPS [23], showing more abundant Ti-OOH species in MT than in P25, since the former material exhibits higher SSA.…”

“…The reactivity of TiO2 with H2O2 involves the formation of Ti-O-O-H (peroxo) bridges [53]. In the presence of H2O2, part of the surface Ti-OH groups reacts with H2O2 by forming Ti-OOH species, more reactive than H2O2 in partial oxidation reactions [20,23]. The formation of such surface Ti-OOH species was already revealed by XPS [23], showing more abundant Ti-OOH species in MT than in P25, since the former material exhibits higher SSA.…”

Role of pH in the Aqueous Phase Reactivity of Zerovalent Iron Nanoparticles with Acid Orange 7, a Model Molecule of Azo Dyes

“…Their removal from water streams is therefore a major environmental concern, since azo dyes are harmful both to humans and to the aquatic life [1,7]. Being recalcitrant to natural degradation, several technologies have been developed for remediation of both streams and wastewaters, including photocatalytic degradation [6,[8][9][10][11], advanced oxidation processes [12][13][14][15][16][17][18], adsorption [19][20][21][22][23], ion flotation [24], and sedimentation [25]. Unfortunately, physicochemical treatments are often expensive, and biological approaches are typically slow and poorly efficient [26][27][28].…”