Photocatalytic Degradation of Perfluorooctanoic Acid (PFOA) From Wastewaters by TiO2, In2O3 and Ga2O3 Catalysts

Abstract

14The aim of the work was to prepare nanosized In2O3 and Ga2O3 photocatalysts for degradation of 15Perfluorooctanoic acid (PFOA) in water. Their commercial references along with TiO2 were used as 16 a comparison basis. The characterization of the materials proved that successful preparation of cubic 17In2O3 and monoclinic ß-Ga2O3 were achieved via solvothermal and hydrothermal methods, 18 respectively. The effect of different parameters such as catalyst dosage, UV light source and 19 utilization of inorganic oxidant in PFOA treatment were evaluated. In2O3, photocatalyst was the most 20 efficient in the degradation of 15 mgL -1 PFOA under UVB irradiation and synthetic air reaching 27% 21 of degradation, which was 20 percentage points higher than for commercial In2O3. This is proposed 22 to be partly due to significantly higher specific surface area of the self-made In2O3 and smaller 23 crystallite size and partly due to more efficient absorption of UVB light compared to the other tested 24 materials. Addition of KBrO3 did not improve the activity of self-made In2O3.

Tailoring photocatalysts and elucidating mechanisms of photocatalytic degradation of perfluorocarboxylic acids (PFCAs) in water: a comparative overview

“…TiO 2 -based photocatalysts Notably, TiO 2 -based photocatalysts are the most commonly studied photocatalytic materials for the destruction of PFOA. Many kinds of bulk TiO 2 , including commercial Degussa P25, 55,59 Degussa Evonik P25, 29,60,61 Aeroxide P25, 62 (Riedel-de Haen, Seelze, Germany, 10.3 m 2 g −1 ), 33 TiO 2 (RdH), 41 and TiO 2 (solgel), 41,63 have been extensively examined with the irradiation of UV light. However, bulk TiO 2 performs a low photocatalytic activity and is not applicable in practice.…”

“…72 Ga 2 O 3 -based photocatalysts Nanostructured Ga 2 O 3 has also received attention, which exhibits wide bandgap semiconductor (bandgap >3.0 eV), interesting photoluminescence, excellent conduction, and tunable optical properties. 73 Diverse nanostructures of Ga 2 O 3 have been synthesized and applied successfully for photodegradation of PFOA, including nanoparticles, 52 monoclinic rod-shaped crystals, 62 needle-like, 74 and sheaf-like nanomaterial. 75 In general, the photogenerated electron of Ga 2 O 3 has much higher reductive capability than that of TiO 2 , the PFOA molecules, which adsorb on Ga 2 O 3 surface, could be more easily attacked by photogenerated electrons than that on TiO 2 , resulting in enhancing photocatalytic activity over Ga 2 O 3 .…”

“…76 Nonetheless, Lopes da Silva et al reported that TiO 2 performed a higher degradation rate than Ga 2 O 3 that was not expected. 62 Fig. 4), such as porous nanoplates, 78 nanoplates, 79 80 License No: 4718770170334; and (e) porous microspheres.…”

Progress, Mechanisms and Applications of Liquid‐Metal Catalyst Systems

“…Among them, α‐Ga 2 O 3 ( a =4.58 Å, b =9.80 Å, c =2.97 Å) and β‐Ga 2 O 3 were investigated as the most common photocatalysts [Figure (b)] and were synthesized using the solvothermal process or hydrothermal method . It has been shown that Ga 2 O 3 exhibits acceptable photocatalytic properties to degrade different pollutants or wastewater under solar‐light irradiation . Park et al.…”

“…[54] It has been shown that Ga 2 O 3 exhibits acceptable photocatalyt-ic properties to degrade different pollutants or wastewater under solar-light irradiation. [35] Park et al reported novel mesoporousand macroporous Ga 2 O 3 spindles that achieved efficient photocatalytic conversion of CO 2 into CH 4 , [34a] as shown in Figure 6(a). Doping Ga 2 O 3 with different metals,i ncluding Pb, [37] Pd, [38] Ni, [36] Zn, [37] Ag, [39b] Au [ Figure 6(c-e)],h ave also been also investigated to overcome the constraints of photocatalytic activities.…”