“…This observation serves to confirm that the incorporation of iron and cobalt does not bring any noticeable changes. Additionally, the determined d-spacing and pore size values align consistently with the results obtained from both powder XRD and nitrogen sorption analysis [ [83] , [84] , [85] , [86] ]. Fig.…”
“…This observation serves to confirm that the incorporation of iron and cobalt does not bring any noticeable changes. Additionally, the determined d-spacing and pore size values align consistently with the results obtained from both powder XRD and nitrogen sorption analysis [ [83] , [84] , [85] , [86] ]. Fig.…”
“…Moreover, radical quenching experiments were conducted to further differentiate the contribution of reactive radicals, and the results are shown in Figure d. Typically, tert -butanol (TBA), ethanol (EtOH), P-benzaldehyde (BQ), and ascorbic acid (ACS) were selected as radical scavengers. , TBA mainly quenched ·OH with a reaction rate of 0.4070 mmol·L –1 ·min –1 , and EtOH mainly quenched ·OH and SO 4 •– with a reaction rate of 0.3544 mmol·L –1 ·min –1 , indicating that SO 4 •– was greater than ·OH in the catalysis. BQ mainly quenches O 2 •– with a reaction rate of 0.3380 mmol·L –1 ·min –1 , indicating that O 2 •– is greater than ·OH and SO 4 •– .…”
Catalytic oxidation of sulfite is critical for the fixation of sulfite in the flue gas desulfurization process and is also an essential step related to the treatment of air and water pollution. This work designed and prepared a nano-MnO 2 -functionalized hydrophobic ceramic membrane with a hydrophobic surface by a hydrothermal method. The chemical composition and the nanostructure of the prepared MnO 2 composite membranes were characterized using several identification techniques (X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy). The results show that the prepared nano-MnO 2 was sea urchin-like, the crystal form was β-MnO 2 , and it grows uniformly on the surface of the ceramic membrane. The molar ratios of Mn 4+ /Mn 3+ and O latt /O total were associated with high catalytic activity and enhanced with increasing preparation concentration. The catalytic ability of nano-MnO 2 composite membranes to Na 2 SO 3 was studied by the membrane dispersion-catalysis process. The catalytic efficiency with a loaded amount of 1.6−4.5 mg was 5.4−8.3 times higher than that without the catalyst. The free radical quenching experiment showed that SO 5•− was identified as the key free radical in the chain reaction. The oxidation kinetics of sulfite were investigated using a membrane dispersion reactor. The results showed that the catalyst, sulfite, and oxygen partial pressure reaction orders were 0.411, 0.243, and 0.640, respectively, and showed an apparent activation energy of 1.89 kJ•mol −1 . Based on the three-phase reaction model analysis, sulfite oxidation was considered to be controlled by the mass transfer process of oxygen from the gas phase to the liquid phase.
“…OV-CoO/CeO 2 had the highest catalytic oxidation rate and a high turnover frequency compared with other catalysts (Mn@ZIF67, 68 Co/C 3 N 4 , 17 Co-MOF-74, 18 Co 3 O 4 -NPs@KIT-6, 10 BISC, 14 and Co-MCM-48 (ref. 19)) owing to the abundance of OVs, high amount of Co, and increased O* transfer.…”
Section: Resultsmentioning
confidence: 99%
“…14–16 In previous studies, we fabricated a series of Co-based monometallic catalysts, including Co/C 3 N 4 , Co-MOF-74, Co 3 O 4 -NPs@KIT-6, BISC, and Co-MCM-48, with SO 3 2− oxidation rates 3–10 times higher than that without a catalyst. 10,14,17–19 Owing to their high catalytic activity, recyclability, and low secondary pollution, Co-based catalysts have great potential for use under real WFGD operating conditions. According to the steady-state assumption 20 and DFT calculations, 14 oxygen diffusion and mass transfer on the heterogeneous catalyst are crucial in SO 3 2− oxidation and determine the overall reaction rate.…”
Section: Introductionmentioning
confidence: 99%
“…CeO 2 is a promising candidate for efficient adsorption of heavy metal ions in wastewater because its edges and surfaces have abundant oxygen-containing functional groups, such as chemisorbed oxygen, hydroxyl groups, and OVs, and CeO 2 readily forms and transfers reactive oxygen species. 19–22 Zhou et al 53 prepared a composite sorbent of CeO 2 –TiO 2 and achieved 98% removal of Hg due to the abundant surface oxygen chemisorbed on the Ce 3+ site. Xiao et al 54 fabricated a CeO 2 /BiOIO 3 photocatalyst for removing gas-phase Hg 0 , and the OVs coupled with Ce 4+ /Ce 3+ redox centers facilitated the adsorption and oxidation of Hg 0 .…”
Synchronously catalytic oxidation of sulfite (SO32-) and separation of selenium (Se) to achieve wastewater detoxication and sulfate purification from flue gas desulfurization wastewater is a desirable circular economy method but...
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