The roles of hydroxyl radicals, photo-generated holes and oxygen in the photocatalytic degradation of humic acid

Yan, Xuehai; Bao, Ruiling; Yu, Shuili; Li, Qiongfang; Jing, Qiangshan

doi:10.1134/s0036024412070333

Cited by 24 publications

(7 citation statements)

References 16 publications

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“…Organic alcohols like methanol, ethanol, t -butanol, etc. , are typically scavengers of hydroxyl radicals [ 13 ]. Ethanol addition exhibited depressing effects for this reaction, as shown in Figure 3 , which might support the involvement of • OH radicals.…”

Section: Resultsmentioning

confidence: 99%

Degradation of Methyl Blue Using Fe-Tourmaline as a Novel Photocatalyst

Bian

Chen

2013

Molecules

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This study investigated the photocatalytic activity of tourmaline by itself. Under irradiation of a 13 W, 254 nm UV lamp, 50% of methyl blue disappeared in the presence of 130 mg·L−1 tourmaline. The reaction was inhibited by the addition of ethanol, Cl−, SO42− and Cu2+, and promoted a little by addition of 50 mg/L Mg2+, which supports the inference of involvement of •OH radicals. This is the first proposal of tourmaline as a single photocatalyst without the need to add any artificial chemical products. Results from this study might contribute to the broadened usage of this mineral to approach the goals of saving energy and eliminate direct or indirect environmental pollution.

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Section: Resultsmentioning

confidence: 99%

Degradation of Methyl Blue Using Fe-Tourmaline as a Novel Photocatalyst

Bian

Chen

2013

Molecules

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“…After being transported to the catalyst's surface, the electrons are captured by the oxygen molecules in the aqueous solution to form active free radicals, such as superoxide radical anions (•O 2− ) and hydroxyl radicals (•OH), which eliminate organic contaminants. At the same time, the remaining holes in the VB can oxidize water to form •OH, which reacts with organic species [59]. As illustrated in Figure 12, photogenerated electrons and holes separately accumulate in the CB of MoS 2 and the VB of TiO 2 .…”

Section: Samplementioning

confidence: 99%

Preparation and Study of Photocatalytic Properties of (M(M=Pt, Ag and Au)-TiO2)@MoS2 Nanocomposites

Hong

Xing

et al. 2023

Inorganics

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There have been many articles on the degradation of pollutants by binary and ternary nanocomposites in the field of photocatalysis. However, there has been no research comparing the photocatalytic performance of Rhodamine B (Rh B) between (M(M=Pt, Ag and Au)-TiO2)@MoS2 nanocomposites and binary nanocomposites. To this end, we prepared and studied (M(M=Pt, Ag and Au)-TiO2)@MoS2 nanocomposites and compared their photocatalytic degradation efficiency with binary composites and parent materials for Rhodamine B. We concluded that the best ternary polymer nanocomposite for degrading Rhodamine B is (Pt(5 wt%)-TiO2(15 wt%))@MoS2. In this work, a series of MoS2, TiO2@MoS2, and (M(M=Pt, Ag and Au)-TiO2)@MoS2 nanocomposites with various compositions were synthesized by the hydrothermal and deposition–precipitation methods, and their photocatalytic characteristics were studied in depth using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) photoluminescence spectra (PL), FTIR spectra, UV–Vis DRS spectra, and BET analyzer. The results confirmed that TiO2 and M(Pt, Ag and Au) nanoparticles (NPs) were evenly distributed on MoS2 nanosheets (NSs) to form (M(M=Pt, Ag and Au)-TiO2)@MoS2 nanocomposite heterojunction. The UV–Vis absorption spectrum test results indicated that (Pt(5 wt%)-TiO2(15 wt%))@MoS2 ternary heterojunction nanocomposites exhibited the highest photocatalysis activity, with the maximum value of 99.0% compared to 93% for TiO2(15 wt%)@MoS2, 96.5% for (Ag(5 wt%)-TiO2(15 wt%))@MoS2, and 97.8% for (Au(5 wt%)-TiO2(15 wt%))@MoS2 within 9 min. The advanced structure of (Pt-TiO2)@MoS2 improved both light harvesting and electron transfer in the photocatalytic composites, contributing to remarkable catalytic effectiveness and extended durability for the photodegradation of Rhodamine B (Rh B). In-depth discussions of the potential growth and photocatalytic mechanism, which will help improve the energy and environmental fields, are included.

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“…Overall, the data presented regarding the influence of the SO −2 4 , Cl − and hydrogen peroxide, shows a good tolerance of the photocatalytic system to these additives. The explanation for the observed influence of the anions in the system can be complex, for example both anions can interact with the vacant holes of the generated in the valence band, inhibiting the recombination of the hole/electron pair on the photocatalysts surface as well as to react with H 2 O, generating hydroxyl radicals, leading to further degradation of Rh6G, however it has been also reported that these ions can also display an inhibitory behavior (Yan et al, 2012), by scavenging hydroxyl radicals generated on the surface of the catalyst, as well as by competing with Rh6G for the adsorption sites available, which seem to be the most likely explanation on the behavior of the data presented for the photodegradation of Rh6G in the studied system.…”

Section: Influence Of Additives On the Tio 2 -Catalyzed Photodegradatmentioning

confidence: 99%

Photocatalytic Degradation of Aqueous Rhodamine 6G Using Supported TiO2 Catalysts. A Model for the Removal of Organic Contaminants From Aqueous Samples

et al. 2020

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As a model for the removal of complex organic contaminants from industrial water effluents, the heterogeneous photocatalytic degradation of Rhodamin 6G was studied using TiO 2-derived catalysts, incorporated in water as suspension as well as supported in raschig rings. UV and Visible light were tested for the photo-degradation process. TiO 2 catalysts were synthesized following acid synthesis methodology and compared against commercial TiO 2 catalyst samples (Degussa P25 and Anatase). The bandgap (E g) of the TiO 2 catalysts was determined, were values of 2.97 and 2.98 eV were obtained for the material obtained using acid and basic conditions, respectively, and 3.02 eV for Degussa P25 and 3.18 eV for anatase commercial TiO 2 samples. Raschig ringssupported TiO 2 catalysts display a good photocatalytic performance when compared to equivalent amounts of TiO 2 in aqueous suspension, even though a large surface area of TiO 2 material is lost upon support. This is particularly evident by taking into account that the characteristics (XRD, RD, Eg) and observed photodegradative performance of the synthesized catalysts are in good agreement with the commercial TiO 2 samples, and that the RH6G photodegradation differences observed with the light sources considered are minimal in the presence of TiO 2 catalysts. The presence of additives induce changes in the kinetics and efficiency of the TiO 2-catalyzed photodegradation of Rh6G, particularly when white light is used in the process, pointing toward a complex phenomenon, however the stability of the supported photocatalytic systems is acceptable in the presence of the studied additives. In line with this, the magnitude of the chemical oxygen demand, indicates that, besides the different complex photophysical processes taking place, the endproducts of the considered photocatalytic systems appears to be similar.

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The roles of hydroxyl radicals, photo-generated holes and oxygen in the photocatalytic degradation of humic acid

Cited by 24 publications

References 16 publications

Degradation of Methyl Blue Using Fe-Tourmaline as a Novel Photocatalyst

Degradation of Methyl Blue Using Fe-Tourmaline as a Novel Photocatalyst

Preparation and Study of Photocatalytic Properties of (M(M=Pt, Ag and Au)-TiO2)@MoS2 Nanocomposites

Photocatalytic Degradation of Aqueous Rhodamine 6G Using Supported TiO2 Catalysts. A Model for the Removal of Organic Contaminants From Aqueous Samples

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