scholarly journals Physicochemical and Photocatalytic Properties under Visible Light of ZnO-Bentonite/Chitosan Hybrid-Biocompositefor Water Remediation

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 102
Author(s):  
Imane Aadnan ◽  
Omar Zegaoui ◽  
Abderrahim El Mragui ◽  
Joaquim Carlos Gomes Esteves da Silva
Keyword(s):  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Active Species ◽  
Water Remediation ◽  
Morphological Properties ◽  
Strong Interactions ◽  
Oh Groups ◽  
Thermal Measurements ◽  
The One ◽  
Hybrid Biocomposite

In this investigation, a hybrid-biocomposite “ZnO-Bentonite/Chitosan” was synthesized using inexpensive and environmentally friendly materials (Bentonitechitosan) and (ZnO). It was used as a photocatalyst for water remediation. The structural, optical, thermal, and morphological properties of the synthesized hybrid-biocomposite were investigated using XRD, FTIR spectroscopy, UV-vis diffuse reflectance spectroscopy, TGA, XPS, and SEM-EDS. The thermal measurements showed that the decomposition of CS was postponed progressively by adding PB and ZnO, and the thermal stability of the synthesized hybrid-biocomposite was improved. The characterization results highlighted strong interactions between the C–O, C=O, -NH2, and OH groups of chitosan and the alumina-silica sheets of bentonite on the one side, and between the functional groups of chitosan (-NH2, OH) and ZnO on the other side. The photocatalytic efficiency of the prepared hybrid-biocomposite was assessed in the presence of Methyl Orange (MO). The experiments carried out in the dark showed that the MO removal increased in the presence of Zn-PB/CS hybrid-biocomposite (86.1%) by comparison with PB (75.8%) and CS (65.4%) materials. The photocatalytic experiments carried out under visible light showed that the MO removal increased 268 times in the presence of Zn-PB/CS by comparison withZnO.The holes trapping experiments indicated that they are the main oxidative active species involved in the MO degradation under both UV-A and visible light irradiations.

scholarly journals Synthesis of TiO2/Pd and TiO2/PdO Hollow Spheres and Their Visible Light Photocatalytic Activity

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Jing Yan ◽  
Xiaojuan Li ◽  
Bo Jin ◽  
Min Zeng ◽  
Rufang Peng
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Diffuse Reflectance Spectroscopy ◽  
Hollow Spheres ◽  
Active Species ◽  
Degradation Efficiency ◽  
Diffraction Field ◽  
Transmission Electron

A series of TiO2, TiO2/Pd, and TiO2/PdO hollow sphere photocatalysts was successfully prepared via a combination of hydrothermal, sol-immobilization, and calcination methods. The structure and optical properties of the as-prepared samples were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Telleranalysis, Barrett-Joyner-Halenda measurement, and UV-Vis diffuse reflectance spectroscopy. The photocatalysis efficiencies of all samples were evaluated through the photocatalytic degradation of rhodamine B under visible light irradiation. Results indicated that TiO2/PdO demonstrated a higher photocatalytic activity (the photocatalytic degradation efficiency could reach up to 100% within 40 min) than the other samples and could maintain a stable photocatalytic degradation efficiency for at least four cycles. Finally, after using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species for the effectiveness of the TiO2/PdO photocatalyst.

In Situ Fabrication of TiO2/Bi3.64Mo0.36O6.55Nanocomposite with High Visible-Light-Driven Photocatalytic Efficiency

NANO ◽  
2017 ◽  
Vol 12 (05) ◽  
pp. 1750059 ◽  
Author(s):  
Zhiyuan Yang ◽  
Junjie Wang ◽  
Lu Chen ◽  
Mengjun Liang ◽  
Yulin Xu ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Diffuse Reflectance Spectroscopy ◽  
Active Species ◽  
Light Irradiation ◽  
Cycle Performance ◽  
X Ray Diffraction ◽  
In Situ Fabrication ◽  
Transmission Electron ◽  
Visible Light Driven

In this work, we developed a simple hydrothermal method toward the fabrication of TiO2/Bi[Formula: see text]Mo[Formula: see text]O[Formula: see text] heterostructure, which had superior photocatalytic performance for degrading of RhB under visible light irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS) and photoelectrochemical measurements. The optimal composite with 15[Formula: see text]wt.% TiO2/Bi[Formula: see text]Mo[Formula: see text]O[Formula: see text] (TBMO3) exhibits a much higher photocatalytic activity than that of Bi[Formula: see text]Mo[Formula: see text]O[Formula: see text] and P25 by degradation of RhB under visible light irradiation within 20[Formula: see text]min. The enhanced performance of TBMO3 is predominantly attributed to the synergistic effect both in the higher surface area and the improved separation of photogenerated charge carriers between the two semiconductors. Recycling experiments indicated that TiO2/Bi[Formula: see text]Mo[Formula: see text]O[Formula: see text] photocatalysts had excellent cycle performance and stability. The photocatalytic mechanism of nanocomposite photocatalysts was proposed, which is confirmed by the active species trapping experiments and photoluminescence tests.

scholarly journals Enhanced Degradation of Rhodamine B by Metallic Organic Frameworks Based on NH2-MIL-125(Ti) under Visible Light

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7741
Author(s):  
Hong-Tham Nguyen Thi ◽  
Kim-Ngan Tran Thi ◽  
Ngoc Bich Hoang ◽  
Bich Thuy Tran ◽  
Trung Sy Do ◽  
...  
Keyword(s):  
Visible Light ◽  
Rhodamine B ◽  
Diffuse Reflectance ◽  
High Efficiency ◽  
Diffuse Reflectance Spectroscopy ◽  
Active Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fundamental Properties ◽  
Adsorption Desorption

Samples of the bimetallic-based NH2-MIL-125(Ti) at a ratio of Mn+/Ti4+ is 0.15 (Mn+: Ni2+, Co2+ and Fe3+) were first synthesized using the solvothermal method. Their fundamental properties were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectra, scanning electron microscopy (SEM), N2 adsorption–desorption measurements, and UV–Vis diffuse reflectance spectroscopy (UV-Vis DRS). The as-acquired materials were used as high-efficiency heterogeneous photocatalysts to remove Rhodamine B (RhB) dye under visible light. The results verified that 82.4% of the RhB (3 × 10−5 M) was degraded within 120 min by 15% Fe/Ti−MOFs. Furthermore, in the purpose of degrading Rhodamine B (RhB), the rate constant for the 15% Fe/Ti-MOFs was found to be 2.6 times as fast as that of NH2-MIL-125(Ti). Moreover, the 15% Fe/Ti-MOFs photocatalysts remained stable after three consecutive cycles. The trapping test demonstrated that the major active species in the degradation of the RhB process were hydroxyl radicals (HO∙) and holes (h+).

scholarly journals The Contrastive Research in the Photocatalytic Activity of BiOBr Synthesized by Different Reactants

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Wang Ling-Li ◽  
Ma Wan-Hong ◽  
Wang Shu-Lian ◽  
Zhang Yu ◽  
Jia Man-Ke ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Removal Rate ◽  
Active Species ◽  
X Ray Diffraction ◽  
Toc Removal ◽  
Transmission Electron ◽  
Uv Visible ◽  
Adsorption Desorption

BiOBr nanoplates, marked asα-BiOBr andβ-BiOBr, were synthesized via hydrothermal method using cetylpyridinium bromide (CPB) and NaBr as reactants, respectively. X-Ray Diffraction (XRD), transmission electron microscope (TEM), N2adsorption/desorption, UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), and cyclic voltammetry (CV) were employed to characterize the obtained BiOBr. The results showed thatα-BiOBr andβ-BiOBr can absorb visible light and both the band gaps of them were about 2.76 eV. Under visible light irradiation, the photodegradation of organic dye sulforhodamine (SRB) and salicylic acid (SA) usingα-BiOBr andβ-BiOBr as the catalysts was carried out. The reaction kinetic constants of the degradation of SRB byα-BiOBr andβ-BiOBr were 0.00602 min−1and 0.0047 min−1, respectively, which indicated that the photocatalytic activity ofα-BiOBr was higher than that ofβ-BiOBr. The UV-Vis DRS and total organic carbon (TOC) were also monitored, and the TOC removal rate ofα-BiOBr andβ-BiOBr was 86% and 48%, respectively. At the same time, hydrogen peroxide (H2O2) and active radicals were measured and analyzed, which showed that the main active species wasOH∙during the photocatalytic reaction.

scholarly journals Fabrication and photoactivity of ionic liquid–TiO2 structures for efficient visible-light-induced photocatalytic decomposition of organic pollutants in aqueous phase

2018 ◽  
Vol 9 ◽  
pp. 580-590 ◽  
Author(s):  
Anna Gołąbiewska ◽  
Marta Paszkiewicz-Gawron ◽  
Aleksandra Sadzińska ◽  
Wojciech Lisowski ◽  
Ewelina Grabowska ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Phenol Degradation ◽  
Active Species ◽  
Photocatalytic Decomposition ◽  
Bet Surface Area ◽  
Light Illumination ◽  
Transmission Microscopy ◽  
X Ray

To investigate the effect of the ionic liquid (IL) chain length on the surface properties and photoactivity of TiO2, a series of TiO2 microspheres have been synthesized via a solvothermal method assisted by 1-methyl-3-octadecylimidazolium chloride ([ODMIM][Cl]) and 1-methyl-3-tetradecylimidazolium chloride ([TDMIM][Cl]). All as-prepared samples were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), scanning transmission microscopy (STEM) and the Brunauer–Emmett–Teller (BET) surface area method, whereas the photocatalytic activity was evaluated by the degradation of phenol in aqueous solution under visible light irradiation (λ > 420 nm). The highest photoefficiency (four times higher than pristine TiO2) was observed for the TiO2 sample obtained in the presence of [TDMIM][Cl] for a IL to TiO2 precursor molar ratio of 1:3. It was revealed that interactions between the ions of the ionic liquid and the surface of the growing titanium dioxide spheres results in a red-shift of absorption edge for the IL–TiO2 semiconductors. In this regard, the direct increase of the photoactivity of IL–TiO2 in comparison to pristine TiO2 was observed. The active species trapping experiments indicated that O2 •− is the main active species, created at the surface of the IL–TiO2 material under visible-light illumination, and is responsible for the effective phenol degradation.

Construction of Z-Scheme Bi2WO6/g-C3N4 Heterojunction Photocatalysts with Enhanced Visible-Light Photocatalytic Activity

2017 ◽  
Vol 70 (8) ◽  
pp. 889 ◽  
Author(s):  
Chunjiao Zhang ◽  
Rong Li ◽  
Yu Zhao ◽  
Mei Wang
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Composite Materials ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Reaction Rate Constant ◽  
Active Species ◽  
Intimate Contact ◽  
Recombination Efficiency ◽  
Transmission Electron

Highly efficient visible-light-induced Z-scheme Bi2WO6/g-C3N4 heterojunction photocatalysts were synthesised by means of a simple hydrothermal method. The prepared Bi2WO6/g-C3N4 composite materials were characterised by means of X-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and photoluminescence. The photocatalytic activity of the Bi2WO6/g-C3N4 composite materials was determined through the degradation of Rhodamine B (RhB) solution as a target pollutant. The results of the experiment revealed that the active species O2•− and h+ play a crucial role in the scavenging system. The Bi2WO6/g-C3N4 composites showed an obviously improved photocatalytic performance compared with pure g-C3N4 and Bi2WO6 in the RhB degradation under visible light irradiation. The 10 wt-% Bi2WO6/g-C3N4 displayed the highest photocatalytic activity, and could completely degrade RhB within 75 min. It gave a reaction rate constant of 0.0439 min−1, which is 5.22 and 2.58 times higher than pure Bi2WO6 and g-C3N4, respectively. The intimate contact interface between the Bi2WO6 and g-C3N4 leads to effective separation of charge carriers and hinders the recombination efficiency of electrons and holes. Hence the photocatalytic activities of the Bi2WO6/g-C3N4 composite materials are significantly improved.

scholarly journals Bi5O7I/g-C3N4 Heterostructures With Enhanced Visible-Light Photocatalytic Performance for Degradation of Tetracycline Hydrochloride

2021 ◽  
Vol 9 ◽  
Author(s):  
Yang Yang ◽  
Min Lai ◽  
Jialei Huang ◽  
Jinze Li ◽  
Ruijie Gao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Active Species ◽  
Tetracycline Hydrochloride ◽  
Light Illumination ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
P Type ◽  
Active Intermediates

Bi5O7I/g-C3N4 p-n junctioned photocatalysts were synthesized by alcohol-heating and calcination in air. The structures, morphologies and optical properties of as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS). Photocatalytic activity of the heterojunctioned composites were evaluated by degradation of Rhodamine B (RhB) and tetracycline hydrochloride (TCH) under visible light illumination. The results indicated that the composites exhibited superior efficiencies for photodegradation of RhB and TCH in comparison with pure BiOI, Bi5O7I and g-C3N4. An effective built-in electric field was formed by the interface between p-type Bi5O7I and n-type g-C3N4, which promoted the efficient separation of photoinduced electron-hole pairs. In addition, 8% Bi5O7I/g-C3N4 composite showed excellent photostability in a five-cycle photocatalytic experiment. Experiments on scavenging active intermediates revealed the roles of active species.

scholarly journals Ionic Liquid-Assisted Synthesis of Ag3PO4 Spheres for Boosting Photodegradation Activity under Visible Light

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 788
Author(s):  
Beibei Zhang ◽  
Lu Zhang ◽  
Yulong Zhang ◽  
Chao Liu ◽  
Jiexiang Xia ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Visible Light ◽  
High Efficiency ◽  
Chemical Precipitation ◽  
Active Species ◽  
Precipitation Method ◽  
Dihydrogen Phosphate ◽  
Xrd Pattern ◽  
Simple Chemical ◽  
Visible Light Driven

In this work, a simple chemical precipitation method was employed to prepare spherical-like Ag3PO4 material (IL-Ag3PO4) with exposed {111} facet in the presence of reactive ionic liquid 1-butyl-3-methylimidazole dihydrogen phosphate ([Omim]H2PO4). The crystal structure, microstructure, optical properties, and visible-light photocatalytic performance of as-prepared materials were studied in detail. The addition of ionic liquids played a crucial role in forming spherical-like morphology of IL-Ag3PO4 sample. Compared with traditional Ag3PO4 material, the intensity ratio of {222}/{200} facets in XRD pattern of IL-Ag3PO4 was significantly enhanced, indicating the main {111} facets exposed on the surface of IL-Ag3PO4 sample. The presence of exposed {111} facet was advantageous for facilitating the charge carrier transfer and separation. The light-harvesting capacity of IL-Ag3PO4 was larger than that of Ag3PO4. The photocatalytic activity of samples was evaluated by degrading rhodamine B (RhB) and p-chlorophenol (4-CP) under visible light. The photodegradation efficiencies of IL-Ag3PO4 were 1.94 and 2.45 times higher than that of Ag3PO4 for RhB and 4-CP removal, respectively, attributing to a synergy from the exposed {111} facet and enhanced photoabsorption. Based on active species capturing experiments, holes (h+), and superoxide radical (•O2−) were the main active species for visible-light-driven RhB photodegradation. This study will provide a promising prospect for designing and synthesizing ionic liquid-assisted photocatalysts with a high efficiency.

scholarly journals Methylofuran is a prosthetic group of the formyltransferase/hydrolase complex and shuttles one-carbon units between two active sites

2019 ◽  
Vol 116 (51) ◽  
pp. 25583-25590 ◽  
Author(s):  
Jethro L. Hemmann ◽  
Tristan Wagner ◽  
Seigo Shima ◽  
Julia A. Vorholt
Keyword(s):  
Active Sites ◽  
Bacterial Species ◽  
Methanogenic Archaea ◽  
Side Chain ◽  
Strong Interactions ◽  
Prosthetic Group ◽  
Additional Function ◽  
Amide Bonds ◽  
Consecutive Reactions ◽  
The One

Methylotrophy, the ability of microorganisms to grow on reduced one-carbon substrates such as methane or methanol, is a feature of various bacterial species. The prevailing oxidation pathway depends on tetrahydromethanopterin (H4MPT) and methylofuran (MYFR), an analog of methanofuran from methanogenic archaea. Formyltransferase/hydrolase complex (Fhc) generates formate from formyl-H4MPT in two consecutive reactions where MYFR acts as a carrier of one-carbon units. Recently, we chemically characterized MYFR from the model methylotrophMethylorubrum extorquensand identified an unusually long polyglutamate side chain of up to 24 glutamates. Here, we report on the crystal structure of Fhc to investigate the function of the polyglutamate side chain in MYFR and the relatedness of the enzyme complex with the orthologous enzymes in archaea. We identified MYFR as a prosthetic group that is tightly, but noncovalently, bound to Fhc. Surprisingly, the structure of Fhc together with MYFR revealed that the polyglutamate side chain of MYFR is branched and contains glutamates with amide bonds at both their α- and γ-carboxyl groups. This negatively charged and branched polyglutamate side chain interacts with a cluster of conserved positively charged residues of Fhc, allowing for strong interactions. The MYFR binding site is located equidistantly from the active site of the formyltransferase (FhcD) and metallo-hydrolase (FhcA). The polyglutamate serves therefore an additional function as a swinging linker to shuttle the one-carbon carrying amine between the two active sites, thereby likely increasing overall catalysis while decreasing the need for high intracellular MYFR concentrations.

Enhanced Photocatalytic Performance of Sn6SiO8 Nanoparticles and Their Reduced Graphene Oxide (rGO) Nanocomposite

2020 ◽  
Vol 20 (9) ◽  
pp. 5426-5432
Author(s):  
G. Gnanamoorthy ◽  
M. Muthukumaran ◽  
P. Varun Prasath ◽  
V. Karthikeyan ◽  
V. Narayanan ◽  
...  
Keyword(s):  
Visible Light ◽  
Photocatalytic Performance ◽  
Separation Efficiency ◽  
Dye Degradation ◽  
Hexagonal Phase ◽  
Active Species ◽  
Organic Chemical ◽  
Light Illumination ◽  
Sem Images ◽  
Radical Trapping

Photocatalysts provide excellent potential for the full removal of organic chemical pollutants as an environmentally friendly technology. It has been noted that under UV-visible light irradiation, nanostructured semiconductor metal oxides photocatalysts can degrade different organic pollutants. The Sn6SiO8/rGO nanocomposite was synthesized by a hydrothermal method. The Sn6SiO8 nanoparticles hexagonal phase was confirmed by XRD and functional groups were analyzed by FT-IR spectroscopy. The bandgap of Sn6SiO8 nanoparticles (NPs) and Sn6SiO8/GO composites were found to be 2.7 eV and 2.5 eV, respectively. SEM images of samples showed that the flakes like morphology. This Sn6SiO8/rGO nanocomposite was testing for photocatalytic dye degradation of MG under visible light illumination and excellent response for the catalysts. The enhancement of photocatalytic performance was mainly attributed to the increased light absorption, charge separation efficiency and specific surface area, proved by UV-vis DRS. Further, the radical trapping experiments revealed that holes (h+) and superoxide radicals (·O−2) were the main active species for the degradation of MG, and a possible photocatalytic mechanism was discussed.

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