scholarly journals Synthetic BiOBr/Bi2S3/CdS Crystalline Material and Its Degradation of Dye under Visible Light

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 899
Author(s):  
Yunhan Jin ◽  
Zhe Xing ◽  
Yinhui Li ◽  
Jian Han ◽  
Heike Lorenz ◽  
...  
Keyword(s):  
Composite Material ◽  
Visible Light ◽  
Dye Degradation ◽  
Degradation Process ◽  
Active Species ◽  
Order Kinetic ◽  
Test Results ◽  
Order Kinetic Model ◽  
Epr Test

Constructing heterojunction has attracted widespread concerns in photocatalysis research. BiOBr/Bi2S3/CdS composite material with a sea urchin shape was directly obtained by first synthesizing BiOBr microspheres. The morphology, structure and composition of the composite material were characterized by XRD, EDX, SEM and XPS. Dye degradation experiments showed that 83.3% of methylene blue removal was achieved after 2 h of visible light irradiation. The reaction rate under optimal conditions was 0.014 min−1 and the photocatalytic degradation process follows a pseudo-first-order kinetic model. Based on the EPR test results, the main active species involved in the reaction were •O2− and h+. The conduction band and valence band edge potential calculations confirmed the key role of CdS in the production of •O2−.

Photodegradation of microcystin-LR catalyzed by metal phthalocyanines immobilized on TiO2-SiO2 under visible-light irradiation

2015 ◽  
Vol 72 (10) ◽  
pp. 1824-1831 ◽  
Author(s):  
Guotao Peng ◽  
Zhengqiu Fan ◽  
Xiangrong Wang ◽  
Xin Sui ◽  
Chen Chen
Keyword(s):  
Visible Light ◽  
High Performance ◽  
Anatase Phase ◽  
Degradation Process ◽  
Visible Range ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Metal Phthalocyanines ◽  
Order Kinetic Model ◽  
Acute And Chronic Effects

Microcystins (MCs) are a group of monocyclic heptapeptide toxins produced by species of cyanobacteria. Since MCs exhibit acute and chronic effects on humans and wildlife by damaging the liver, they are of increasing concern worldwide. In this study, we investigated the ability of the phthalocyanine compound (ZnPc-TiO2-SiO2) to degrade microcystin-LR (MC-LR) in the presence of visible light. X-ray diffraction (XRD) and UV-Visible diffuse reflectance spectra (UV-Vis DRS) were utilized to characterize the crystalline phase and the absorption behavior of this catalyst. According to the results, XRD spectra of ZnPc-TiO2-SiO2 powders taken in the 2θ configuration exhibited the peaks characteristic of the anatase phase. UV-Vis DRS showed that the absorption band wavelength shifted to the visible range when ZnPc was supported on the surface of TiO2-SiO2. Subsequently, several parameters including catalyst dose, MC-LR concentrations and pH were investigated. The MC-LR was quantified in each sample through high-performance liquid chromatography (HPLC). The maximum MC-LR degradation rate of 80.2% can be obtained within 300 minutes under the following conditions: catalyst dose of 7.50 g/L, initial MC-LR concentration of 17.35 mg/L, pH 6.76 and the first cycling run of the photocatalytic reaction. Moreover, the degradation process fitted well with the pseudo-first-order kinetic model.

scholarly journals Application of Silver-Loaded Composite Track-Etched Membranes for Photocatalytic Decomposition of Methylene Blue under Visible Light

Membranes ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 60 ◽  
Author(s):  
Anastassiya A. Mashentseva ◽  
Murat Barsbay ◽  
Nurgulim A. Aimanova ◽  
Maxim V. Zdorovets
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Degradation Kinetics ◽  
Composite Membranes ◽  
Degradation Process ◽  
Decomposition Reaction ◽  
Photocatalytic Decomposition ◽  
Order Kinetic ◽  
Langmuir Hinshelwood Mechanism ◽  
Order Kinetic Model

In this study, the use of composite track-etched membranes (TeMs) based on polyethylene terephthalate (PET) and electrolessly deposited silver microtubes (MTs) for the decomposition of toxic phenothiazine cationic dye, methylene blue (MB), under visible light was investigated. The structure and composition of the composite membranes were elucidated by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction technique. Under visible light irradiation, composite membrane with embedded silver MTs (Ag/PET) displayed high photocatalytic efficiency. The effects of various parameters such as initial dye concentration, temperature, and sample exposure time on the photocatalytic degradation process were studied. The decomposition reaction of MB was found to follow the Langmuir–Hinshelwood mechanism and a pseudo-first-order kinetic model. The degradation kinetics of MB accelerated with increasing temperature and activation energy, Ea, was calculated to be 20.6 kJ/mol. The reusability of the catalyst was also investigated for 11 consecutive runs without any activation and regeneration procedures. The Ag/PET composite performed at high degradation efficiency of over 68% after 11 consecutive uses.

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.

In situ synthesis of hierarchical nitrogen-doped MoS2 microsphere with an excellent visible light-driven photocatalytic nitrogen fixation ability

2020 ◽  
Vol 13 (05) ◽  
pp. 2051031
Author(s):  
Abulikemu Abulizi ◽  
Hujiabudula Maimaitizi ◽  
Dilinuer Talifu ◽  
Yalkunjan Tursun
Keyword(s):  
Visible Light ◽  
High Performance ◽  
Nucleation Site ◽  
Active Species ◽  
Nitrogen Doped ◽  
Photogenerated Electrons ◽  
The Hierarchical Structure ◽  
Visible Light Driven

A photocatalyst of high-performance hierarchical nitrogen-doped MoS2 (N-MoS2) microsphere was fabricated by an in situ hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB). The as-prepared N-MoS2 microsphere was self-assembled by extremely thin interleaving petals, where CTAB acts as a nucleation site for the formation of the interleaving petals due to the strong interaction between CTA+ and [Formula: see text]. N-MoS2 showed higher N2 fixation ability (101.2 [Formula: see text] mol/g(cat)h) than the non-doped MoS2 under the visible light irradiation, and the improved photocatalytic activity could be ascribed to that the doped N narrows the band gap, and the surface reflecting and scattering effect caused by the hierarchical structure enhance the light adsorption. The trapping experiment of active species was also investigated to evaluate the role of photogenerated electrons in the photocatalytic reaction process. Meanwhile, the possible mechanism for the formation and excellent photocatalytic performance of N-MoS2 microsphere were also presented.

scholarly journals Preparation of Nanosized Zero-Valent zinc (Zn0) Immobilized on ZnO as Redox Nanocomposite for Degradation of Methyl Orange from Aqueous Solution

2019 ◽  
Author(s):  
Samira Taherkhani ◽  
Ali Khani
Keyword(s):  
Aqueous Solution ◽  
Methyl Orange ◽  
Gas Flow ◽  
Degradation Process ◽  
Degradation Efficiency ◽  
Effect Of Temperature ◽  
Order Kinetic ◽  
Zno Nanopowder ◽  
Order Kinetic Model ◽  
Degradation Of Methyl Orange

Introduction: In this study, nanosized zero-valent zinc (Zn0) as a reducing agent, simultaneously synthesized and immobilized on an oxidizing agent, ZnO photocatalyst for degradation of methyl orange (MO) from the aqueous solution. Materials and Methods: The prepared redox nanocomposite (nZn0-ZnO) was characterized by the XRD and SEM techniques. The prepared sample was separated by centrifuging. The preparation process of nZn0-ZnO including synthesis-immobilization, washing, and drying carried out under Argon gas flow. Moreover, the effect of temperature and kinetics reaction was studied. Results: The results showed that degradation efficiency of prepared redox nanocomposite was increased compared to each ZnO nanopowder and Zn0 under the same operational condition. The calculated activation energy for the degradation process was 4.05 KJ.mol-1. Finally, the results showed that the degradation processes followed pseudo first order kinetic model in the basic condition by the relative deviation modulus. Conclusion: As compared to ZnO nanopowder and Zn0, the prepared redox nanocomposite showed high degradation efficiency for the removal of methyl orange from the aqueous solution.

scholarly journals Thermal Stability and Degradation Kinetics of Patulin in Highly Acidic Conditions: Impact of Cysteine

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 662
Author(s):  
Enjie Diao ◽  
Kun Ma ◽  
Hui Zhang ◽  
Peng Xie ◽  
Shiquan Qian ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Correlation Coefficients ◽  
Degradation Process ◽  
Weibull Model ◽  
Degradation Efficiency ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Acidic Conditions ◽  
Kinetics Of

The thermal stability and degradation kinetics of patulin (PAT, 10 μmol/L) in pH 3.5 of phosphoric-citric acid buffer solutions in the absence and presence of cysteine (CYS, 30 μmol/L) were investigated at temperatures ranging from 90 to 150 °C. The zero-, first-, and second-order models and the Weibull model were used to fit the degradation process of patulin. Both the first-order kinetic model and Weibull model better described the degradation of patulin in the presence of cysteine while it was complexed to simulate them in the absence of cysteine with various models at different temperatures based on the correlation coefficients (R2 > 0.90). At the same reaction time, cysteine and temperature significantly affected the degradation efficiency of patulin in highly acidic conditions (p < 0.01). The rate constants (kT) for patulin degradation with cysteine (0.0036–0.3200 μg/L·min) were far more than those of treatments without cysteine (0.0012–0.1614 μg/L·min), and the activation energy (Ea = 43.89 kJ/mol) was far less than that of treatment without cysteine (61.74 kJ/mol). Increasing temperature could obviously improve the degradation efficiency of patulin, regardless of the presence of cysteine. Thus, both cysteine and high temperature decreased the stability of patulin in highly acidic conditions and improved its degradation efficiency, which could be applied to guide the detoxification of patulin by cysteine in the juice processing industry.

Effective Dye Degradation Using Sol-Gel Synthesized Titania Nanostructures

2020 ◽  
Vol 16 ◽  
Author(s):  
Priyanka Karathan Parakkandy ◽  
Kagalagodu Manjunthiah Balakrishna ◽  
Thomas Varghese
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Crystallite Size ◽  
Organic Dyes ◽  
Dye Degradation ◽  
Sol Gel ◽  
Blue Shift ◽  
Degradation Process ◽  
Rutile Phase ◽  
Visible Absorption

Background: The organic effluents from industry remain one of the reasons for water contamination. By natural degradation process, it is difficult to remove this; hence finding an effective solution for this is inevitable. TiO2-based materials have received enormous attention in the area of semiconductor photocatalysis, particularly for the degradation of organic dyes. This work emphasize on the degradation of two industrial dyes methylene blue and rhodamine blue by visible light irradiation of TiO2 based nanoparticles. Methods: In the present study, pristine and La3+ and Ce3+ doped nanotitania were synthesized by sol-gel method. The samples under investigation were characterized using X-ray diffraction, Transmission electron microscopy to study the variation of crystallite size and UV-Visible absorption spectroscopy. Results: The increase in crystallite size for the pristine samples calcined at various temperatures confirms the effect of calcination temperature. Also, the doping reduced the size of the synthesized nanotitania. Visible light extended absorption spectra have been observed for the calcined samples and Ce3+ doped nanotitania. The La3+ doped sample showed a blue shift in the absorption confirming quantum confinement. The photocatalytic activity in the context of degradation of certain industrial dyes such as methylene blue and rhodamine blue has been investigated for the samples. Conclusion: The studies found that nanotitania consisting of mixed anatase-rutile phase exhibits higher degradation efficiency than that of pure anatase or rutile samples. Besides, photocatalytic dye degradation has been significantly improved for Ce3+ doped nanotitania compared to the pristine sample.

scholarly journals AgCl-ZnAl Layered Double Hydroxides as Catalysts with Enhanced Photodegradation and Antibacterial Activities

Inorganics ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 120 ◽  
Author(s):  
Morena Nocchetti ◽  
Monica Pica ◽  
Berardo Ridolfi ◽  
Anna Donnadio ◽  
Elisa Boccalon ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Degradation Process ◽  
Antibacterial Activities ◽  
Positive Control ◽  
Active Species ◽  
Interlayer Region ◽  
Surface Modified ◽  
Double Hydroxides ◽  
Crystalline Domains

Surface-modified ZnAl layered double hydroxides (LDHs) were prepared by reaction of AgNO3, with both ZnAlCl (LDH1) and ZnAlCO3 exchanged on the surface with chloride anions (LDH3). In this way, AgCl nanoparticles with crystalline domains ranging from 40 to 100 nm were grown on the LDH surface. An additional sample was prepared by partial reduction of silver to obtain Ag@AgCl-LDH (LDH2). The composites were tested as catalysts in Rhodamine B (RhB) degradation, wherein LDH2 showed complete cleavage of RhB after 45 min of irradiation versus 70 min needed in the presence of AgCl. This time decreased to 35 min for LDH1 and 15 min for LDH3, underlining the role of the AgCl dimensions and anion in the interlayer region. Studies on the reactive species involved in the degradation process revealed that, for all catalysts, O2·− was the main active species, while, to some extent, holes contribute to the activity of the LDH3. Finally, the composites showed high bactericidal activity, under irradiation, against Escherichia coli, comparable with that of Gentamicin, the positive control. A synergic effect of silver released from the composites and the production of reactive oxygen species was considered.

scholarly journals Photocatalytic and Photo-Fenton Catalytic Degradation Activities of Z-Scheme Ag2S/BiFeO3 Heterojunction Composites under Visible-Light Irradiation

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 399 ◽  
Author(s):  
Lijing Di ◽  
Hua Yang ◽  
Tao Xian ◽  
Xueqin Liu ◽  
Xiujuan Chen
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Dye Degradation ◽  
Synergistic Effects ◽  
Active Species ◽  
Light Irradiation ◽  
Precipitation Method ◽  
Photoexcited Electron ◽  
Catalytic Mechanisms ◽  
Ag2s Nanoparticles

Z-scheme Ag2S/BiFeO3 heterojunction composites were successfully prepared through a precipitation method. The morphology and microstructure characterization demonstrate that Ag2S nanoparticles (30–50 nm) are well-decorated on the surfaces of polyhedral BiFeO3 particles (500–800 nm) to form Ag2S/BiFeO3 heterojunctions. The photocatalytic and photo-Fenton catalytic activities of the as-derived Ag2S/BiFeO3 heterojunction composites were evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The photocatalytic result indicates that the Ag2S/BiFeO3 composites exhibit much improved photocatalytic activities when compared with bare Ag2S and BiFeO3. The optimum composite sample was observed to be 15% Ag2S/BiFeO3 with an Ag2S mass fraction of 15%. Furthermore, the addition of H2O2 can further enhance the dye degradation efficiency, which is due to the synergistic effects of photo- and Fenton catalysis. The results of photoelectrochemical and photoluminescence measurements suggest a greater separation of the photoexcited electron/hole pairs in the Ag2S/BiFeO3 composites. According to the active species trapping experiments, the photocatalytic and photo-Fenton catalytic mechanisms of the Ag2S/BiFeO3 composites were proposed and discussed.

scholarly journals Oxidative degradation of p-chlorophenol by the persulfate-doped Fe-Mn bimetallic hydroxide, the parametrical significance, and systematical optimization

2021 ◽  
Author(s):  
Tao Huang ◽  
Jing Du ◽  
Danni Yu ◽  
Shihan Deng ◽  
Shuwen Zhang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Organic Contaminants ◽  
Oxidative Degradation ◽  
Degradation Process ◽  
Catalytic Degradation ◽  
Molar Ratio ◽  
Order Kinetic ◽  
Valence Transition ◽  
Order Kinetic Model ◽  
Oxidation Performance

Abstract Aqueous Fe(II)-catalyzed activation commonly deteriorates the oxidation performance of persulfate (PS) to the treatment of organic contaminants. In this study, a PS-doped layered bimetallic hydroxide (Fe-Mn hydroxide) was synthesized to construct a heterogeneously catalytic system to solve the issue brought by homogeneity. The molar ratio of Fe(II) to Mn(II) and the mass ratio of PS to Fe-Mn hydroxide both had a significant impact on the catalytic degradation of p-CP. Reaction temperatures engaged in the most essential role in influencing the degradation and removal of p-chlorophenol (p-CP). The optimal combination of factors for the preparation of PS-hydroxide and the treatment of p-CP was finally determined by significance analysis. The degradation process was appropriately fitted by the pseudo-first-order kinetic model. the benzene ring in p-CP was broken by PS-hydroxide during the adsorption. The surface modification of PS-hydroxide caused by the valence transition of Mn was beneficial to the adsorption and catalytic degradation of p-CP.CapsuleA persulfate-doped layered bimetallic hydroxide was synthesized to construct a heterogeneously catalytic system to solve the drawback of homogeneity for the effective treatment of p-chlorophenol.

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