Photocatalytic degradation of ofloxacin by ZnO/CsxWO3 composite synthesized by two-step method: A kinetic study

2019 ◽  
Vol 12 (05) ◽  
pp. 1950068 ◽  
Author(s):  
Wenwen Ning ◽  
Zhihuan Zhao ◽  
Honghong Chang ◽  
Zhanyong Gu ◽  
Bing Zhang ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Photocatalytic Performance ◽  
Solvothermal Method ◽  
Active Species ◽  
Step Method ◽  
Full Spectrum ◽  
First Order ◽  
First Order Kinetics ◽  
Photogenerated Electrons ◽  
Prepared Composite

The composite of ZnO/CsxWO3 with heterojunction was prepared by a two-step solvothermal method and the degradation of ofloxacin solution under full-spectrum light irradiation was carried out to evaluate the performance. The composites were characterized by XRD, SEM, EDS and UV-Vis-NIR reflectance. The result shows that the prepared composite has an ideal optical absorption in the spectral region of 200–2500[Formula: see text]nm and higher photocatalytic performance compared with ZnO and CsxWO3. Moreover, [Formula: see text], [Formula: see text]OH and [Formula: see text][Formula: see text] radicals are determined to be the active species. It is suggested that the heterojunction between ZnO and CsxWO3 for ZnO/CsxWO3 composite is important for improving the charge separation and thus restraining the recombination of photogenerated electrons and holes. Photodegradation of ofloxacin catalyzed by ZnO/CsxWO3 followed the first-order kinetics and the degradation rate of ZnO/2CsxWO3 was about two times higher than those of CsxWO3 and ZnO.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

scholarly journals Fabrication of La2O3/g-C3N4 Heterojunction with Enhanced Photocatalytic Performance of Tetracycline Hydrochloride

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1349
Author(s):  
Zhengru Zhu ◽  
Haiwen Xia ◽  
Rina Wu ◽  
Yongqiang Cao ◽  
Hong Li
Keyword(s):  
Hydroxyl Radicals ◽  
Degradation Rate ◽  
Photocatalytic Performance ◽  
Superoxide Radical ◽  
Active Species ◽  
Tetracycline Hydrochloride ◽  
Radical Anions ◽  
Photocatalytic Process ◽  
Composite Photocatalysts ◽  
Ultrasound Assisted

In this study, La2O3/g-C3N4 heterojunction photocatalysts doped with different dosages of La2O3 were constructed by a facile ultrasound-assisted calcination approach. The as-prepared photocatalysts were characterized by XRD, FTIR, FESEM, TEM, XPS, PL and DRS to verify the composite photocatalysts’ purity and to investigate their structural, morphological and elemental composition, and their energy band. According to the results, a type of pure rod–sheet-shaped, heterostructured nanoparticle was successfully obtained. Decorated with 10% La2O3, 2 g/L of the composite sample had a 93% degradation rate for 20 mg/L tetracycline hydrochloride within 2 h under visible light at a pH of 7. After four successive photocatalytic runs, satisfactory stability and reusability was exhibited, with 70% of the tetracycline hydrochloride being removed in the final experiment. Electrons (e−), photogenerated holes (h+), superoxide radical anions (O2−) and hydroxyl radicals (OH) were the fundamental active species during the photocatalytic process and were investigated via quenching experiments. Furthermore, possible photocatalytic mechanisms were analyzed in this work.

Fabrication Porous Ag/BiVO4 Film for Efficient Degradation of Phenol under Visible Light

2012 ◽  
Vol 518-523 ◽  
pp. 732-735 ◽  
Author(s):  
Xi Qiang Li ◽  
Xiu Fang Zhang ◽  
Xiao Li Dong ◽  
Chun Ma ◽  
Xin Xin Zhang ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Degradation Rate ◽  
Photocatalytic Performance ◽  
Xrd Analysis ◽  
Diffusion Resistance ◽  
Photocatalytic Efficiency ◽  
Photogenerated Electrons ◽  
Ag Particles ◽  
Carrier Separation ◽  
Rapid Transfer

Porous BiVO4 film was fabricated by templating procedure with polystyrene (PS) balls as the template. Ag particles were loaded on the porous BiVO4 film by photoreduction technique. SEM revealed there were many pores in the film and Ag particles were successfully loaded on the porous BiVO4 film. XRD analysis indicated that the chemical state of Ag particles was metallic Ag. The experiment of photocatalytic degradation of phenol showed that the degradation rate on porous Ag/BiVO4 film was 4.74 times as much as that on the BiVO4 film. The enhanced photocatalytic performance was firstly attributed to the rapid transfer of the photogenerated electrons from BiVO4 to Ag, which could increase the charge carrier separation, limit their recombination, and enhance the photocatalytic efficiency. Furthermore, porosity of the photocatalyst may enhance diffusion process and decrease diffusion resistance of the reactants throughout the channels in the photocatalyst, and thus improves the surface reactions.

scholarly journals Rapid Solar-Light Driven Superior Photocatalytic Degradation of Methylene Blue Using MoS2-ZnO Heterostructure Nanorods Photocatalyst

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2254 ◽  
Author(s):  
Ritika ◽  
Manjot Kaur ◽  
Ahmad Umar ◽  
Surinder Mehta ◽  
Surinder Singh ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Performance ◽  
Hexagonal Phase ◽  
Rhombohedral Phase ◽  
Active Species ◽  
Charge Carriers ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Photocatalytic Removal ◽  
Wurtzite Hexagonal Phase

Herein, MoS2-ZnO heterostructure nanorods were hydrothermally synthesized and characterized in detail using several compositional, optical, and morphological techniques. The comprehensive characterizations show that the synthesized MoS2/ZnO heterostructure nanorods were composed of wurtzite hexagonal phase of ZnO and rhombohedral phase of MoS2. The synthesized MoS2/ZnO heterostructure nanorods were used as a potent photocatalyst for the decomposition of methylene blue (MB) dye under natural sunlight. The prepared MoS2/ZnO heterostructure nanorods exhibited ~97% removal of MB in the reaction time of 20 min with the catalyst amount of 0.15 g/L. The kinetic study revealed that the photocatalytic removal of MB was found to be in accordance with pseudo first-order reaction kinetics with an obtained rate constant of 0.16262 min−1. The tremendous photocatalytic performance of MoS2-ZnO heterostructure nanorods could be accredited to an effective charge transportation and inhibition in the recombination of photo-excited charge carriers at an interfacial heterojunction. The contribution of active species towards the decomposition of MB using MoS2-ZnO heterostructure nanorods was confirmed from scavenger study and terephthalic acid fluorescence technique.

Microwave-Assisted Fabrication of Recyclable CdS/Fe3O4/rGO Photocatalysts to Improve the Photocatalytic Performance Under Visible Light

NANO ◽  
2016 ◽  
Vol 11 (11) ◽  
pp. 1650129 ◽  
Author(s):  
Xinlin Liu ◽  
Yingying Qin ◽  
Mingjun Zhou ◽  
Yongsheng Yan
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Activity ◽  
Charge Transfer ◽  
Visible Light ◽  
Degradation Rate ◽  
Photocatalytic Performance ◽  
Active Species ◽  
Microwave Method ◽  
Composite Photocatalyst ◽  
Microwave Assisted

A unique CdS/Fe3O4/rGO composite photocatalyst is successfully synthesized by the microwave method. It displays promising photocatalytic activity towards the photo-degrading of tetracycline (TC) in aqueous solution, the degradation rate of TC is 69% with adding 0.1[Formula: see text]g CdS/Fe3O4/rGO photocatalyst into 20[Formula: see text]mg/L tetracycline for 2[Formula: see text]h under visible light irradiation. Furthermore, the mechanism was systematically investigated by active species trapping experiment. It can be known that [Formula: see text] the major active species in the photodegradation process and the possible process of charge transfer for CdS/Fe3O4/rGO was proposed based on the experimental results. The as-prepared samples were carefully evaluated by XRD, TEM, XPS, VSM, PL spectra, Raman spectrometer.

scholarly journals Photocatalytic Performance and Degradation Pathway of Rhodamine B with TS-1/C3N4 Composite under Visible Light

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 756 ◽  
Author(s):  
Jingjing Yang ◽  
Hongqing Zhu ◽  
Yuan Peng ◽  
Pengxi Li ◽  
Shuyan Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Degradation Products ◽  
Nitrogen Adsorption ◽  
Degradation Pathway ◽  
Active Species ◽  
Photogenerated Electrons

TS-1/C3N4 composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption–desorption isotherm. The photocatalytic performance of TS-1/C3N4 composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C3N4; TS-1/C3N4-B composite (the measured mass ratio of TS-1 to C3N4 is 1:4) had best performance, with a rate constant of 0.04166 min−1, which is about two and ten times higher than those of C3N4 and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C3N4 with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C3N4 composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O2−, ·OH and h+. The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed.

Effect of Ultrasonic Frequency on Chlorpyrifos Degradation in Sonolytic Ozonolysis

2014 ◽  
Vol 587-589 ◽  
pp. 578-581
Author(s):  
Jin Zhu ◽  
Chang Ping Zhu ◽  
Bin Wang ◽  
Run Hang Gong ◽  
Qing Gong Ren ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Degradation Rate ◽  
Degradation Kinetics ◽  
Degradation Pathway ◽  
Frequency Effect ◽  
Ultrasonic Frequency ◽  
Kinetics Parameters ◽  
First Order ◽  
First Order Kinetics ◽  
Degradation Reaction

The degradation of chlorpyrifos is investigated with the treatments of sonolysis, ozonolysis, and sonolytic ozonolysis at various frequencies. Results show that there exists frequency effect in sonolytic ozonolysis. In sonolytic ozonolysis, the maximum degradation rate is obtained at 495 kHz, and the degradation kinetics is fitted to the first-order kinetics model well. However, the most significant synergistic effect between ultrasonic and ozone is at 124 kHz. The kinetics parameters indicate that chlorpyrifos is much more labile to ultrasonic at 495 kHz, while ozone is much more soluble at 124 kHz. The hydrolysis and oxidation are deduced to contribute to the degradation reaction and the degradation pathway for chlorpyrifos degradation is proposed.

scholarly journals Photodegradation of levofloxacin in aqueous and organic solvents: A kinetic study

2013 ◽  
Vol 63 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Iqbal Ahmad ◽  
Raheela Bano ◽  
Muhammad Ali Sheraz ◽  
Sofia Ahmed ◽  
Tania Mirza ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Degradation Rate ◽  
Hplc Method ◽  
Ph Profile ◽  
Degree Of Ionization ◽  
First Order ◽  
First Order Kinetics ◽  
Anionic Species ◽  
Ph Range ◽  
Kinetics Of

The kinetics of photodegradation of levofloxacin in solution on UV irradiation in the pH range 2.0-12.0 has been studied using a HPLC method. Levofloxacin undergoes first-order kinetics in the initial stages of the reaction and the apparent first-order rate constants are of the order of 0.167 to 1.807×10-3 min-1. The rate-pH profile is represented by a curve indicating the presence of cationic, dipolar and anionic species during the reaction. The singly ionized form of the molecule is non-fluorescent and is less susceptible to photodegradation. The increase in the degradation rate in the pH range 5.0-9.0 may be due to greater reactivity of the ionized species existing in that range. The rate appears to vary with a change in the degree of ionization of the species present in a particular pH range and their susceptibility to photodegradation. Above pH 9, the decrease in the rate of photodegradation may be a result of deprotonation of the piperazinyl group. The levofloxacin molecule is more stable in the pH range around 7, which is then suitable for formulation purposes. The photodegradation of levofloxacin was found to be affected by the dielectric constant and viscosity of the medium

scholarly journals The Research on the Construction and the Photocatalytic Performance of BiOI/NH2-MIL-125(Ti) Composite

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Juan Du ◽  
Jiaxin Zhang ◽  
Tingyu Yang ◽  
Renming Liu ◽  
Zhiyi Li ◽  
...  
Keyword(s):  
High Stability ◽  
Diffuse Reflectance ◽  
Photocatalytic Performance ◽  
Separation Efficiency ◽  
Solvothermal Method ◽  
Degradation Mechanism ◽  
Active Species ◽  
Absorption Region ◽  
Composite Photocatalyst ◽  
Recombination Efficiency

The BiOI/NH2-MIL-125(Ti) composite photocatalyst with excellent photocatalytic performance was prepared by the solvothermal method. For the BiOI/NH2-MIL-125(Ti) (BNMT) system, the contents of NH2-MIL-125(Ti) in BNMT-4, BNMT-5, BNMT-7, BNMT-9, and BNMT-10 were 4 wt %, 5 wt %, 7 wt %, 9 wt %, and 10 wt %, respectively. XRD, XPS, SEM, and TEM characterizations indicated that BiOI/NH2-MIL-125(Ti) was successfully prepared. Brunauer, Emmett, and Teller (BET) and UV–vis diffuse reflectance spectra photoelectrochemical analysis indicated that BNMT-9 can make the specific surface area and photo absorption region larger than BiOI. In addition, the separation efficiency of photogenerated carriers was improved, and the recombination efficiency was reduced. The degradation percentages of Rhodamine B (RhB) and p-chlorophenol (P-CP) reached 99% and 90% over BNMT-9 under visible light irradiation. Additionally, the catalysts had high stability. The results of the active spices trapping experiments test indicated that h+ was the main active species. The possible degradation mechanism was proposed.

scholarly journals Degradation kinetics and in vitro digestive stability of selected bioactive compounds from a beverage formulated with butterfly pea flowers

2022 ◽  
Vol 52 (5) ◽  
Author(s):  
Renata Oliveira Santos ◽  
Laura Monteiro Keller ◽  
Vanessa Sales de Oliveira ◽  
Carlos Alberto Bucher ◽  
José Lucena Barbosa Junior ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Degradation Rate ◽  
Degradation Kinetics ◽  
Model Systems ◽  
First Order ◽  
Ph Values ◽  
First Order Kinetics ◽  
Butterfly Pea ◽  
Effects Of Temperature

ABSTRACT: This study evaluated the effects of temperature on the pH of extracts of ascorbic acid and anthocyanins from petals of butterfly pea, as well as their in vitro digestive stability in model systems at 60, 70, and 80 °C. The pH values significantly decreased with an increase in the temperature (P < 0.05). The findings were similar for the degradation of anthocyanins and ascorbic acid, which followed first-order kinetics in all the systems. The samples heated at 80 °C presented the highest degradation rate (kobs), as well as higher percentages of degradation at the end of digestive stability in vitro.

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