scholarly journals Enhanced Photocatalytic Degradation of Perfluorooctanoic Acid by Mesoporous Sb2O3/TiO2 Heterojunctions

2021 ◽  
Vol 9 ◽  
Author(s):  
Xinyun Yao ◽  
Jiaqi Zuo ◽  
Yu-Jue Wang ◽  
Ning-Ning Song ◽  
Huang-Hao Li ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Active Sites ◽  
Uv Light ◽  
Degradation Kinetics ◽  
Direct Electron Transfer ◽  
Perfluorooctanoic Acid ◽  
Term Operation ◽  
Spin Resonance ◽  
Light Utilization

Perfluorooctanoic acid (PFOA), a typical perfluorinated carboxylic acid, is an emerging type of permanent organic pollutants that are regulated by the Stockholm Convention. The degradation of PFOA, however, is quite challenging largely due to the ultra-high stability of C-F bonds. Compared with other techniques, photocatalytic degradation offers the potential advantages of simple operation under mild conditions as well as exceptional decomposition and defluorination efficiency. Titanium dioxide (TiO2) is one of the most frequently used photocatalysts, but so far, the pristine nanosized TiO2 (e.g., the commercial P25) has been considered inefficient for PFOA degradation, since the photo-generated hydroxyl radicals from TiO2 are not able to directly attack C-F bonds. Mesoporous Sb2O3/TiO2 heterojunctions were therefore rationally designed in this work, of which the confined Sb2O3 nanoparticles in mesoporous TiO2 framework could not only tune the band structure and also increase the number of active sites for PFOA degradation. It was found that, after loading Sb2O3, the absorption of UV light was enhanced, indicating a higher efficiency of light utilization; while the band gap was reduced, which accelerated the separation of photo-generated charge carriers; and most importantly, the valence band edge of the Sb2O3/TiO2 heterojunction was significantly lifted so as to prevent the occurrence of hydroxyl radical pathway. Under the optimal ratio of Sb2O3–TiO2, the resulting catalysts managed to remove 81.7% PFOA in 2 h, with a degradation kinetics 4.2 times faster than the commercial P25. Scavenger tests and electron spin resonance spectra further revealed that such improvement was mainly attributed to the formation of superoxide radicals and photo-generated holes, in which the former drove the decarboxylation from C7F15COOH–C7F15•, and the latter promoted the direct electron transfer for the conversion of C7F15COO−–C7F15COO•. The Sb2O3/TiO2 photocatalysts were highly recyclable, with nearly 90% of the initial activity being retained after five consecutive cycles, guaranteeing the feasibility of long-term operation.

scholarly journals How Photocatalyst Dosage and Ultrasound Application Influence the Photocatalytic Degradation Rate of Phenol in Water: Elucidating the Mechanisms Behind

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1672 ◽  
Author(s):  
Wim Van de Moortel ◽  
Mohammadreza Kamali ◽  
Kristel Sniegowski ◽  
Leen Braeken ◽  
Jan Degrève ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Degradation Rate ◽  
Uv Light ◽  
Degradation Kinetics ◽  
Phenol Degradation ◽  
Process Conditions ◽  
Oh Radicals ◽  
Tio2 Particles ◽  
Ultrasound Application

Photocatalysis is of high interest for the treatment of wastewater containing non-biodegradable organic components. In this work, the photocatalytic degradation of phenol by TiO2 photocatalysis was assessed, the influence of ultrasound (US) treatment was evaluated, and the mechanisms behind it were elucidated. It was shown that the TiO2 concentration (in suspension) has a large influence on the degradation kinetics. At high TiO2 concentrations, a reduced efficiency was observed due to the shielding of the UV light by TiO2 particles. US treatment effectively increased phenol degradation by improving the mass transfer while it was shown by the experimental data that particle deagglomeration did not play a significant role. The degradation mainly occurred through indirect phenol oxidation by hydroxyl (OH*) radicals, which were formed in situ at the surface of the photocatalyst. Finally, based on the partial least squares (PLS) methodology, a mathematical model was developed, representing phenol degradation as a function of the selected process conditions.

Analysis of crystallite size changes in a hematite and magnetite formed on steel used in the power idustry

2017 ◽  
Vol 1 (21) ◽  
pp. 65-73
Author(s):  
Monika Gwoździk
Keyword(s):  
Elevated Temperature ◽  
Oxide Layer ◽  
Cross Section ◽  
X Ray ◽  
Term Operation ◽  
Diffraction Line Profile ◽  
Crystallite Sizes ◽  
Scherrer Formula ◽  
Pipe Outlet

The paper presents results of studies on the crystallite sizes of oxide layer formed during a long-term operation on 10CrMo9-10 steel at an elevated temperature (T = 545° C, t = 200,000 h). This value was determined by a method based on analysis of the diffraction line profile, according to a Scherrer formula. The oxide layer was studied on a surface and a cross-section at the outer and inner site on the pipe outlet, at the fire and counter-fire wall of the tube. X-ray studies were carried out on the surface of a tube, then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer.

Retention and expression of recombinant plasmids in suspended and biofilm-bound bacteria degrading trichloroethene (TCE)

1997 ◽  
Vol 36 (10) ◽  
pp. 1-8 ◽  
Author(s):  
James D. Bryers ◽  
Robert R. Sharp
Keyword(s):  
Biofilm Reactor ◽  
Bacterial Biofilm ◽  
Laboratory Evaluation ◽  
Recombinant Bacteria ◽  
Suitable Host ◽  
Term Operation ◽  
Open Environment ◽  
Recombinant Microorganisms ◽  
Extracellular Polymer

Exposure of plasmid recombinant microorganisms to an open environment, either inadvertently or intentionally, requires research into those fundamental processes that govern plasmid retention, transfer and expression. In the open environment, a majority of the microbial activity occurs associated with an interface, within thin biological layers consisting of cells and their insoluble extracellular polymer, layers known as biofilms. Current toxic wastewater or wastegas treatment reactors exploit bacterial biofilm systems for certain system operating advantages. Using recombinant bacteria within a biofilm reactor to degrade xenobiotic wastes requires finding a suitable host to harbor and express the desired plasmid phenotype. Suitable host characteristics include: the ability to produce copious amounts of biofilm, resistance to waste-related injury and toxicity, and the ability to retain and express the desired plasmid during long term operation. This paper reports on a laboratory evaluation of factors governing plasmid retention and the expression of trichloroethene (TCE) degradative capacity in both suspended and biofilm cultures.

Study of Photocatalytic Dergradation, Kinetics and Microbial Activities of Copper (ii) Soya Urea Complex in Non Aqueous Media

2020 ◽  
Vol 17 ◽  
Author(s):  
Vandana Sukhadia ◽  
Rashmi Sharma ◽  
Asha Meena
Keyword(s):  
Staphylococcus Aureus ◽  
Photocatalytic Degradation ◽  
Degradation Kinetics ◽  
Waste Water Treatment ◽  
Aqueous Media ◽  
Research Work ◽  
Solvent Polarity ◽  
Urea Complex ◽  
Pseudo First Order Reaction ◽  
Aqueous Solvent

Aims: The aim of this research work is to synthesise, study and analyse photocatalytic degradation, kinetics and microbial activity of new surfactant Copper (II) soya urea complex(CSU). Background: Photocatalytic degradation has attracted the attention of scientific community throughout the world due to its multiple applications in environment, energy, waste water treatment, pollution control, green chemistry, etc. Copper (II) soya urea complex has been synthesized and characterized through FT-IR, NMR, ESR studies. Objective: Present work deals with the study of photocatalytic degradation of Copper (II) soya urea complex by using ZnO as semiconductor. This study employs a semiconductor catalyst using non polar and non aqueous solvent in photocatalytic degradation. Reaction rate is chosen as the photocatalytic activity, which has been governed by several factors. Antibacterial activities of Copper (II) complex have also been studied against Staphylococcus aureus. Method: Optical density (O.D.) was measured after different time intervals spectrophotometrically to measure the degradation of complex. Mueller-Hinton agar medium was used for antimicrobial activity of synthesized compound at different concentrations by disk/ well diffusion susceptibility testing. Result: Plot of 2+log O.D. (absorbance) versus time was plotted and found linear. The heterogeneous photocatalysis followed pseudo-first-order reaction kinetics.The present study suggests that Copper (II) soya urea (CSU) complex shows antibacterial activity against Staphylococcus aureus at different concentrations. Conclusion: The results were used to determine the rate of photocatalytic degradation of CSU complex .It has been found that rate of degradation varies with different parameters like concentration of complex, amount of catalyst, light intensity, solvent polarity etc. CSU complex derived from soyabean oil has been shown an inhibitory effect on the growth of S. aureus which may causes skin disease.

Photocatalytic Degradation and Antibacterial Study of Copper(II) Mustard Thiourea Complex

2020 ◽  
Vol 10 (3) ◽  
pp. 229-242
Author(s):  
Vandana Sukhadia ◽  
Rashmi Sharma ◽  
Asha Meena
Keyword(s):  
Photocatalytic Degradation ◽  
Skin Diseases ◽  
Polar Solvent ◽  
Degradation Kinetics ◽  
Research Work ◽  
Solvent Polarity ◽  
Inhibitory Effect ◽  
Mustard Oil ◽  
Urea Complex ◽  
Pseudo First Order Reaction

Aims: The aim of this research work is to synthesise, study and analyse photocatalytic degradation, kinetics. Background: Copper(II) mustard thio urea complex has been synthesized and characterized through FT-IR, NMR, ESR studies. Objective: Photocatalytic degradation of copper(II) mustard thio urea complex was studied in the presence of ZnO as a catalyst in the solution form, using a non polar solvent benzene and a polar solvent methanol with different compositions. Antibacterial activities of copper(II) complex have also been studied against Staphylococcus aureus. Method: O.D. was measured after different time intervals spectrophotometrically to measure the degradation of the complex. Result: Plot of 2+ log O.D. (absorbance) versus time was plotted and found to be linear. The heterogeneous photocatalysis followed pseudo-first-order reaction kinetics. The present study suggests that the CMT complex shows antibacterial activity at different concentrations. Conclusion: The rate of photocatalytic degradation of CMT complex was studied and analyzed. It has been found that the rate of degradation varies with different parameters like the concentration of complex, the amount of catalyst, light intensity, solvent polarity etc. The CMT complex derived from natural mustard oil has shown an inhibitory effect on the growth of S. aureus which may cause skin diseases.

Sign in / Sign up

Export Citation Format

Share Document