scholarly journals Photocatalytic Degradation of Monolinuron and Linuron in an Aqueous Suspension of Titanium Dioxide Under Simulated Solar Irradiation

2007 ◽  
Vol 20 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Razika Zouaghi ◽  
Abdennour Zertal ◽  
Bernard David ◽  
Sylvie Guittonneau
Keyword(s):  
Photocatalytic Degradation ◽  
Degradation Rate ◽  
Ph Value ◽  
Degradation Kinetics ◽  
Aqueous Suspension ◽  
Operating Conditions ◽  
Solar Irradiation ◽  
Point Of Zero Charge ◽  
Degradation Rates ◽  
Simulated Solar Irradiation

Abstract The photocatalytic degradation of two phenylurea herbicides, monolinuron (MLN) and linuron (LN), was investigated in an aqueous suspension of TiO2 using simulated solar irradiation. The objective of the study was to compare their photocatalytic reactivity and to assess the influence of various parameters such as initial pesticide concentration, catalyst concentration and photonic flux on the photocatalytic degradation rate of MLN and LN. A comparative study of the photocatalytic degradation kinetics of both herbicides showed that these two compounds have a comparable reactivity with TiO2/simulated sun light. Under the operating conditions of this study, the photocatalytic degradation of MLN and LN followed pseudo first-order decay kinetics. The kobs values indicated an inverse dependence on the initial herbicide concentration and were fitted to the Langmuir-Hinshelwood equation. Photocatalytic degradation rates increased with TiO2 dosage, but overdoses did not necessarily increase the photocatalytic efficiency. The degradation rate of MLN increased with radiant flux until an optimum at 580 W m‑2 was reached and then decreased. Under these conditions, an electron-hole recombination was favored. Finally, the photocatalytic degradation rate depended on pH, where an optimum was found at a pH value close to the pH of the point of zero charge (pH = 6).

Photocatalytic degradation kinetics of humic acid in aqueous TiO2 dispersions: the influence of hydrogen peroxide and bicarbonate ion

1996 ◽  
Vol 34 (9) ◽  
pp. 73-80 ◽  
Author(s):  
Miray Bekbölet ◽  
Isil Balcioglu
Keyword(s):  
Hydrogen Peroxide ◽  
Humic Acid ◽  
Photocatalytic Degradation ◽  
Rate Constants ◽  
Degradation Rate ◽  
Ph Value ◽  
Degradation Kinetics ◽  
Color Removal ◽  
Degradation Data ◽  
Kinetics Of

The degradation of humic acid in water by means of photocatalytic method has been studied. The influence of hydrogen peroxide and bicarbonate has also been investigated. The kinetics of the photocatalytic degradation of humic acid in various concentrations (50-500 mg/L) has been followed by the determination of TOC, COD and UV-vis spectra of the reaction solution. While the pseudo first order rate constants of 50 mg/L humic acid were found 0.016, 0.03 and 0.036 for TOC, Color400 and UV254, the degradation rate constants for these parameters were found 0.029, 0.069 and 0.057 in the presence of 1×10−2M H2O2. The Langmuir-Hinshelwood kinetic has also been sucessfully applied to the photocatalytic degradation data. It was found that bicarbonate ions slowed down the degradation rate by scavenging the hydroxyl radicals. Low pH value has been found to be favorable for color removal in the absence of hydrogen peroxide whereas natural pH gave the best results for color removal in the presence of hydrogen peroxide.

scholarly journals Effect of oxidants in the photocatalytic degradation of DEET under simulated solar irradiation in aqueous TiO2 suspensions

2014 ◽  
Vol 16 (3) ◽  
pp. 507-515 ◽  
Keyword(s):  
Photocatalytic Degradation ◽  
Alkaline Media ◽  
Solar Irradiation ◽  
Quantum Yields ◽  
Oh Radicals ◽  
Solution Ph ◽  
Photodegradation Rate ◽  
Degradation Rates ◽  
Decreasing Ph ◽  
Simulated Solar Irradiation

<div> <p>Recently, considerable efforts have been devoted to overcome a major limitation in semiconductor photocatalysis, the recombination of photogenerated e<sup>-</sup>-h<sup>+</sup> pairs which leads to reduced quantum yields. Considering the impacts of various parameters on the photocatalytic degradation efficiency, our attention has been mainly focused on the improvement of the TiO<sub>2</sub> mediated photocatalysis for the degradation of a representative emerging micro-pollutant, DEET (N,N-dimethyl-<em>m</em>-toluamide), a widespread insect repellent. The efficiency of TiO<sub>2</sub> photocatalysis to degrade DEET was investigated in the presence of hydrogen peroxide and persulfate ions as oxidants-sacrificial electron acceptors under simulated solar irradiation (SSL). The degradation rates were found to be strongly influenced by the addition of oxidants. Higher degradation rates were observed in the presence of oxidants with the following order: S<sub>2</sub>O<sub>8</sub> <sup>2-</sup> &gt; H<sub>2</sub>O<sub>2. </sub>Τhe effect of solution pH in the range of 3&ndash;10 was investigated and the photodegradation rate was found to increase along with decreasing pH. Scavenging experiments indicated that that sulfate radicals were predominant species at acidic pH while <sup>&bull;</sup>OH radicals were principally responsible for DEET degradation in alkaline media using SSL/TiO<sub>2</sub>/S<sub>2</sub>O<sub>8</sub><sup>2-</sup>, the most efficient process.</p> </div> <p>&nbsp;</p>

scholarly journals Preparation of Ti-Nb-Fe-O Nanotubes on Ti10NbxFe Alloy and the Application for Photocatalytic Degradation under Solar Irradiation

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 327
Author(s):  
Yujie Zhao ◽  
Qiquan Li ◽  
Yan Li
Keyword(s):  
Photocatalytic Degradation ◽  
Mixed Oxide ◽  
Tio2 Nanotubes ◽  
Degradation Rate ◽  
Solar Irradiation ◽  
Methylene Blue Degradation ◽  
Co Doping ◽  
Secondary Pollution ◽  
The Rich ◽  
Thick Layers

Highly oriented and self-ordered titanium-niobium-iron mixed oxide nanotubes were synthesized by anodizing Ti10NbxFe alloys in ethylene glycol electrolytes containing NH4F and water at 20 °C. The nanostructure morphologies were found to depend closely on the nature of the alloy substrates. The results demonstrate the possibility of growing mixed oxide nanotubes possessing several-micrometer-thick layers by a simple and straightforward electrochemical route. The methylene blue degradation rate of fabricated Ti-Nb-Fe-O nanotubes increased by 33% compared to TiO2 nanotubes and TiO2 nanoparticle films under solar irradiation. The combination of the gully-like morphology and the rich defects introduced by Nb and Fe co-doping in Ti-Nb-Fe-O mixed nanotube oxides was demonstrated to be beneficial for enhanced photocatalytic degradation performance. Ti-Nb-Fe-O nanotubes can achieve effective photodegradation without secondary pollution with more reusability than powder photocatalysts.

Study on the Properties of Photocatalytic Degradation of DMP on WO3/TNAs Photoelectrodes

2013 ◽  
Vol 850-851 ◽  
pp. 12-15 ◽  
Author(s):  
Yan Shi ◽  
Yong Ping Liu ◽  
Yan Jun Xin
Keyword(s):  
Photocatalytic Degradation ◽  
Degradation Rate ◽  
Ph Value ◽  
Photocatalytic Property ◽  
Alkaline Condition ◽  
Deposition Method ◽  
Dimethyl Phthalate ◽  
Nanotube Array ◽  
Electro Deposition ◽  
Positive Effect

In this study, WO3/TiO2nanotube array photoelectrodes were fabricated by anodic oxidation and electro-deposition method. The effects of WO3, H2O2, oxygen, and pH value were investigated in the degradation of Dimethyl phthalate (DMP). Results show that the photocatalytic property of the photoelectrode was improved by the modification of WO3. The degradation rate of DMP was increased by 9.3% after 120min irradiation. H2O2could significantly promote the degradation of DMP. The degradation rate of DMP was increased by 27.9% and arrived 97.5% after 120 min irradiation. A certain amount of O2added to the solution had positive effect on the degradation of DMP. While excessive O2would undermine the degradation. The degradation rate of DMP was improved in both acidic condition and alkaline condition. It was separately increased by 38.4% and 40.2% at the pH value of 3.0 and 7.0, compared with that of pH = 7.

scholarly journals Comparison of the degradation of molecular and ionic ibuprofen in a UV/H2O2 system

2018 ◽  
Vol 77 (9) ◽  
pp. 2174-2183 ◽  
Author(s):  
Rongkui Su ◽  
Liyuan Chai ◽  
Chongjian Tang ◽  
Bo Li ◽  
Zhihui Yang
Keyword(s):  
Quantum Yield ◽  
Rate Constant ◽  
Degradation Rate ◽  
Molecular Form ◽  
Degradation Kinetics ◽  
Dominant Role ◽  
Radical Scavenging ◽  
Operating Conditions ◽  
Direct Photolysis ◽  
H2o2 System

Abstract The advanced oxidation technologies based on •OH can effectively degrade the pharmaceutical and personal care products under operating conditions of normal temperature and pressure. In this study, direct photolysis of ibuprofen (IBU) is slow due to the relatively low molar extinction coefficient and quantum yield. Compared to direct photolysis, the degradation kinetics of IBU was significantly enhanced in the UV/H2O2 system, mainly by •OH radical mediated oxidation. In the UV/H2O2 system, the degradation rate of ionic IBU was slightly faster than that of the molecular form. Kinetic analysis showed that the second-order reaction rate constant of ionic IBU (5.51 × 109 M−1 s−1) was higher than that of the molecular form (3.43 × 109 M−1 s−1). The pseudo first-order rate constant for IBU degradation (kobs) increased with increasing H2O2 dosage. kobs can be significantly decreased in the presence of natural organic matter (NOM), which is due to (i) NOM radical scavenging effects (dominant role) and (ii) UV absorption. The degradation of IBU was inhibited by HCO3–, which was attributed to its scavenging effect. Interestingly, when NO3– was present in aqueous solution, a slight increase in the degradation rate was observed, which was due to NO3– absorbing photons to generate •OH at a low quantum yield. No obvious effects were observed when SO42 and Cl− were present.

scholarly journals Improving the ZnO-photocatalytic degradation of humic acid using powdered residuals from water purification plant

2021 ◽  
Author(s):  
Mohamed Elmougi ◽  
Hisham El-Etriby ◽  
Ragab Barakat ◽  
Mohamed Gar Alalm ◽  
Mohamed Mossad
Keyword(s):  
Humic Acid ◽  
Photocatalytic Degradation ◽  
Removal Efficiency ◽  
Water Purification ◽  
Degradation Kinetics ◽  
Irradiation Time ◽  
Treatment Plant ◽  
Operating Conditions ◽  
Coefficient Of Determination ◽  
Purification Plant

Abstract Alum residuals were collected from a water treatment plant and used for improving the photocatalytic degradation of humic acid (HA) by combinations of zinc oxide (ZnO) and powdered residuals from water purification plant (PRWPP). The influence of operating conditions such as initial humic acid concentration, pH, irradiation time, PRWPP to ZnO ratio, catalyst dose, and light illuminance have been investigated. The optimum PRWPP to ZnO ratio was 10:90. Using the prepared composites instead of bare ZnO raised the HA removal efficiency from 85.5% to 97.8%, and from 38% to 48.1% at catalyst doses of 1.2 g/l and 0.4 g/l, respectively. Moreover, it reduced energy consumption from 210.4 to 166.2 Wh per mg of HA. An artificial neural network model (ANN) was developed to predict the removal efficiency under different operating conditions. The optimum ANN structure yielded a coefficient of determination (R2 = 0.993). Modified Langmuir-Hinshelwood pseudo-first-order model was used for describing the degradation kinetics at different initial concentrations of HA.

scholarly journals Photocatalytic Degradation of Tobacco Tar Using CsPbBr3 Quantum Dots Modified Bi2WO6 Composite Photocatalyst

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2422
Author(s):  
Runda Huang ◽  
Menglong Zhang ◽  
Zhaoqiang Zheng ◽  
Kunqiang Wang ◽  
Xiao Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photocatalytic Degradation ◽  
Solar Irradiation ◽  
Composite Photocatalyst ◽  
Polycyclic Aromatic ◽  
Cigarette Paper ◽  
Novel Applications ◽  
Simulated Solar Irradiation ◽  
First Time ◽  
Cspbbr3 Quantum Dots

Polycyclic aromatic hydrocarbons (PAHs) in tobacco tar are regarded as a significant threat to human health. PAHs are formed due to the incomplete combustion of organics in tobacco and cigarette paper. Herein, for the first time, we extended the application of CsPbBr3 quantum dots (CsPbBr3) to the photocatalytic degradation of tobacco tar, which was collected from used cigarette filters. To optimize the photoactivity, CsPbBr3 was coupled with Bi2WO6 for the construction of a type-II photocatalyst. The photocatalytic performance of the CsPbBr3/Bi2WO6 composite was evaluated by the degradation rate of PAHs from tobacco tar under simulated solar irradiation. The results revealed that CsPbBr3/Bi2WO6 possesses a large specific surface area, outstanding absorption ability, good light absorption and rapid charge separation. As a result, in addition to good stability, the composite photocatalyst performed remarkably well in degrading PAHs (over 96% were removed in 50 mins of irradiation by AM 1.5 G). This study sheds light on promising novel applications of halide perovskite.

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