scholarly journals Kinetics and mechanisms of EDTA photocatalytic degradation withTiO2under different experimental conditions

2001 ◽  
Vol 3 (4) ◽  
pp. 193-199 ◽  
Author(s):  
Paola A. Babay ◽  
Carina A. Emilio ◽  
Rosana E. Ferreyra ◽  
Eduardo A. Gautier ◽  
Raquel T. Gettar ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Photocatalytic Degradation ◽  
Reaction Rate ◽  
Initial Rate ◽  
Uv Light ◽  
Degradation Process ◽  
Kinetic Regime ◽  
Experimental Conditions ◽  
Initial Ph ◽  
Limiting Values

The photocatalytic degradationof EDTA overTiO2has been analyzed to establish the influence of oxidants on the reaction rate, the nature of the intermediates and the kinetic regime. Degussa P-25 suspensions containing EDTA at initial pH 3 in different concentrations were irradiated under near UV light. A Langmuirian behavior was observed.O2at saturation concentrations was found to be crucial for EDTA degradation. The rapid depletion of EDTA was not accompanied by a corresponding TOC decrease, indicating formation of refractory intermediates. An enhancement in TOC reduction could be achieved by keeping pH constant or by hydrogen peroxide addition. Addition of Fe(III) caused a remarkable increase on the initial rate of EDTA consumption and also on TOC decrease. Changes in both parameters clearly increased under the simultaneous addition of Fe(III) andH2O2, until limiting values.Some of the possible intermediates of EDTA degradation were evaluated in the filtered solution. So far, glycine, ethylenediamine, ammonium, formaldehyde, and formic, iminodiacetic, oxalic, oxamic, glycolic and glyoxylic acids have been identified in different proportions, depending on the experimental conditions. Different degradationpathways are proposed. Inthe presence of Fe(III), photo-Fenton reactions would contribute also to the degradation process.

Photocatalytic Degradation of 2,4,5–TCP in TiO2/UV/H2O2 System

2012 ◽  
Vol 518-523 ◽  
pp. 2649-2652
Author(s):  
Yan Ping Zong ◽  
Xian Hua Liu ◽  
Xi Wen Du ◽  
Yi Ren Lu ◽  
Xiao Xuan Shi
Keyword(s):  
Hydrogen Peroxide ◽  
Photocatalytic Degradation ◽  
Absorption Spectroscopy ◽  
Degradation Mechanism ◽  
Analysis Method ◽  
Photocatalytic System ◽  
Initial Ph ◽  
Effects Of Ph

The photocatalytic degradation of 2,4,5–Trichlorophenol(2,4,5–TCP) in TiO2/UV/ H2O2 photocatalytic system was examined using absorption spectroscopy and GC-MS. It was found that 2,4,5–TCP could be degraded almost completely within 100 min under the conditions of initial pH 3, C(H2O2) = 0.08 mol/L and C(TiO2) = 0.5 g/L. The effects of pH and the concentration of hydrogen peroxide on the degradation of 2,4,5–TCP were also studied. Besides, the degradation mechanism was concluded accorrding to convertional analysis method too.

PHOTOCATALYTIC DEGRADATION OF PYRENE IN POROUS Pt/TiO2–SiO2 PHOTOCATALYST SUSPENSION UNDER UV IRRADIATION

NANO ◽  
2008 ◽  
Vol 03 (05) ◽  
pp. 317-322 ◽  
Author(s):  
ZHAOHUI LUO ◽  
KEIKO KATAYAMA-HIRAYAMA ◽  
KIMIAKI HIRAYAMA ◽  
TETSUYA AKITSU ◽  
HIDEHIRO KANEKO
Keyword(s):  
Molecular Weight ◽  
Photocatalytic Degradation ◽  
High Molecular Weight ◽  
Uv Irradiation ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Bet Surface Area ◽  
Experimental Conditions ◽  
Initial Concentration ◽  
X Ray

Pyrene is a high molecular weight polycyclic aromatic hydrocarbon (PAH) that is found in water systems worldwide. It is harmful to living organisms, even when taken in very small amounts. The photocatalytic degradation of pyrene in porous Pt / TiO 2– SiO 2 photocatalyst (PPtPC) suspension under UV irradiation was investigated in this study. PPtPC was prepared by a simple heat treatment of the compacted powder mixtures of anatase TiO 2 and amorphous SiO 2 with camphor as a pore directing template, followed by coating platinum by the dip-coating method. X-ray diffraction (XRD), scanning electron microscopy (SEM) with an integrated energy-dispersive analysis of the X-ray (EDX) system, and Brunauer–Emmett–Teller (BET) were used to characterize PPtPC. The degradation kinetics of pyrene in different experimental conditions, such as initial concentration of pyrene, oxygen concentrations, pH, and temperature, were investigated. The durability of PPtPC was also tested. The results indicate that the structure of TiO 2 in PPtPC is anatase. The aggregated size of PPtPC is in the range of 10–100 μm, the mean pore diameter is 3 nm, and the BET surface area is 109 m2 g-1. The photocatalytic degradation process of pyrene follows pseudo-first-order kinetics. The rate constants increase as the initial concentration of pyrene and pH decrease. Higher temperature slightly enhances the rate constant. The dissolved oxygen in the photocatalytic degradation process is not as important as in the photolysis process. The recovered PPtPC still shows high photoactivity. This work suggests that PPtPC offers a promising method for high molecular weight PAH removal.

Degradation Kinetics and Mechanics of Methylene Blue by Complex Ultraviolet and Hydrogen Peroxide Process

2011 ◽  
Vol 356-360 ◽  
pp. 1066-1069
Author(s):  
Hang Xu ◽  
Qiang Tang ◽  
Ya Na Liu ◽  
Yong Jiang ◽  
Hong Yan Tang
Keyword(s):  
Hydrogen Peroxide ◽  
Methylene Blue ◽  
Reaction Rate ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Hyperbolic Model

Hyperbolic model could be established to describe the degradation performance of Methylene Blue (MB) using UV/H2O2 process. The effects of initial H2O2 dosage on MB removal, instant ▪OH concentration and reaction rate were investigated. The results show that the optimal H2O2 dosage is 13.24 mM and after 50min the MB removal is around 85%. The MB degradation process is followed the hyperbolic model which can calculate instant ▪OH concentration and reaction rate.

Optimization of Operating Parameters for Decolorization of Metal Complex Dyes by UV/H2O2 Process

2011 ◽  
Vol 347-353 ◽  
pp. 2245-2248
Author(s):  
Jing Jian Zhu ◽  
Long Lu ◽  
Jian Xin Chen
Keyword(s):  
Activation Energy ◽  
Hydrogen Peroxide ◽  
Metal Complex ◽  
Uv Light ◽  
Operating Parameters ◽  
Light Wavelength ◽  
Initial Ph ◽  
Suitable Amount ◽  
Reaction Activation Energy ◽  
Metal Complex Dyes

In this paper, the effects of operating parameters such as UV light wavelength, initial pH, reaction temperature and hydrogen peroxide concentration on decolorization of metal complex dyes (Neutral Bordeaux GRL, Neutral Pink BL and Neutral Blue BNL) by UV/H2O2process were studied in detail. The results showed that the decolorization rate constants were obviously enhanced with the increase of UV intensity. In UV (254nm)/H2O2system, 94.4% decolorization of Neutral Bordeaux GRL, 99.2% decolorization of Neutral Pink BL and 65.4% decolorization of Neutral Blue BNL were achieved after 60 min reaction. The results also indicated that both suitable amount of H2O2and initial pH were needed for effective decolorization of different metal complex dyes. The reaction activation energy of Neutral Bordeaux GRL, Neutral Pink BL and Neutral Blue BNL were 3.43, 14.4 and 23.39 KJ mol-1, respectively.

Kinetics and mechanisms of EDTA photocatalytic degradation with TiO2

2001 ◽  
Vol 44 (5) ◽  
pp. 179-185 ◽  
Author(s):  
P.A. Babey ◽  
C.A. Emilio ◽  
R.E. Ferreyra ◽  
E.A. Gautier ◽  
R.T. Gettar ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Ethylenediaminetetraacetic Acid ◽  
Uv Light ◽  
Degradation Products ◽  
Glyoxylic Acid ◽  
Iminodiacetic Acid ◽  
Order Kinetic ◽  
Kinetic Regime ◽  
Complete Study ◽  
Degussa P25

A complete study on the photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) over TiO2 has been initiated, to establish the influence of several parameters on the reaction rate, the nature of the intermediates and the kinetic regime. TiO2 (Degussa P25) suspensions containing EDTA at pH 3 at different concentrations were irradiated under near UV light. A Langmuirian behavior was observed, from which kinetic constants have been obtained. Experiments with 5.0 mM EDTA (zero order kinetic regime) were performed for 3 hours irradiation under different conditions. Under N2 bubbling, depletion of EDTA was very low. Under O2 bubbling, the concentration of EDTA decreased around 90%. However, the corresponding decrease of TOC ranged only between 4.5% and 9%. A higher TOC reduction (22% or more) was obtained by keeping the pH constant by HClO4 addition, or by hydrogen peroxide addition. Addition of 0.5 mM Fe(III) caused a dramatic increase on the initial rate of EDTA depletion and approximately a 32% TOC decrease. Analysis of the filtered solution was performed by ion chromatography and capillary electrophoresis to monitor the disappearance of EDTA and the formation of degradation products after different irradiation times. So far, glycine, ethylenediamine, formic acid, ammonium, iminodiacetic acid, oxalic acid and glyoxylic acid have been identified.

Photooxidation of 2,4-dichlorophenoxyacetic acid by ferrous oxalate-mediated system

2004 ◽  
Vol 49 (4) ◽  
pp. 117-122 ◽  
Author(s):  
C.Y. Kwan ◽  
W. Chu
Keyword(s):  
Hydrogen Peroxide ◽  
Uv Light ◽  
Reaction Rates ◽  
Dichlorophenoxyacetic Acid ◽  
Ferrous Ions ◽  
Solution Ph ◽  
Ferrous Oxalate ◽  
Radical Production ◽  
Initial Ph ◽  
2,4 Dichlorophenoxyacetic Acid

The photodegradation of a herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by ferrous oxalate/UV/H2O2 was studied. Ferrous oxalate, the more photoactive and reactive species, was found to react faster with hydrogen peroxide for hydroxyl radical production than ferrous ions under UV irradiation. About 2.9 times greater rate enhancement was found with the addition of 0.3 mM oxalate than that of a solution containing 0.1 mM Fe2+ and 1 mM H2O2 in the presence of UV light at 253.7 nm. The kinetics dependence of hydrogen peroxide concentration and initial solution pH were also investigated. A threefold increase in peroxide concentration could accelerate the removal of 2,4-D and nearly complete the reaction in 30 min of illumination. The initial decay rate of 2,4-D treated by ferrous oxalate/UV/H2O2 accelerated from 0.0029 to 0.0034 s-1 and the overall removal of the starting material increased from 78% to 99.9%. The 2,4-D transformation at lower initial pH had higher reaction rates than that at higher pH and different reaction mechanisms were identified. The efficiency of the herbicide decomposition was retarded 2.6 times and 9.6 times as initial pH increased from 2.8 to 5.1 and 9.0, respectively.

Photocatalytic Degradation of Antibacterial Sulfanilamide from Aqueous Solution Using TiO2 Nanocatalyst

2017 ◽  
Vol 46 ◽  
pp. 111-122 ◽  
Author(s):  
Hosein Ghahremani
Keyword(s):  
Photocatalytic Degradation ◽  
Uv Irradiation ◽  
Reaction Rate ◽  
Inorganic Salt ◽  
Uv Light ◽  
Kinetic Constant ◽  
Nano Particles ◽  
Order Kinetic ◽  
First Order ◽  
Low Concentrations

Photocatalytic degradation of sulfanilamide (SNM) as a kind of pollutant agent through titanium dioxide nano particles (TiO2) under UV irradiation was evaluated. The effect of different parameters, such as TiO2 and SNM concentrations, amount of pH, inorganic salt and type of light source on the reaction rate was investigated. The results show that SNM was completely removed from the solution after 60 min under UV irradiation. Furthermore, kinetic studied were performed at 25°C over different ranges of SNM concentrations from 100 to 300 ppm, TiO2 concentrations from 0.05 to 1 gL-1 and pH of suspensions from 3 to 11. In this range of concentration of materials, a Langmuir–Hinshelwood kinetic model can describe the process. An overall pseudo-first order kinetic constant was calculated for sulfanilamide conversion. The optimum TiO2 loading, which provides enough surface area for reaction without irradiation loss due to scattering of UV light, was found to be 0.1gL-1, and SNM concentration was100 ppm. Higher degradation efficiency of SNM was observed at pH=9. Finally, the results of this work proved that photocatalysis of SNM is a promising technology to reduce persistent substances even if they are present in low concentrations.

scholarly journals A Brief Photocatalytic Study of ZnO Containing Cerium towards Ibuprofen Degradation

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5891
Author(s):  
Alexandro S. Sá ◽  
Rodrigo P. Feitosa ◽  
Luzia Honório ◽  
Ramón Peña-Garcia ◽  
Luciano C. Almeida ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Photocatalytic Activity ◽  
Environmental Remediation ◽  
Uv Light ◽  
Degradation Process ◽  
Artemia Salina ◽  
Experimental Conditions ◽  
Transmission Electron ◽  
Effects Of Ph

Ibuprofen (IBU) is one of the most-sold anti-inflammatory drugs in the world, and its residues can reach aquatic systems, causing serious health and environmental problems. Strategies are used to improve the photocatalytic activity of zinc oxide (ZnO), and thosethat involvethe inclusion of metalhave received special attention. The aim of this work was to investigate the influence of the parameters and toxicity of a photoproduct using zinc oxide that contains cerium (ZnO-Ce) for the photodegradation of ibuprofen. The parameters include the influence of the photocatalyst concentration (0.5, 0.5, and 1.5 g L−1) as well as the effects of pH (3, 7, and 10), the effect of H2O2, and radical scavengers. The photocatalyst was characterized by Scanning Electron Microscopy-Energy Dispersive Spectroscopy, Transmission electron microscopy, Raman, X-Ray Diffraction, surface area, and diffuse reflectance. The photocatalytic activity of ibuprofen was evaluated in an aqueous solution under UV light for 120 min. The structural characterization by XRD and SEM elucidated the fact that the nanoparticle ZnO contained cerium. The band gap value was 3.31 eV. The best experimental conditions for the photodegradation of IBU were 60% obtained in an acidic condition using 0.50 g L−1 of ZnO-Ce in a solution of 20 ppm of IBU. The presence of hydrogen peroxide favored the photocatalysis process. ZnO-Ce exhibited good IBU degradation activity even after three photocatalytic cycles under UV light. The hole plays akey role in the degradation process of ibuprofen. The toxicity of photolyzed products was monitored against Artemia salina (bioindicator) and did not generate toxic metabolites. Therefore, this work provides a strategic design to improve ZnO-Ce photocatalysts for environmental remediation.

scholarly journals Photocatalytic removal of the herbicide clopyralid from water

2007 ◽  
Vol 72 (12) ◽  
pp. 1477-1486 ◽  
Author(s):  
Biljana Abramovic ◽  
Vesna Anderluh ◽  
Daniela Sojic ◽  
Ferenc Gaál
Keyword(s):  
Visible Light ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Direct Photolysis ◽  
Experimental Conditions ◽  
Pyridine Moiety ◽  
Photolytic Degradation ◽  
Initial Substrate ◽  
Degussa P25 ◽  
The Stability

The stability of the herbicide clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) was studied under different experimental conditions of pH, illumination and initial substrate concentration. It was found that in the pH interval from 1.0 to 9.0 in the presence/absence of daylight, clopyralid solutions were stable for at least a period of two months. The kinetics of the photocatalytic degradation of clopyralid in aqueous suspensions of TiO2 (Degussa P25) under UV and visible light, as well as of direct photolysis using the same radiation sources, were also investigated. It was found that the rate of photocatalytic degradation in the presence of UV light was more than five times higher compared to direct photolysis, whereas in the presence of visible light, the corresponding rates of photocatalytic/photolytic degradation were much lower (more than 15 times). The reaction in the investigation concentration range is zero-order with respect to the degradation of the clopyralid pyridine moiety, with a reaction rate of 3.4?10-6 mol dm-3 min-1 and an adsorption coefficient of the substrate of 2.5?104 dm3 mol-1.

Photocatalytic Treatment of MO in Water with BiOBr Photocatalyst

2011 ◽  
Vol 694 ◽  
pp. 554-558 ◽  
Author(s):  
Xiao Xia Zhao ◽  
Yan Wang ◽  
Zhu Qing Shi ◽  
Cai Mei Fan
Keyword(s):  
Degradation Rate ◽  
Ph Value ◽  
Degradation Process ◽  
Xenon Lamp ◽  
Experimental Conditions ◽  
Initial Concentration ◽  
X Ray ◽  
Hydrolysis Method ◽  
Methylene Orange ◽  
Initial Ph

The BiOBr catalyst prepared by the hydrolysis method was investigated with the X-ray diffractometry(XRD) and scanning electron microscope (SEM). The results show that the catalyst was the tetragonal primitive crystal structure and composed of homogeneous particles of fine ferrite plates. At the same time, the photocatalytic activity of BiOBr catalyst was evaluated by methylene orange (MO) in aqueous solution illuminated by Xenon lamp, and the degradation process parameters, such as initial concentration of MO, initial pH value and amount of BiOBr catalyst were discussed to the degradation rate of the MO. Under the following experimental conditions of C0=10mg/L, pH=8, m(BiOBr)=1.0g/L, MO can be entirely degraded after 2.5 hours.

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