scholarly journals Direct photolysis and photocatalytic degradation of 2-amino-5-chloropyridine

2003 ◽  
Vol 68 (12) ◽  
pp. 961-970 ◽  
Author(s):  
Biljana Abramovic ◽  
Vesna Anderluh ◽  
Andjelka Topalov ◽  
Ferenc Gaal
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Parent Compound ◽  
Analytical Techniques ◽  
Direct Photolysis ◽  
Pyridine Moiety ◽  
Initial Substrate ◽  
Zero Order Reaction ◽  
Degradation Reaction

The direct photolysis and photocatalytic degradation of a pyridine pesticide analogue, 2-amino-5-chloropyridine, were investigated employing different analytical techniques ? potentiometry, for monitoring the pH and chloride genera- tion, spectrophotometry, for studying the degradation of the pyridine moiety, ion chromatography, for monitoring nitrate formation, and total organic carbon analysis for investigating the efficiency of the process. The photocatalytic degradation was studied in aqueous suspensions of titanium dioxide under illumination by UV light. It was found that chloride evolution was a zero-order reaction which takes place by direct photolysis, in that way differing from the degradation of the pyridine moiety, which takes place in the presence of titanium dioxide. Changes in pH during degradation indicate the formation of acidic intermediates and nitrate in addition to chloride. The effect of the initial substrate concentration was also investigated by monitoring the reaction of chloride generation as well as the degradation reaction of the pyridine moiety. It was found that degradation of the parent compound (2.5 mmol/dm3) by direct photolysis is completed in about 20 minutes, and of the pyridine moety by photocatalytic degradation in about nine hours. Based on the obtained data a possible reaction mechanism is proposed.

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.

scholarly journals Kinetics of photocatalytic removal of 2-amino-5-chloropyridine from water

2004 ◽  
pp. 79-86 ◽  
Author(s):  
Biljana Abramovic ◽  
Vesna Anderluh ◽  
Andjelka Topalov ◽  
Ferenc Gaal
Keyword(s):  
Titanium Dioxide ◽  
Kinetic Model ◽  
Substrate Concentration ◽  
Zero Order ◽  
Direct Photolysis ◽  
Pyridine Moiety ◽  
Initial Substrate ◽  
Photocatalytic Removal ◽  
Kinetics Of ◽  
Initial Substrate Concentration

Titanium dioxide sensitized photocatalytic degradation of a pyridine pesticide analogue, 2-amino-5-chloropyridine, was investigated by monitoring the pyridine moiety degradation, as well as by monitoring the chloride generated in the process. Effect of the initial substrate concentration on the rate of its degradation is reported. Here we show that the kinetics of both reactions are of the zero-order in the entire investigated concentration range. The Langmuir-Hinshelwood kinetic model successfully described the influence of the initial substrate concentration on the rate of the pyridine moiety degradation. It was found that dechlorination of the substrate takes place by direct photolysis. The differences in the kinetics of pyridine moiety degradation and dechlorination were explained on the basis of the electrostatic potential for the investigated compound.

The Photocatalytic Properties of Br-Doped Titania Nanotube Arrays and its Application in Degradation of Sugar Wastewater

2013 ◽  
Vol 641-642 ◽  
pp. 11-17 ◽  
Author(s):  
Zhi Peng Meng ◽  
Fu Xin Zhong ◽  
Dan Yu Wang ◽  
Zhong Ming Zhang ◽  
Hua Ying Li ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Nanotube Arrays ◽  
Illumination Time ◽  
Novel Approach ◽  
Titanium Dioxide Nanotube Arrays

This paper presents a novel approach for preparing titanium dioxide nanotube arrays (TNTs) loaded with highly dispersed Br through an ultrasound aided photochemical route. The content of Br doped on the arrays was controlled by changing the concentration of NaBr and the ultrasound time. The Br doped TiO2nanotube arrays were characterized by SEM, XRD and UV–Vis spectrum. Doping the bromine did not basically affect the morphology of the surface of the TNTs, but part of the anatase phase transformed into rutile phase, which led to the formation of the mixed crystal and increased the photocatalytic activity. The results showed that Br doping significantly enhanced the photocatalytic degradation rate of titanium dioxide nanotube arrays under UV-light irradiation. The main factors which affected photocatalytic degradation of sugar wastewater were the illumination time and pH. The results showed that the longer the exposure time was, the initial pH of wastewater was more favorable to photocatalytic degradation of the sugar wastewater for the Br-TiO2nanotube arrays, and compared to undoped TiO2nanotube arrays Br doped TiO2nanotube arrays had better photocatalytic properties.

scholarly journals Cobalt Oxide-Modified Titanium Dioxide Nanoparticle Photocatalyst for Degradation of 2,4-Dichlorophenoxyacetic Acid

2017 ◽  
Vol 17 (2) ◽  
pp. 284 ◽  
Author(s):  
Leny Yuliati ◽  
Nur Azmina Roslan ◽  
Wai Ruu Siah ◽  
Hendrik Oktendy Lintang
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Photocatalytic Degradation ◽  
Cobalt Oxide ◽  
Uv Light ◽  
Dichlorophenoxyacetic Acid ◽  
Photocatalytic Reaction ◽  
Impregnation Method ◽  
Titanium Dioxide Nanoparticle ◽  
2,4 Dichlorophenoxyacetic Acid

2,4-dichlorophenoxyacetic acid (2,4-D) has been recognized as a possibly carcinogenic compound to human, therefore, 2,4-D should be treated before it is discharged to the environment. Photocatalytic degradation of 2,4-D has been proposed as one of the best methods that offer environmentally safe process. In the present research, titanium dioxide (TiO2) was modified with cobalt oxide (CoO) and tested for photocatalytic degradation of 2,4-D under UV light irradiation. Different amounts of CoO (0.1, 0.5, 1 and 5 mol%) were added onto TiO2 by an impregnation method. The photocatalytic reaction was monitored and analyzed by measurement of 2,4-D absorbance using UV spectrophotometer. After 1 h photocatalytic reaction, it was confirmed that the sample with low loading of 0.1 mol% gave the highest photocatalytic activity among the bare and modified TiO2 photocatalysts. The photocatalytic activity was decreased with the increase of CoO loading, suggesting that the optimum amount of CoO was an important factor to improve the performance of TiO2. Based on fluorescence spectroscopy, such addition of CoO resulted in the reduced emission intensity, which showed the successful decrease in the electron-hole recombination.

scholarly journals Effect of Various Additives on Photocatalytic Degradation of 4-Nitrophenol

2009 ◽  
Vol 6 (s1) ◽  
pp. S422-S428 ◽  
Author(s):  
Kashif Naeem ◽  
Feng Ouyang
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Degradation ◽  
Rice Husk ◽  
Uv Light ◽  
Aqueous Suspension ◽  
Degradation Efficiency ◽  
Optimal Amount ◽  
Supporting Materials ◽  
Better Than

The photocatalytic degradation of 4-nitrophenol (4-NP) assisted by titanium dioxide (TiO2) was investigated in aqueous suspension under irradiation by UV light. The effect of different supporting materials mixed physically with TiO2on the photocatalytic degradation of 4-NP has been studied. TiO2with all supports exhibits good degradation efficiency of 4-NP and was better than TiO2alone. The addition of SiO2and ZSM-5 only caused a little change in 4-NP degradation. However, degradation of 4-NP was improved from 34.89% to 60.53% within 120 min photocatalysis in the presence of optimal amount of AC. The degradation was also fairly enhanced in the presence of cheaper rice husk and the activity was closed to AC.

ZnO Photocatalysis Using Solar Energy for the Removal of Trace Amounts of Alfa-Methylstyrene, Diquat and Indigo Carmine from Water

2014 ◽  
Vol 17 (2) ◽  
Author(s):  
O. M. Shibin ◽  
B. Rajeev ◽  
V. Veena ◽  
E. P. Yesodharan ◽  
Yesodharan Suguna
Keyword(s):  
Visible Light ◽  
Chemical Oxygen Demand ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Indigo Carmine ◽  
Parent Compound ◽  
Oxygen Demand ◽  
Solar Photocatalyst ◽  
Significant Chemical ◽  
Trace Pollutants

AbstractSemiconductor photocatalysis using ZnO has been extensively investigated for the chemical and bacterial decontamination of water and air. In most of these cases, UV light is the source of energy and visible light induced photocatalytic degradation of trace pollutants in water has not received adequate attention. In the present study, ZnO is evaluated as a solar photocatalyst for the removal of trace amounts of three typical pollutants, i.e. alpha- Methylstyrene (AMS, a petrochemical), Diquat (herbicide) and Indigo carmine (IC, a dye) from water. Degradation by itself does not result in complete mineralisation and decontamination as seen from the significant Chemical Oxygen Demand even after the parent compound has disappeared. However, the intermediates also get mineralized eventually. The study indicates that solar photocatalysis can be used as a viable tool for the purification water contaminated with these chemicals. The degradation follows variable kinetics depending on the concentration of the substrates. H

Photocatalytic degradation of bisphenol A using titanium dioxide@nanodiamond composites under UV light illumination

2021 ◽  
Vol 582 ◽  
pp. 1058-1066 ◽  
Author(s):  
Y.M. Hunge ◽  
A.A. Yadav ◽  
Sovann Khan ◽  
Kai Takagi ◽  
Norihiro Suzuki ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Bisphenol A ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Light Illumination

Preparation of Titanium Dioxide Nanotube Arrays and Photocatalytic Degradation of Methyl Orange

2014 ◽  
Vol 886 ◽  
pp. 262-265
Author(s):  
Ying Cao Xu ◽  
Hong You
Keyword(s):  
Titanium Dioxide ◽  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Pure Titanium ◽  
Methyl Orange Solution ◽  
Nanotube Arrays ◽  
Nanotube Array ◽  
Orange Solution ◽  
Degradation Of Methyl Orange

This paper adopted electrochemistry anodic oxidation method for preparing TiO2nanotube array membrane on a pure titanium sheet. The results showed that TiO2nanotube arrays were regularly obtained when anodizing voltage at 25V, anodizing time in 60min , NH4F concentration at 0.25mol·L-1, and volume ratio of glycerol and water at 2:1. Using of this titanium dioxide nanotube array photocatalyst, and Under light of ultraviolet lamp, the photocatalytic degradation of methyl orange solution was studied in this paper. The main factors affecting the test selection was: the concentration of methyl orange solution (5mg·L-1, 10mg·L-1, 15mg·L-1, 25mg·L-1, 35mg·L-1), pH of methyl orange solution (2.0,2.5,3.0,3.5, 4.0,5.0,5.5,6.0), catalytic time (30min.60min, 90min, 120min, 150min, 180min, 240min), UV light source (6w, 11w, 15w).

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