scholarly journals Supported TiO2 on Borosilicate Glass Plates for Efficient Photocatalytic Degradation of Fenamiphos

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
A. El Yadini ◽  
H. Saufi ◽  
P. S. M. Dunlop ◽  
J. Anthony Byrne ◽  
M. El Azzouzi ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Borosilicate Glass ◽  
High Performance ◽  
Order Kinetic ◽  
Degussa P25 ◽  
Plausible Mechanism ◽  
Kinetics Of Degradation ◽  
Glass Plates ◽  
Kinetics Of ◽  
Sulfonamide Group

Supported titanium dioxide (TiO2) was investigated for the photodegradation of the insecticide fenamiphos in water. The photocatalyst was immobilised on borosilicate glass plates and the kinetics of degradation were studied in a stirred tank reactor under UV irradiation. Two types of TiO2, for example, Millennium PC500 (100% anatase) and Degussa P25 (80% anatase, 20% rutile), were used. Their activities have been based on the rates of insecticide disappearance. Experiments were investigated to evaluate the effect of pH and initial concentrations of fenamiphos as well as catalyst doses on the photocatalytic degradation of fenamiphos. Kinetic parameters were experimentally determined and an apparent first-order kinetic was observed. For photolysis process of fenamiphos, two photoproducts were identified and characterized using high performance liquid chromatography/mass spectrometry (HPLC/MS). The plausible mechanism of photolysis involved is the oxidation of sulfonamide group. In presence of photocatalyst TiO2, photodegradation was observed. Under identical conditions, Degussa P25 shows higher photocatalytic activity in regard to PC500 Millennium and complete degradation was observed after 180 min.

scholarly journals Desorption and re-adsorption of PAHS on aircraft soot surface

2020 ◽  
Vol 42 (4) ◽  
Author(s):  
Nguyen Mai Lan
Keyword(s):  
High Performance ◽  
Flow Reactor ◽  
Activation Energies ◽  
Binding Energies ◽  
Desorption Kinetics ◽  
Chemical Transformations ◽  
Polycyclic Aromatic ◽  
Kinetics Of Degradation ◽  
Kinetics Of ◽  
Pyrex Tube

Polycyclic Aromatic Hydrocarbons (PAHs) in aircraft soot are capable to distribute in the gas phase and particulate phase in chemical transformations in the atmosphere. The desorption of PAHs from the soot surface is a preliminary step in the study of the reactivity of particulate PAHs. The desorption kinetics of PAHs are measured from soot samples to determine desorption rate constants for different PAHs as a function of temperature and the binding energies between PAHs and soot. The kinetics of degradation of particulate PAHs were studied in the flow reactor. The soot samples previously deposited on a Pyrex tube are introduced into the reactor along its axis and the concentrations of PAHs adsorbed on soot are determined by the High-Performance Liquid Chromatography (HPLC) as a function of the desorption time. The results show a correlation between the size of PAHs and the thermodynamics of desorption: with the PAHs have the same number of carbon atoms, their energies of desorption are very similar and increase with this number. The activation energies EA and the number of carbon atoms in PAHs have a linear correlation. It is consistent with the additivity of the laws Van der Waals. The similarity between the activation energies of desorption of PAHs and the corresponding sublimation enthalpies is consistent with the similarity between the graphitic structure of soot and the structure of PAHs.

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.

A study of ofloxacin and levofloxacin photostability in aqueous solutions

10.20883/178 ◽  
2016 ◽  
Vol 85 (4) ◽  
pp. 238
Author(s):  
Anita Frąckowiak ◽  
Bartosz Kamiński ◽  
Bartosz Urbaniak ◽  
Paweł Dereziński ◽  
Agnieszka Klupczyńska ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
High Performance ◽  
Degradation Products ◽  
Mercury Vapor ◽  
Degradation Process ◽  
Hplc Method ◽  
Photodegradation Products ◽  
Kinetics Of Degradation ◽  
High Performance Capillary Electrophoresis ◽  
Kinetics Of

Introduction. The photostability is one of the most important properties of drugs. A comprehensive study of ofloxacin (OFX) and levofloxacin (LVX) photostability in aqueous solutions was performed. Ofloxacin is a chemotherapeutic agent belonging to the second generation fluoroquinolones and is a racemate of (R)-(+)-ofloxacin and (S)-(-)-ofloxacin (LVX).Material and Methods. Samples of OFX and LVX were subjected to stress conditions of UV irradiation using a mercury‑vapor lamp. The study involved development of enantioselective high‑performance liquid chromatography (HPLC) and high‑performance capillary electrophoresis (HPCE) methods for separation of OFX enantiomers and their degradation products. These methods were used to monitor the degradation process of OFX and LVX under irradiation and to determine the kinetics of degradation of these antibacterial agents. Moreover, the identification of photoproducts was also attempted. The structure of the main photoproducts was examined by mass spectrometry (MS).Results and Conclusions. Using HPLC method it was possible to observe two products of OFX degradation and only one for LVX, while using HPCE method eight products of OFX degradation and six of LVX were observed. Some of the photoproducts retain character of optically active compounds. The trend of the photodegradation of both tested compounds was described by autocatalytic reaction proceeding according to the Prout‑Tompkins model. Some of the products of the decomposition catalyze this reaction. The rate of degradation was similar for both enantiomers but t0.5 was slightly longer for LVX than OFX. Based on MS experiments the photodegradation products of the studied fluoroquinolones and possible pathways of UV induced decay were identified.

scholarly journals Photocatalytic degradation of carbamate insecticides: Effect of different parameters

2019 ◽  
Vol 34 (3-4) ◽  
pp. 193-200
Author(s):  
Andjelka Tomasevic ◽  
Dusan Mijin ◽  
Aleksandar Marinkovic ◽  
Ilija Cvijetic ◽  
Slavica Gasic
Keyword(s):  
Photocatalytic Degradation ◽  
High Performance ◽  
Model Compound ◽  
Uv Spectroscopy ◽  
Complete Removal ◽  
Order Kinetic ◽  
Operational Parameters ◽  
Reaction Conditions ◽  
Order Kinetic Model ◽  
Optimized Conditions

Photocatalytic degradation of a model compound of the carbamate insecticide carbofuran in water was studied using polychromatic light and ZnO and TiO2 catalysts. The influence of operational parameters, such as reaction time and initial carbofuran concentration, on photocatalytic degradation was studied. A pseudo-first-order kinetic model was established and an almost complete removal of 88.4 mg L-1 of carbofuran occurred within 2 h under optimized conditions. The reactions were examined by UV spectroscopy and high performance liquid chromatography (HPLC). In addition, the photocatalytic efficiencies of ZnO and TiO2 were compared under the same reaction conditions.

scholarly journals STUDY OF BAICALIN HYDROLYSIS KINETICS IN THE PROCESS OF ITS EXTRACTION FROM SCUTELLARIA BAICALENSIS GEORGI ROOTS

2019 ◽  
Vol 7 (3) ◽  
pp. 129-137
Author(s):  
N. N. Boyko ◽  
D. I. Pisarev ◽  
E. T. Zhilyakova ◽  
A. Yu. Maljutina ◽  
O. O. Novikov ◽  
...  
Keyword(s):  
High Performance ◽  
Water Solution ◽  
Scutellaria Baicalensis ◽  
Raw Material ◽  
Order Kinetic ◽  
Hydrolysis Kinetics ◽  
Scutellaria Baicalensis Georgi ◽  
Analytical Wavelength ◽  
Kinetics Of ◽  
Method Of Extraction

The aim of this study was to investigate the kinetics of baicalin hydrolysis in the process of its extraction from Scutellaria baicalensis Georgi roots.Materials and methods. For the studies, Scutellaria baicalensis Georgi roots with a particle range of 0.1–0.5 mm were used. The method of extraction was a simple maceration during a specified period of time, the ratio of plant raw material : extractant was 1:10 w/v at the temperature of 24±1°С. Baicalin and baicalein contents were analyzed by reverse phase high performance liquid chromatography (RP HPLC) at the analytical wavelength of 275 nm. The extractant was a water solution of ethanol 26, 43, 59, 72, 81, 97±1% v/v. The time of the extraction was from 1 to 24 hours.Results. The experimental points of dependency of baicalin concentration in the extract on the time of extraction for ethanol solutions with a concentration of 43 and 72% v/v are closely approximated by a linear equation in coordinates lnC=f(t). The value of determination coefficient is more than R²˃0,99. Half lifetime for baicalin has been calculated: for ethanol with the concentration of 43% v/v it is 4.3±0.7 hours, and for ethanol with the concentration of 72% v/v it is 42.3±1.8 hours.Conclusion. Baicalin hydrolysis kinetics in the process of its extraction from Scutellaria baicalensis Georgi roots with 43 and 72% v/v ethanol concentration. has been studied. It has been established that the process of baicalin hydrolysis is well described by the first order kinetic equation. The constants of baicalin hydrolysis during its extraction from Scutelaria baicalensis roots with ethanol having different concentrations have been calculated. Recommendations on technology optimization for baicalin or baicalein extraction from Scutellaria baicalensis Georgi roots have been given. 

Photocatalytic Degradation Kinetics of Reactive Red 3BS Using Ag Doped TiO2

2012 ◽  
Vol 441 ◽  
pp. 598-602 ◽  
Author(s):  
Bo Yu ◽  
Zai Sheng Cai ◽  
Wei Ming Wang ◽  
Chun Chun Lu
Keyword(s):  
Photocatalytic Degradation ◽  
Catalyst Concentration ◽  
Degradation Kinetics ◽  
Light Attenuation ◽  
Order Kinetic ◽  
Rate Of Reaction ◽  
Degradation Reaction ◽  
The Relationship ◽  
Kinetics Of ◽  
Apparent Reaction Rate

The photocatalyst of Ag doped TiO2 in liquid state was applied to decolorize the Reactive Red 3BS under UV irradiation. The rate of photocatalytic degradation of the dye was improved with increasing the concentration of catalyst from 1 g/L to 8 g/L. But as a result of light attenuation for the rising catalyst concentration, the rate of reaction was constant at 8-12 g/L of the catalyst concentration. The rate of dye photocatalytic degradation decreased with increasing initial concentration of dye. The kinetics of photocatalytic reaction was also studied. The results showed that degradation reaction is congruent with an apparent first-order kinetic equation, and the relationship between apparent reaction rate and initial dye concentration fits approximately a negative second-order kinetic relationship.

scholarly journals Fractional kinetics of photocatalytic degradation

2018 ◽  
Vol 08 (05) ◽  
pp. 1850034 ◽  
Author(s):  
C. L. Wang
Keyword(s):  
Kinetic Model ◽  
Photocatalytic Degradation ◽  
Degradation Process ◽  
Order Kinetic ◽  
Material Parameters ◽  
First Order ◽  
Fractional Kinetics ◽  
Order Kinetic Model ◽  
Kinetics Of ◽  
Degradation Time

In this paper, photocatalytic degradation processes of different materials are fitted to the first-order kinetic model, second-order kinetic model and fractional first-order kinetic model. Deterministic coefficients are calculated for the evaluation of the validity of these models. The fitting results show clearly that the degradation process can fit the fractional first-order kinetic model in a very good manner. In this way, two material parameters can be well defined. One is the degradation time, which can be used to describe the photocatalytic degradation process quantitatively. Another is the order of the derivative, which could be related to the material’s microstructure.

scholarly journals Optimization of Alachlor Photocatalytic Degradation with Nano-TiO2 in Water under Solar Illumination: Reaction Pathway and Mineralization

2018 ◽  
Vol 1 (1) ◽  
pp. 141-153 ◽  
Author(s):  
Md. Molla ◽  
Mai Furukawa ◽  
Ikki Tateishi ◽  
Hideyuki Katsumata ◽  
Satoshi Kaneco
Keyword(s):  
Photocatalytic Degradation ◽  
Reaction Pathway ◽  
Irradiation Time ◽  
Low Cost ◽  
Solar Irradiation ◽  
Order Kinetic ◽  
Operational Parameters ◽  
Sunlight Irradiation ◽  
Kinetics Of ◽  
Sunlight Intensity

In the present study, the photocatalytic degradation of alachlor was investigated using TiO2 under sunlight irradiation. The effects of some operational parameters, such as photocatalyst concentration, temperature, pH, sunlight intensity and irradiation time, were optimized. The kinetics of photodegradation was found to follow a pseudo-first-order kinetic law, and the rate constant at optimal condition is 0.245 min−1. The activation energy (Ea) is 6.4 kJ/mol. The alachlor mineralization can be completed under sunlight irradiation after 10 h. The formations of chloride, nitrate and ammonium ions are observed during the photocatalytic degradation. The eight photoproducts were identified by the GC–MS technique. The photodegradation reaction pathways are proposed based on the evidence of the detected photoproducts and the calculated frontier electron densities of the alachlor structure. The photocatalytic degradation treatment for the alachlor wastewater under solar irradiation is simple, convenient and low cost.

scholarly journals Effect of pH and concentration on the chemical stability and reaction kinetics of thiamine mononitrate and thiamine chloride hydrochloride in solution

BMC Chemistry ◽  
2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Adrienne L. Voelker ◽  
Lynne S. Taylor ◽  
Lisa J. Mauer
Keyword(s):  
Reaction Kinetics ◽  
High Performance ◽  
Degradation Kinetics ◽  
Degradation Pathway ◽  
Reaction Rate Constant ◽  
Solution Ph ◽  
Kinetics Of Degradation ◽  
One Year ◽  
Kinetics Of ◽  
Over Time

AbstractThiamine (vitamin B1) is an essential micronutrient in the human diet, found both naturally and as a fortification ingredient in many foods and supplements. However, it is susceptible to degradation due to heat, light, alkaline pH, and sulfites, among effects from other food matrix components, and its degradation has both nutritional and sensory implications as in foods. Thiamine storage stability in solution was monitored over time to determine the effect of solution pH and thiamine concentration on reaction kinetics of degradation without the use of buffers, which are known to affect thiamine stability independent of pH. The study directly compared thiamine stability in solutions prepared with different pHs (3 or 6), concentrations (1 or 20 mg/mL), and counterion in solution (NO3−, Cl−, or both), including both commercially available salt forms of thiamine (thiamine mononitrate and thiamine chloride hydrochloride). Solutions were stored at 25, 40, 60, and 80 °C for up to one year, and degradation was quantified by high-performance liquid chromatography (HPLC) over time, which was then used to calculate degradation kinetics. Thiamine was significantly more stable in pH 3 than in pH 6 solutions. In pH 6 solutions, stability was dependent on initial thiamine concentration, with the 20 mg/mL thiamine salt solutions having an increased reaction rate constant (kobs) compared to the 1 mg/mL solutions. In pH 3 solutions, kobs was not dependent on initial concentration, attributed to differences in degradation pathway dependent on pH. Activation energies of degradation (Ea) were higher in pH 3 solutions (21–27 kcal/mol) than in pH 6 solutions (18–21 kcal/mol), indicating a difference in stability and degradation pathway due to pH. The fundamental reaction kinetics of thiamine reported in this study provide a basis for understanding thiamine stability and therefore improving thiamine delivery in many foods containing both natural and fortified thiamine.

scholarly journals SYNTHESIS AND STUDY OF THE REACTION KINETICS OF HOMOVERATRILAMINE WITH BRASSYLIC ACID BY HPLC

2020 ◽  
Vol 9 (10) ◽  
pp. 1-7
Keyword(s):  
High Performance ◽  
Condensation Reaction ◽  
High Performance Liquid Chromatographic ◽  
Order Kinetic ◽  
First Order ◽  
Liquid Chromatographic Separation ◽  
Brassylic Acid ◽  
Liquid Chromatographic ◽  
Kinetics Of ◽  
Order Kinetic Equation

In this work, amide, isoquinoline were synthesized and the kinetics of the reaction of homoveratrylamine with brassilic acid was studied by HPLC. The conditions of (high-performance liquid) chromatographic separation were revealed, which allow satisfactory separation of the components of the reaction mixture consisting of reagents, intermediates and products of the reactions of condensation and cyclization. By studying the kinetic laws, it was found that the reactions of condensation and cyclization obey the first-order kinetic equation and the activation energy is, respectively, 172.3 kJ / mol for the amide condensation reaction, and 118.8 kJ / mol for the cyclization reaction.

Sign in / Sign up

Export Citation Format

Share Document