Microcystin-LR Degradation of Titanium Dioxide Process by Solar/ S-Doped

2010 ◽  
Vol 33 ◽  
pp. 327-331 ◽  
Author(s):  
Cheng Liu ◽  
Wei Chen ◽  
Man Wang ◽  
Zhe Cao
Keyword(s):  
Humic Acids ◽  
Degradation Rate ◽  
Oxidation Process ◽  
Solar Irradiation ◽  
Sulfur Source ◽  
Order Model ◽  
Doped Tio2 ◽  
First Order ◽  
Hydrolysis Method ◽  
Acid Catalyzed

The removal efficiency of microcystin-LR in water and the influencing factors by combined process of solar irradiation and S-doped TiO2 were studied in detail, in which S-doped TiO2 photo-catalyst with high sunlight activity was prepared by acid catalyzed hydrolysis method using thiourea as sulfur source. The experiment results showed that MC-LR could be more effectively oxidized by the solar/S-doped TiO2 process than by solar/ TiO2 process, whose removal effect were about 70% and 55% after 40 min’s irradiation, respectively. Pseudo-first-order model could be used to simulate the oxidation process. Degradation rate could be greatly affected by the concentration of H2O2, the optimum concentration for the system of solar/S-doped TiO2 was found to be 20mg/L, which was 5mg/L higher than that of solar/TiO2 system. Humic acids decreased the degradation rate, and solar/S-doped TiO2 process more easily affected, for the humic acids could not only compete with molecular MC-LR for radicals but also adsorb part of sunlight which can excite radical with TiO2.

Degradation of Ametryn in Aqueous Solution by Solar/ S-Doped Titanium Dioxide Process

2010 ◽  
Vol 113-116 ◽  
pp. 1375-1378 ◽  
Author(s):  
Cheng Liu ◽  
Wei Chen
Keyword(s):  
Removal Efficiency ◽  
Degradation Rate ◽  
Solar Irradiation ◽  
Rate Coefficients ◽  
Sulfur Source ◽  
Doped Tio2 ◽  
Photo Catalyst ◽  
Hydrolysis Method ◽  
Water Ph ◽  
Acid Catalyzed

The removal efficiency of ametryn in water and the influencing factors by the combined process of solar irradiation and S-doped TiO2 were studied in detail, in which S-doped TiO2 photo-catalyst with high sunlight activity was prepared by acid catalyzed hydrolysis method with thiourea as sulfur source; As a comparison, solar/TiO2 process was studied in the meantime; The experiment results showed that ametryn could be more effectively oxidized by the solar/S-doped TiO2 process than the solar/ TiO2 one, while the removal efficiency of 60% and 40% respectively after 30 min’s irradiation; Pseudo-first-order model could be used to simulate the oxidation process in which the degradation rate coefficients were independent of the initial concentration of ametryn; Degradation rate could be greatly affected by the concentration of H2O2, the optimum concentration for the system of solar/S-doped TiO2 was found to be 20mg/L, which was 5mg/L higher than that of solar/TiO2 system; Lower water pH favored the degradation of ametryn for the change of charge density of both the ametryn molecular and photo-catalyst surface.

Kinetics and Mechanism of Oxidation of Selenium(IV) by Permanganate Ion in Aqueous Perchlorate Solutions

1993 ◽  
Vol 58 (3) ◽  
pp. 538-546 ◽  
Author(s):  
Refat M. Hassan ◽  
Sahr A. El-Gaiar ◽  
Abd El-Hady M. El-Summan
Keyword(s):  
Reaction Mechanism ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Selenium Dioxide ◽  
Order Reaction ◽  
Acid Solutions ◽  
First Order ◽  
Acid Catalyzed ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

The kinetics of permanganate oxidation of selenium dioxide in perchloric acid solutions at a constant ionic strength of 2.0 mol dm-3 has been investigated spectrophotometrically. A first-order reaction in [MnO4-] and fractional order with respect to selenium(IV) were observed. The reaction rate was found to be pH-independent at lower acid concentrations ([H+] < 0.5 mol dm-3) and was acid-catalyzed beyond this range. Addition of Mn2+ and F- ions leads to the prediction that MnO4- is the sole reactive species in the oxidation process. A tentative reaction mechanism consistent with the reaction kinetics has been proposed.

Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents

2013 ◽  
Vol 67 (6) ◽  
pp. 1260-1271 ◽  
Author(s):  
I. Michael ◽  
E. Hapeshi ◽  
C. Michael ◽  
D. Fatta-Kassinos
Keyword(s):  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
Heterogeneous Photocatalysis ◽  
Solar Irradiation ◽  
Fenton Process ◽  
Iron Salt ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Initial Substrate ◽  
Initial Substrate Concentration

The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe2+/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe2+ and H2O2 for homogeneous ([Fe2+] = 5 mg L−1, [H2O2] = 3.062 mmol L−1) and TiO2 ([TiO2] = 3 g L−1) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir–Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal.

Modeling of Photo Catalytic Degradation of Chloramphenicol using Full Factorial Design

2015 ◽  
Vol 4 (2) ◽  
pp. 1-12
Author(s):  
Mamta Dubey ◽  
Mumtaj Shah
Keyword(s):  
Factorial Design ◽  
Degradation Rate ◽  
Degradation Process ◽  
Catalytic Degradation ◽  
Full Factorial Design ◽  
Order Model ◽  
First Order ◽  
Negative Effect ◽  
Full Factorial ◽  
Positive Effect

In this study, photo catalytic degradation of chloramphenicol (CAP) using TiO2 as photo catalyst in an annular batch photo reactor was carried out. A full factorial design with three experimental factors; pH (X1), TiO2 concentration (X2) and CAP initial concentration (X3) was selected for degradation process. A multiple regression first order model obtained as which shows a functional relationship between the degradation rate of CAP, three experimental factors and the interactions of the factors on the entire process. The results show that the factor pH and TiO2 have strong effect on the process while CAP concentration has weak effect in comparison to other factors, within the range tested. Interaction (X2X3) and (X1X2X3) also significantly affect the degradation experiment. TiO2 concentration has a positive effect but pH and CAP concentration have negative effect on the entire degradation process. An average of 80.22% of degradation rate of CAP can be achieved from current setup. The regression model is adequate enough with R2 value of 0.9708 and adj-R2 value of 0.9453.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

A first-order model of thermal lensing of laser propagation in the eye and implications for laser safety

2005 ◽  
Author(s):  
Robert J. Thomas ◽  
Rebecca L. Vincelette ◽  
Gavin D. Buffington ◽  
Amber D. Strunk ◽  
Michael A. Edwards ◽  
...  
Keyword(s):  
Thermal Lensing ◽  
Order Model ◽  
Laser Safety ◽  
First Order ◽  
Laser Propagation

The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid

1985 ◽  
Vol 50 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Miloslav Šorm ◽  
Miloslav Procházka ◽  
Jaroslav Kálal
Keyword(s):  
Catalyst Concentration ◽  
Low Molecular Weight ◽  
Imidazolium Chloride ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Ethanol In Water ◽  
Direct Attack

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.

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.

A kinetic standard for precise calibration of spectrophotometer cell temperature.

1981 ◽  
Vol 27 (5) ◽  
pp. 753-755 ◽  
Author(s):  
P A Adams ◽  
M C Berman
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Cell Temperature ◽  
First Order ◽  
Order Rate ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

Abstract We describe a simple, highly reproducible kinetic technique for precisely measuring temperature in spectrophotometric systems having reaction cells that are inaccessible to conventional temperature probes. The method is based on the temperature dependence of pseudo-first-order rate constants for the acid-catalyzed hydrolysis of N-o-tolyl-D-glucosylamine. Temperatures of reaction cuvette contents are measured with a precision of +/- 0.05 degrees C (1 SD).

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