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.

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 The effect of systematic error on the accuracy of Michaelis constants and maximum velocities estimated by using the integrated Michaelis–Menten equation (Short Communication)

1974 ◽  
Vol 143 (3) ◽  
pp. 779-781 ◽  
Author(s):  
Peter F. J. Newman ◽  
Gordon L. Atkins ◽  
Ian A. Nimmo
Keyword(s):  
Reaction Time ◽  
Systematic Error ◽  
Substrate Concentration ◽  
Unknown Parameter ◽  
Short Communication ◽  
Systematic Errors ◽  
Product Concentration ◽  
Initial Substrate ◽  
Michaelis Constants ◽  
Initial Substrate Concentration

Systematic errors in initial substrate concentration (s0), product concentration and reaction time give much larger errors in the Michaelis–Menten parameters unless s0 is treated as an unknown parameter. These errors are difficult to detect because the fitted curve deviates little from the data. The effect of non-enzymic reaction is also examined.

scholarly journals Evaluating the Performance of Three Chambers Microbial Salinity Cell (MSC) Subjected to Different Substrate Concentrations to Accomplish Simultaneous Organic and Salt Removal in the Wastewater

2020 ◽  
Vol 11 (1) ◽  
pp. 19-26
Author(s):  
Rustiana Yuliasni ◽  
Nur Zen ◽  
Nanik Indah Setianingsih
Keyword(s):  
Substrate Concentration ◽  
Carbon Cloth ◽  
Anode Chamber ◽  
Initial Substrate ◽  
Conductivity Increase ◽  
Maximum Current ◽  
Maximum Conductivity ◽  
Vulcan Carbon ◽  
Substrate Concentrations ◽  
Initial Substrate Concentration

This study aimed to identify the effect of substrate concentration on the performance of A Three chambers Microbial Salinity Cell (a three chambers MSC). In this study, 3 three chambers MSC was made of plexy glass with total volume of 200 ml.  Alumunium wrapped with with platinum on vulcan carbon cloth were used as electrodes,with each working area 63 cm2. The results showed that a Three chambers Microbial Salinity Cell was able to generate electricity and at the same time removed salinity. The degree of electricity deneration and salinity removal were influenced by initial substrate concentration in the anode chamber. The higher substrate concentration, the better performance of MSC. The best performance of MSC achieved when COD was 2034 mg/L, resulted in maximum  voltage of 0. 44 V, and  maximum current density of 0.29 mA/m2. With % CE was 5.4%. The maximum conductivity increase in salinity chamber was  from 11.2 µS/cm  to 1027 µS/cm (salinity 0.57% ppt).

Influence of So/Xo Ratio on Anaerobic Activity Test

1999 ◽  
Vol 40 (8) ◽  
pp. 9-15 ◽  
Author(s):  
Gloria Moreno ◽  
Arturo Cruz ◽  
Germán Buitrón
Keyword(s):  
Substrate Concentration ◽  
Reaction Rate ◽  
Biomass Concentration ◽  
Sole Source ◽  
Yield Coefficient ◽  
Initial Biomass Concentration ◽  
Activity Test ◽  
Initial Substrate ◽  
Kinetic Coefficients ◽  
Initial Substrate Concentration

The effect of the substrate/microorganism ratio during the development of anaerobic activity test was studied. The experimentation was carried out in serum bottles at 35°C. Two sets of experiments utilizing acetate and an azo dye (blue disperse 79) as the sole source of carbon were studied. It was observed that mixing has an important influence on the results. The initial substrate concentration and the initial biomass concentration had a significant effect on the reaction rate and on the biomass yield coefficient, Yobs. Different kinetic coefficients were found for the case of equal So/Xo ratio, but different initial substrate concentration.

Synthesis of (S)-Tert-Butyl 3-Hydroxybutyrate by Asymmetric Reduction of Tert-Butyl Acetoacetate with Saccharomyces cerevisiae B5

2013 ◽  
Vol 704 ◽  
pp. 12-17
Author(s):  
Zhi Min Ou ◽  
Wen Fei Feng ◽  
Li Xu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Substrate Concentration ◽  
Asymmetric Reduction ◽  
Optical Purity ◽  
Lower Amount ◽  
High Optical Purity ◽  
Initial Substrate ◽  
Initial Ph ◽  
H 30 ◽  
Initial Substrate Concentration

S)-tert-butyl 3-hydroxybutyrate was synthesized by asymmetric reduction of tert-butyl acetoacetate with Saccharomyces cerevisiae B5 as catalyst. The enantiometric excess of (S)-tert-butyl 3-hydroxybutyrate increased with addition of more amount of substrate. High optical purity of product can be obtained when 6 g/L chloroform was used as inhibitor. The optimum reduction time, temperature, and initial pH of reaction mixture were 60 h, 30 °C, and 6.2. Addition of more biomass and lower amount of substrate helped to get high conversion. Conversion and enantiometric excess of product reached 100% when initial substrate concentration and biomass were 2.0 g/L and 140 g/L with 6 g/L chloroform as inhibitor.

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