Correlation and prediction of azo dye degradation by nonlinear least-square regression in combined ozonation and ultrasonolysis processes

2011 ◽  
Vol 46 (3) ◽  
pp. 250-258 ◽  
Author(s):  
Masroor Mohajerani ◽  
Mehrab Mehrvar ◽  
Farhad Ein-Mozaffari
Keyword(s):  
Azo Dyes ◽  
Rate Constants ◽  
Reaction Rate ◽  
Synergetic Effect ◽  
Operating Conditions ◽  
Least Square ◽  
Combined Processes ◽  
Reaction Rate Constants ◽  
Least Square Regression ◽  
The Impact

Correlative reaction kinetics based on nonlinear least square regression were obtained to predict the degradation of p-aminophenol (PAP), C.I. Reactive Yellow 84 (RY84), C.I. Reactive Blue 19 (RB19), and C.I. Direct Red 23 (DR23) in combined ultrasonolysis and ozonation. Effects of ultrasonolysis and ozonation as individual processes, as well as the synergetic effect for the degradation of azo dyes, were studied by linear and nonlinear regression methods. An initial dye concentration correlation index (φ) for each compound was developed to study the effects of initial concentrations of organics on their reaction rate constants. Reaction rate constants for the azo dyes’ degradation in ozonation and ultrasonolysis alone and their combination were obtained for different operating conditions. Results showed that ultrasonolysis alone was almost ineffective for decolorization and mineralization of azo dyes, but the combination of ozonation and ultrasonolysis had a significant effect on their degradation. Both ozone dose and ultrasonic density had a direct effect on the reaction rate constants, where the impact of ozone was greater with respect to that of the ultrasound. The synergetic effect of combined processes as a function of ozone concentration and ultrasound density varied from 0 to 5, 0 to 4, and 0 to 35 for RY84, RB19, and DR23, respectively.

scholarly journals The role of atom tunneling in gas-phase reactions in planet-forming disks

2019 ◽  
Vol 627 ◽  
pp. A45 ◽  
Author(s):  
J. Meisner ◽  
I. Kamp ◽  
W.-F. Thi ◽  
J. Kästner
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Reaction Rate ◽  
Tunneling Effect ◽  
Gas Phase Reactions ◽  
Disk Model ◽  
Reaction Rate Constants ◽  
T Tauri ◽  
Simple Molecules ◽  
The Impact

Context. Chemical Gas-phase reactions of simple molecules have been recently revised to include atom tunneling at very low temperatures. This paper investigates the impact of the increased reaction rate constant due to tunneling effects on planet-forming disks. Aims. Our aim is to quantify the astrophysical implications of atom tunneling for simple molecules that are frequently used to infer disk structure information or to define the initial conditions for planet (atmosphere) formation. Methods. We quantify the tunneling effect on reaction rate constants by using H2 + OH → H2O + H as a scholarly example in comparison to previous UMIST2012 rate constants. In a chemical network with 1299 reactions, we identify all chemical reactions that could show tunneling effects. We devise a simple formulation of reaction rate constants that overestimates tunneling and screen a standard T Tauri disk model for changes in species abundances. For those reactions found to be relevant, we find values of the most recent literature for the rate constants including tunneling and compare the resulting disk chemistry to the standard disk model(s), a T Tauri and a Herbig disk. Results. The rate constants in the UMIST2012 database in many cases already capture tunneling effects implicitly, as seen in the curvature of the Arrhenius plots of some reactions at low temperature. A rigorous screening procedure identified three neutral-neutral reactions where atom tunneling could change simple molecule abundances. However, by adopting recent values of the rate constants of these reactions and due to the layered structure of planet-forming disks, the effects are limited to a small region between the ion-molecule dominated regime and the ice reservoirs where cold (<250 K) neutral-neutral chemistry dominates. Abundances of water close to the midplane snowline can increase by a factor of two at most compared to previous results with UMIST2012 rates. Observables from the disk surface, such as high excitation (>500 K) water line fluxes, decrease by 60% at most when tunneling effects are explicitly excluded. On the other hand, disk midplane quantities relevant for planet formation such as the C-to-O ratio and also the ice-to-rock ratio are clearly affected by these gas-phase tunneling effects.

On the Accurate Determination of Reaction Rate Constants in Batch-Type Solar Photocatalytic Oxidation Facilities

1994 ◽  
Vol 116 (1) ◽  
pp. 19-24 ◽  
Author(s):  
J. F. Klausner ◽  
A. R. Martin ◽  
D. Y. Goswami ◽  
K. S. Schanze
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Photocatalytic Oxidation ◽  
Reaction Rate ◽  
Accurate Determination ◽  
Operating Conditions ◽  
Total System ◽  
Reaction Rate Constants ◽  
Batch Type

A rigorous analysis is presented which allows for the accurate determination of reaction rate constants in batch-type photocatalytic oxidation facilities as well as any other batch-type chemical process where the reaction kinetics are known. Experimental verification of the model is accomplished using an indoor facility which utilizes an ultraviolet (UV) lamp source for the destruction of 4-chlorophenol (4CP). It has been observed that the first-order reaction rate constant increases by about 50 percent with an order of magnitude increase in flow rate. Using the present analysis, it is demonstrated that the approximate method of determining rate constants (the product of the apparent rate constant and the ratio of the reactor volume to the total system volume) is useful over a surprisingly wide range of operating conditions.

Ease of Doing Business and Its Impact on Inward FDI

2018 ◽  
Vol 1 (1) ◽  
pp. 52 ◽  
Author(s):  
Mohamed Tareq Hossain ◽  
Zubair Hassan ◽  
Sumaiya Shafiq ◽  
Abdul Basit
Keyword(s):  
Regression Model ◽  
Causal Relationship ◽  
World Bank ◽  
Least Square ◽  
Doing Business ◽  
Least Square Regression ◽  
Foreign Countries ◽  
Ease Of Doing Business ◽  
The Impact ◽  
Starting A Business

This study investigates the impact of Ease of Doing Business on Inward FDI over the period from 2011 to 2015 across the globe. This study measures ease of doing business using starting a business, getting credit, registering property, paying taxes and enforcing contracts. The research used a sample of 177 countries from 190 countries listed in World Bank. Least square regression model via E-views software used to examine causal relationship. The study found that ease of doing business indicators ‘Enforcing Contracts’ was found to have a positive significant impact on Inward FDI. Nevertheless, ‘Getting Credit’ and ‘Registering Property’ were found to have a negative significant impact on Inward FDI. However, ‘Starting a Business’ and ‘Paying Taxes’ have no significant impact on Inward FDI in the studied timeframe of this research. The findings of the study suggested the ease of doing business enables inward FDI through better contract enforcements, getting credit and registering property. The findings of the research will assist international managers and companies to know the importance of ease of doing business when investing in foreign countries through FDI.

Measurement of the OH Reaction Rate Constants for CF3CH2OH, CF3CF2CH2OH, and CF3CH(OH)CF3

1999 ◽  
Vol 103 (15) ◽  
pp. 2664-2672 ◽  
Author(s):  
Kazuaki Tokuhashi ◽  
Hidekazu Nagai ◽  
Akifumi Takahashi ◽  
Masahiro Kaise ◽  
Shigeo Kondo ◽  
...  
Keyword(s):  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Rate Constants
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