Photocatalytic Degradation of Methyl Orange by TiO2/Schorl Photocatalyst: Kinetics and Thermodynamics

2015 ◽  
Vol 713-715 ◽  
pp. 2789-2792
Author(s):  
Huan Yan Xu ◽  
Xue Li ◽  
Yan Li ◽  
Ping Li ◽  
Wei Chao Liu
Keyword(s):  
Methyl Orange ◽  
Reaction Rate ◽  
Reaction Kinetic ◽  
Kinetic Studies ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Solution Ph ◽  
Kinetics And Thermodynamics ◽  
Hoff Equation ◽  
Degradation Of Methyl Orange

An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.

TiO2 Supported Clinoptilotile: Characterization and Optimization of Operational Parameters for Methyl Orange Removal

2013 ◽  
Vol 781-784 ◽  
pp. 2249-2252 ◽  
Author(s):  
Sanni O. Saheed ◽  
Sekomeng J. Modise ◽  
Allworth M. Sipamla
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Kinetic Studies ◽  
Methyl Orange Solution ◽  
Order Reaction ◽  
Operational Parameters ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Orange Solution ◽  
Degradation Of Methyl Orange

Titania dispersed on dealuminated Clinoptilotile (TiO2/HCP) was synthesized and characterized by Scanning Electron Microscope (SEM). Supporting characterization techniques reveals partly dispersion of TiO2 within the cavities of dealuminated Clinoptilotile (HCP) and TiO2 exist as nanoparticles or clusters on the HCP surface ascribed to lower loading of TiO2. The photocatalytic degradation of methyl orange solution was conducted under UV-irradiation in the presence of TiO2/HCP. The photocatalytic degradation of methyl orange in the presence of the photocatalyst was optimized at lower loading of TiO2, at a lower initial dye concentration (30 ppm), calcination temperature of 873K and nitrate ion accelerates degradation activities of methyl orange. Kinetic studies depict the photocatalytic degradation of methyl orange follows the pseudo-first order reaction.

scholarly journals Determination of exothermic batch reactor specific model parameters

2019 ◽  
Vol 292 ◽  
pp. 01063
Author(s):  
Lubomír Macků
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Specific Model ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
First Order Reaction ◽  
Model Parameters ◽  
Reactor Model ◽  
First Order

An alternative method of determining exothermic reactor model parameters which include first order reaction rate constant is described in this paper. The method is based on known in reactor temperature development and is suitable for processes with changing quality of input substances. This method allows us to evaluate the reaction substances composition change and is also capable of the reaction rate constant (parameters of the Arrhenius equation) determination. Method can be used in exothermic batch or semi- batch reactors running processes based on the first order reaction. An example of such process is given here and the problem is shown on its mathematical model with the help of simulations.

scholarly journals Kinetics and Thermodynamics Study of Ultrasound-Assisted Depolymerization of k-Carrageenan in Acidic Solution

2020 ◽  
Vol 15 (1) ◽  
pp. 280-289
Author(s):  
Ratnawati Ratnawati ◽  
Nita Indriyani
Keyword(s):  
Molecular Weight ◽  
Rate Constant ◽  
Reaction Rate ◽  
Acidic Solution ◽  
Biomedical Application ◽  
Bond Cleavage ◽  
Reaction Rate Constant ◽  
Order Kinetic ◽  
Kinetics And Thermodynamics ◽  
Ultrasound Assisted

K-carrageenan is a natural polymer with high molecular weight ranging from 100 to 1000 kDa. The oligocarrageenan with low molecular weight is widely used in biomedical application. The aim of this work was to depolymerize k-carrageenan in an acidic solution with the assistance of ultrasound irradiation. The ultrasonication was conducted at various pH (3 and 6), temperatures (30-60 °C), and depolymerization time (0-24 minutes). The results show that the depolymerization reaction follows pseudo-first-order kinetic model with reaction rate constant of 1.856×10-7 to 2.138×10-6 s-1. The reaction rate constant increases at higher temperature and lower pH. The Q10-temperature coefficients of the depolymerization are 1.25 and 1.51 for pH 6 and 3, respectively. The enthalpy of activation (ΔH‡) and the Gibbs energy of activation (ΔG‡) are positive, while the entropy of activation (ΔS‡) is negative, indicating that the activation step of the ultrasound-assisted depolymerization of k-carrageenan is endothermic, non-spontaneous, and the molecules at the transition state is more ordered than at the ground state. The ΔH‡ and the ΔS‡ are not affected by temperature, while the ΔG‡ is a weak function of temperature. The ΔH‡ and ΔS‡ become smaller at higher pH, while the ΔG‡ increases with the increase of pH. The kinetics and thermodynamics analysis show that the ultrasound-assisted depolymerization of k-carrageenan in acidic solution is possibly through three mechanisms, i.e. bond cleavage due to cavitational effect of microbubbles, hydroxyl radical and hydrogen peroxide, as well as proton. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate

2000 ◽  
Vol 65 (12) ◽  
pp. 857-866
Author(s):  
Mladjen Micevic ◽  
Slobodan Petrovic
Keyword(s):  
Kinetic Data ◽  
Reaction Rate ◽  
Frequency Factor ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Activation Entropy ◽  
Second Order Reaction ◽  
Third Order ◽  
First Order ◽  
Kinetics Of

The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate (soman) was examined with a series of alkoxides and in corresponding alcohols: methanol, ethanol, 1-propanol, 2-propanol, 2-methoxyethanol and 2-ethoxyethanol. Soman reacts with the used alkoxides in a second order reaction, first order in each reactant. The kinetics of the reaction between 1,2,2-trimethylpropyl-methylfluorophosphonate and ethanol in the presence of diethylenetriamine was also examined. A third order reaction rate constant was calculated, first order in each reactant. The activation energy, frequency factor and activation entropy were determined on the basis of the kinetic data.

scholarly journals Fast and Efficient Piezo/Photocatalytic Removal of Methyl Orange Using SbSI Nanowires

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4803
Author(s):  
Krystian Mistewicz ◽  
Mirosława Kępińska ◽  
Marian Nowak ◽  
Agnieszka Sasiela ◽  
Maciej Zubko ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Sonochemical Method ◽  
Reaction Rate Constants ◽  
Short Period ◽  
Photocatalytic Removal ◽  
Antimony Sulfoiodide ◽  
Novel Method

Piezocatalysis is a novel method that can be applied for degradation of organic pollutants in wastewater. In this paper, ferroelectric nanowires of antimony sulfoiodide (SbSI) have been fabricated using a sonochemical method. Methyl orange (MO) was chosen as a typical pollutant, as it is widely used as a dye in industry. An aqueous solution of MO at a concentration of 30 mg/L containing SbSI nanowires (6 g/L) was subjected to ultrasonic vibration. High degradation efficiency of 99.5% was achieved after an extremely short period of ultrasonic irradiation (40 s). The large reaction rate constant of 0.126(8) s−1 was determined for piezocatalytic MO decomposition. This rate constant is two orders of magnitude larger than values of reaction rate constants reported in the literature for the most efficient piezocatalysts. These promising experimental results have proved a great potential of SbSI nanowires for their application in environmental purification and renewable energy conversion.

Kinetic Studies on the Synthesis of Hydroxyapatite Nanowires by Solvothermal Methods

2007 ◽  
Vol 60 (2) ◽  
pp. 99 ◽  
Author(s):  
Shiying Zhang ◽  
Chen Lai ◽  
Kun Wei ◽  
Yingjun Wang
Keyword(s):  
Activation Energy ◽  
Reaction Rate ◽  
Kinetic Studies ◽  
Axial Ratio ◽  
Reaction Rate Constant ◽  
Rate Equations ◽  
Solvothermal Reaction ◽  
Growth Order ◽  
Constant Diffusion ◽  
Solvothermal Methods

Hydroxyapatite nanowires with a high axial ratio have been synthesized in reverse micelle solutions that consist of cetyltrimethylammonium bromide (CTAB), n-pentanol, cyclohexane, and the reactant solution by solvothermal methods. This paper focusses on the kinetic studies of the solvothermal reaction and the linear growth of hydroxyapatite nanowires. When the reaction was carried out at low temperatures (65°C), the experimental results showed that the reaction rate was of zero order since the whole reaction was diffusion controlled with constant diffusion coefficients. In the middle to high temperature range (130–200°C), the kinetics were characterized by second order reaction kinetics. Since the controlling factor was activation energy and the apparent activation energy was large, the reaction rate was more sensitive to the temperature. Therefore, the exponent of the reaction rate constant increased by two when the temperature was increased from 130 to 200°C. By calculating the yields of products and the specific surface areas at different times, the linear and overall growth rate equations of the hydroxyapatite nanowires could be obtained. The experimental effective growth order of the crystals was 11. The larger growth order indicated that the crystal could grow more effectively in one direction because of the induction of the surfactant in the experiment system.

An Investigation into the Conversion of Propylene Glycol to 2,4-dimethyl-1,3-dioxolane over an Acid Catalyst Using Gas Chromatography

2013 ◽  
Vol 850-851 ◽  
pp. 82-85
Author(s):  
Zuo You Zhang ◽  
Hui Chen ◽  
Xia Li ◽  
Zhao Hui Yang ◽  
Bao Chen Liang
Keyword(s):  
Aqueous Solution ◽  
Reaction Rate ◽  
Acid Catalyst ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Molar Ratio ◽  
Temperature Reaction ◽  
Gas Chromatograph ◽  
Second Order Reaction ◽  
Operational Parameters

In the presence of an acid catalyst, PG react reversibly with acetaldehyde to form 2,4-dim-ethyl-1,3-dioxolane (24DMD). The effects of different operational parameters on PG conversion had been analyzed in paper, parameters included temperature, reaction time, amount of catalyst and aqueous acetaldehyde/PG molar ratio. Under optimal condition, 85% conversion of PG in aqueous solution was achieved within 180 min of reaction. The analysis of PG was conducted by gas chromatograph. Furthermore, reaction followed the second-order reaction kinetics, and the reaction rate constant was found to be 29.68min-1.

Milling and Additive Effects on Hydrogen Desorption Reactions of Li-N-H and Li-Mg-N-H Hydrogen Storage Systems

2006 ◽  
Vol 971 ◽  
Author(s):  
Mitsuru Matsumoto ◽  
Yoshitsugu Kojima ◽  
Shin-ichi Towata ◽  
Yuko Nakamori ◽  
Shin-ichi Orimo
Keyword(s):  
Hydrogen Storage ◽  
Reaction Rate ◽  
Kinetic Studies ◽  
Hydrogen Desorption ◽  
Reaction Rate Constant ◽  
Lithium Hydride ◽  
Nano Particles ◽  
Desorption Process ◽  
Temperature Programmed ◽  
Desorption Reaction

ABSTRACTHydrogen desorption reactions of the mixtures of (i) lithium amide and lithium hydride (LiNH2/LiH), and (ii) magnesium amide and lithium hydride (Mg(NH2)2/4LiH) were studied. Titanium compounds and nano-particles including fullerene (C60), were doped to those hydrogen storage mixtures respectively. The hydrogen desorption reactions were monitored by means of temperature programmed desorption (TPD) technique under an Ar atmosphere. The reaction of LiNH2/LiH was accelerated by adding either 1 mol% of Ti species or 0.2 mol% of fullerene (C60), while those additives did not show significant acceleration effects on the reaction of Mg(NH2)2/4LiH. Kinetic studies revealed the enhanced hydrogen desorption reaction rate constant for TiCl3 doped LiNH2/LiH, k = 3.1 × 10−4 s−1 at 493 K, and the prolonged ball-milling further improved reaction rate, k = 1.1 × 10−3 s−1 at the same temperature. For the dehydrogenation reaction of TiCl3 doped LiNH2/LiH, the activation energies estimated by Kissinger plot (95 kJ mol−1) and Arrhenius plot (110 kJ mol−1) were in reasonable agreement each other. The LiNH2/LiH mixture without additive exhibited slower hydrogen desorption process and the kinetic traces deviated from single exponential behavior. The results indicated the Ti(III) additives change the hydrogen desorption reaction mechanism of LiNH2/LiH.

scholarly journals KINETIKA REAKSI FERMENTASI ALKOHOL DARI BUAH SALAK

2013 ◽  
Vol 2 (2) ◽  
pp. 16-20
Author(s):  
Fatimah ◽  
Febrina Lia G ◽  
Lina Rahmasari G
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Alcoholic Fermentation ◽  
Reaction Kinetic ◽  
Reaction Rate Constant ◽  
Hydrolysis Reaction ◽  
Diffusion Reaction ◽  
Bioethanol Production ◽  
Film Diffusion ◽  
Hydrolysis Of

Research about bioethanol production from salak that are not marketable has been done. Salak containing 16.07% starch and 32.96% glucose, so that salak is potential to be converted into bioethanol by fermentation. This research aimed to study reaction kinetic of alcoholic fermentation that are the reaction kinetic of the hydrolysis of starch to glucose and fermentation of glucose to alcohol from salak by using Saccharomyces cereviseae. Hydrolysis of starch reaction containing two reaction rate controls that are chemical reaction and film diffusion. The results obtained for the hydrolysis reaction that the reacion rate constant is 1,41 x 10-11 and the film diffusion coefficient constant is 0,47 x 10-11 so the rate of the hydrolysis reaction is controlled by the film diffusion. Reaction rate constant for fermentation is 169,88. During the process of fermentation, the concentration of starch and glucose tended to decreased by time of fermentation and bioethanol concentration tended to increase by time of fermentation.

Photo-Catalytic Activity of Ag-N Co-Doped ZnO/CuO Nanocomposite for Degradation of Methyl Orange

2016 ◽  
Vol 32 (1-2) ◽  
pp. 49
Author(s):  
Jemal Mohammed Yasin ◽  
O. P. Yadav ◽  
Abi M. Taddesse
Keyword(s):  
Catalytic Activity ◽  
Methyl Orange ◽  
Band Gap Energy ◽  
Spectroscopic Techniques ◽  
Solution Ph ◽  
Photo Catalytic Activity ◽  
Composite Photocatalysts ◽  
Doped Zno ◽  
Co Doped ◽  
Degradation Of Methyl Orange

Nano-size Ag-N co-doped ZnO-CuO composites have been synthesized and tested for their photo-catalytic activity towards degradation of methyl orange in aqueous solution under visible as well as UV radiations. Crystal structure, surface functional groups, metallic composition and band structure of as-synthesized nano-material were investigated using XRD, FTIR, AAS and UV-Vis spectroscopic techniques, respectively. Ag-N co-doped ZnO-CuO photocatalyst showed higher photo-catalytic activity than Ag- or N-doped and undoped composite photocatalysts. The observed highest activity of Ag-N co-doped ZnO-CuO among the studied photo-catalysts, is attributed to the cumulative effects of lowering of band-gap energy and decrease of recombination rate of photo-generated electrons and holes owing to doped N and Ag, respectively. Effects of photo-catalyst load, solution pH and substrate initial concentration on the degradation of methyl orange have also been studied.

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