APPLICATION OF CVD DIAMOND FILMS FOR UV THERMOLUMINESCENCE DOSIMETER

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1003-1007 ◽  
Author(s):  
J. AHN ◽  
B. GAN ◽  
Q. ZHANG ◽  
S. F. YOON ◽  
V. LIGATCHEV ◽  
...  
Keyword(s):  
Activation Energy ◽  
Glow Curve ◽  
Diamond Films ◽  
Frequency Factor ◽  
Cvd Diamond ◽  
Order Kinetic ◽  
First Order ◽  
Order Kinetic Model ◽  
Ionizing Radiations ◽  
Trap Activation

This study presents the investigation of CVD diamond for the application of an UV TL dosimeter. A 9-μm-thick film used in this study presents a TL glow curve with a well-defined first-order kinetic peak (at about 273 K), which norm ally presents in the glow curve from ionizing radiations, is not observed. By fitting the glow curve to a first-order kinetic model, the trap activation energy E t = 0.95 eV and frequency factor s = 5.6 x 106 s -1 have been resolved.

Hydration of Partially Sulfated Lime Particles From Fluidized Bed Combustors

2000 ◽  
Vol 123 (2) ◽  
pp. 173-178 ◽  
Author(s):  
M. F. Couturier ◽  
Y. Volmerange ◽  
F. Steward
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Hydration Reaction ◽  
Order Kinetic ◽  
First Order ◽  
Thermogravimetric Analyzer ◽  
Order Kinetic Model ◽  
Increasing Temperature

The reaction between water and partially sulfated lime particles was studied under isothermal conditions using a microcalorimeter. Experiments were performed with spent sorbent particles from two industrial circulating fluidized bed combustors and with lime particles sulfated in the laboratory using a thermogravimetric analyzer. The rate of hydration of the partially sulfated lime particles was found to be independent of particle size, to increase with increasing temperature, and to decrease with increasing level of sulfation of the particles. A first-order kinetic model is shown to correlate well the effect of time and temperature on the extent of hydration of spent sorbent particles from fluidized bed combustors. The apparent activation energy of the hydration reaction is 45 kJ/mol.

Kinetics of bioactive compounds in functional spice Jiangpo during thermal processing

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Xiaoyan Dai ◽  
Chenhuan Yu ◽  
Qiaofeng Wu
Keyword(s):  
Kinetic Parameters ◽  
Bioactive Compounds ◽  
Thermal Processing ◽  
Order Rate Constant ◽  
Heat Processing ◽  
Order Kinetic ◽  
Time Intervals ◽  
First Order ◽  
Order Kinetic Model ◽  
Kinetics Of

Abstract Jiangpo is an increasingly popular East Asian spice which is made from Mangnolia officinalis bark and ginger juice. Since it induces bioactive compounds decomposition and has influence on final flavor and fragrance, cooking is regarded as the key operation in preparation of Jiangpo. To evaluate the bioactive compounds content changes of Jiangpo during thermal processing, kinetic parameters including reaction order, rate constant, T1/2 and activation energy of bioactive markers namely honokiol, magnolol and curcumin were determined. Cooking was set at temperatures 60, 90 and 120 °C for selected time intervals. Results displayed the thermal kinetic characteristics of the three compounds. Thermal degradation of Honokiol and magnolol both followed first order kinetic model and the loss of curcumin fitted second order. A mathematical model based on the obtained kinetic parameters has also been developed to predict the degradation of honokiol, magnolol and curcumin in non-isothermal state. All the information in this paper could contribute necessary information for optimizing the existing heat processing of Jiangpo.

scholarly journals Municipal Leachate Treatment by Fenton Process: Effect of Some Variable and Kinetics

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mohammad Ahmadian ◽  
Sohyla Reshadat ◽  
Nader Yousefi ◽  
Seyed Hamed Mirhossieni ◽  
Mohammad Reza Zare ◽  
...  
Keyword(s):  
Reaction Time ◽  
Color Removal ◽  
Molar Ratio ◽  
Order Kinetic ◽  
Fenton Process ◽  
Solution Ph ◽  
Leachate Treatment ◽  
First Order ◽  
Order Kinetic Model ◽  
Better Than

Due to complex composition of leachate, the comprehensive leachate treatment methods have been not demonstrated. Moreover, the improper management of leachate can lead to many environmental problems. The aim of this study was application of Fenton process for decreasing the major pollutants of landfill leachate on Kermanshah city. The leachate was collected from Kermanshah landfill site and treated by Fenton process. The effect of various parameters including solution pH, Fe2+and H2O2dosage, Fe2+/H2O2molar ratio, and reaction time was investigated. The result showed that with increasing Fe2+and H2O2dosage, Fe2+/H2O2molar ratio, and reaction time, the COD, TOC, TSS, and color removal increased. The maximum COD, TOC, TSS, and color removal were obtained at low pH (pH: 3). The kinetic data were analyzed in term of zero-order, first-order, and second-order expressions. First-order kinetic model described the removal of COD, TOC, TSS, and color from leachate better than two other kinetic models. In spite of extremely difficulty of leachate treatment, the previous results seem rather encouraging on the application of Fenton’s oxidation.

Performance of poly-o-phenylenediamine and its carbon dot composite electrode in the removal of Cu2+ from its aqueous solution

2021 ◽  
pp. 2151037
Author(s):  
Yu Meng ◽  
Qing Zhong ◽  
Arzugul Muslim
Keyword(s):  
Aqueous Solution ◽  
Electrochemical Reduction ◽  
Composite Electrode ◽  
Reduction Process ◽  
Order Kinetic ◽  
Carbon Dot ◽  
First Order ◽  
Oxidation Reduction ◽  
Order Kinetic Model ◽  
Optimal Ph

Because −NH2 and −NH− in poly-[Formula: see text]-phenylenediamine (P[Formula: see text]PD) can interact strongly with the empty orbitals of Cu to show unique electrochemical activity, P[Formula: see text]PD is suitable for the removal of Cu[Formula: see text] by electrochemical oxidation–reduction process. In this study, with P[Formula: see text]PD and its carbon dot composite (CDs/P[Formula: see text]PD) as working electrodes, the electrochemical reduction and removal of Cu[Formula: see text] in the aqueous solution were carried out with the potentiostatic method. According to effects of voltage, pH of the solution, initial concentration of Cu[Formula: see text], and electrochemical reduction time on the Cu[Formula: see text] removal, the Cu[Formula: see text] removal ratios of P[Formula: see text]PD and CDs/P[Formula: see text]PD were up to 64.69% and 73.34%, respectively, at −0.2 V and the optimal pH. Additionally, results showed that these processes were in line with the quasi-first order kinetic model. Both P[Formula: see text]PD and CDs/P[Formula: see text]PD showed good reproducibility in six cycles. After five times of repeated usage, the regeneration efficiencies of P[Formula: see text]PD and CDs/P[Formula: see text]PD dropped to 77.04% and 79.36%, respectively.

scholarly journals Enhanced photocatalytic activity of wool-ball-like TiO2 microspheres on carbon fabric and FTO substrates

2018 ◽  
Vol 38 ◽  
pp. 02014
Author(s):  
Yu Zhang ◽  
Jian Gu ◽  
Mengqi Zhang
Keyword(s):  
Hydrothermal Method ◽  
Order Kinetic ◽  
Carbon Fabric ◽  
Facile Hydrothermal Method ◽  
Sem Images ◽  
First Order ◽  
Good Crystallinity ◽  
Degradation Rate Constant ◽  
Order Kinetic Model ◽  
Pseudo First Order

The wool-ball-like TiO2 microspheres on carbon fabric (TiO2-CF) and FTO substrates (TiO2-FTO) have been synthesized by a facile hydrothermal method in alkali environment, using commercial TiO2 (P25) as precursors. The XRD results indicate that the as-prepared TiO2 have good crystallinity. And the SEM images show that the wool-ball-like TiO2 microspheres with a diameter of 2-3 μm are composed of TiO2 nanowires, which have a diameter of ~50 nm. The photocatalytic behavior of the wool-ball-like TiO2 microspheres, TiO2-CF and TiO2-FTO under ultraviolet light was investigated by a pseudo first-order kinetic model, using methyl orange (MO) as pollutant. The wool-ball-like TiO2 microspheres obtained a degradation rate constant (Kap) of 6.91×10-3 min-1 . The Kap values of TiO2-FTO and TiO2-CF reach 13.97×10-3 min-1 and 11.80×10-3 min-1, which are 2.0 and 1.7 times higher than that of pristine wool-ball-like TiO2 microspheres due to the “sum effect” between TiO2 and substrates. This study offers a facile hydrothermal method to prepare wool-ball-like TiO2 microspheres on CF and FTO substrates, which will improve the recyclability of phtocatalysts and can be extended to other fields.

An Overview on Peak Shape Method for Thermoluminescence Glow Curve Analysis

2018 ◽  
pp. 26-52
Author(s):  
Sukhamoy Bhattacharyya ◽  
Partha Sarathi Majumdar
Keyword(s):  
Activation Energy ◽  
Glow Curve ◽  
Frequency Factor ◽  
Curve Analysis ◽  
Peak Shape ◽  
Order Of Kinetics ◽  
Symmetry Factor ◽  
Alternative Approach ◽  
General Order ◽  
Thermoluminescence Glow Curve

The shape of a thermoluminescence (TL) glow curve has fundamental importance for calculating the characteristic parameters of trap levels within the band gap. TL analysis are mostly based on the three-parameter general order kinetics model. The parameters are activation energy, order of kinetics, and frequency factor. Peak shape method is one of the most prominent methods for extracting the activation energy from a TL curve. An overview of different peak shape methods along with an alternative approach formulated directly from basic TL equations is presented in this chapter. Generally, peak shape method requires prior knowledge of order of kinetics to determine activation energy which creates a difficulty due to the non-uniqueness of symmetry factor for a particular value of order of kinetics. A modified version of peak shape method which is free from this constraint is discussed here. Activation energies from experimental curves of tremolite and actinolite are estimated using peak shape method. Limitation of peak shape method for saturated TL peaks with heavy retrapping is also discussed.

scholarly journals Waste to Carbon: Influence of Structural Modification on VOC Emission Kinetics from Stored Carbonized Refuse-Derived Fuel

2019 ◽  
Vol 11 (3) ◽  
pp. 935 ◽  
Author(s):  
Andrzej Białowiec ◽  
Monika Micuda ◽  
Antoni Szumny ◽  
Jacek Łyczko ◽  
Jacek Koziel
Keyword(s):  
Structural Modification ◽  
Solid Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Order Kinetic ◽  
Voc Emissions ◽  
Voc Emission ◽  
First Order ◽  
Refuse Derived Fuel ◽  
Volatile Organic ◽  
Order Kinetic Model

The torrefaction of municipal solid waste is one of the solutions related to the Waste to Carbon concept, where high-quality fuel—carbonized refuse-derived fuel (CRDF)—is produced. An identified potential problem is the emission of volatile organic compounds (VOCs) during CRDF storage. Kinetic emission parameters have not yet been determined. It was also shown that CRDF can be pelletized for energy densification and reduced volume during storage and transportation. Thus, our working hypothesis was that structural modification (via pelletization) might mitigate VOC emissions and influence emission kinetics during CRDF storage. Two scenarios of CRDF structural modification on VOC emission kinetics were tested, (i) pelletization and (ii) pelletization with 10% binder addition and compared to ground (loose) CRDF (control). VOC emissions from simulated sealed CRDF storage were measured with headspace solid-phase microextraction and gas chromatography–mass spectrometry. It was found that total VOC emissions from stored CRDF follow the first-order kinetic model for both ground and pelletized material, while individual VOC emissions may deviate from this model. Pelletization significantly decreased (63%~86%) the maximum total VOC emission potential from stored CDRF. Research on improved sustainable CRDF storage is warranted. This could involve VOC emission mechanisms and environmental-risk management.

scholarly journals Zeolite-Based Fast-Responding Sensors for Respiratory Rate Monitoring

Proceedings ◽  
2019 ◽  
Vol 42 (1) ◽  
pp. 9
Author(s):  
Gianfranco Carotenuto ◽  
Carlo Camerlingo
Keyword(s):  
Kinetic Analysis ◽  
Water Concentration ◽  
Adsorbed Water ◽  
Current Intensity ◽  
Specific Rate ◽  
Order Kinetic ◽  
First Order ◽  
Order Kinetic Model ◽  
Water Sensor ◽  
Breath Monitoring

Wearable electrical sensors based on zeolites can be used for breath monitoring. The high silicon content of clinoptilolite makes this type of zeolite very adequate for fabricating sensitive water sensors. In addition to sensitivity, response fastness also represents a sensor characteristic of fundamental importance for breath monitoring. Here, the response fastness of a clinoptilolite-based water sensor has been evaluated by measuring the current intensity behavior upon exposition to a constant humidity atmosphere (75%). In particular, the clinoptilolite surface has been biased with a sinusoidal signal (20 Vpp, 5 kHz), and the true-RMS current intensity value has been recorded during exposition to the constant humidity atmosphere. Since current intensity is proportional to the adsorbed water concentration (only hydrated cations are charge carriers) a kinetic analysis has been possible. The clinoptilolite dehydration kinetics in a dry atmosphere have been evaluated too. According to this kinetic analysis, water adsorption is described by a Lagergren pseudo-first-order model with a rate constant of (58.6 ± 0.9)·10−4 min−1, while desorption in dry air follows a first-order kinetic model with a specific rate of (202.7 ± 0.3)·10−4 min−1 at 25 °C.

scholarly journals Microwave-Assisted Transesterification of Kusum Oil: Parametric, Kinetic and Thermodynamic Studies

2020 ◽  
Vol 32 (11) ◽  
pp. 2893-2903
Author(s):  
SHEETAL N. NAYAK ◽  
MILAP G. NAYAK ◽  
CHANDRAKANT P. BHASIN
Keyword(s):  
Activation Energy ◽  
Reaction Rate ◽  
Frequency Factor ◽  
Molar Ratio ◽  
Pseudo First Order Reaction ◽  
Time Intervals ◽  
First Order ◽  
Microwave Assisted ◽  
Lower Heat ◽  
Kinetic And Thermodynamic Studies

Microwave-assisted transesterification of non-edible oil to produce biodiesel is gaining attention due to lower heat loss as well as rapid conversion. In this study, esterified kusum oil as a feedstock was transesterified in the presence of Ba(OH)2. At 800 W microwave power and constant magnetic stirring the effect of important process parameters such as solvent methanol molar ratio, Ba(OH)2, temperature, and time on biodiesel yield were evaluated. The parametric study suggested that 9:1 M methanol, 65 ºC reaction temperature, 2.5 wt% Ba(OH)2 catalyst and 3.5 min of transesterification time gave close to 96% biodiesel yield. At the above conditions of methanol and catalyst, the reaction kinetics and thermodynamic study were performed using different time intervals. The microwave-assisted transesterification followed pseudo-first-order reaction rate with 34.57 kJ/mol K activation energy and 205664 min-1 frequency factor. The reduction in activation energy and increase in the frequency factor reveal the non-thermal effect associated with microwave heating. The thermodynamic properties evaluated using the Eyring equation suggests non-spontaneity and endothermic nature of transesterification.

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