scholarly journals Thermodynamic and kinetics analysis of the sulfur-fixed roasting of antimony sulfide using ZnO as sulfur-fixing agent

2018 ◽  
Vol 54 (3) ◽  
pp. 411-418 ◽  
Author(s):  
Z. Ouyang ◽  
Y.F. Chen ◽  
S.Y. Tian ◽  
L. Xiao ◽  
C.B. Tang ◽  
...  
Keyword(s):  
Frequency Factor ◽  
High Energy ◽  
Reaction Model ◽  
Antimony Sulfide ◽  
Volatilization Of Sb2s3 ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Kinetics Of ◽  
High Energy Consumption ◽  
So2 Pollution

Currently, the commercial antimony metallurgy is mainly based on pyrometallurgical processes and oxidative volatilization of Sb2S3 is an essential step. This step includes the problems of high energy consumption and low concentration of SO2 pollution. Aiming at these problems, we present a new method of sulfur-fixing roasting of antimony sulfide. This method uses ZnO as a sulfur-fixing agent, and roasting with Sb2S3 was carried out at 673 K~1073 K to produce Sb2O3 and ZnS. By calculating the thermodynamics of the reactions, we can conclude that the Gibbs Free Energy Change (?G?) of roasting reaction is below -60 kJ/mol and the predominance areas of Sb2O3 and ZnS are wide and right shifting with the temperature increase, which all indicates that this method is theoretically feasible. The reacted products between Sb2S3 and ZnO indicated that the reaction began at 773 K and finished approximately at 973K. We used the Ozawa-Flynn-Wall, Kissinger and Coats-Redfern method to calculate the kinetics of the roasting reaction. The conclusion is as follows: The average values of apparent activation energy (E) and natural logarithmic frequency factor (lnA) calculated by Ozawa-Flynn-Wall, Kissinger and Coats-Redfern were 189.72 kJ?mol-1 and 35.29 s-1, respectively. The mechanism of this reaction was phase boundary reaction model. The kinetic equation is shown as follow, where ? represents reaction fraction: 1-(1-?)1/3 = 2.12 x1015 exp(-1.90x105/RT) t.

Synthesis and Determination of the Kinetic Parameters for Non-Isothermal Decomposition of Complexes Ln(thd)3phen

2006 ◽  
Vol 530-531 ◽  
pp. 506-512 ◽  
Author(s):  
Wilton Silva Lopes ◽  
Crislene Rodrigues da Silva Morais ◽  
A.G. de Souza
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Lanthanide Complexes ◽  
Reaction Order ◽  
Decomposition Reaction ◽  
Cylindrical Symmetry ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Kinetics Of

In this work the kinetics of the thermal decomposition of two ß-diketone lanthanide complexes of the general formula Ln(thd)3phen (where Ln = Nd+3 or Tm+3, thd = 2,2,6,6- tetramethyl-3,5-heptanodione and phen = 1,10-phenantroline) has been studied. The powders were characterized by several techniques. Thermal decomposition of the complexes was studied by non-isothermal thermogravimetry techniques. The kinetic model that best describes the process of the thermal decomposition of the complexes it was determined through the method proposed by Coats-Redfern. The average values the activation energy obtained were 136 and 114 kJ.mol-1 for the complexes Nd(thd)3phen and Tm(thd)3phen, respectively. The kinetic models that best described the thermal decomposition reaction the both complexes were R2. The model R2 indicating that the mechanism is controlled by phase-boundary reaction (cylindrical symmetry) and is defined by the function g(α) = 2[1-(1-a)1/2], indicating a mean reaction order. The values of activation energy suggests the following decreasing order of stability: Nd(thd)3phen > Tm(thd)3phen.

Study on Smelting Metallic Magnesium by Siliconthermic Reducing Method and its Reaction Kinetics

2010 ◽  
Vol 129-131 ◽  
pp. 1133-1137
Author(s):  
Feng Gao ◽  
Wang Guo Sheng ◽  
Liu Yun Yi ◽  
Ying Xin Ge ◽  
Wang Zhu Min
Keyword(s):  
Activation Energy ◽  
Raw Materials ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Reduction Process ◽  
Frequency Factor ◽  
Reduction Temperature ◽  
Metallic Magnesium ◽  
Boundary Reaction ◽  
Phase Boundary Reaction

The metallic magnesium by siliconthermic reducing method was studied by magnetite as raw materials. The Mg reduction rate, such as reduction temperature and time, Si-Fe added mount, mineralize CaF2 added, briquette pressure, were discussed by experiments. Through siliconthermic reducing process analyzed, the result showed reduction process was in line with three-dimensional phase boundary reaction D3 model and kinetic equitation were expressed as , with an apparent activation energy 313.58 KJ/mol, frequency factor 2.7×106 s-1.

Rheed Measurement and Chemical Kinetics of Chemical Beam Epitaxial growth of GaAs

1989 ◽  
Vol 145 ◽  
Author(s):  
T.H. Chiu
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Atomic Layer ◽  
High Energy ◽  
Reaction Model ◽  
Atomic Layer Epitaxy ◽  
Dynamic Evolution ◽  
High Energy Electron ◽  
Incident Flux ◽  
Kinetics Of

AbstractRecent efforts employing reflection high energy electron diffiaction measurements to study the chemical beam epitaxial growth of GaAs is reviewed. A reaction model which assumes the dominance of Ga alkyls and their derivatives adsorbed on the growing surface can explain most of the growth results in a consistent way. Dynamic evolution of the reconstruction pattern of the adsorbed triethylgallium or trimethylgallium overlayer illustrates how the alkyl-Ga bonds are cleaved sequentially. The growth rate dependence on temperature and incident flux can be fitted quite well in this reaction model. In the absence of As flux, the existence of a metastable Ga alkyl overlayer makes possible the atomic layer epitaxy of GaAs.

Study on the Kinetics of Wet Flue Gas Desulfurization by Carbide Slag

2011 ◽  
Vol 322 ◽  
pp. 252-255
Author(s):  
Sheng Yu Liu ◽  
Li Chao Nengzi ◽  
Cheng Wei Lu ◽  
Wei Qiu ◽  
Yun Ming Hu
Keyword(s):  
Activation Energy ◽  
Chemical Reaction ◽  
Flue Gas ◽  
Reaction Order ◽  
Frequency Factor ◽  
Reaction Model ◽  
Flue Gas Desulfurization ◽  
Economic Costs ◽  
Carbide Slag ◽  
Kinetics Of

Current industrial desulfurization processes involve in economic costs, if carbide slag can be used in those processes, the costs will be reduced and the goal treating waste with waste can be achieved. A mathematic reaction model was built based on the chemical reaction of desulfurization by carbide slag, the overall reaction order n=α+β=1.74, the activation energy Ea=21749.56173J/mol and the frequency factor k0=0.349533643 .

Parallel reaction kinetics of smectite to illite conversion

Clay Minerals ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 365-376 ◽  
Author(s):  
H. Wei ◽  
E. Roaldset ◽  
M. Bjorøy
Keyword(s):  
Electrostatic Interactions ◽  
Gulf Coast ◽  
Sedimentary Basins ◽  
Frequency Factor ◽  
Reaction Model ◽  
Activation Energies ◽  
Parallel Reaction ◽  
First Order ◽  
Maximum Reaction ◽  
Kinetics Of

AbstractA parallel reaction model is developed for describing the conversion of smectite to illite. Each reaction represents a group of similar smectite layers that require the same activation energy and have the same illitization rate. The model considers that the rate-determining reactant is smectite itself which follows first-order Arrhenius kinetics. By modelling the data from hydrothermal illitization experiments and from a Gulf Coast well, the activation energies are found to be distributed in the range of 11–24 kcal/mol with a maximum reaction at 18 kcal/mol, which involves 65% of reactive smectite. A frequency factor in the order of 10−3–10−4/s, obtained from the data fitting, appears to be adequate for modelling natural diagenesis in sedimentary basins. The distribution pattern of activation energies is considered to be controlled by the degree of heterogeneity of the initial smectite and the degree of electrostatic interactions between smectite layers and the newly formed illite layers during reaction.

Kinetics of Chemical Vapor Deposition of Sic Between 750 and 850°C at 1 Bar Total Pressure

1991 ◽  
Vol 250 ◽  
Author(s):  
Dieter Neuschütz ◽  
Farzin Salehomoum
Keyword(s):  
Deposition Rate ◽  
Total Pressure ◽  
Reaction Rate ◽  
Chemical Vapor ◽  
Deposition Mechanism ◽  
Reaction Orders ◽  
Si Content ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Kinetics Of

AbstractThe deposition rate from mixtures of methyltrichlorosilane (MTS), hydrogen and methane was measured thermogravimetrically using a hot wall vertical reactor and planar SiC substrates. Below 850 °C and at sufficiently high gas velocities, the rate of the phase boundary reaction could be determined. In the absence of CH4 and at H2 :MTS=55, Si was deposited together with SiC. Addition of CH4 lowered the Si content, pure SiC being deposited at CH4 :MTS above 10. The deposition rate j in the range 750 to 850 °C follows the equation with E(Si) = 160 and E(SiC) = 300 kJ/mol. Reaction mechanisms are presented to account for the observed reaction orders with respect to MTS. Between 900 and 970 °C, the reaction rate decreased with temperature indicating a change in the deposition mechanism.

Non-Isothermal Decomposition Kinetic of Polypropylene/Hydrotalcite Composite

2019 ◽  
Vol 19 (11) ◽  
pp. 7493-7501 ◽  
Author(s):  
Sheng Xu ◽  
Min Zhang ◽  
Siyu Li ◽  
Moyu Yi ◽  
Shigen Shen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Nitrogen Atmosphere ◽  
Heating Rates ◽  
Decomposition Reactions ◽  
Kinetic And Thermodynamic Parameters ◽  
Málek Method ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Thermal Stability Of

P3O5-10 pillared Mg/Al hydrotalcite (HTs) as a functional fire-retarding filler was successfully prepared by impregnation-reconstruction, where the HTs was used to prepare polypropylene (PP) and HTs composite (PP/HTs). Thermal decomposition was crucial for correctly identifying the thermal behavior for the PP/HTs, and studied using thermogravimetry (TG) at different heating rates. Based on single TG curves and Málek method, as well as 41 mechanism functions, the thermal decompositions of the PP/HTs composite and PP in nitrogen atmosphere were studied under non-isothermal conditions. The mechanism functions of the thermal decomposition reactions for the PP/HTs composite and PP were separately “chemical reaction F3” and “phase boundary reaction R2,” which were also in good agreement with corresponding experimental data. It was found that the addition of the HTs increased the apparent activation energy Ea of the PP/HTs comparing to the PP, which improved the thermal stability of the polypropylene. A difference in the set of kinetic and thermodynamic parameters was also observed between the PP/HTs and PP, particularly with respect to lower ΔS≠ value assigned to higher thermal stability of the PP/HTs composite.

Oxygen Supply Method Using Gas-Permeable Film for Wastewater Treatment

1993 ◽  
Vol 28 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Y. Suzuki ◽  
S. Miyahara ◽  
K. Takeishi
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Oxygen Supply ◽  
Oxygen Transfer Rate ◽  
High Energy ◽  
High Rate ◽  
N Removal ◽  
High Energy Consumption

Gas-permeable film can separate air and water, and at the same time, let oxygen diffuse from the air to the water through the film. An oxygen supply method using this film was investigated for the purpose of reducing energy consumption for wastewater treatment. The oxygen transfer rate was measured for the cases with or without biofilm, which proved the high rate of oxygen transfer in the case with nitrifying biofilm which performed nitrification. When the Gas-permeable film with nitrifying biofilm was applied to the treatment of wastewater, denitrifying biofilm formed on the nitrifying biofilm, and simultaneous nitrification and denitrification occurred, resulting in the high rate of organic matter and T-N removal (7 gTOC/m2/d and 4 gT-N/m2/d, respectively). However, periodic sloughing of the denitrifying biofilm was needed to keep the oxygen transfer rate high. Energy consumption of the process using the film in the form of tubes was estimated to be less than 40% of that of the activated sludge process.

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