Papers by Keyword: Reaction Kinetics

Abstract: EM enrichment culture liquid was immobilized on nano-silica carrier to form microbial nano ball, so as to investigate the reaction kinetics of ammonia nitrogen (NH4+-N) by microbial nano ball. The results showed that first order reaction kinetics model could describe NH4+-N removal by different diameter microbial nano-silica balls well. And the microbe could keep higher biological activity between 0-72h. Reaction kinetic equations of NH4+-N were: (1) when diameter was 10mm, (0-48h), (48-72h); (2) when diameter was 20mm, (0-48h), (48-72h); (3) (0-48h), (48-72h).

Abstract: A thermogravimetric system was designed, in which a large amount of sample (about 10 g) can be examined. Test of the combustion characteristics of cooking oil tar in pipe was conducted. Wavelet transform was introduced to the thermogravimetric data smoothing and differentiation analysis according to the experiment results, and the orthogonal test method was used to find the optimize wavelet parameter. Wavelet transform results were compared to the traditional Moving average,Gaussian Smoothing and Vondrak smoothing methods and it was proved that the signal-to-noise ratio () of the measurement is increased significantly. The kinetic parameters calculated from the original TG curves and smoothed DTG curves have excellent agreement,and thus the wavelet transform smoothing algorithms can be used directly and accurately in kinetic analysis.

Abstract: Slag filter material made from steel slag and clay was used for phosphate adsorption, and adsorption characteristic was studied by batch experiments. Results showed that the uptake of phosphate on slag filter material at different temperature fitted with pseudo-second-order model, and the activation energy was more than 40kJ/mol. In addition, isotherm adsorption data on slag filter material followed the Langmuir model well, and the maximum adsorption capacity at 20°C, 30°C and 40°C were 1.166, 1.826 and 2.422mg/g, respectively. Thermodynamic parameters G⁰, H⁰ andS⁰ showed that the adsorption was spontaneous, endothermic and entropy increase process and chemical adsorption was dominant for phosphate uptake.

Abstract: An unsymmetrical photochromic diarylethene 1-(2-trifluoromethylphenyl)-2-[2-methyl-5-(3-N,N-dimethylphenyl)-3-thienyperfluorocyclopentene (1a) was synthesized and its photochromism, fluorescent properties and reaction kinetics of cyclization and cycloreversion were studied in detail. The compound exhibited remarkable photochromism and its absorption maxima were observed at 552 nm in hexane and at 569 nm in PMMA films upon irradiation with 297 nm UV light. The fluorescence intensity of diarylethene decreased upon irradiation with 297 nm UV light. In addiation, reaction kinetics of the cyclization and cycloreversion processes of the compound were determined to be the zeroth and first order reaction by UV-Vis spectra, respectively.

Abstract: A two-dimensional pseudo-homogenous mathematical model was established according to the Au-Cu non-mercury catalytic reaction kinetics. The Crank-Nicholson method was used to solve the equations on the basis of experimental data. The results showed that a violent reaction at the entrance of the fixed bed reactor led to a hot spot in the acetylene hydrochlorination reaction over the Au-Cu Non-mercury catalyst. The conversion increased rapidly initially, and then flattened gradually in the axial direction. The result of simulation provided valuable data to optimize the design of reactor and the industrial operation conditions.

Abstract: Test of the combustion characteristics of cooking oil tar in pipe was conducted. Wavelet transform was introduced to the thermogravimetric data smoothing and differentiation analysis according to the experiment results, and the orthogonal test method was used to find the optimize wavelet parameter. Wavelet transform results were compared to the traditional Moving average,Gaussian Smoothing and Vondrak smoothing methods and it was proved that the signal-to-noise ratio () of the measurement is increased significantly. The kinetic parameters calculated from the original TG curves and smoothed DTG curves have excellent agreement,and thus the wavelet transform smoothing algorithms can be used directly and accurately in kinetic analysis.

Abstract: The metallurgy reactions in the weld pool were analyzed with the application of reaction kinetics. Furthermore a formula to quantificationally calculate the amount of Mg2Si was generated. By means of calculating the thermodynamic condition of the reaction and combined with the verification testing, this article indicates that the metallurgical product Mg2Si was created in the liquid weld pool but not separated out from the arborescent crystal during its solid state. This thesis summarizes the precipitation mechanism of Mg2Si and explains the configuration, amount and location where Mg2Si was separated out by analyzing the phase diagrams and constitution diagrams. Relevant data suggests that: the content of Mg2Si is slightly less than Mg.

Abstract: Takovite, a kind of hydrotalcite-like compounds (HTlcs), was used for boron removal from water. It was prepared by coprecipitation method and characterized by X-ray diffraction technique (XRD). The equilibrium time of boron sorption by takovite as well as its boron uptake capacities was determined by the reaction kinetic experiments and isotherm sorption experiments. The effects of experimental conditions on boron removal efficiency were also evaluated. Generally, the boron uptake by takovites increases with increasing initial boron concentration in solution. The isotherm sorption data match well with the Freundlich model, indicating that the anion exchange contributes a lot to solution deboronation. Moreover, at higher temperature, greater boron removal by takovite was observed. As compared to calcined takovite, uncalcined takovite has better performance in terms of boron uptake, since the structural restoration of calcined takovite didnt happen during its contact with boron-containing solution, which is quite different from the behavior of other HTlcs as reported.

Abstract: The larch bark was examined by non-isothermal means to determine the mass loss kinetics of the thermal decomposition with linear temperature programming in nitrogen atmosphere. In this work, mechanism equation of = was used for Coats-Redfern integral method at the different heating rates. The apparent activation energy, pre-exponential factor and the pyrolysis kinetic equations at the different heating rates were obtained. The pyrolysis temperature area was divided into two separate temperature regions for the pyrolysis kinetic equation and the two components were decomposed respectively at the two separate temperature regions. The global mass loss rate of the bark is considered as controlled respectively by the reactions of the two components respectively during the lower and higher temperature ranges. The kinetics of the two components are found to abide by the mechanism equation of =, which gave the best fits to the experimental data. The obtained kinetic equations of the bark at the different heating rates were additionally validated by the reasonable agreement between the experimental and calculated results.

Abstract: A new unsymmetrical photochromic diarylethene 1-(2-methyl-benzothiophenyl) - 2-((5-(9, 9-dibutyl-fluorenyl)-2-methylthiophen-3-yl)) perfluoroncyclopentene (1o), was synthesized and its optoelectronic properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous films and fluorescence were investigated. The photochromic reaction kinetics indicated that the cyclization process of 1o belongs to the zeroth order reaction and the cycloreversion process belongs to the first order reaction. When the concentration at 5 × 10^-5 mol/L the fluorescence peak have the maximum.