Papers by Keyword: Kinetic Parameters

Abstract: The prospects of implementing the mechanochemical activation method of volcanic silicate and aluminosilicate rocks - perlites, tuffs, pumice, etc. are being considered for the production of a wide range of building materials using energy-conserving technologies. The thermodynamic and kinetic parameters of interaction in the systems of aluminosilicate – NaOH have been presented, indicating low-temperature sintering of volcanic rocks with sodium hydroxide. According to the degree of activity, the rocks have the following order: perlites, tuffs, obsidian, microcline. Kinetic parameters are presented: concentration, temperature, conversion degree, reaction rate constant, time of complete reaction and product layer thickness.

Abstract: The result of burning hydrogen which is environmentally friendly makes hydrogen as a very attractive fuel. Hydrogen storage is interesting research material. One alternative to hydrogen storage is a metal-hydride as NaBH₄. In this paper, the catalyst for hydrogen production from storage, namely The result of burning hydrogen, which is environmentally friendly, makes hydrogen a desirable fuel. Hydrogen storage is exciting research material. One alternative to hydrogen storage is a metal-hydride as NaBH₄. In this paper, the catalyst for hydrogen production from storage, namely NaBH₄, was synthesized by electrochemical. Ni-B catalyst with hydroxyapatite as catalyst support was prepared by electrochemical. Ni-B/HA catalyst was synthesized at various current densities (namely 67, 133, and 200 mA/cm²) and various electrolysis times (namely 30, 60, and 90 minutes). The resulting catalysts were analyzed by XRD and used as the catalyst for hydrogen production from the hydrolysis reaction of NaBH₄. The fastest hydrogen production was obtained using a catalyst generated at 133 mA/cm² and an electrolysis time of 60 minutes. The reaction rate equation for the hydrolysis of NaBH₄ has a first-order reaction to the concentration of NaBH₄. The resulting reaction rate constant ranged from 233.33 mL/g/min to 861.11 mL/g/min. The relationship between reaction temperature and reaction rate constant can be expressed by the equation k = 2.2x10⁶exp (5534/T).

Abstract: Locally available malt waste or brewers' spent grain, a by-product of brewing industry, was found to be a low cost and promising biomass for pyrolysis. A kinetic studied of pyrolysis of malt waste was investigated by non-isothermal thermogravimetric analyses (TG-DTG), applying slow heating rates, 10, 15, 30 and 50 K/min, and well-defined conditions. Activation energies and Arrhenius exponential factors were inferred by different estimation methods: Kissinger, Ozawa, Starink, K-A-S and. The methods presented energy activation values of 214 - 238.23 kJ/mol. The Literature studies found activations energies values similar to those found for sugarcane bagasse pyrolysis and other types of biomasses with predominance of hemicelluloses, cellulose and lignin, respectively.

Abstract: In this study, kinetic parameters of fast and slow pyrolysis is compared. For fast pyrolysis, cylindrical wood pieces of 20 mm diameter and 50 mm length is pyrolysed in a tube furnace at temperatures ranging from 300°C to 500°C. Solid, liquid and gas products are collected and the yields are calculated. For slow pyrolysis, thermogravimetric analysis (TGA) is used using sawdust from the same biomass. Using the experimental data from two different methods the kinetic parameters are calculated such as activation energy and pre-exponential factor for the two different pyrolysis methods. For fast pyrolysis the parameters are found to be E = 32.5 kJ/mol and A = 35/min and for slow pyrolysis E_s = 50.48 kJ/mol and A_s = 3179.86/min. The large difference between the values show that kinetic studies and modelling work using thermogravimetric analysis data is not suitable for commercial scale simulation. Also, the pre-exponential value for fast pyrolysis shows that the kinetic equation used from flash pyrolysis is not exactly suitable for this situation. Therefore, it is recommended that more studies on the kinetic parameters of fast pyrolysis of thermally thick biomass need to be done.

Abstract: The kinetic of lithium-zinc ferrite synthesis reaction up to temperatures 800°C was studied in air using non-isothermal thermogravimetric analysis. Mathematical treatment of thermogravimetric curves was carried out using Netzsch Thermokinetics software where the kinetic model with minimal adjustable parameters quantitatively describe the synthesis reaction of lithium-zinc ferrite was chosen. It was shown that the experimental TG curves clearly suggest a multi-step process for the ferrite synthesis and therefore a model-fitting kinetic analysis based on multivariate non-linear regressions was conducted. The complex reaction can be best described with a three-step reaction scheme consisting of parallel reaction steps. It is established that the best results were obtained with the using at the first stage the diffusion model of Yander, on the second and third stage were used the reactions of n-order. Kinetic parameters of lithium-zinc ferrite synthesis reaction were found.

Abstract: In this paper, the catalytic co-gasification of rubber seed shell and high density polyethylene mixtures (0.2:0.8 weight ratio of HDPE:RSS) are investigated using a non-isothermal thermogravimetric analysis (TGA) system in a range of heating rates of 10, 20, 30 and 50 K/min within the temperature range of 323-1173 K. The argon gas is supplied at a flowrate of 100 ml/min and the steam is generated from superheater at 383 K. The steam is injected at flowrate of 300 μL/hour into the TGA system. A commercial nickel powder is used as the catalyst for the gasification process. The thermal decomposition behavior and synergistic effect of the HDPE/RSS mixture are investigated. The activation energy, E_A and pre-exponential factor, A are determined based on one step integral method.

Abstract: In this paper, the author points out several key problems needed to be solved about the dynamics of frozen soil by reviewing related literatures about hysteretic curve of frozen soil ,dynamic constitutive relation and dynamical parameter. The problems are the insufficient understanding on morphological characteristics of hysteretic curve and how to transform qualitative understanding into quantitative understanding about morphological characteristics of hysteretic curve. The problem is the rationality of selecting the dynamic constitutive model, namely how to establish the engineering applicable model which conforms to the actual soil mechanics performance.The problem is the rationality of the calculation method about dynamic elastic modulus and damping ratio, namely how to define dynamic modulus of elasticity of frozen soil correctly and the limitation of using the classical method to calculate the damping.

Abstract: The paraffin, pre-treated paraffin and hydroxyl-terminated polybutadiene (HTPB) were measured by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) in different conditions. Thermal degradation characteristics of the paraffin, pre-treated paraffin and HTPB were studied; Influences of different pressure and different temperatures on thermal degradation characteristics of pre-treated paraffin were analyzed. Experiments show that the decomposition temperature of pre-treated paraffin is higher than that of the untreated paraffin, but lower than that of HTPB; the initial reaction temperature, the reaction exothermic peak temperature and the reaction heat release of pre-treated paraffin were all affected by pressure and heating rate; Kinetic parameters of pre-treated paraffin in oxygen atmosphere were calculated.

Abstract: The paper presents the structural characteristics of solid wastes separation sieve. Pieces of plastic film and sandstones with different friction factors and elasticity coefficients are chosen as the research objects. The motion and the separation mechanism of materials in the sorting process are studied. According to the motion analysis on pieces of plastic film and sandstones on solid wastes separation sieve, it can be concluded that the materials with different friction factors and elasticity coefficients can all be sorted by solid wastes separation sieve. The more difference they have in friction factors and elasticity coefficients, the better separation performance can be achieved. The selection and calculation on the kinetic parameters of solid wastes separation sieve is carried out, which provides the theory evidence for the design of new friction sorting equipment and opens up new prospects for the application of solid wastes separation sieve.

Abstract: The adsorbent was prepared from peanut shell by using Zncl₂ as activating agent, copper in aqueous solution was used as the adsorbate, the influence of pH, adsorbent dosage, temperature, contact time were investigated through dynamic tests. Then the kinetics of modified peanut shell was studied. The results showed that the modified peanut shell had maximum adsorption efficiencies when the pH was 6; the dosage was 0.2g; the temperature was 25°C and the contact time was 12h.By substituting experimental data into kinetics models, quasi-second-order kinetics model could better describe the kinetics of modified peanut shell adsorbing Cu²⁺.