Papers by Keyword: Kinetic Analysis

Abstract: Chemical engineering frequently uses "process intensification" to consciously combine various phenomena or procedures. By treating the molecules in such a system in a way that every single molecule experiences the same processing, the selectivity is raised, enhancing productivity. For mass transfer limited reactions, the enhancement of the transport rates & the specific interfacial area are the typical approaches. These enable the reduction of diffusion path length, reduce hold-up and improve the controlling on temperature control, even for highly exothermic reactions. Micro reactor technology (MRT) is a subset of process intensification that aims to reduce the size of equipment, energy consumption, and waste generation. The research of peracetic acid (PAA) and perform acid (PFA) preparation is the focus of the current investigation. Amberlite IR-120H catalyst was used to study the synthesis of PAA and PFA in batch and micro-structured reactors while ultrasonic irradiations were present.. The current research describes a method for synthesizing both compounds in a batch and micro-structured reactors, with and without ultrasonic irradiation. Such a technology might be crucial in the online synthesis of these chemicals as it eliminates the need for harmful components to be transported and stored, assuring safety among other benefits. For these substances, various safety characteristics could be improved.

Abstract: Chicken meat has a high nutritional content that makes its freshness rapidly deteriorates. A color change characterized the degradation. Color changes could influence the consumer perception toward food quality. Human perception and evaluation of color are often subjective. Sensors can provide better detection accuracy toward this phenomenon than the human senses. This study aims to determine the change of color attribute of chicken breast meat kinetically and classify meat quality based on color changes during meat storage using Principal Component Analysis (PCA). The experiment was performed with equipment consisting of a Raspberry Pi, Arduino, and a TCS 3200 color sensor. The meat sample was stored in a dark-colored container along with the sensor for 24 hours storage at room temperature. The measurement was done every hour in three replications. Color data from sensor readings in the frequency form was then converted into RGB (Red, Green, Blue) values and finally to L*, a*, b* values during the experiment. The data obtained was sent to the database for kinetic analysis and quality classification using PCA. It was found that the change of color attribute of Chroma (C), Hue Angle (Ho), Color Difference with True Red (DE), and Color Difference (AE) followed zero-order or first-order kinetics reactions. While from the PCA resulted, two chicken meat quality classes, PC 1, explained 85.4%, and PC 2 explained 12.5%.

Abstract: Nanotechnology especially Zero Valent metals is a modern technology for the degradation of extensive ranges of biological wastewater contaminants. Due to their effectiveness, economically and safely properties, this study successfully prepared and characterized nanoZero Valent Iron (nZVI) to be encapsulated into natural alginate biopolymer. The effect of operating parameters was studied at different environmental conditions; pH, dose (g/L), contact time (min), stirring rate (rpm), and BOD concentrations. Adsorption isotherm, kinetic studies, and statistical analysis (Response Surface Methodology (RSM) and Artificial neural networks (ANNs)) were examined to describe the removal behavior. The obtained results indicated that the maximum removal efficiency was 81.2 % for initial BOD concentration 300 mg/L, at pH 7, using wet dose 3g/L, 25min, and stirring rate 200 rpm. Also, adsorption and kinetic data indicated that the adsorption mechanism runs toward the Sips model to approximate the Freundlich model at low concentration and to solve the Freundlich limitation at high concentration with a maximum adsorption capacity of 181mg/g. Kinetic results describe the solid transformation from one phase to another at a constant temperature by approving Avrami model. Finally, RSM results agree with ANNs results that the “Concentration effect” is the most significant variable that controls the removal efficiency.

Abstract: Wastewater treatment by nanotechnology, specifically magnetic nanosorbent as nanoZero Valent Iron (nZVI), is a new technology for degradation of wide ranges of organic pollutants by the effect of free electrons as Advanced Oxidation Processes (AOPs) and adsorption processes. Due to their effectiveness, economic, and safety properties, this study prepared and characterized nZVI to be entrapped into natural alginate biopolymer (Ag/nZVI). The removal of wastewater chemical pollutants was tested by studying the variations of COD levels. The effect of operating conditions was studied at different pH, Ag/nZVI doses (g/L), contact time (min), stirring rate (rpm), and initial COD concentrations. Also, Adsorption isotherm, kinetic studies were conducted to estimate equilibrated reaction mechanisms. Linear regression analysis was tested to find the Response Surface Methodology (RSM) relations between variables and removal percentages. Nonlinear Feed-Forward backpropagation system was built for Artificial intelligence neural networks (ANNs) importance detections. Finally, this study approved effective COD removal percentages reached 76%. The maximum removal efficiency for initial COD concentration 400 mg/L was observed at pH 6, using wet dose 3g/L, 30min, and 150 rpm.

Abstract: Three-dimensional step polymerization of ABB^/ and В₃ monomers (ABB^/+В₃) was described using the new structural-kinetic model. Polymerization process was simulated with the variation of reactivity of B groups in the ABB^/ and B₃ monomers during the process (substitution effect). Polymerization simulation with substitution effect represents the most general case of three-dimensional step polymerization ABB^/+В₃.

Abstract: In nuclear water reactors, zirconium alloys are extensively used as fuel cladding material and in other structural applications. Uniaxial hot compression tests were performed to understand the deformation behavior of Zr-1Nb alloy. Therefore, hot compression tests were performed in the temperature range of 700-1050°C, which envelopes α-phase, (α+β) phase, and β-phase. True stress-strain curves, processing maps, microstructural observation and kinetic analysis were used to discuss the deformation behavior of Zr-1Nb alloy. Deformation at a strain rate of 10^-2 s^-1 reveals softening at lower temperatures and steady state behavior at higher temperatures. Processing map also reveals domain of high efficiency at 10^-2 s^-1 strain rate for a wide range of deformation temperatures. The flow softening and high power dissipation efficiency predicts dynamic recrystallization or dynamic recovery during the hot deformation of studied alloy.

Abstract: The austenitization and inter-critical annealing of X4CrNiMo16-5-1 (1.4418) supermartensitic stainless steel were investigated in-situ with synchrotron X-ray diffraction (XRD), dilatometry and differential scanning calorimetry (DSC) under isochronal heating conditions. Austenitization occurred in two stages: the austenitization started at approx. 600 °C, decelerated at approx. 700 °C at 60 to 75 v.% of transformed austenite, and first resumed after heating for approx. 100 °C. This plateau in the transformation curve was more dominant for faster heating rates. Inter-critical annealing at 675 and 700 °C revealed, that austenite can to a certain extent be stabilized to room-temperature. There was good agreement for the transformation curves yielded by dilatometry and XRD. Some deviation occurred due to the different applied heating principles, different temperature monitoring and the impact of surface martensite formation on the XRD measurement. The applicable temperature range for DSC as well as the close proximity of the A_c1- and the Curie-temperature limited the usage of the technique in the present case.

Abstract: The combustion of bituminous coal, bio-oil, and their slurry mixtures were performed under air atmosphere using Thermogravimetric Analyzer (TGA). All samples were run from room temperature to 110°C and held for 10 minutes before the temperature was ramped to 1100°C and held again for 10 minutes at 1100°C at the heating rate of 10°C/min and gas flow rate of 50mL/min. Kinetic evaluation was conducted using a simple Arrhenius-type kinetic model with first-order decomposition reaction. Apparent activation energy, E_a, and pre-exponential factor, A, were calculated from the modelling equation. Results reveal that the reactivity of CBS fuel is higher than a single coal fuel to which the addition of bio-oil helps to increase the combustion performance of the blends. The optimum fuel ratio appears at 50:50 ratio with equal contribution of coal and bio-oil properties that contribute to the increase in volatile matter causing maximum combustion rate achievable at much lower temperature compared to single coal fuel.

Abstract: Errors was generate when use integral methods to calculate pyrolysis kinetic. It was analyzed by considered the effects of methods and reaction orders. A α-T curve was established for the error discussion depending on basic kenotic theory. For analysis methods, both single curve and multiple curve methods can obtain reliable activation energy values (≤3%), but the error of frequency factor was significant (up to 40%). Frequency factor is sensitive to intercept changing and is also to reaction order. Magnitude error could show if reaction order deviates to true value.

Abstract: In this work, hot compression tests on columniform TC18 titanium alloy specimens were performed with a Gleeble^® 3500 thermal and mechanical simulator in the temperature range of 820-875 °C and at constant strain rates of 0.01, 0.1 and 1 s⁻¹. Relationship model of true stress versus true strain as well as peak stress versus deformation temperature were established, and microstructural micrographs of TC18 titanium alloy were analyzed. The results showed that the flow stress decreased as the deformation temperature increased or the strain rate decreased. Besides, the deformation resistance at temperature above T_β (β transus temperature) was obviously lower than that at below T_β. In addition, flow stresses kept almost constant when it deformed in β region where hot deformation mechanism is DRV, but significant flow softening occurred in α+β region, where deformation mechanism is mainly dominated by DRX. And in α+β region, DRX is prone to occur at a low strain rate, and it is difficult for DRX to occur at high strain rate.