Isopropanol dehydration reaction rate kinetics measurement using H 2 O time histories

2020 ◽  
Author(s):  
Sean P. Cooper ◽  
Clayton R. Mulvihill ◽  
Olivier Mathieu ◽  
Eric L. Petersen
Keyword(s):  
Reaction Rate ◽  
Dehydration Reaction ◽  
Isopropanol Dehydration ◽  
Time Histories ◽  
Rate Kinetics ◽  
Kinetics Measurement

A Novel, Label-Free Method for Quantifying Collagen Fibril Formation and Degradation Using DIC Microscopy, Electromagnetic Wave Theory, and Image Processing

2009 ◽  
Author(s):  
Brendan P. Flynn ◽  
Amit Bhole ◽  
Charles DiMarzio ◽  
Jeffrey W. Ruberti
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Electromagnetic Wave ◽  
Collagen Fibril ◽  
Reaction Rate ◽  
Wave Theory ◽  
Label Free ◽  
Averaging Methods ◽  
Rate Kinetics ◽  
Dic Microscopy

Methods to assay fibrillar growth and degradation at sub-light scales include: fluorescence assays using FITC-collagen or FRAP, destructive preparation and measurement using electron microscopy, and light occlusion methods including turbidity and absorption methods. Many of these methods require the outright destruction, or at least modification via labelling, of the sample in question. This requirement can slow experimentation and introduce additional variability or even alter the reaction rate kinetics. The two methods (absorption and turbidity) which are label-free are bulk averaging methods and cannot isolate subsets of fibrils (e.g. fibrils under load).

Modelling thermal runaway and criticality in systems with diminishing reaction rates: the uniform temperature (Semenov) approximation

1982 ◽  
Vol 380 (1778) ◽  
pp. 29-47 ◽  
Keyword(s):  
Reaction Rate ◽  
Reaction Rates ◽  
Dimensionless Temperature ◽  
Temperature Excess ◽  
Time Histories ◽  
Continuous Responses ◽  
Rate Of Heat Release ◽  
Zero Values ◽  
Pass Through ◽  
Temperature Time

Various complex exothermic oxidations of considerable technical importance can be represented by an empirical rate-law in which the isothermal reaction rate diminishes with the elapsed time t according to rate ∝t ─ α or, more generally, rate ∝ ( t + t pr ) ─ α . Here t pr is a ‘prior reaction’ time and the exponent α lies between 0 and 1. We have computed the generalized behaviour of such a system with a near-Arrhenius dependence of reaction rate on temperature under Semenov conditions, i. e. uniform internal temperature. Temperature-time histories fall into three categories. In subcritical behaviour, temperatures pass through a finite maximum and then decay asymptotically to zero. In supercritical behaviour, temperatures rise steeply to infinite values. Critical behaviour is the frontier between these: a common temperature-time stem from which the other temperature histories diverge and which itself tends to infinite values at infinite times. The rate equation can be written in a general dimensionless form d θ / d τ = ψ 1 e θ / τ α ─ θ . For any given value of α the behaviour of the system is solely determined by the value of ψ 1 , the role of which is analogous to that played by the Semenov number ψ under zero-order conditions ( α = 0). In terms of real variables, the Newtonian cooling time t N emerges as the natural yardstick for time, and τ = t / t N . The parameter ψ 1 represents a dimensionless rate of heat release of the system after one Newtonian time-scale has elapsed (i. e. at τ = 1), and θ has its usual meaning as a dimensionless temperature excess. The dependences of critical values of ψ 1 on α and times to ignition are reported. The model reproduces many features of the distributed temperature case. It also allows the investigation of transition from discontinuous to continuous responses to slow changes in ψ 1 (disappearance of criticality) for non-zero values of RT a / E .

Modelling biological Cr(VI) reduction in aquifer microcosm column systems

2013 ◽  
Vol 67 (12) ◽  
pp. 2733-2738 ◽  
Author(s):  
Pulane E. Molokwane ◽  
Evans M. N. Chirwa
Keyword(s):  
Reaction Rate ◽  
Removal Rate ◽  
Groundwater Resources ◽  
Cost Effective ◽  
Threshold Concentration ◽  
Batch Reactors ◽  
Flow Process ◽  
Detailed Evaluation ◽  
Rate Kinetics ◽  
Contamination Levels

Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection–reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems.

scholarly journals Metallic Hydrides I: Hydrogen Storage and Other Gas-Phase Applications

MRS Bulletin ◽  
2002 ◽  
Vol 27 (9) ◽  
pp. 688-693 ◽  
Author(s):  
Robert C. Bowman ◽  
Brent Fultz
Keyword(s):  
Hydrogen Storage ◽  
Reaction Rate ◽  
Separation And Purification ◽  
Hydrogen Storage Capacity ◽  
Fuel Gas ◽  
Thermal Switches ◽  
Rate Kinetics ◽  
Initial Activation ◽  
Alloys And Compounds

AbstractA brief survey is given of the various classes of metal alloys and compounds that are suitable for hydrogen-storage and energy-conversion applications. Comparisons are made of relevant properties including hydrogen absorption and desorption pressures, total and reversible hydrogen-storage capacity, reaction-rate kinetics, initial activation requirements, susceptibility to contamination, and durability during long-term thermal cycling. Selected applications are hydrogen storage as a fuel, gas separation and purification, thermal switches, and sorption cryocoolers.

The Reactions of Thrombin with Fibrinogen and Plasma Antithrombin

1965 ◽  
Vol 13 (02) ◽  
pp. 343-360 ◽  
Author(s):  
L. A Kazal ◽  
G. F Grannis ◽  
L. M Tocantins
Keyword(s):  
Amino Acid ◽  
Reaction Rate ◽  
Optimal Conditions ◽  
Bovine Thrombin ◽  
First Order ◽  
Antithrombin Activity ◽  
Effects Of Ph ◽  
Rate Kinetics ◽  
Independent Parameters ◽  
Amino Acid Concentrations

SummaryThe effects of pH, salt and amino acid (β-alanine) concentration on the rate of thrombin formation and antithrombin activity in recalcified plasma was studied from the viewpoint of reaction rate kinetics, and units of thrombin and antithrombin activity defined on this basis. Optimal thrombin activity (fibrin formation) was observed between pH 6.5 and 8.0 and at 0.19 M NaCl. Maximal antithrombin activity occurred at pH 8.5 and 0.10 M sodium chloride.Antithrombin activity, examined under optimal conditions as well as under the influence of changes in pH, and of salt and amino acid concentrations proved to follow first-order reaction kinetics. The activities of thrombin and antithrombin changed in a diphasic manner with increasing concentrations of salt or amino acid and such change may represent subtle protein-protein or protein-salt interactions.The antithrombin activity of fifteen normal plasmas was determined from reaction rate studies of thrombin destroyed during recalcification of human plasma and compared to the inactivation of bovine thrombin by citrated plasma.A concept of “coagulability” of plasma based on the measurement of two independent parameters, fibrinogen and antithrombin, and their kinetic interrelationships, was developed as an approach to a functional concept of hemostasis.

scholarly journals Lithium Hydroxide Reaction for Low Temperature Chemical Heat Storage: Hydration and Dehydration Reaction

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3741 ◽  
Author(s):  
Jun Li ◽  
Tao Zeng ◽  
Noriyuki Kobayashi ◽  
Haotai Xu ◽  
Yu Bai ◽  
...  
Keyword(s):  
Reaction Rate ◽  
Heat Storage ◽  
Steam Pressure ◽  
Lithium Hydroxide ◽  
Hydration Reaction ◽  
Dehydration Reaction ◽  
Storage Material ◽  
Chemical Heat ◽  
Heat Storage Material ◽  
Hydration And Dehydration

As a key parameter of a chemical heat storage material, the hydration and dehydration reaction characteristics of lithium hydroxide (LiOH) at pure vapor condition is unclear. In this study, we focused on the hydration reaction and dehydration process of LiOH at the pure vapor condition. The pressure–temperature diagram of LiOH equilibrium was measured. The hydration and dehydration of LiOH at various conditions have been experimentally investigated. The results show that the steam diffusion can be greatly enhanced at vacuum condition. A thin layer of LiOH is uniformly dispersed in the reactor, which can greatly increase the heat transfer between the LiOH material and reactor, leading to a higher hydration reaction rate of LiOH. Furthermore, the steam pressure, reaction temperature, and the particle size of LiOH can greatly influence the hydration reaction. A maximum hydration reaction rate of 80% is obtained under the conditions of 47 °C, steam pressure of 9 kPa, and particle size of 32–40 μm. LiOH exhibits a different reaction property at the condition of pure steam without air and below atmospheric pressure. A store and reaction condition of LiOH with isolation of air is recommended when apply LiOH as a heat storage material at low temperature.

Fractal Time And Fractal Reactant In Reaction Rate Kinetics

2004 ◽  
Vol 8 (4) ◽  
pp. 164-165 ◽  
Author(s):  
P. H. Fang
Keyword(s):  
Reaction Rate ◽  
Rate Kinetics ◽  
Fractal Time

Reaction-Rate Kinetics and Distribution of Activation Energies

1970 ◽  
Vol 1 (2) ◽  
pp. 932-933 ◽  
Author(s):  
P. H. Fang
Keyword(s):  
Reaction Rate ◽  
Activation Energies ◽  
Rate Kinetics

Reaction Rate Kinetics and Film Textures of Palladium Silicide Formed on Hydrogenated Amorphous Silicon

1993 ◽  
Vol 311 ◽  
Author(s):  
N. R. Manning ◽  
Haydn Chen ◽  
J. R. Abelson ◽  
L. H. Allen
Keyword(s):  
Reaction Rate ◽  
Isothermal Annealing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Rate Kinetics ◽  
Palladium Silicide ◽  
Hydrogenated Amorphous ◽  
Kinetics Of

ABSTRACTThe reaction rate kinetics of the thin film solid-state reaction between 120 nm of Pd and 100 or 300 nm of a-Si:H(18at%) to form Pd2Si were studied in situ using x-ray diffraction and four-point probe resistivity measurements during isothermal annealing. These two techniques yielded activation energies and prefactors of Ea=1. 36±:0.11 eV with ko=4.29 cm2/sec for the x-ray diffraction experiments; and Ea=0.97±0.22 eV with ko=3.42x10-4 cm2/sec for the resistivity measurements. The activation energy and prefactor obtained from the c-Si substrate of the resistivity measurements yielded Ea=l.41±0.31 eV and ko=10.6 cm2/sec. Comparisons showed that the silicide formed from the a-Si:H reacted approximately 1.4 times faster than the silicide formed from the c-Si in the same sample, but three times faster than silicide formed on pure c-Si(111). The crystalline texture and grain size of the metal and silicide films were examined.

Feasibility of Polysulfide Detoxification of Concentrated Waste-water

1985 ◽  
Vol 20 (1) ◽  
pp. 118-128 ◽  
Author(s):  
P.T. Takaoka ◽  
J.J. Ganczarczyk
Keyword(s):  
Reaction Rate ◽  
Initial Reaction Rate ◽  
Initial Reaction ◽  
Concentrated Solutions ◽  
Capital Costs ◽  
Rate Kinetics ◽  
High Concentrations ◽  
Cyanide Solutions ◽  
Considerable Work ◽  
Kinetics Of

Abstract Collecting of concentrated cyanide solutions in electroplating shops is quite a common occurrence. These accumulations of 4.5 to 9.0 cu m volume, which may be collected over a period of years, are usually in the concentration range of 1 to 3 per cent cyanide and present considerable dangers as they are stored on-site or transported for treatment or disposal. Common technologies available for the treatment of cyanide-containing wastewaters are generally not applicable to concentrated cyanide solutions, and some special technologies which could be applicable, usually show high capital costs and/or complexity of operation which render them unsuitable for smaller plating shop practice. In recent years, considerable work has been carried out to investigate a reaction of cyanide with polysulphide to form relatively innocuous thiocyanate. However, this reaction has been studied_only for cyanide solutions of low concentration (less than 100 mg/L CN-). This study was undertaken to investigate the feasibility of using the cyanide-polysulphide reaction to detoxify concentrated cyanide solutions (e.g. 2% CN-) and to investigate the initial kinetics of the cyanide-polysulphide reaction. It was found that the cyanide-polysulphide reaction is moderately exothermic and proceeds very rapidly both at room temperature and at 3°C. This process was capable of reducing cyanide concentrations to non-detectable levels within two weeks at a cyanide-to-polysulphide-sulphur ratio of 1:2 by weight. It was also found that the initial reaction rate kinetics of the cyanide-polysulphide reaction in concentrated solutions differed significantly from previously reported values for solutions low in cyanide concentration and that high concentrations of polysulphides tended to suppress the reaction rate.

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