scholarly journals Effect of Metal Sequestrants on the Decomposition of Hydroxylammonium Nitrate

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1488
Author(s):  
Emil J. Broemmelsiek ◽  
Joshua L. Rovey ◽  
Steven P. Berg
Keyword(s):  
Decomposition Rate ◽  
Ethylenediaminetetraacetic Acid ◽  
Reaction Rates ◽  
Isothermal Decomposition ◽  
First Order ◽  
Satellite Technology ◽  
Hydroxylammonium Nitrate ◽  
Green Propellant ◽  
Negative Effect ◽  
Wall Method

Hydroxylammonium nitrate (HAN) is an energetic salt used in flight-proven green monopropellants such as ASCENT (formerly AF-M315E), flown in NASA’s 2019 Green Propellant Infusion Mission, and SHP163, flown in JAXA’s Rapid Innovative Satellite Technology Demonstration-1. The decomposition of HAN is catalyzed by metals commonly found in storage tanks, a factor limiting its use. This work investigates the ability of metal-sequestering chelating agents to inhibit the decomposition of HAN. Isothermal and dynamic thermogravimetric analysis (TGA) were used to find isothermal decomposition rates, decomposition onset temperatures, and first-order Arrhenius reaction rate parameters. In the present research, 2,2′-bipyridine (Bipy), triethanolamine (TEA), and ethylenediaminetetraacetic acid (EDTA) were studied as 0.05, 0.1, 0.5, 1, and 5% by weight additives in 90% aqueous HAN. An isothermal decomposition rate of 0.137%/h at 348 K was observed for HAN. The addition of 1% Bipy and 1% TEA reduced the isothermal decomposition rate by 20.4% to 0.109%/h, and by 3.65% to 0.132%/h, respectively, showing that Bipy can inhibit decomposition. The addition of 1% EDTA increased the isothermal decomposition rate by 12.4% to 0.154%/h. Bipy was found to increase the decomposition onset temperature from 454.8 K to 461.8 K, while the results for TEA and EDTA were inconclusive. First order reaction rates calculated by the Ozawa-Flynn-Wall method were found to be insufficient to capture the effects of the tested additives. Bipy was found to inhibit the decomposition of HAN, while TEA and EDTA produced little or negative effect, a result believed to be due to poor metal complex stability at low pH and high acidity, respectively. Spectrophotometry, used for colorimetric analysis of Bipy+iron complexes, showed that Bipy forms chelate complexes with trace iron impurities when added to HAN solutions.

Designing Experiments for Model Identification of the Nitrification Process

1991 ◽  
Vol 24 (6) ◽  
pp. 9-16 ◽  
Author(s):  
P. J. Ossenbruggen ◽  
H. Spanjers ◽  
H. Aspegren ◽  
A. Klapwijk
Keyword(s):  
Mechanistic Model ◽  
Nonlinear Differential Equations ◽  
Model Identification ◽  
Reaction Rates ◽  
Variable Coefficients ◽  
Model Specification ◽  
First Order ◽  
Interactive Behavior ◽  
Batch Tests ◽  
Nitrification Process

A series of batch tests were performed to study the competition for oxygen by Nitrosomonas and Nitrobacter in the nitrification of ammonia in activated sludge. Oxygen uptake rate (OUR) and dynamic (compartment) models describing the process are proposed and tested. The OUR model is described by a Monod relationship and the biogradation process by a set of first order nonlinear differential equations with variable coefficients. The results show a mechanistic model and ten reaction rates are sufficient to capture the interactive behavior of the nitrification process. Methods for model specification, calibrating, and testing the model and the design of additional experiments are described.

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation

2007 ◽  
Vol 55 (10) ◽  
pp. 145-153 ◽  
Author(s):  
T. Ölmez ◽  
I. Kabdaşlı ◽  
O. Tünay
Keyword(s):  
Organic Matter ◽  
Textile Industry ◽  
Reaction Rates ◽  
Textile Dye ◽  
Pseudo First Order Reaction ◽  
Ozone Oxidation ◽  
Reactive Dyeing ◽  
First Order ◽  
Organic Matter Oxidation ◽  
Pseudo First Order

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.

scholarly journals Reactivity of Phenol and Aniline towards Quinolinium Chloro Chromate: A Comparative Oxidation Kinetic Study

2015 ◽  
Vol 59 ◽  
pp. 81-92
Author(s):  
Seplapatty Kalimuthu Periyasamy ◽  
H. Satham Hussain ◽  
R. Manikandan
Keyword(s):  
Oxidation Kinetic ◽  
Activation Parameters ◽  
Dipole Interaction ◽  
Reaction Rates ◽  
Hydrogen Ion ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
First Order ◽  
Different Temperatures ◽  
Kinetics Of

The kinetics of Oxidation of Phenol and aniline by quinolinium Chlorochromate (QCC) in aqueous acetic acid medium leads to the formation of quinone and azobenzene respectively. The reactions are first order with respect to both Phenol and aniline. The reaction is first order with respect to quinolinium chlorochromate (QCC) and is catalyzed by hydrogen ion. The hydrogen-ion dependence has the form: kobs = a+b [H+]. The rate of oxidation decreases with increasing dielectric constant of solvent, indicating the presence of an ion-dipole interaction. The reaction does not induced the polymerization of acrylonitrile. The retardation of the rate by the addition of Mn2+ ions confirms that a two electron transfer process is involved in the reaction. The reaction rates have been determined at different temperatures and the activation parameters have been calculated. From the above observations kinetic results a probable mechanism have been proposed.

scholarly journals Extrapolation and interpolation by time-scaling in systems with diffusion-controlled kinetics and first-order reaction rates.

1989 ◽  
Vol 37 (1) ◽  
pp. 47-60
Author(s):  
S.E.A.T.M. van der Zee ◽  
W.H. van Riemsdijk ◽  
J.J.M. van Grinsven
Keyword(s):  
Reaction Rates ◽  
Order Reaction ◽  
Management Tool ◽  
First Order ◽  
Physicochemical Processes ◽  
Time Scaling ◽  
Diffusion Controlled ◽  
Scaling Procedure ◽  
Exposure Variable ◽  
Scaling Rule

The interpolation or extrapolation in time of physicochemical processes from experimental data is often difficult. A theoretically derived time-scaling procedure using an exposure variable of the concentration integrated in time, with at most one adjustable parameter was applied successfully to three systems taken from metallurgical, agricultural and environmental engineering. This scaling rule is potentially useful as a research or management tool for systems that are too complex for mechanistic modelling. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Thiol–disulphide interchange in tubulin: kinetics and the effect on polymerization

2005 ◽  
Vol 389 (2) ◽  
pp. 549-558 ◽  
Author(s):  
P. J. Britto ◽  
Leslie Knipling ◽  
Peter Mcphie ◽  
J. Wolff
Keyword(s):  
Protein Concentration ◽  
Critical Concentration ◽  
Reaction Rates ◽  
High Ionic Strength ◽  
Cd Spectra ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Cysteine Substitution ◽  
Disulphide Bonds ◽  
Stop Flow

All 20 cysteine residues are accessible to disulphide reagents in the tubulin dimer, whereas only four are accessible in taxol-stabilized microtubules. Reaction rates with disulphide reagents are a function of the reagent, are decreased by G nucleotides, and increased with increase in pH and urea. With transient (stop-flow) kinetics, DTNB [5,5′-dithiobis-(2-nitrobenzoic acid)] and 2,2′-dithiodipyridine progress curves cannot be fitted by the sum of exponential terms based only on classes of cysteines. The mixed disulphide products react further to form both intra- and intermonomer disulphide bonds that can be reversed by reducing agents. With MMTS (methyl methanethiosulphonate) or ODNB (n-octyl-dithio-2-nitrobenzoate), virtually no protein–protein disulphide bonds are formed and the ODNB reaction can be given as the sum of three exponential terms with pseudo-first-order rate constants of 0.206, 0.069 and 0.010 s−1 at pH 6.5, suggesting three classes of thiol reactivities. Limited cysteine substitution leads to only small changes in tryptophan or CD spectra, whereas complete substitution leads to loss of the helix content. MMTS-induced loss of SH groups leads to progressive increases in the critical concentration and loss of polymerization competence that can be reversed by assembly promoters such as higher protein concentration, taxol or high ionic strength. Under such conditions, the substituted tubulin forms protofilament-based structures such as microtubules, open tubules, sheets and/or bundles.

Bisulfite Degrades Aflatoxin: Effect of Temperature and Concentration of Bisulfite

1978 ◽  
Vol 41 (10) ◽  
pp. 774-780 ◽  
Author(s):  
M. P. DOYLE ◽  
E. H. MARTH
Keyword(s):  
Rate Constant ◽  
Aflatoxin B1 ◽  
Reaction Rate ◽  
Reaction Rates ◽  
Reaction Rate Constant ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
First Order ◽  
Potassium Acid Phthalate ◽  
Acid Phthalate

Bisulfite reacted with aflatoxin B1 and G1 resulting in their loss of fluorescence. The reaction was first order with rate depending on bisulfite (or the bisulfite and sulfite) concentration(s). Aflatoxin G1 reacted more rapidly with bisulfite than did aflatoxin B1. In the presence of 0.035 M potassium acid phthalate-NaOH buffer (pH 5.5) plus 1.3% (vol/vol) methanol at 25 C, the reaction rate constant for degradation of aflatoxin G1 was 2.23 × 10−2h− and that for aflatoxin B1 was 1.87 × 10−2h− when 50 ml of reaction mixture contained 1.60 g of K2SO3. Besides bisulfite concentrations, temperature influenced reaction rates. The Q10 for the bisulfite-aflatoxin reaction was approximately 2 while activation energies for degrading aflatoxin B1 and aflatoxin G1 were 13.1 and 12.6 kcal/mole, respectively. Data suggest that treating foods with 50 to 500 ppm SO2 probably would not effectively degrade appreciable amounts of aflatoxin. Treating foods with 2000 ppm SO2 or more and increasing the temperature might reduce aflatoxin to an acceptable level.

The Influence of Boria and EDTA on the Hydrodesulfurization Activity on CoMoS Supported Catalysts

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Matin Parvari ◽  
Peyman Moradi
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Supported Catalysts ◽  
Batch Reactor ◽  
Kinetic Constant ◽  
Order Kinetic ◽  
First Order ◽  
Pseudo First Order ◽  
Xrd Studies ◽  
Al2o3 Catalyst ◽  
Hydrodesulfurization Activity

The hydrodesulfurization of dibenzothiophene (HDS of DBT) in a high pressure batch reactor at 320°C was carried out over CoMo/Al2O3-B2O3 catalysts with different B2O3 contents (4, 10, and 16 wt%). Ethylenediaminetetraacetic acid (EDTA) with different EDTA/Co mole ratios (0.6, 1.2 and 1.8) was used as a chelating ligand during the preparation of CoMo/Al2O3-B2O3. XRD studies, FTIR, TPD of NH3, and BET experiments were used to investigate the catalyst samples. The results showed that the catalyst using the support with 4 wt% B2O3 and an EDTA/Co mole ratio of 1.2 had a hydrodesulfurization activity (in pseudo first order kinetic constant basis) value of ~2.96 times higher than that of the simple CoMo/Al2O3 catalyst.

KINETIC STUDIES ON THE HYDROLYSIS OF BENZOYLCHOLINE BY HUMAN SERUM CHOLINESTERASE

1956 ◽  
Vol 34 (1) ◽  
pp. 637-653 ◽  
Author(s):  
W. Kalow ◽  
K. Genest ◽  
N. Staron
Keyword(s):  
Kinetic Studies ◽  
Reaction Rates ◽  
Serum Cholinesterase ◽  
Initial Reaction ◽  
Ultraviolet Spectrophotometry ◽  
First Order ◽  
Low Concentrations ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations

Benzoylcholine stands out from other known substrates of serum cholinesterase because of its high apparent affinity for this enzyme combined with a rapid rate of destruction. The reaction kinetics of the hydrolysis of benzoylcholine can be studied by ultraviolet spectrophotometry, since the absorbance decreases in proportion to the concentration of substrate. Kinetic data obtained by measuring initial reaction rates, and by analyzing continuous hydrolysis curves, are the same within the range of experimental error. The enzymatic data are compatible with the assumption that in the presence of high substrate concentrations a complex consisting of esterase and two substrate molecules is formed. This complex is hydrolyzed more slowly than the complex containing one molecule of substrate which is formed at low concentrations of benzoylcholine. Alkaline hydrolysis of benzoylcholine follows the kinetics of a first order reaction.

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