69 research outputs found
Visible light photoactivity of Polypropylene coated Nano-TiO2 for dyes degradation in water
The use of Polypropylene as support material for nano-TiO2 photocatalyst in the photodegradation of Alizarin Red S in water solutions under the action of visible light was investigated. The optimization of TiO2 pastes preparation using two commercial TiO2, Aeroxide P-25 and Anatase, was performed and a green low-cost dip-coating procedure was developed. Scanning electron microscopy, Atomic Force Microscopy and X-Ray Diffraction analysis were used in order to obtain morphological and structural information of as-prepared TiO2 on support material. Equilibrium and kinetics aspects in the adsorption and successive photodegradation of Alizarin Red S, as reference dye, are described using polypropylene-TiO2 films in the Visible/TiO2/water reactor showing efficient dyes degradation
Predicting detonation velocity of ideal and less ideal explosives via specific impulse
429-432A novel method is
given to estimate the detonation velocity of mostly ideal and less ideal
composition explosives. This method is based on the utilization of theoretical
specific impulse of the explosive, which can be designated as a monopropellant,
and loading density. The simple empirical equation in calculating the
detonation velocity has the form: DCJ=1.453ISPĻ0 + 1.98, where DCJ is the Chapman-Jouguet detonation velocity, ISP is the specific impulse
and Ļ0 is
the initial density. Calculated detonation velocity by this procedure shows
good agreement with respect to measured detonation velocity
Predicting adiabatic exponent as one of the important factors in evaluating detonation performance
259-263A new
correlation is given to estimate the Chapman-Jouguet adiabatic (gamma)
exponent, CJ,
as a criterion for choice among conflicting detonation pressure measurements at
any loading densities, greater as well as less than 1 g/cc. The CJ value obtained by new correlation
is relatively insensitive to elemental composition and is primarily a function
of loading density. Calculated gCJ by this procedure shows good agreement with respect to
corresponding measured values as compared to complicated computer code BKW-EOS
as well as reported empirical methods
The Catalytic Effect of Mn2O3 Nanoparticles on the Ignition Reaction of Pyrotechnic of Ammonium Nitrate(V)/Thiourea
The non-isothermal TG/DSC technique has been used to study the kinetic triplet and heat of ignition reaction of ammonium nitrate(V) (AN)/thiourea (TU) pyrotechnic in the presence of Mn2O3 catalyst nanoparticles under an argon atmosphere at different heating rates (5 KĀ·minā1, 10 KĀ·minā1, 15 KĀ·minā1 and 20 KĀ·minā1). The activation energies for the ignition reaction of AN/TU were calculated using the non-isothermal isoconversional Kissinger-Akahira-Sunose (KAS) and Friedman equations for different conversion fraction (Ī±) values in the range 0.1-0.9. The pre-exponential factor and kinetic model were determined by means of the compensation effect and the selected model was confirmed by a nonlinear fitting method. The average activation energies in the absence and presence of 5 wt.% Mn2O3 nanoparticles were 110.1 kJĀ·molā1 to 117.3 kJĀ·molā1 for the reaction model A3 (g(Ī±) = [āln(1āĪ±)]1/3), and 86.5 kJĀ·molā1 to 101.8 kJĀ·molā1 for the reaction model A4 (g(Ī±) = [āln(1āĪ±)]1/4). The evolved heat (ĪH) of ignition reaction in the presence of Mn2O3 was about 4 times that in the absence of the nano-sized Mn2O3
A simple way to predict electric spark sensitivity of nitramines
505-509This work presents a new simple method for predicting electric spark sensitivity of nitramine energetic compounds. This method is based on the calculated detonation velocity at maximum nominal density (theoretical maximum density) and then corrected for some nitramines which have some specific molecular structure. The predicted electric spark sensitivity by new method are compared with calculated results on the basis of quantum mechanical computations for 17 nitramines so that the root mean square (rms) deviations from experiment for new and complicated quantum mechanical methods are 1.23 and 4.02 J, respectively. The new model is also used for two new nitamine explosives TNAZ [1,3,3-trinitroazatidine] and TEX [4,10-dinitro-2,6,8,10-tetraoxa-4,10-diazaisowurtzitane] in which predicted results are close to measured values
Relationship between thermal stability and molecular structure of polynitro arenes
61-64A simple relationship has been derived to predict thermal stability of CHNO polynitro arenes on the basis of onsets of thermal decomposition, which can be obtained by means of non-isothermal differential thermal analysis (DTA). The model is optimized using a set of 12 polynitro arenes so that R-squared value or the coefficient of determination of the new correlation is 0.95. The new correlation has also been applied to 6 polynitro arenes explosives from a variety of chemical families in order to assess the predictive capability of new method. Predicted results are close to the measured values for all of tested polynitro arenes on the basis DTA
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