PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: V. FURTHER STUDIES ON THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH HYDROGEN CHLORIDE

1959 ◽  
Vol 37 (9) ◽  
pp. 1432-1441 ◽  
Author(s):  
J. R. McDowell ◽  
C. C. McDonald ◽  
H. E. Gunning
Keyword(s):  
Steady State ◽  
Hydrogen Chloride ◽  
Mercury Vapor ◽  
Recovery Process ◽  
Pure Hydrogen ◽  
Exchange Reactions ◽  
Recovery Techniques ◽  
Specific Step ◽  
Recovery Technique ◽  
Mercury Recovery

A further study has been made of the reaction of Hg2026(3P1) atoms, in natural mercury vapor (HgN), with hydrogen chloride under flow conditions at room temperature. Emphasis has been placed in this study on the effect of reaction parameters and mercury-recovery techniques on the Hg202 content of the solid calomel formed in the reaction.For pure hydrogen chloride the Hg202 content of the calomel was found to be 39.9 ± 0.3%, compared to the natural abundance of 29.8%. With 20–40 mole % of butadiene-1,3 in the hydrogen chloride, calomels containing 83–84% of Hg202 were consistently obtained.The isotopically specific aspects of the reaction in pure hydrogen chloride can be adequately explained by the sequence:[Formula: see text]where M in reaction [3] is a third body or the wall. From the Hg202-abundance data and steady-state considerations, it has been shown that the ratio of partitioning of the absorbed radiation to [1] and [2], respectively, = Φ1/Φ2 = 0.40 ± 0.02. In short, 29% of the primary reaction proceeds by the isotopically specific step [1].The Hg202 content of the calomel product was found to increase markedly when unsaturated hydrocarbons were added to the hydrogen chloride stream. The addends studied included butadiene-1,3, benzene, isoprene, acetylene, propylene, and ethylene in order of decreasing effectiveness. In the presence of the unsaturated addend (U) two additional reactions were postulated to occur:[Formula: see text]From steady-state calculations the effectiveness of the addend can be shown to be determined by the rate ratio, k8/k4.For the maximally enriching mixture of hydrogen chloride and butadiene, the effect of variations in lamp temperature and reaction pressure was studied. At lamp temperatures exceeding approximately 35 °C, reduced enrichments were obtained owing to emission-line broadening. A progressive reduction in enrichment was also observed with substrate pressures greater than 25 mm, owing presumably to Lorentz-broadening of the hyperfine absorption contours of the HgN in the reaction cell.The Hg202 content of the calomel product was determined by resonance radiation absorbiometry. The apparent Hg202 abundances of the mercury recovered from the calomel product were found to depend strongly on the method used for isolating the enriched mercury from the calomel. Evidence was obtained for the occurrence of isotopically degradative exchange reactions during the recovery process. A recovery technique was developed which appeared to eliminate this exchange degradation.

PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: III. THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH HYDROGEN CHLORIDE

1959 ◽  
Vol 37 (5) ◽  
pp. 930-939 ◽  
Author(s):  
C. C. McDonald ◽  
J. R. McDowell ◽  
H. E. Gunning
Keyword(s):  
Emission Line ◽  
Hydrogen Chloride ◽  
Mercury Vapor ◽  
Pure Hydrogen ◽  
Hydrogen Atoms ◽  
Unsaturated Compounds ◽  
Depletion Effect ◽  
Flowing Hydrogen ◽  
Fast Flow ◽  
Static Conditions

An investigation has been made of the reaction of Hg2026(3P1) atoms, photoexcited in natural mercury vapor, with flowing hydrogen chloride at 28–30 °C. Emphasis has been placed on the effect of reaction parameters on the Hg202 content of the calomel product of the reaction.Under fast-flow conditions it has been found that the calomel product contains 44% Hg202, corresponding to an enrichment of 48% over the normal abundance of 29.8%.In the presence of unsaturated compounds such as butadiene and benzene the enrichment is markedly increased. With butadiene and benzene as addends, the maximum enrichments were 98% and 85% respectively.The reaction with pure hydrogen chloride can be explained in terms of the sequence:[Formula: see text]where HgN is natural mercury and M is a third body, including the wall.In the presence of unsaturated compounds (U), additional reactions are postulated to occur:[Formula: see text]The increased enrichment in the presence of unsaturated addends is explained by the reduced rate of formation of HgNCl through cleanup of chlorine and hydrogen atoms by reactions [6] and [7].Under static conditions, the pure hydrogen chloride reaction formed a calomel product of normal Hg202 abundance. This finding is explained as a localized depletion of the unexcited mercury in Hg202, through reaction [1]. With increasing linear flow rate the depletion effect gradually disappears and enrichments maximize at high flow rates.The Hg202 enrichment was found to be very sensitive to the wall temperature of the Hg202 source. In a 50:50 v/v mixture of hydrogen chloride and butadiene the enrichment was found to decrease from 68% to 24% as the lamp temperature was raised from 25.5 °C to 50 °C. The effect is explained by temperature broadening of the emission line leading to overlap of the emission line on absorption contours adjacent to that of Hg202.Both the rate of deposition of the calomel product and the Hg202 enrichment were found to depend upon the concentration of natural mercury in the gas stream for hydrogen chloride – butadiene mixtures. Optimum conditions corresponded to a slight supersaturation of the stream with mercury vapor.

PRIMARY PROCESSES IN REACTIONS INITIATED BY PHOTOEXCITED MERCURY ISOTOPES

1958 ◽  
Vol 36 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Harry E. Gunning
Keyword(s):  
Water Vapor ◽  
Hydrogen Chloride ◽  
Methylene Chloride ◽  
Methyl Chloride ◽  
Mercury Vapor ◽  
Enrichment Factors ◽  
Exchange Reactions ◽  
Boron Trichloride ◽  
Mercury Compounds ◽  
Similar Enrichment

A study has been made of the reaction of Hg2026(3P1) atoms, photoexcited in natural mercury vapor; with a number of substrates which form solid mercury compounds in mercury photo-sensitization. Some data are also given for reactions initiated by Hg1986(3P1) atoms. The solid mercury compounds formed were examined for enrichment in the isotope initiating the reaction. Such enrichment would be evidence for the primary formation of the mercury compound.Three HgO-forming substrates were studied: water vapor, nitrous oxide, and oxygen. The Hg2Cl2-forming substrates studied included hydrogen chloride, methyl chloride, methylene chloride, chloroform, carbon tetrachloride, isopropyl chloride, and boron trichloride. One Hg2Br2-forming substrate was examined—isopropyl bromide.Among the HgO-forming substrates only water vapor gave enrichment in Hg202 in the HgO product. The Hg202 content of the oxide was found to vary from 32 to 35%, depending on reaction conditions, compared to a natural abundance of 29.6%. With water vapor – butadiene mixtures, oxides containing as high as 90% Hg202 were obtained. Similar enrichment factors were obtained for Hg1986(3P1) reactions.Hydrogen chloride and the alkyl chlorides yielded calomels containing a maximum of 45% Hg202. Methyl chloride gave similar enrichment factors in Hg198 for the Hg1986(3P1) reaction. The calomel formed in the boron trichloride reaction showed no enrichment.Addends such as butadiene and benzene, when added to hydrogen chloride, increased the Hg202 enrichment from 45% to 60%.For those reactions which yield mercury compounds enriched in the initiating mercury isotope, evidence is presented for a single primary process. Failure to obtain pure isotopes is attributed to exchange reactions with adsorbed natural mercury during recovery of the enriched mercury from the product. It is postulated that the addends react with the mercury product and reduce chemisorption of natural mercury on the product.The significance of these findings in the mechanisms of the reactions studied is discussed.

Computational design of recovery experiments for ductile metals

2005 ◽  
Vol 461 (2062) ◽  
pp. 3297-3312 ◽  
Author(s):  
N.K Bourne ◽  
G.T Gray
Keyword(s):  
Fracture Toughness ◽  
Shock Loading ◽  
Computational Design ◽  
Current Paper ◽  
Uniaxial Loading ◽  
Ductile Metals ◽  
One Dimensional ◽  
Recovery Techniques ◽  
Recovery Technique

Previous work on the shock loading of metals, has shown that one-dimensional strain histories may be only be approximated in a loaded sample if it is to be recovered at late times to examine microstructure. This proceeds through the use of a system of partial momentum traps and soft, shock-recovery techniques. However, limitations in the degree of uniaxial loading, and on the trapping of tensile pulses, have led to redesign of the target. In the current paper the technique is first assessed, and then modifications are explored to further refine it. Additionally it is illustrated how it may be applied to successfully recover targets of lower innate fracture toughness than has been previously documented. In the first part of the paper, the authors review work undergone to shock recover metals, and highlight associated constraints. In the latter part of the paper, a series of hydrocode simulations is presented to illustrate the design of an improved shock recovery technique that has now been adopted.

γ-RADIATION-INDUCED HYDROGEN EXCHANGE REACTION IN LIQUID CYCLOHEXANE – HYDROGEN CHLORIDE SOLUTIONS

1966 ◽  
Vol 44 (22) ◽  
pp. 2645-2649 ◽  
Author(s):  
J. W. Fletcher ◽  
G. R. Freeman
Keyword(s):  
Exchange Reaction ◽  
Hydrogen Chloride ◽  
Hydrogen Exchange ◽  
Spectroscopic Method ◽  
Exchange Reactions ◽  
Radical Chain ◽  
Chloride System ◽  
Γ Radiation ◽  
Radiation Induced ◽  
A Chain

The overall exchange reactions[Formula: see text]have been initiated by radiolysis and measured by a nuclear magnetic resonance spectroscopic method. The reactions occur by a chain mechanism, with a chain length of ~ 104 in a 1 M solution of hydrogen chloride in cyclohexane. The mechanism is complex.The exchange reaction can also be initiated by the photolysis of chlorine or of hydrogen chloride.A chain exchange reaction does not occur between c-C6H12 and DI, D2S, or ND3. These results are consistent with the suggestion that the exchange reaction in the cyclohexane – hydrogen chloride system occurs by a free radical chain mechanism.This type of exchange reaction can cause difficulties in isotopic tracer studies.

scholarly journals NO<sub>x</sub> cycle and the tropospheric ozone isotope anomaly: an experimental investigation

2014 ◽  
Vol 14 (10) ◽  
pp. 4935-4953 ◽  
Author(s):  
G. Michalski ◽  
S. K. Bhattacharya ◽  
G. Girsch
Keyword(s):  
Steady State ◽  
Isotopic Composition ◽  
Isotope Composition ◽  
Dominant Role ◽  
Isotope Effects ◽  
Rate Coefficients ◽  
Atmospheric Conditions ◽  
Exchange Reactions ◽  
Mixing Ratios ◽  
High Concentrations

Abstract. The oxygen isotope composition of nitrogen oxides (NOx) in the atmosphere is a useful tool for understanding the oxidation of NOx into nitric acid / nitrate in the atmosphere. A set of experiments was conducted to examine change in isotopic composition of NOx due to NOx–O2–O3 photochemical cycling. At low NOx / O2 mixing ratios, NOx became progressively and nearly equally enriched in 17O and 18O over time until it reached a steady state with Δ17O values of 39.3 ± 1.9‰ and δ18O values of 84.2 ± 4‰, relative to the isotopic composition of the initial O2 gas. As the mixing ratios were increased, the isotopic enrichments were suppressed by isotopic exchange between O atoms, O2, and NOx. A kinetic model was developed to simulate the observed data and it showed that the isotope effects occurring during O3 formation play a dominant role in controlling NOx isotopes and, in addition, secondary kinetic isotope effects or isotope exchange reactions are also important during NOx cycling. The data and model were consistent with previous studies which showed that the NO + O3 reactions occur mainly via the transfer of the terminal atoms of O3. The model predicts that under tropospheric concentrations of NOx and O3, the timescale of NOx–O3 isotopic equilibrium ranges from hours (for ppbv NOx / O2 mixing ratios) to days (for pptv mixing ratios) and yields steady state Δ17O and δ18O values of 45‰ and 117‰ respectively (relative to Vienna Standard Mean Ocean Water (VSMOW)) in both cases. Under atmospheric conditions when O3 has high concentrations, the equilibrium between NOx and O3 should occur rapidly (h) but this equilibrium cannot be reached during polar winters and/or nights if the NOx conversion to HNO3 is faster. The experimentally derived rate coefficients can be used to model the major NOx–O3 isotopologue reactions at various pressures and in isotope modeling of tropospheric nitrate.

scholarly journals The Effect of Recovery Technique Physical Training Combination in Improving Vo2max of Volleyball Athlete

2019 ◽  
Vol 4 (2) ◽  
pp. 231-236
Author(s):  
Dian Helaprahara ◽  
Rachlai Eko Arisetiawan ◽  
Mas’odi Mas’odi
Keyword(s):  
Experimental Study ◽  
Lactic Acid ◽  
Control Group ◽  
Passive Recovery ◽  
Recovery Techniques ◽  
Anaerobic Energy ◽  
Massage Treatment ◽  
Recovery Technique ◽  
Randomized Control ◽  
Fatigue Recovery

Volleyball uses a lot of anaerobic energy which can produce a lot of lactic acid that causes fatigue. Recovery is an important factor in increasing an athlete performance. The purpose of this study was to investigate the modification of recovery techniques by combining active and passive recovery techniques combined with massage. This research was an experimental study using a pure experimental design - Randomized Control Group Pretest-Posttest. The conclusion of this study is that there is a significant influence on changes in VO2max after the presence of massage treatment in the active and passive recovery groups. Massage can be an additional recovery technique during practice or competition. 

scholarly journals High availability of data using Automatic Selection Algorithm (ASA) in distributed stream processing systems

2019 ◽  
Vol 8 (2) ◽  
pp. 690-698
Author(s):  
Sultan Alshamrani ◽  
Hesham Alhumyani ◽  
Quadri Waseem ◽  
Isbudeen Noor Mohamed
Keyword(s):  
Stream Processing ◽  
Processing System ◽  
High Availability ◽  
Selection Algorithm ◽  
Advantages And Disadvantages ◽  
Automatic Selection ◽  
Recovery Techniques ◽  
Recovery Technique ◽  
System Requirements ◽  
Distributed Stream Processing

High Availability of data is one of the most critical requirements of a distributed stream processing systems (DSPS). We can achieve high availability using available recovering techniques, which include (active backup, passive backup and upstream backup). Each recovery technique has its own advantages and disadvantages. They are used for different type of failures based on the type and the nature of the failures. This paper presents an Automatic Selection Algorithm (ASA) which will help in selecting the best recovery techniques based on the type of failures. We intend to use together all different recovery approaches available (i.e., active standby, passive standby, and upstream standby) at nodes in a distributed stream-processing system (DSPS) based upon the system requirements and a failure type). By doing this, we will achieve all benefits of fastest recovery, precise recovery and a lower runtime overhead in a single solution. We evaluate our automatic selection algorithm (ASA) approach as an algorithm selector during the runtime of stream processing. Moreover, we also evaluated its efficiency in comparison with the time factor. The experimental results show that our approach is 95% efficient and fast than other conventional manual failure recovery approaches and is hence totally automatic in nature.

scholarly journals Simulation Study of a Membrane Reactor for Ultrapure Hydrogen Recovery from Methanol Steam Reforming Reaction under Periodic Steady-State

2018 ◽  
Vol 13 (2) ◽  
pp. 275
Author(s):  
Lemnouer Chibane
Keyword(s):  
Steady State ◽  
Simulation Study ◽  
Steam Reforming ◽  
Membrane Reactor ◽  
Operating Conditions ◽  
Methanol Steam Reforming ◽  
Pure Hydrogen ◽  
Unsteady State ◽  
Hydrogen Recovery ◽  
Periodic Steady State

Steam reforming of methanol over Cu/ZnO/Al2O3 catalyst was theoretically studied under created unsteady state. A mathematical approach was proposed to evaluate the effect of periodic inputs on reactor performance. The efficacy of the periodic separating reactor in term of pure hydrogen and of methanol conversion was measured during the reaction of methanol steam reforming. The obtained results showed that under certain operating conditions the periodic operation can be used advantageously to increase the reactor ability up to a level higher than the maximal steady-state. Moreover, our findings showed that the pumping of hydrogen through the membrane was stimulated by the effect of periodic operations. The predicted results suggested that the created unsteady state mode by using a square wave function could give the better performances compared to the sinusoidal mode. Copyright © 2018 BCREC Group. All rights reservedReceived: 15th July 2017; Revised: 26th November 2017; Accepted: 8th December 2017; Available online: 11st June 2018; Published regularly: 1st August 2018How to Cite: Chibane, L. (2018). Simulation Study of a Membrane Reactor for Ultrapure Hydrogen Recovery from Methanol Steam Reforming Reaction under Periodic Steady-State. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2): 275-285 (doi:10.9767/bcrec.13.2.1340.275-285) 

scholarly journals The photosynthesis of hydrogen chloride. II. —“Oxygen free” mixtures

1933 ◽  
Vol 140 (840) ◽  
pp. 112-125 ◽  
Keyword(s):  
Comparative Study ◽  
Transition Region ◽  
Hydrogen Chloride ◽  
The Other ◽  
Pure Hydrogen ◽  
Self Consistent ◽  
Complete Study ◽  
Chlorine Reaction ◽  
Kinetics Of ◽  
Rich Mixtures

The complete study of the photochemical hydrogen-chlorine reaction falls into four sections consequent upon the fact that the presence of oxygen in large or small quantity very materially alters the kinetics of the process. These may be classified as follows:— (1) The kinetics of pure hydrogen-chlorine mixtures. (2) The kinetics of oxygen-rich mixtures. (3) The transition region between (1) and (2). (4) The photosensitized formation of water associated with (2) and (3). A mechanism proposed for any one of the above processes must be consistent with the other three, and a full and comparative study of all four should lead to a self-consistent mechanism by which all the above aspects of the problem can be unified in one explanation.

Sign in / Sign up

Export Citation Format

Share Document