Aerogel nanoscale magnesium oxides as a destructive sorbent for toxic chemical agents

CEJC 2(1) 2004 1633

Aerogel nanoscale magnesium oxides as a destructivesorbent for toxic chemical agents

Vaclav middotStengl1curren Snejana Bakardjieva1 Monika Mamiddotrparasup3kovparaa1 Jan middotSubrt1Frantimiddotsek Oplumiddotstil2 Marcela Olmiddotsanskparaa2

1 Institute of Inorganic ChemistryAS CR

250 68 middotRemiddotz Czech Republic2 Military Technical Institute of Protection Brno

Veslamiddotrskparaa 230 628 00 BrnoCzech Republic

Received 21 August 2003 accepted 16 October 2003

Abstract An autoclave hypercritical drying procedure has been used to prepare precursors of

MgO from Mg(OCH3)2 This material was prepared with a specishy c surface area of 1200 m2g1

The dehydrated materials consisted of much smaller crystallites than conventionally prepared

MgO and were free of OCH3 groups The precursors and samples of magnesium oxide were

taken for experimental evaluation of their reactivity with mustard The largest percentage of

the conversion mustard into non-toxic products after the elapse of the reaction was 77

creg Central European Science Journals All rights reserved

Keywords Nanostructures organometallic compounds chemical synthesis electron microscopy

surface properties

1 Introduction

Nanosized inorganic oxides are regarded as promising non-aggressive reagents useable for

the treatment of sensitive materials contaminated with lethally toxic chemical agents

namely the nerve agents (sarin soman VX agent etc) as well as blistering agents (eg

mustard) The detoximacrcation capability of those highly dispersed oxides (eg MgO CaO

ZnO AlOx(HO)y ZrO TiO2) has been extensively studied and reported [1-5] Products

of corresponding reactions have been investigated and the respective detoximacrcation re-

action mechanisms have already been proposed The detoximacrcation reactions have been

curren E-mail stengliiccascz

V microStengl et al Central European Journal of Chemistry 2(1) 2004 1633 17

shown to proceed mainly on the surface of the nanoparticles leading to non-toxic products

even at ambient temperature

Reactivity of the nanosized MgO towards the toxic agents has been described more

profoundly by Wagner et al [4] The following basic knowledge has been revealed

All mentioned toxic agents can be detoximacred ie converted into their non-toxic

products within a reasonable time period so that the activity of the reagent is

versatile

The chemical activity of the MgO surface cannot be considered uniform but the

more active centres are preferentially located at activated sites or defects along the

surface of the nanoparticles eg edges corners etc

Heterogeneous reactions of the respective neat toxic agents exhibit two-stage kinetics

when proceeded on the MgO nanoparticle surface The initial fast stage can be

attributed to the reaction of a given agent at highly active reaction centres and

the second stage is explained as a process of slower transport of the agent along

surface from less active site(s) to more reactive one(s) The process of a secondary

redistribution of the neat agent over a surface was convincingly correlated with the

respective evaporation rate (agent vapour pressure) as to be a rate-limiting factor

The main aims of the work were

To investigate the respective method and procedure of preparation of the nanosized

magnesium oxide

Characterise the respective synthesised magnesium oxide samples

Evaluate the prepared oxides for their respective detoximacrcation activities

Assess whether the overall activity of the prepared oxides could be increased utilising

an eregective solvent which is potentially more capable of distributing the toxic agent

over the whole surface of the oxide

Magnesium oxide is commonly obtained by thermal decomposition of magnesium hy-

droxide or carbonate [6] [7] and more recently by a sol-gel process [8] [9] The oxide

morphology particle size and specimacrc surface area depend on the preparation conditions

(pH gelling agent calcinations rate and temperature) It has been documented that

methoxide or alkoxide-based solgel synthesis of metal hydroxides followed by supercrit-

ical drying and vacuum dehydration can lead to the formation of nanoparticles of metal

oxides [10-15]

In considering the ways in how to additionally facilitate the respective detoximacrcation

reaction the two following approaches may be proposed to stimulate the overall course

of the reaction namely

The initial uniform spreading of the agent over the whole surface

A degow of the agent along the surface

Since the capillarity of the toxic agents is limited the agent distribution over the surface

of the solid (powdery) reagent could be enhanced utilising a solvent that is capable of

both dissolving the toxic agent and wetting the powdery reagent surface thus penetrating

its whole deposit and spreading there evenly Moreover if the chosen solvent is volatile

enough it evaporates at the upper layers causing a slow but benemacrcial degux of the solvent

18 V microStengl et al Central European Journal of Chemistry 2(1) 2004 1633

containing the dissolved toxic agent which passes from bulk up to surface of the reagent

deposit (batch)

The detoximacrcation activities of the prepared samples of magnesium oxides and mag-

nesium hydroxides (ie precursors of macrnal nanosized MgO syntheses were evaluated using

sulphur mustard bis(2-chloroethyl) sulphide The agent was chosen deliberately for the

experiments because it has been reported to be relatively resistant to detoximacrcation [4]

When it is brought together with the nanosized MgO it can yield 2-chlorethyl vinyl sul-

phide and divinyl sulphide both of which are products of an elimination reaction and

the thiodiglycol a product of a nucleophilic substitution reaction

2 Experimental section

21 Preparation of nanoscale magnesium oxide

A modimacred autoclave hypercritical procedure has been developed to prepare nanoscale

MgO particles This method has four steps preparation of Mg(OCH3)2 by the reaction

of magnesium metal with methanol hydrolysis of Mg(OCH3)2 in the presence of toluene

hypercritical drying in an autoclave and thermal activation Commercially available

Mg(OCH3)2 solution (Aldrich 6 wt in methanol) were used in lieu of macrrst step The

experimental conditions are summarised in Table 1 Ultrasound waves [16] were used

for hydrolysis of Mg(OCH3)2 The hydroxide gel solution was transferred into a 100 ml

stainless-steel autoclave After nitrogen gas degushing the autoclave was slowly heated from

room temperature to 265plusmnC at a rate of 3plusmnCmin by the PID controller The temperature

was allowed to equilibrate at 265plusmnC for 15 min The autoclave was vented to release the

pressure which took about 05 1 min The autoclave was immediately removed from

the oven and cooled to room temperature The product was removed from the autoclave

and dried at 120plusmnC The macrnal product was stored in a bottle under normal conditions

On the basis of DTA results (Figure 1) the hydrated MgO precursors obtained from the

autoclave were heated under dynamic vacuum by using a furnace controlled by the PID

controller in a stainless steel tube The temperature ramp was 1plusmnCmin After the heat

treatment the sample was allowed to cool to room temperature

22 Characterization methods

The specimacrc surface area of the samples was determined via nitrogen adsorption-desorptions

isotherms at liquid nitrogen temperature by using a Coulter SA 3100 instrument TEM

micrographs were obtained using Philips 201 transmission electron microscope SEM pho-

tographs were obtained using Philips XL30 CP scanning electron microscope and X-ray

powder diregraction was performed with Siemens D5005 diregractometer Qualitative analy-

sis was performed with Bede ZDS for Windows version 199 and JCPDS PDF-2database

[17] DTA-TG measurements were carried out using NETZSCH STA 409 apparatus


23 Methodic of disintegrations mustard

Nanosized magnesium samples (precursors Mg(OH)2 as well as magnesium oxides) were

evaluated for their ability to convert sulphur mustard (hereafter also signed as HD) into

non-toxic products Synthesised powdery samples were dried over 24 hours in a vacuum

kiln (at 100 plusmnC 400 Pa) before tests A weighed portion of a given evaluated nanosized

sample was put into a glass vial provided with a solid screw cap (Supelco type CRS-33)

The toxic agent in a solution of a chosen solvent was dosed onto the powder reagent

layer The vial was sealed with a cap and placed into the thermostat All experiments

were performed at 25plusmnC and each run was repeated four to six times An addition of

isopropylalcohol (ca 2 mL) terminated the reaction The suspension was vigorously

agitated and the liquid fraction was separated from the solid using a centrifuge (9 000

cc miniexcl1 for 3 minutes) and subsequently analysed for a residual content of the mus-

tard The respective detoximacrcation capabilities of the evaluated nanosized samples were

expressed as percentages of mustard elimination from the reaction mixture under given

experimental conditions

3 Results and discussion

31 Characterization of samples magnesium aerogels

Figure 1 shows a typical thermal analysis of the precursors used in the synthesis Water

evolution started at a low temperature (sup1 100plusmnC) with a maximum at 139plusmnC Carbon

dioxide and water from the decomposition of residual OCH3 groups was detected in

the gas phase at sup1 300plusmnC and peaked at 396plusmnC The calcination temperature used in the

synthesis was 500plusmnC At this temperature the macrnal solids obtained were found to consist

primarily of particles of MgO without any traces of precursors The specimacrc surface area

and total pore volume are shown in Table 1 and Table 2 The specimacrc surface area de-

creases with increasing temperature of the annealing of precursors Figure 2 shows the

X-ray diregraction patterns of the precursor Mg151 and the samples prepared by their

thermal treatment They are all similar and exhibit three characteristic peaks for MgO

(periclas PDF 45-0496) With increasing annealing temperature the intensity of the

peaks has been evolved No diregraction lines of Mg(OH)2 were detected Electron mi-

crographs of the selected samples are shown in Figure 3 (TEM micrographs) Precursor

particles (sample Mg151) have uniform morphology and particle size as periclase par-

ticles (samples Mg152-156) The particle size from electron micrographs is similar to

that of the calculated size from X-ray diregraction (see Table 2) The Scherrer equation

was applied to estimate a crystallite size and a programme WinFit v12 was used for

calculation of particle size


32 The reactivity towards sulphur mustard

Two precursors Mg(OH)2 with high specimacrc surface areas (Mg 151 and Mg 252) and

three diregerent samples of magnesium oxide (Mg 151380 Mg 16380 Mg 252380)

were taken for experimental evaluation of their respective reactivities

The eregect of the solvent type used on the course of the detoximacrcation reaction was also

tested Five solvents diregering in their basic chemical properties (eg polarity proticity

viscosity capillarity and volatility) were taken for the experiment as follows

deg petrolether - non-polar distinct capillarity highly volatile

deg diethylether - non-polar aprotic oxygen-containing distinct capillarity highly volatile

deg acetone - weakly polar aprotic distinct capillarity volatile

deg N N-dimethylpyrrolidone - polar aprotic

deg methylalcohol - protic

The eregect of the solvent type on detoximacrcation reaction was only tested with the MgO

sample Mg 252380

Mustard was dissolved in the solvents in order to dose approximately the same

amounts of the toxic agent onto a layer of the solid tested The initial concentrations

of the mustard in the used solvents are shown in the Table 3 A 30 mg sample of the

Mg 252380 was weighed into each lockable glass vial where subsequently 10 sup1L of HD

dissolved in the respective solvents was pipetted onto the magnesium sample The vials

were immediately sealed and put into a thermostat for two hours Stoichiometric ratios

of MgO to HD were ca (20 - 30) to 1 so that the MgO samples were in excess in all

experimental cases Residual content of the HD in the reaction medium was estimated

analytically after macrnishing the reaction The results are summarised in Table 3

From the obtained data it is obvious that the extent of the HD conversion is appre-

ciably dependent on the kind of the solvent used under the given reaction conditions

Diethylether seems to be the most convenient solvent which might mainly be attributed

to its pronounced capillarity (based on its low surface tension and viscosity) Except for

NN-dimethyl-pyrrolidone the observed eregects of the other solvents on the HD distribu-

tion and reaction course do not direger too much and within an experimental error they

can be considered equally eregective

Since diethylether is not practical for use since it is narcotic (as well as its other

hazardous properties) it was decided that petrolether was a suitable solvent for all further

experimental work

Two common factors should also be considered which can adversely aregect the repro-

ducibility of the experiments for when HD is dissolved in certain solvents and is dosed

onto a layer of a powder reagent

The structure of the powder layer in a vial can hardly be standardised since the

magnesium samples are lumpy (granulated) and the individual lumps do not have a

reproducible macrt thus the penetration of the reagent with a solvent can somewhat

direger in the individual experiments

The extent of wetting the surface of the powder can hardly be controlled or checked


so far so that the actual extent of loading the surface with toxic agent with mustard

is unknown

Also taking into consideration the fact that the observed reactivity of nanosized reagents

is proportionally related to the area of their accessible surface (although diregering in

their respective specimacrc reactivity) then such a parameter as the extent of wetting

should play an important role The surface of the nanosized reagents are moistened as

evenly and reproducibly as possible however this may not be attainable in all replicated

experiments Only when the solvent is dosed in excess can it wet the whole surface

reliably However in such a case the (local) concentration of the dissolved toxic agent by

the surface of the powdered reagent should be appreciably diminished and consequently

the appeared reactivity would be lowered These circumstances may account for the

observed diregerences within a series of the replicated experiments

The importance of the extent of loading the nanosized reagent with the toxic agent

was investigated Using the same volume of the solvent as well as the charge of powder

reagents two extents of loading the nanosized reagent were decided for evaluation namely

the mass ratios of the respective magnesium samples vs the HD and were chosen as

follows 1001 or 2001 (ie a stoichiometry where the MgO exceeded the HD by a factor

of ca 50 or 100) The reaction time was 1 hour The results obtained are summarised in

the tables below (Table 4 and Table 5) At least two conclusions can be made redegecting

these results

a) the yield of the observed reaction can be increased as the loading of the magnesium

reagent surface is decreased under given experimental conditions and

b) magnesium oxides commonly exhibit higher reactivity towards the HD compared

with the related magnesium hydroxides although their respective dispersities (thus

specimacrc surface area) of the hydroxides (precursors) are comparatively greater namely

by a factor of two or three Therefore the observed lower capability of magnesium

hydroxides to convert the HD into non-toxic products might be attributed either

to their lower inherent reactivity (more likely) or lower ability of the solvent to

penetrate into a macrne-grained structure of those reagents

The kinetic promacrles that characterise the course of surface heterogeneous reaction of the

neat mustard on nanosized magnesium oxides were reported by Wagner et al [4] to have

two stages The reaction is relatively fast during the initial stage while its subsequent

course is comparatively slow since being controlled by the redistribution of HD over the

surface It was of interest to investigate the overall course of the reaction if the toxic agent

is spread over the nanosized sample being dissolved in petrolether The Mg 252380

sample was prepared in larger quantity and the current sample was chosen for a kinetic

study of the reaction A sample of 500 mg was weighed and put into six sealable vials

Mustard was dissolved in petrolether to contain 42 mg in 1 mL of the solvent Aliquots

of 01 ml were pipetted onto a layer of the magnesium sample the vials were immediately

sealed and put into a thermostat for a certain time Then the reaction mixtures were

analysed for the HD residual content Each experiment was repeated four times Results

are summarised in Table 6 The results of the kinetics evaluations are illustrated in Figure


4 The conversion of the HD by the evaluated reagent is not very fast the conversion

can reach up to ca 40 during a three-hour reaction Logarithmic kinetic data gave a

smooth curve showing that the course of the observed heterogeneous reaction does not

exhibit two stages Conversely itrsquos apparent from the graph that the reaction proceeds

quickly at the beginning and as time of the reaction elapses the reaction rate continuously

slows down This behaviour might be attributed to the gradual depletion of the mustard

at the active centers of the magnesium reagent followed by a diregusion-controlled process

of the HD redistribution over the reagent surface Another explanation for the kinetic

curve can be based on the concept of a gradual consumption of the magnesium sample

since it is present as the stoichiometric reagent whose surface is considered uniformly

(evenly) reactive In any case the observed course of the reaction can be considered to

be faster compared to that of a reaction performed without solvent

4 Conclusion

The following conclusions can be made from the reactivity experiments The observed

reaction rate of the toxic agent with the powdered nanosized reagent can be accelerated

when the agent dissolved in a suitable solvent is spread over the powdered reagent

making sure that wetting is even over the whole reagent surface Among the solvents

tested petrolether was the most suitable both for eplusmnciency and safety reasons

Acknowledgements

This work was supported by the Ministry of Education of the Czech Republic in the

frame of the Project No LN00A028

References

[1] O Koper E Lucas and KJ Klabunde Development of reactive topical skinprotectants against sulfur mustard and nerve agents Journal of Applied ToxicologyVol 19 (1999) pp 59 70

[2] O Koper E Lucas and KJ Klabunde Oxide Nano particles as Countermeasuresagainst Chemical and Biological Threats In Proceedings of the Joint ServiceChemical and Biological Decontamination Conference Salt Lake City (USA) May2000

[3] GW Wagner and OW Bartram Reactions of the nerve agent simulant diisopropyldeguorophosphate with self-decontaminating adsorbents A P-31 MAS NMR studyJournal of Molecular Catalysis A Chemical Vol 144 (1999) pp 419 424

[4] GW Wagner OW Bartram O Koper and KJ Klabunde Reactions of VX GDand HD with nanosize Mgo Journal Phys Chem B Vol 103 (1999) pp 3225 3228

[5] GWWagner O Koper E Lucas S Decker and KJ Klabunde Reactions ofVX GD and HD with nanosize CaO Autocatalytic dehydrohalogenation of HD Journal of Physical Chemistry B Vol 104 (2000) pp 5118 5123


[6] DR Lide (Ed) CRC Handbook of Chemistry and Physics A Ready-Reference Bookof Chemical and Physical Data 77th Edition CRC Press Boca Raton New York London Tokyo

[7] MA Aramendia V Borau and CJimenez Synthesis and characterization of variousmgo and related systems J Mater Chem Vol 6(12) (1996) pp 1943 1949

[8] BQ Xu JM Wei and HY Wang Nano-MgO Novel preparation and applicationas support of Ni catalyst for CO2 reforming of methane Catalysis Today Vol 68(1-3) (2001) pp 217 225

[9] HS Choi and ST Hwang Sol-gel-derived magnesium oxide precursor for thin-macrlmfabrication J Mat Res Vol 15 (2000) pp 842 845

[10] T Lopez RGomez J Navarrete and E Lopez-Salinas Evidence for Lewis andBronsted acid sites on MgO obtained by sol-gel Journal of Sol-Gel Science andTechnology Vol 13 (1998) pp 1043 1047

[11] S Utamapanya KJ Klabunde and JR Schlup Nanoscale metal-oxide particlesclusters as chemical reagents - synthesis and properties of ultrahigh surface-areamagnesium-hydroxide and magnesium-oxide ChemMater Vol 3 (1991) pp 175 181

[12] JV Stark and KJ Klabunde Nanoscale metal oxide particlesclusters as chemicalreagents Adsorption of hydrogen halides nitric oxide and sulfur trioxide onmagnesium oxide nanocrystals and compared with microcrystals Chem Mater Vol8(8) (1996) pp1913 1918

[13] JV Stark DG Park and I Lagadic Nanoscale metal oxide particlesclustersas chemical reagents Unique surface chemistry on magnesium oxide as shown byenhanced adsorption of acid gases (sulfur dioxide and carbon dioxide) and pressuredependence Chem Mater Vol 8(8) (1996) pp 1904 1912

[14] L Znaidi KChhor and C Pommier Batch and semi-continuous synthesisof magnesium oxide powders from hydrolysis and supercritical treatment ofMg(OCH3)2 MatResBull Vol 31 (1996) pp 1527 1535

[15] OB Koper I Lagadic AVolodin and KJ Klabunde Alkaline-earth oxidenanoparticles obtained by aerogel methods Characterization and rational forunexpectedly high surface chemical reactivities Chem Mater Vol 9 (1997) pp2468 2480

[16] V middotStengl S Bakardjieva M Mamiddotrparasup3kovparaa PBezdimiddotcka and J middotSubrt Magnesium oxidenanoparticles prepared by ultrasound enhanced hydrolysis of Mg-alkoxides MatLett Vol 57(24-25) (2003) pp 3998 4003

[17] JCPDS PDF 2 database Release 2001 International Centre for Diregraction DataNewton Square PA USA


Sample Mg-methoxide Methanol+water Toluene SBET Vp

[mL] [mL] [mL] [m2giexcl1] [ccgiexcl1]

Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142

6 solution of magnesium methoxide other 868 solution

Table 1 Experimental conditions and resulting specishy c surface areas SBET and total porevolume Vp of Mgaerogels prepared from magnesium methoxide


Sample T SBET Vp Phase L442micro

[plusmnC] [m2giexcl1] [ccgiexcl1] identishy ed by [nm]

XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20

Table 2 Specishy c surface areas and crystallite sizes of nanoscale dehydrated MgO samples


Characteristics Solvent

Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether

Surface tension at 25plusmnC (reg )

[mNmiexcl1]

167 235 220 - 177

Viscosity at 25plusmnC ( sup2 ) [mPas] 02 03 08 - 03

Initial content of the HD (mg HD

per 30 mg charge of Mg reagent)

0511 0392 0471 0487 0530

Average residual content of the

HD (mg HD per 30 mg charge of

Mg reagent)

0207 0260 0298 0420 0295

Standard deviation of the aver-

age

1523 659 1367 336 458

Percentage of the HD conversion

after the reaction []

595 336 366 138 442

Table 3 Residual content of the HD after reaction on the magnesium sample Mg 151380(reaction time 2 h temperature 25macrC charge of the reagent 30 mg the HD dissolved in 002mlof solvent)


Characteristics Precursors MgO

Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286

Standard deviation of the average 11 16 84 27 16


after the elapse of the reaction []

392 419 529 688 427

Table 4 Residual content of HD after reaction on the magnesium samples (reaction time 1 htemperature 25macrC charge of the respective samples in the reaction 30 mg 05 mg of HD dissolvedin 01 ml of petrolether)



Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471

Table 5 The residual content of HD after its reaction on the magnesium samples (reaction time1 hour temperature 25macrC charge of the respective samples in the reaction 30 mg 025mg HDdissolved in 01 ml petrolether)


Time of reaction (ie the HD

conversion) [min]

0 15 30 60 120 180

Average residual content of HD

(mg HD per 500 mg charge of Mg

reagent)

0422 0363 0327 0299 0272 0261

Standard deviation of the average 94 349 17 71 61 50



00 139 224 291 355 382

Table 6 Time dependence of the mustard conversion on Mg 252380 sample (the Mg reagentcharge of 500 mg 042 mg of HD in 01 ml of petrolether temperature of 25macrC)


Fig 1 DTA - TG of sample Mg151


Fig 2 XRD spectra sample Mg15 1 and samples Mg151360 - Mg151500


Fig 3 TEM micrographs of precursor Mg15 and heated samples Mg151360-151500


Fig 4 Time dependence of the HD conversion on the Mg 252380 reagent


shown to proceed mainly on the surface of the nanoparticles leading to non-toxic products

even at ambient temperature

Reactivity of the nanosized MgO towards the toxic agents has been described more

profoundly by Wagner et al [4] The following basic knowledge has been revealed

All mentioned toxic agents can be detoximacred ie converted into their non-toxic

products within a reasonable time period so that the activity of the reagent is

versatile

The chemical activity of the MgO surface cannot be considered uniform but the

more active centres are preferentially located at activated sites or defects along the

surface of the nanoparticles eg edges corners etc

Heterogeneous reactions of the respective neat toxic agents exhibit two-stage kinetics

when proceeded on the MgO nanoparticle surface The initial fast stage can be

attributed to the reaction of a given agent at highly active reaction centres and

the second stage is explained as a process of slower transport of the agent along

surface from less active site(s) to more reactive one(s) The process of a secondary

redistribution of the neat agent over a surface was convincingly correlated with the

respective evaporation rate (agent vapour pressure) as to be a rate-limiting factor

The main aims of the work were

To investigate the respective method and procedure of preparation of the nanosized

magnesium oxide

Characterise the respective synthesised magnesium oxide samples

Evaluate the prepared oxides for their respective detoximacrcation activities

Assess whether the overall activity of the prepared oxides could be increased utilising

an eregective solvent which is potentially more capable of distributing the toxic agent

over the whole surface of the oxide

Magnesium oxide is commonly obtained by thermal decomposition of magnesium hy-

droxide or carbonate [6] [7] and more recently by a sol-gel process [8] [9] The oxide

morphology particle size and specimacrc surface area depend on the preparation conditions

(pH gelling agent calcinations rate and temperature) It has been documented that

methoxide or alkoxide-based solgel synthesis of metal hydroxides followed by supercrit-

ical drying and vacuum dehydration can lead to the formation of nanoparticles of metal

oxides [10-15]

In considering the ways in how to additionally facilitate the respective detoximacrcation

reaction the two following approaches may be proposed to stimulate the overall course

of the reaction namely

The initial uniform spreading of the agent over the whole surface

A degow of the agent along the surface

Since the capillarity of the toxic agents is limited the agent distribution over the surface

of the solid (powdery) reagent could be enhanced utilising a solvent that is capable of

both dissolving the toxic agent and wetting the powdery reagent surface thus penetrating

its whole deposit and spreading there evenly Moreover if the chosen solvent is volatile

enough it evaporates at the upper layers causing a slow but benemacrcial degux of the solvent



deposit (batch)





















































































sample Mg 252380



















experimental work











is unknown


















these results




































4 Conclusion






Acknowledgements



References






















Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142






XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382












deposit (batch)





















































































sample Mg 252380



















experimental work











is unknown


















these results




































4 Conclusion






Acknowledgements



References






















Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142






XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382




























































sample Mg 252380



















experimental work











is unknown


















these results




































4 Conclusion






Acknowledgements



References






















Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142






XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382












is unknown


















these results




































4 Conclusion






Acknowledgements



References






















Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142






XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382























4 Conclusion






Acknowledgements



References






















Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142






XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382


























Mg151 834 0 + 21 4166 1047 141

Mg16 102 0 + 21 510 754 078

Mg251 94 42 + 028 68 1099 138

Mg252 94 42 + 028 68 1236 142






XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382













XRD

Mg151360 360 537 035 Periclase 17

Mg152380 380 497 038 Periclase 20

Mg153400 400 377 042 Periclase 29

Mg154450 450 328 047 Periclase 36

Mg155500 500 288 056 Periclase 42

Mg16380 380 327 039 Periclase 19

Mg251380 380 246 038 Periclase 21

Mg252380 380 358 039 Periclase 20




Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382












Diethyl-

etherAcetone

Methyl

alcohol

NN-

Dimethyl-

pyrrolidone

Petrol-

ether


[mNmiexcl1]

167 235 220 - 177




0511 0392 0471 0487 0530



Mg reagent)

0207 0260 0298 0420 0295


age

1523 659 1367 336 458



595 336 366 138 442




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382












Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0303 0290 0235 0156 0286




392 419 529 688 427




Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382












Mg151 Mg252Mg151

380

Mg16

380

Mg252

380



Mg reagent)

0132 0144 0100 0057 0132




469 424 599 770 471




conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382












conversion) [min]

0 15 30 60 120 180



reagent)

0422 0363 0327 0299 0272 0261




00 139 224 291 355 382










Aerogel nanoscale magnesium oxides as a destructive sorbent for toxic chemical agents

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Transcript of Aerogel nanoscale magnesium oxides as a destructive sorbent for toxic chemical agents