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选择性溶解法

Methods for determination of degree of reaction of slag in blended cement pastes

Vanessa Kocaba ?,Emmanuel Gallucci,Karen L.Scrivener

Laboratory of Construction Materials,Ecole Polytechnique Fédérale de Lausanne,Lausanne,Switzerland

a b s t r a c t

a r t i c l e i n f o Article history:

Received 23May 2010

Accepted 14November 2011Available online xxxx Keywords:Slag

Degree of reaction SEM-BSE-IA-mapping Calorimetry

Chemical shrinkage

To measure the degree of reaction of slag in blended pastes,?ve methods were studied.Selective dissolution and differential scanning calorimetry are shown to be unreliable,SEM-BSE-IA-mapping is time consuming,but does provide good results with a reasonable degree of precision.The difference in cumulative calorimetry and chemical shrinkage curves of slag blends in comparison to blends with inert ?ller shows potential to iso-late the reaction of the slag.These methods have the advantage of being continuous,techniques with good precision,but the absolute heat of hydration,or contribution to chemical shrinkage of any particular slag is not known.Calibration of the calorimetry technique with SEM-BSE-IA-mapping seems to be a promising method to understand and quantify the degree of reaction of slag.

1.Introduction

The need to limit the environmental impact of cementitious mate-rials and to dispose of by-products such as slag leads to the increasing use of supplementary cementitious materials,either preblended with ground clinker or added during fabrication of concrete.It is well known that these SCMs react more slowly than cement clinker and this limits the levels of substitution,due to the need for adequate prop-erties at early ages.In order to better understand the factors affecting the rate of reaction of SCMs,it is essential to have a good method to evaluate the degree of reaction of these materials independently from the degree of reaction of the clinker component.

The classic method for measurement of degree of reaction is from the bound water content [1–3].However this depends on assumptions about the quantity of water bound by the hydrate phases.The following equations illustrate the amount of bound water depends on the phase reacting (number of reacting water molecules are shown in bold).

Hydration of tricalcium silicate:C 3S te3?x ty TH →C x \S \H y te3?x TCH

e1T

Hydration of dicalcium silicate:C 2S te2?x ty TH →C x \S \H y te2?x TCH

e2THydration of tricalcium aluminate with calcium sulphate:C 3A t3C t32H →C 6A 3H 32eettringite T

e3Tor

C 3A t3CH 2t26H →C 6A 3H 32eettringite T

e4T2C 3A tC 6A 3H 32t4H →C 4AH 12emonosulfoaluminate Te5TC 3A t6H →C 3AH 6

e6T

Hydration of tetracalcium aluminoferrite:C 4AF t3CH 2t30H →C 6A 3H 32tCH tFH 3

e7TC 6A 3H 32t2C 4AF t12H →3C 4AH 12t2CH t2FH 3e8TC 4AF t10H →C 3AH 6tCH tFH 3

e9TIt can be seen that even for typical Portland cements,the stoichi-ometry of the hydration reactions is not precisely known.In particu-lar it is known that the amount of water bound in the C \S \H varies with temperature and that the overall water combined by the alumi-nate containing phases changes over time due to sulfate and carbon-ate contents,and to the extent of ferrite reactions;all of which remain unclear [4,5].

When slag is present,the use of bound water as a measure of the overall degree of hydration becomes completely unreliable due to the unknown stoichiometry of the reactions,which will also depend on the slag composition and will be further complicated by the changes in C \S \H composition which occur in blended materials.

In recent decades,the use of image analysis [6]and quantitative X-ray diffraction [7–10],particularly coupled with Rietveld analysis,has proven to be effective for the measurement of the degree of reaction of clinker in cement pastes.There is good agreement between these techniques [8,11]which can also be used to compute the degree of reac-tion of the clinker components.In principle,these methodologies can

Cement and Concrete Research xxx (2012)xxx –xxx

?Corresponding author.

E-mail address:Vanessa.Kocaba@https://www.wendangku.net/doc/0718522092.html, (V.Kocaba).

CEMCON-04371;No of Pages 15

Contents lists available at SciVerse ScienceDirect

Cement and Concrete Research

j ou r n a l h o m e p a g e :h t t p ://e e s.e l s e v i e r.c o m /C E MC ON /d e f a ul t.a s p

also be used to measure the degree of reaction of the clinker component in blended systems.

Measurement of the degree of reaction of the SCM itself poses new challenges.The reactive part of most of these materials is amorphous, so it cannot be measured directly by X-ray diffraction but the homo-geneous regions of slag can be detected and quanti?ed by image anal-ysis[12,13].

Several authors[14–20]have used selective dissolution methods (discussed in more detail below)whose intention is to dissolve the re-action products and unhydrated cement,leaving the unreacted slag.It has also been suggested[1,21]that differential thermal analysis(DTA) can be used to recrystallise slag at high temperatures(between800°C and1100°C).Some studies[22–24]have reported the use of cumula-tive heat obtained from isothermal calorimetry or the volume changes associated with chemical shrinkage.The advantage of these methodol-ogies is that they are continuous and in-situ.The problem,however,is to convert the resulting curves to a degree of slag reaction.

This paper evaluates?ve methods to measure the degree of reac-tion of slag in blended pastes:

–Selective dissolution.

–Recrystallisation of slag from differential scanning calorimetry.

–Image analysis from BSE grey level images and EDS mappings from SEM.

–Cumulative heat evolution curves from isothermal calorimetry.

–Chemical shrinkage curves.

2.Previous work on the selected methods

2.1.Selective dissolution

This method is based on a preferential chemical dissolution of the hydration products and unhydrated cement[14–20]leaving the unreacted slag.In recent studies[19,20,25]a modi?ed method was pre-sented which was used in this work.Its principle is based on the as-sumption that clinker phases,their hydrates and the hydrates formed from the slag are mostly dissolved leaving the unhydrated slag as a res-idue.Ethylenediaminetetraacetic acid(EDTA),triethanolamine and so-dium hydroxide solution are claimed to dissolve the clinker minerals and calcium sulphate,at pH11.5,without a notable dissolution of the slag.Precipitation of silica and hydroxides is avoided by the addition of sodium hydroxide[14].By means of a comparative study,Luke and Glasser[17]concluded that this EDTA based modi?ed method of Demoulian[14]was the most suitable.

Previous researchers already noted that in fact the dissolution is incomplete.Taylor and Mohan[26]noted that large corrections must be made for incomplete dissolution of others phases,and esti-mated the error on the results to be about±10%.In previous studies [27,28],the authors mentioned that besides slag,some cementitious phases(such as periclase and aluminate)and hydrated phases from slag(hydrotalcite)are not dissolved either by selective dissolution. In addition,Goguel[29]identi?ed high amounts around2to5%of undissolved cement hydration products.

2.2.Differential thermal analysis/differential scanning calorimetry

One of the oldest method to determine the glass content of slag is thermal analysis:differential thermal analysis(DTA)is the most used [21,30–34]with differential scanning calorimetry(DSC)[35]as an al-ternative.The?rst reversible exothermic peak in the temperature range700–800°C corresponds to the glass-transition temperature T g.This transition temperature mainly depends on thermal history (cooling rate)and structure[36].The two exothermic peaks with well-de?ned maxima in the range925–1040°C are attributed to the devitri?cation https://www.wendangku.net/doc/0718522092.html,ing X-ray diffraction,these peaks were respectively assigned to merwinite(metastable phase)and melilite with minor components(such as larnite)[21,35].

It has been suggested that quanti?cation of the peaks could be used to determine the degree of reaction of slag[1,21,37,38].Howev-er,it is not always easy to isolate the contribution of anhydrous slag because of the background contribution.

2.3.Backscattered electron images analysis

Backscattered electron images(BSE/IA)allow phases to be identi-?ed according to their brightness,which depends on their average atomic number.Several studies have shown that the amount of unreacted cement measured this way corresponds well to the other in-dependent measures of degree of hydration[39].For a cement paste, Scrivener et al.[39]showed that ten?elds at400×magni?cation were suf?cient to give a standard error of around0.6%.Another statisti-cal analysis[40]showed that a set of30images at200×magni?cation gave a mean with an error of b0.2%in pastes and mortars.In this study [40]50?elds were analysed at200×magni?cation to obtain the lowest reasonable standard error.More recently,it was shown that the degree of hydration of cement measured by BSE/IA agrees well with that obtained by X-ray diffraction–Rietveld analysis[8].

The amorphous component of a given slag source generally has a homogeneous grey level,which should allow it to be identi?ed by image analysis.Brough and Atkinson[12,13]used this to quantify the degree of reaction of slag in alkali-activated cement mortars. Therefore,BSE/IA seems to have good potential for slag blended systems.

2.4.Isothermal calorimetry

Isothermal calorimetry is mainly used to the heat released by the hydration reaction at early ages(?rst24h)while at longer times the heat output is quite low and hardly resolved from the back-ground.Nevertheless previous researchers[41,42]suggested that fol-lowing the long term heat evolution of blended pastes could allow the reaction of supplementary cementitious materials to be monitored. This technique is investigated in the present study.

2.5.Chemical shrinkage

Measurement of chemical shrinkage is based on the fact that the volume occupied by the hydration products is lower than that of the reactants.This is due to the fact that“water”has a lower speci?c volume when bound to a solid than when free in a liquid as re?ected in the following equation:

V cement t?0

eTtV water t?0

eT>V hydrates teTe10TWhere:

V cement(t=0):initial volume of cement;

V waters(t=0):initial volume of water;

V hydrates(t):volume of hydrates at time t.

The method chosen here is dilatometry based on the protocol developed by Geiker[24]and optimised by Costoya[43].

3.Materials and methods

3.1.Materials

The chemical compositions of the three cements and the two slags investigated are given in Table1.

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3.2.Mix design and sample preparation

60%wt of cement and 40%wt of slag were preblended together for 5h in a TURBULA shaker –mixer to ensure a good homogenisation of the mixture.Hydrated mixes were prepared at room temperature (20°C)with deionised water.To avoid any scattering of measured data due to the quantity of mixed components,160g of paste were mixed in one batch to provide all the specimens for all analyses (calorimetry,chemical shrinkage,SEM and XRD).The cementitious pastes were mechanically mixed (IKA LABORTECHNIK RW20.n)at a speed of 500rpm for 3min,stopped for 2min and ?nally mixed at 2000rpm for 2min.The neat cement pastes were prepared at a water to cement ratio (by weight)of 0.40while the water to cement ratio of the blend pastes was adapted so that the volume to water binder remains the same as for the pure cement;this corresponds to a 0.42water to solids ratio by weight for the 40%slag blend.

The hydration was stopped at different ages ranging from a few hours to several days.At early ages the hydration was stopped by freeze-drying.The sample was frozen at ?80°C in a cold mixture of solid CO 2and liquid ethanol and subsequently dried by sublimation.At later ages,the water in older samples was removed by solvent ex-change in isopropanol for one week.Once dried,all specimens for SEM examination were impregnated under vacuum in an epoxy resin (EPOTEK 301)and carefully polished with decreasing grades of diamond powders down to 1/4μm.3.3.Selective dissolution

Selective dissolution was used according to the protocol given by Luke and Glasser [17]and recently used by Dyson [25].The following solutions were used:

–0.05M ethylenediaminetetraacetic acid (EDTA);–0.1M Na 2CO 3solution;

–a 1:1solution (by volume)of triethanolamine:water mixture;–1.0M NaOH.

The different steps are the following:

–125mL of EDTA and 125mL of Na 2CO 3were mixed together in a one litre conical ?ask.

–12.5mL of the triethanolamine/water mixture was then added and the pH was checked to be 11.6±0.1.If necessary,the pH was adjusted by addition of small quantities of 1.0M NaOH.

–A 0.25g of ground sample was then weighed and slowly added to the mixture in the conical ?ask while agitating the ?ask to avoid agglomeration.

–The mixture was shaken in a mechanical shaker,for 30min.

–The mixture was ?ltered through a vacuum ?lter using GF/C ?lter paper supported on a glass frit (before use the GF/C ?lter paper was dried at 105°C and weighed).

–Care was taken to wash all residual material from the conical ?ask and also the walls of the funnel on to the ?lter.

–The residue on the ?lter paper was washed with deionised water seven times and three times with methanol.

–The ?lter paper was carefully removed and dried in an oven at 105°C until a constant weight was achieved.This method was followed for cement,and cement plus slag hy-drated samples.In order to study the reliability of the selective

Table 1

Chemical composition of raw materials from X-ray ?uorescence analysis.Oxides Cement A Cement B Cement C Slag 1Slag 8Error SiO 224.6820.5121.0136.6134.600.40Al 2O 3 2.11 5.10 4.6312.2119.980.20Fe 2O 30.43 3.33 2.600.850.470.10CaO 68.6761.2964.1841.5932.480.40MgO 0.58 2.82 1.827.189.170.10SO 3 1.82 2.78 2.780.63 1.990.10K 2O 0.06 1.400.940.280.780.04Na 2O 0.170.240.200.180.160.03MnO 0.010.050.030.140.060.01TiO 20.050.190.140.350.670.01P 2O 50.450.370.400.010.010.01LOI 0.97 1.94 1.26?0.03?0.370.10Na 2Oeq 0.22 1.160.810.360.670.07CO 2 1.300.80 1.40––0.20Total

100

–

Fig.1.Schematic grey level histogram for hydrated cement –slag paste at 20

°C.

Fig.2.Grey scale histograms showing the different components of Cement A –Slag 1paste at 28days (a)before and (b)after application of a median ?lter.

V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

dissolution,the residues were analysed by X-ray diffraction and ex-amined by SEM.

3.4.Differential scanning calorimetry

Differential scanning calorimetry measurements were made with a Netzsch DSC/DTA Model 404C Pegasus,using a 10°C/min heating rate.The hydrated samples were ground,weighed (20±4mg)and placed in an alumina crucible pan,with an empty alumina crucible as a reference.A nitrogen ?ux was maintained in the heating chamber to avoid carbonation of the samples during the experiment.

3.5.Image analysis from BSE grey level images and EDS mappings from SEM

The polished sections were studied in backscattered electron (BSE)mode using a FEI quanta 200SEM at an accelerating voltage of 15

kV.

Fig.3.BSE-image analysis combined with elemental mapping illustrated on example of Cement A –Slag 8paste at 90

days.

Fig.4.Heat ?ow of 3cements with different experimental conditions.

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The phases were discriminated on the basis of the grey level histogram as shown in Fig.1.

Slag 1had a grey level suf ?ciently different from that of calcium hydroxide (CH)to allow its discrimination on the basis of the grey level only and after the application of a median ?lter,as illustrated in Fig.2.A median ?lter replaces a pixel value by the median value of the pixels in the ?lter (3×3)and reduces the noise produced by imperfections in the image,while preserving strong contrast varia-tions.On the other hand,Slag 8had a composition and density which lead to a grey level matching exactly that of CH,which pre-vents the discrimination of the two phases on the basis of grey level segmentation.Therefore,in order to have a consistent methodology the slag in both systems was discriminated and segmented on the basis of their chemical signature using EDS chemical mappings of magnesium (signi ?cant levels of magnesium being present in the slag while not in CH)in addition to grey level as described below.

The challenge of this approach is the time to acquire Mg maps with a conventional EDS detector.To improve this,a silicon drift detector (SDD),type XFlash 4030Detector from Bruker AXS Microanalysis was used

which can accept a maximum input count rate of one million counts per second (cps).It also has a large active detecting area of 30mm 2(com-pared to 10mm 2for the conventional EDS detector)and at the same time achieves very good energy resolution of 133eV (Mn K α)at 100,000cps.Even with this fast detector the time required to acquire 150–200?elds was about 10h,but this was automated to run overnight.

For all blended systems,as illustrated in Fig.3,the procedure consisted of:

?Acquisition of 150–200BSE images (recorded in 30s)combined with Mg maps (recorded in 1min 30s),at a nominal magni ?ca-tion of ×1000(corresponding to 254×190μm),at an accelerating voltage of 15kV and a number of counts between 80,000and 100,000cps.

?Image analysis processing which combined the BSE image with the Mg map.The grains of unreacted slag were identi ?ed when the grey level of the pixel corresponded to the slag (from the BSE image)and contained Mg (from the EDS mapping image).?Calculation of the degree of reaction according to Eq.(15).

Table 2

Undissolved materials and corresponding degree of reaction of slag after selective https://www.wendangku.net/doc/0718522092.html,bel of samples

Undissolved materials (%)Degree of reaction of slag (%)Average

Standard deviation Average Standard deviation Anhydrous S860.1 6.0––Anhydrous A-S867.5 5.7––Anhydrous B-S863.8 5.0––Anhydrous C-S8

61.9 5.9–

–A-S8hydrated for 1day 71.6 1.8?79.0 4.4B-S8hydrated for 1day 66.5 1.8?66.3 4.6C-S8hydrated for 1day 65.2 5.8?63.114.6A-S8hydrated for 90days 72.8 4.2?82.010.5B-S8hydrated for 90days 77.4 3.5?93.58.8C-S8hydrated for 90days

70.1

4.0

?75.1

9.9

Fig.5.XRD patterns of Cement B hydrated 90days and Cement B –Slag 8hydrated 90days after selective

dissolution.

Fig.6.BSE image of Cement B –Slag 8hydrated 90days after selective dissolution (C:Cement and S:Slag).

V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

3.6.Isothermal calorimetry

The heat of reaction of the pastes at 20°C was measured with an iso-thermal calorimeter (TAM Air from TA instruments).It consists of 8par-allel twin measurement channels maintained at a constant temperature:one from the sample,the other for the reference sample.

Preliminary work [44]underlined that it is critical to balance the speci ?c heats of the sample and reference,particularly for measure-ments over the long time periods used here,where the rate of heat evolution becomes very low.In this work,the reference was deionised water calculated to have the same speci ?c heat as the paste [45]:

C paste p

x water C water p

x cement C cement

e11T

Where:

x water :mass fraction of water in paste;

x cement :mass fraction of cement in paste;C p

water

:speci ?c heat of water;C p

cement

:speci ?c heat of cement.Considering,the water-cement ratio of 0.4,C p water

=4.18J.g ?1.K ?1

[46]and C p cement

=0.75J.g ?1.K ?1(based on the measured values for tricalcium silicate and dicalcium silicate [47])we found a speci ?c heat of cement paste of 1.73J.g ?1.K ?1.The optimal quantity of paste was 15g with a 6.2g glass ampoule of water as a reference.

The thermal inertia is expressed by the time constant of a calorim-eter which depends on two parameters:the sample heat capacity and the heat transfer properties of the calorimeter.The measured time constant has been used to correct the output signal (Tian correction)

for the thermal inertia of the calorimeter especially at very early ages as shown below:P t eT?εU tτ

e12T

With:

P (t ):the thermal power produced in the sample (Watts);U :the voltage output of the heat ?ow sensors (Volts);ε:the calibration factor (W/V);

τ:the time constant of the calorimeter (s)which has been calcu-lated to be 4min.

Fig.4shows the importance of correct calibration and choice of reference sample to the rate of heat evolution curves.Although the general shapes of the peaks are similar,the absolute values vary,which can lead to substantial errors when the total heat evolution is calculated by integration over long times.3.7.Chemical shrinkage

The chemical shrinkage setup was designed and optimised at EPFL [43]and it consists of a cylindrical ?ask (2cm height by 1cm of diam-eter)that contains the paste,on top of which a pipette is connected.The level of paste introduced in the ?ask was kept constant in all measurements and equal to 1cm (5g of paste).The paste was tapped in order avoid the presence of entrapped bubbles.Water was added immediately to the top of the paste,taking special care to avoid as much as possible the dilution of the paste.

Table 3

Results of analysis of residues after selective dissolution.

100%dissolved phases

Partly dissolved phases Non-dissolved phases Anhydrous A-S8C 3S,C 2S,C 3A,anhydrite

–Slag 8Anhydrous B-S8C 2S,C 3A,C 4AF,anhydrite C 3S Slag 8Anhydrous C-S8C 2S,C 3A,anhydrite C 3S

C 4AF,Slag 8Hydrated A-S8Ettringite

C 3S,C 2S,C \S \H,CH Hydrotalcite,Slag 8Hydrated B-S8C 4AF,ettringite C 3S,C 2S,C \S \H,CH Hydrotalcite,Slag 8Hydrated C-S8

C 4AF,ettringite

C 3S,C 2S,C \S \H,CH

Hydrotalcite,Slag

Fig.7.Degree of reaction of slag from selective dissolution after corrections suggested in [17]

Fig.8.DSC curves of anhydrous

powders.

Fig.9.DSC curves of Cement A blended with Slag 8at different ages.

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Water is added on top of the cement paste until it ?lls also the pi-pette.The system is sealed at the interface between the pipette and the ?ask with rubber lids and on top of the pipette with a coloured oil drop.This coloured oil drop is used as a tracer in the image analy-sis of the pictures of the capillary taken with a webcam.The ?asks are maintained in a thermostatic bath at 20°C to avoid effects of heat re-lease on volumetric changes of the paste.

As the hydration proceeds and the paste shrinks,the level of water in the pipette decreases.This level is monitored using a webcam con-nected to a computer that allows automated acquisition every 5min.To extract the level of water in the pipette,the pictures were numer-ically processed.Each curve presented is the average of a minimum of 3,but mostly 6,replicates of a cement paste system.

4.Results and discussion 4.1.Selective dissolution

Considering that the selective dissolution does dissolve the unhy-drated cement grains and their hydration products,leaving only

the

Fig.10.Method for background removal algorithm on DSC curve of Cement A –Slag 8hydrated 7

days.

Fig.11.Apparent degree of reaction of Slag 8from DSC in Cement A –Slag 8blended pastes.

V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

unreacted slag grains as undissolved residue,the degree of hydration of slag grains in pastes can be calculated from Eq.(13):αSelectivedissolution

SLAG

R cement ?R paste

R cement

e13T

Where:

R cement :undissolved residue from the blended anhydrous cement;R paste :undissolved residue from the cement paste.

Table 2shows the percentage of non-dissolved materials and the supposed degree of reaction of slag for the hydrated mixes.From the data it is evident that the undissolved materials (expressed as a per-centage of the total amount),do not correspond only to the unreacted slag because the percentage is much higher than the initial content of the slag (40%wt),which would imply a negative degree of reaction.

In order to study the reliability of the selective dissolution,the res-idues were examined by XRD and SEM.The residues showed undis-solved phases (other than slag)in both the anhydrous blends and hydrated samples.Fig.5shows XRD patterns of Cement B hydrated for 90days and Cement B –Slag 8hydrated 90days after selective dis-solution.The pattern of Cement B clearly shows the presence of phases from the cement that selective dissolution should remove in the blended pastes:notably belite and portlandite.The pattern from the blended paste also indicates the presence of hydrotalcite from the hydration of slag and which should also be removed by the selec-tive dissolution.Fig.6shows the residue from the selective dissolu-tion of Cement B –Slag 8hydrated 90days,embedded in resin and polished for examination by SEM-BSE,this clearly shows the presence of undissolved cement grains,hydrated phases and agglomerates.

The characterisation of the different phases in the selective disso-lution residues by XRD analysis and SEM is summarised in Table 3.For the anhydrous blends,selective dissolution did not completely dis-solve the clinker phases for Cements B and C.Dissolution was better for Cement A probably due to its higher ?neness compared to Ce-ments B and C.For the hydrated mixes,only ettringite and ferrite were 100%dissolved,the other anhydrous and hydrated

phases

Fig.12.Degree of reaction of slag from SEM-BSE-IA-mapping in (a)systems A,(b)systems B and (c)systems

C.Fig.13.Degree of reaction of (a)Slag 1and (b)Slag 8from SEM-BSE-IA-mapping in blended pastes.

8V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

were not completely dissolved and hydrotalcite was also observed in the residues by XRD.

Since the sample mass of0.25g appeared very small,measure-ments were repeated adapting the procedure with higher masses (0.5g,1.0g and1.5g)and some tests with smaller?ltration system were also conducted.These modi?cations made no signi?cant differ-ence to the results.

Some authors[17]have proposed a modi?cation to recalculate the degree of reaction of slag with the following formula:

αSelectivedissolution SLAG teT?100?

w2t%SLAG t?0

eT%DISSOLVEDSLAG w1

eT?%CEMENT t?0

eTC r w1

SLAG1

100

e14T

Where:

w1:weight of sample(ignited weight);

w2:weight of residue(105°C dry weight);

C r:percentage of residue from cement divided by100;

%SLAG(t=0):percentage of initial slag in the blended cement

(equal to40%);

%CEMENT(t=0):percentage of initial cement in the blended ce-ment(equal to60%).

%DISSOLVED SLAG:assumption of6%of slag dissolves.

This approach gives the results shown in Fig.7.Although the degrees of reaction are now positive,they are very high,especially at1day.

It might be argued that further work,for example,on optimising the grinding process could have led to better results for the selective disso-lutions method.However,this underlines the problem of the reproduc-ibility of the method betweens labs.In a recent study of selective dissolution methods for?y ash,Ben Haha et al.[48]noted the different assumptions needed to calculate the amount of reaction are a major cause of errors,which renders such methods inadequate for quantifying the degree of reaction.It is also clear from the literature that very diver-gent results are reported for this method by different workers studying nominally similar slags:For example,Escalante et al.[20]?nd degrees of reaction of about20%after3months compared to values of around 40%reported by Luke and Glasser[17]and Lumley et al.[19].

In the light of the current results and the diversity of results in the literature,we consider,that;while such methods could be suitable to enrich materials with respect to certain phases for other characterisa-tion methods such as NMR[28,49],they are not reliable for the quan-titative determination of the degree of reaction.

4.2.Differential scanning calorimetry

Fig.8shows the DSC curves of three anhydrous powders:pure Ce-ment A,pure Slag8and the A-S8blended powder.For the raw slag and the blended powder,the recrystallisation peaks of slag can be identi?ed between850and1050°C.The objective was to isolate and measure the recrystallisation peak in order to quantify the degree of reaction of slag.The experiments were conducted on one blended system(Cement A–Slag8).The DSC curves at various hydration times(Fig.9)show that the recrystallisation peak decreases with time,but there is also a strong change in the background.The large contribution of the background was already noted in previous DSC analyses on plain OPC[50].

To remove the contribution of the background,a manual method with the DSC software was judged too subjective.So a background re-moval algorithm was applied with two different choices of reasonable backgrounds which led to two different degrees of reaction of slag for each analysed sample.An example of the method is shown in Fig.10 and the results are shown in Fig.11.As for results from selective dis-solution,it is seen that there is an unreasonably high degree of hydra-tion at7days and little evolution in time thereafter.It was concluded that the DSC method was unreliable due to the large error produced by the background.

4.3.Image analysis from BSE grey level images and EDS mappings from SEM

Assuming the original volume of the slag in the paste,the degree of reaction of slag can be estimated by image analysis of the area frac-tion(equivalent to volume fraction)remaining at a given time:

αSEM‐IA

SLAG

teT?

Vf anhydrousslag t?0

eT?Vf anhydrousslag teT

anhydrousslag

e15TWhere:

Vf anhydrous slag(t=0):remaining volume fraction of initial anhy-drous slag;

Vf anhydrous slag(t):remaining volume fraction of unreacted slag after time t.

Fig.12shows the degree of reaction of slag for all the systems as a function of type of cement.With the fast EDS detector it was possible to obtain results with reasonable precision;the errors indicated in Fig.12take into account the deviation between different sets of im-ages from the same sample and the deviation from different possible treatments to de?ne the border of slag grain.The errors are higher

Fig.15.Degree of reaction of Slag8from SEM-BSE-IA-mapping,DSC and selective dissolution.

0,0110100

100

(

)

Time (days)

DR-SEM of S8 in A-S8

DR-SEM of S8 in B-S8

DR-SEM of S8 in C-S8

DR-Dissolution of S8 in A-S8

DR-Dissolution of S8 in B-S8

DR-Dissolution of S8 in C-S8

Fig.14.Degree of reaction of Slag8from selective dissolution and SEM-BSE-IA-mapping.

V.Kocaba et al./Cement and Concrete Research xxx(2012)xxx–xxx

early ages.The results clearly show that Slag 8is more reactive than Slag 1.Fig.13shows the degree of reaction of slag for each slag for the different cements.It seems that the reaction of slag is not strongly affected by type of cement.

The results from SEM-BSE-IA-mapping are compared to the ones from selective dissolution and DSC in Figs.14and 15.These indicate that selective dissolution and DSC signi ?cantly overestimate the de-gree of reaction of slag at early ages.

Despite being a time consuming method,the determination of the degree of reaction of slag using SEM with image analysis and elemen-tal mapping treatment appears to be the most reliable of the methods based on analyses of the systems as discrete time intervals.4.4.Isothermal calorimetry

Fig.16shows the cumulative heat evolution curves,normalised to clinker content,of pastes blended with Cement B over a period of 28days.The heat evolved from the blended pastes (normalised per gram of cement (i.e.ground clinker plus calcium sulfate compo-nent))rapidly surpasses that of the 100%cement paste.This differ-ence includes both the contribution from the reaction of the slag itself and the impact of the physical presence of slag on the rate of hy-dration of the clinker phases,?ller effect .The ?ller effect consists of two possible elements.As the ?ller does not react,the space available for the hydrates of the clinker is increased which leads to a higher de-gree of reaction of the cement.For ?llers with high surface area there may be an additional effect of stimulating nucleation.To sepa-rate these effects,a blend with 40%quartz (presumed inert)was used as another reference.The quartz was ground to have a similar particle size range as the slag (d 50of ?ller=10μm and d 50of Slag 1=20μm and d 50of Slag 8=15μm).For each cementitious sys-tem,all calorimetry experiments were run in concurrently over 28days.To insure a good accuracy of the results and to verify

the

Fig.17.(a)Cumulative heat per gram of anhydrous and (b)resulting difference curves which isolate the slag

contribution.

Fig.16.Normalised cumulative heat curves for (a)systems A,(b)systems B and (c)systems C.10V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

stability of the baseline,all the experiments were repeated twice.Fig.16shows that the repeatability between different batches was good even for long term acquisition.

The divergence of the curves from the ?ller reference is attributed to the reaction of the slag itself.In agreement with the image analysis results Slag 8is clearly more reactive than Slag 1.In order to quantify the contribution of slag the curve of the blend with quartz is sub-tracted from that of the blend with slag and then normalised by the amount of slag,Fig.17.However the resulting curve of J.g ?1of slag cannot be directly related to a degree of reaction as we do not know the heat evolved by the reaction of a unit weight of slag.A value of 460J.g ?1of slag can be found in the literature [51],but,it seems [52]this was derived from the adiabatic heat rise in the ?rst day,when the degree of reaction of slag is negligible and in fact describes the ?ller effect of slag on the hydration of cement.Some old papers [53,54]suggest to use of the solubilities of hydroxides which form hy-drates of slag to calculate the enthalpy of slag,but the values obtained by this method were too high to be reasonable.

To obtain calibration values for the enthalpy of slags,the difference curve from calorimetry was compared to the values of degree of reac-tion from image analysis (Fig.18).Given the larger error in the BSE-IA results at early ages the curves were calibrated from the values at 28days giving the values shown in Table 4.Although one may expect the calibration factors to be the same for the same slag with different cements higher values are found for systems B with Cement B and Slag 1.The reasons for this discrepancy are not yet

understood.

Fig.18.Calorimetry curves calibrated with SEM-BSE-IA-mapping in (a)systems A-S1,(b)systems A-S8,(c)systems B-S1,(d)systems B-S8,(e)systems C-S1and (f)systems C-S8.

V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

4.5.Chemical shrinkage

For chemical shrinkage,an approach analogous to that described for calorimetry was used.For each system,the curve of?ller was sub-tracted from the blended one to isolate the contribution of the slag. Fig.19shows a good repeatability between two different batches. Here again,the curves indicate the higher reactivity of Slag8compared to Slag1in all blended pastes.The plot of calorimetry versus chemical shrinkage shows a linear relation for pure and blended pastes,Fig.21. This indicates no major change in the nature of reaction or density of hydration products for the plain and blended systems.

As explained above for calorimetry,an independent calibration of each chemical shrinkage curve was made using the degree of reaction of the slag from SEM-BSE-IA-mapping(Fig.20).The calibration factors used the28days as the reference values(see Table5).As previously found for calorimetry,the calibration factor is higher for system B-S1.

5.Conclusions and discussion

A number of methods were studied to determine the amount of slag reacted in hydrated blended systems.Two of these methods—selective dissolution and thermal analysis,did not give reasonable re-sults in this study.

The results presented indicate that the most promising methods to study the degree of reaction of the slag are image analysis and iso-thermal calorimetry or chemical shrinkage.

By image analysis the degree of reaction can be measured directly from the amount of unhydrated slag remaining.However this method has some limitations:

?First it is rather time consuming,the essential prerequisite is a well polished sample,this takes5h and due to the differential hardness of the slag it is especially dif?cult to obtain good sample preparation at young ages(up to one day).

?Second the differentiation of the slag grey level alone is not reli-able for some compositions,due to the close similarity of the grey levels of slag and calcium hydroxide.For some slag composi-tions,the use of appropriate?lters can differentiate these two phases,but nevertheless these image processing steps will mean that very small particles are not well measured,which increases the error at young ages.For other compositions the BSE images must be combined with Mg maps to isolate the slag,which re-quires an image acquisition time of around10h(although this

process can be automated and carried out overnight).In both cases,the low amount of slag remaining leads also to relatively low precision in the degree of hydration.

Isothermal calorimetry,if performed in a well calibrated and sta-ble instrument is a potentially powerful method to measure degree of reaction.The technique provides continuous and precise values, but is dif?cult to calibrate.Calibration against the image analysis re-sults was done in this study and some results seem anomalous,so clearly more work is needed on a wider range of materials.

Chemical shrinkage measurements give results analogous to iso-thermal https://www.wendangku.net/doc/0718522092.html,ing the methodology described here,this is by far the least expensive method.

Table6summarises the main parameters in different methods. The validity of our quanti?cation of slag reaction was veri?ed using comparison with results from NMR given by Poulsen[55,56].It is very dif?cult to determine the degree of hydration for slags directly from the29Si MAS NMR spectra due to severe overlap of the slag peak with the resonances from alite,belite,and the C\S\H

phase Fig.19.Evolution of chemical shrinkage for(a)systems A,(b)systems B and (c)systems C.

Table4

Calibration factor to correlate difference of cumulative curves from calorimetry with degree of reaction of slag from SEM-BSE-IA-mapping.

Degree of reaction of slag from SEM-BSE-IA-mapping Cumulative heat

(J.g?1of slag)

Calibration factor

(J.g?1of slag)

A-S1at28days0.418±0.008182±10436±32

B-S1at28days0.326±0.014170±10521±53

C-S1at28days0.375±0.014165±10440±43

A-S8at28days0.554±0.009237±10428±25

B-S8at28days0.508±0.012213±10419±30

C-S8at28days0.552±0.009223±10404±25

12V.Kocaba et al./Cement and Concrete Research xxx(2012)xxx–xxx

of the hydrating cement.Therefore,a new method based on 27Al MAS NMR was used to obtain quantitative estimates for the degree of slag hydration.

Fig.22shows that the results from NMR are a bit lower than the ones from SEM-BSE-IA-mapping for systems A-S1and C-S8.However,

for

Fig.21.Calorimetry versus chemical shrinkage results for systems A.

Table 5

Calibration factor to correlate difference of chemical shrinkage curves with degree of reaction of slag from SEM-BSE-IA-mapping.

Degree of reaction of slag from SEM-BSE-IA-mapping

Chemical shrinkage (mL.g ?1of slag)Calibration factor (mL.g ?1of slag)A-S1at 28days 0.418±0.0080.0128±0.0025 3.1E ?02±6.6E ?03B-S1at 28days 0.326±0.0140.0154±0.0025 4.7E ?02±9.7E ?03C-S1at 28days 0.375±0.0140.0131±0.0025 3.5E ?02±8.0E ?03A-S8at 28days 0.554±0.0090.0163±0.0025 2.9E ?02±5.0E ?03B-S8at 28days 0.508±0.0120.0177±0.0025 3.5E ?02±5.7E ?03C-S8at 28days

0.552±0.009

0.0206±0.0025

3.7E ?02±5.1E ?

Fig.20.Chemical shrinkage calibrated with SEM-BSE-IA-mapping for (a)systems A-S1,(b)systems A-S8,(c)systems B-S1,(d)systems B-S8,(e)systems C-S1and (f)systems C-S8.

V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

system A-S8,there was a good agreement with SEM-BSE-IA-mapping results.At present the errors for the NMR method are not well estab-lished.However,the NMR results also clearly show that the Slag 8was more reactive than Slag 1and con ?rm that the values obtained by selec-tive dissolution and DTA at early ages are over estimates.

All our investigations indicated that Slag 8(high alumina and alka-li contents)had a higher reactivity than Slag 1(high amorphous con-tent).This difference in reactivity was con ?rmed for reaction of slag

in pure NaOH solution as shown by the calorimetry results for such systems in Fig.23.Slag 8is quickly and strongly dissolved in NaOH so-lution comparing to Slag 1which reacts more slowly.

The relative rate of reaction of Slag 8and Slag 1can be compared with different reactivity indices.For example,Fig.24plots M1=CaO/SiO 2and M5=(CaO+MgO+Al 2O 3)/SiO 2against degree of reaction of slag from SEM.These reactivity indices rank the two slags differ-ently,and while the ranking given by the M5index corresponds to the ranking of reactivity by image analysis it is not possible to draw further conclusions based on the study of only two slags.

Comparison of the effects of using low and high alkali cement (re-spectively Cements C and B)in combination with slag did not indicate any signi ?cant difference in reaction rate at early ages.In this work,it was observed that the differences in cement clinker had very little impact on the reaction of the slags.

Acknowledgments

The authors thank the NANOCEM consortium for funding this study.Dr Shashank Bishnoi is thanked for the program to process the chemical shrinkage data.Dr Cyrille Dunant is thanked for his con-tribution to establish the background removal algorithm to treat the DSC curves.Dr Patrick Juilland is thanked for his help to perform the calibration and the stability of the calorimeter.Dr S?ren Poulsen and Professor J?rgen Skibsted are thanked for their results on degree of reaction of slag obtained by NMR.

Table 6

Comparison between different methods used to calculate the degree of reaction of slag.Method

Type of measurement Time of acquisition per sample Time to treat the

results

Comments Selective dissolution

Discrete 20min 5min

Remaining undissolved phases which induced large errors on the degree of reaction of slag

DSC Discrete 2h 20min

Overlap between peak of belite and the one of slag which does not allow to isolate the slag contribution SEM-BSE-Image analysis-mapping Discrete 10h 1h Good accuracy but time consuming

Calorimetry Continuous 1h Needs to be calibrated with an external method Chemical shrinkage

Continuous

Needs to be calibrated with an external

method

https://www.wendangku.net/doc/0718522092.html,parison of degree of reaction of (a)Slag 1and (b)Slag 8from NMR and

SEM-BSE-IA-mapping.Fig.23.Heat curves of both slags activated by NaOH

solution.

Fig.24.Reactivity indices M1and M5versus degree of reaction of slag from SEM-BSE-IA-mapping.

14V.Kocaba et al./Cement and Concrete Research xxx (2012)xxx –xxx

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试剂溶解方法

试剂溶解方法(供参考) 试剂名称溶解方法 ABA 脱落酸溶于碳酸氢钠水溶液、氯仿、丙酮、乙酸乙酯和乙醚，微溶于苯和水。 ACES 该品0.1ml/L水溶液（20℃），PH值为3.0－4.5 丫啶橙溶于水和乙醇。水溶液带橙黄色荧光。PH值8.4－10.4（由无色至黄绿色）丙烯酰胺无色透明片状结晶。溶于水、乙醇、丙酮、乙醚和三氯甲烷，微溶于甲苯，不溶于苯和庚烷。腺苷溶于水，微溶于乙醇和乙醚。 ADP Na2 5′-二磷酸腺苷二钠溶于水。琼脂缓溶于热水成湖状，呈中性。不溶于冷水和乙醇。琼脂糖溶于热水，遇冷凝结成胶 L-丙氨酸溶于水，微溶于乙醇，不溶于乙醚和丙酮。卵清白蛋白溶于水和缓冲液 BSA V 牛血清白蛋白V 溶于水、氯化钠溶液及缓冲液后，成澄清溶液。过硫酸铵溶于水，但能缓慢水解并生成过氧化氢，热至120℃开始分解。苦杏苷味苦，溶于水和乙醇，不溶于乙醚。

AMV反转录酶溶于PH缓冲液中，一般试剂1ul含有10－100单位。 α-淀粉酶溶于水 L-精氨酸易溶于水，不溶于乙醇和乙醚。 L-精氨酸盐酸盐溶于水，微溶于乙醇。抗坏血酸（维生素C）溶于水，微溶于乙醇，不溶于乙醚、苯、三氯甲烷和石蜡醚等。 L-天门冬酰胺无色或白色晶体。溶于酸和碱溶液，不溶于乙醇、乙醚和苯。 L-天门冬氨酸溶于热水和稀酸，不溶于乙醇。 ATP Na2 溶于水。 BCIP 5-溴-4-氯-3-吲哚磷酸 BCIP的钠盐用水溶，BCIP游离酸用DMSO溶。 6-BA 6-苄氨基嘌呤溶于稀碱、稀酸溶液，不溶于乙醇。 BES 溶于水。生物素较易溶于热水和稀碱溶液，水溶液极易生长霉菌。 Bis-Tris 溶于水。溴酚蓝溶于乙醇、乙醚、苯和稀碱溶液，微溶于水。 CAPS 溶于水。

细胞因子溶解方法

细胞因子溶解方法 PeproTech细胞因子中不含载体蛋白（Carrier Protein）或其他添加剂（如BSA、HAS或蔗糖等），并且通常以最少量的盐来进行冻干处理，因此微量的细胞因子在冻干过程中会沉积于管内，形成很薄或不可见的蛋白层。所以我们建议在收到产品后，务必在开盖前先离心，使粘在管盖或管壁上的蛋白聚集于管底（此时能否见到白色沉淀均属正常现象）。 1．离心：高速离心 (10, 000 rpm) 20-30 秒，或低速离心 (2, 000 rpm) 5 分钟。 2．溶解（Reconstitution）：用去离子水或其它缓冲液（根据说明书要求进行选择）溶解至说明书要求的浓度 (一般为 0.1-1.0 mg/mL，如10ug的产品，需用10uL-100uL的去离子水或缓冲液溶解)。溶解时不可振荡，避免因化学键的断裂造成蛋白失活，可加入适当的溶剂轻摇并静置一段时间，待细胞因子完全溶解后使用。溶剂的选择： 1）要求用去离子水溶解的产品，务必不可用盐溶液，避免过高的盐浓度造成蛋白不可逆的析出； 2) 要求用盐溶液溶解的产品，请依照说明书上的浓度，同样也是为了避免过高的盐浓度。 3．分装和贮存（Aliquot and Storage）：蛋白溶解后可根据自己的实验需要进一步稀释成工作液，稀释可用RPMI 1640、DMEM或PBS等溶液，其中最好含有5-10%的FCS （小牛或胎牛血清）或0.5 %的BSA（牛血清白蛋白）来稳定蛋白。工作液在4℃可保存1周，如需长期保存，则需分装冻存于-20℃ （注意：不可冻存于-80℃）。分装时每管中工作液的体积最好是一次实验的用量，以实现每次实验用完一只工作液，避免反复冻融引起蛋白活性的降低。

实验室抗生素溶解方法

抗生素概念、作用机制简介及实验室常用抗生素抗生素概念：（Antibiotic）是微生物(例如：放线菌)的代谢产物或合成的类似物，在体外能抑制微生物的生长和存活，而对宿主不会产生严重的副作用。抗生素基本上可分为二大類，一为抑制病原的生長，一为直接殺死病原。 ?可用于治疗大多数细菌感染性疾病。 ?除了抗感染外，某些抗生素还具有抗肿瘤活性，用于肿瘤的化学治疗。 ?有些抗生素还具有免疫抑制和刺激植物生长作用。 ?抗生素不仅用于医疗，还应用于农业、畜牧业和食品工业等方面。在畜牧业中非治疗用途的抗生素，稱为生長促進劑。杀菌或抑菌机制： 1.抑制细菌细胞壁的合成：抑制细胞壁的合成会导致细菌细胞破裂死亡，以这种方式作用的抗菌药物包括青霉素类和头孢菌素类，哺乳动物的细胞没有细胞壁，不受这些药物的影响。 2.与细胞膜相互作用：一些抗菌素与细胞的细胞膜相互作用而影响膜的渗透性，这对细胞具有致命的作用。以这种方式作用的抗生素有多粘菌素和短杆菌素。 3.干扰蛋白质的合成：干扰蛋白质的合成意味着细胞存活所必需的酶不能被合成。干扰蛋白质合成的抗生素包括福霉素类、氨基糖苷类、四环素类和氯霉素。 4.抑制核酸的转录和复制：抑制核酸的功能阻止了细胞分裂和/或所需酶的合成。以这种方式作用的抗生素包括萘啶酸和二氯基吖啶。抗生素相对分子质量作用方式放线菌素D 1255.4 结合双链DNA抑制RNA合成两性霉素 924.1 来自链霉素菌的广谱抗真菌剂氨苄青霉素 349.1 干扰肽聚糖交联抑制细胞壁的合成博来霉素抑制DNA合成，切割单链DNA 卡唑霉素 422.4 抑制细菌细胞壁的合成氯霉素 323.1 阻断50S核糖体亚基上的肽基转移酶而抑制翻译遗传霉素 692.7 氨基糖苷对许多细胞类型有毒性庆大霉素 692.7 与50S核糖体亚基上的L6蛋白结合而抑制蛋白合成潮霉素B 527.5 抑制蛋白质合成卡那霉素 582.6 与70S核糖体亚基结合抑制革兰氏阳性和阴性菌及支原体氨甲蝶呤 454.45 叶酸类似物，抑制二氢叶酸还原酶丝裂霉素C 334.33 抑制DNA合成，对革兰氏阳性／阴性菌和耐酸杆菌有效新霉素B硫酸盐 908.9 与30S核糖体亚基结合，抑制蛋白质合成新生霉素钠盐 634.62 抑制革兰氏阳性菌的生长青霉素G钠盐 356.4 抑制细菌细胞壁中肽聚糖的合成嘌呤霉素 544.4 氨酰基tRNA的类似物，抑制蛋白质合成利福平 823 强烈抑制原核的RNA聚合酶和哺乳动物的RNA

各种化学元素溶解方法

Al 和它的合金：易溶于盐酸，在浓硝酸和稀硝酸及稀硫酸中溶解缓慢。易溶于浓苛性碱溶液（20-40%）。Al2O3将试样与过量4-6倍的无水碳酸钠和碳酸钾（1：1）在镍或铁坩埚中熔融，冷却后，将熔块溶于水中，而不溶碳盐可用碳酸溶解，也可以用硫酸铵熔融，熔块用水浸取。 B：溶于氧化性酸，浓硫酸和浓硝酸中，甚至于加热至冒烟的高氯酸中，与苛性碱熔融生成偏硼酸盐。 V：溶于硝酸及硝酸和盐酸的混合酸中，加热溶于浓硫酸中，不溶于稀硫酸和盐酸。与碱一起熔融形成矾酸盐。 W：溶于氢氟酸和硝酸混合酸中，溶于含有碳酸的酸混合物中，在过氧化氢存在下溶于饱和草酸溶液中，粉状钨易溶于过氧化氢溶解中，在氧化剂存在下（例如KClO3），用碱或碳酸钠熔融形成钨酸盐。 F：易溶于稀硫、盐酸和硝酸中。 Fe2O3：溶于硫酸、盐酸和硝酸，用6倍KHSO4熔融并浸出熔块于稀硫酸中。 Y：溶于硫酸、硝酸和盐酸溶液中。 Co：溶于稀硝酸、稀盐酸、稀硫酸中，浓硝酸和浓硫酸使钴“钝化”。 La和其它稀土：易溶于盐酸、硝酸和硫酸溶液中。 Mg：溶于稀硫酸、盐酸和硝酸中，在浓硫酸中也溶解。 Cu：溶于硝酸中，加热至冒烟时浓硫酸溶解铜。在氧化剂（加Fe（Ⅲ）、H2O2、HNO3 等）共存时盐酸也能溶解铜。 Mo：易溶于硝酸、硝酸和盐酸混合酸中，在强烈加热时浓硫酸也溶解钼，粉末的钼溶于过氧化氢溶解中。As：溶于硝酸，盐酸和硝酸的混合酸中，用强热浓硫酸也能溶解砷。 Ni：溶于稀硝酸中及盐酸和硝酸混合酸溶解中。 Nb：溶于硝酸和氢氟酸中，溶于浓硫酸与硫酸铵或硫酸钾的混合物（加热至冒烟）中。 Sn：溶于盐酸、盐酸和硝酸的混合酸中，也溶于热的浓硫酸中。铂属元素或贵金属：钯是铂金属最活泼的一个元素，它溶于浓硝酸及热硫酸中，溶于王水中，铂溶于王水中，钌、铑、铱、锇不溶于一般无机酸和王水中，铂族金属在有氧化剂存在时与碱一起熔融，均可转变为可溶化合物。 Re：溶于硝酸而形成铼酸溶液，粉状铼易溶于过氧化氢溶液。 Pb：易溶于稀硝酸中，加热时溶于浓盐酸和浓硫酸中。 Ag：易溶于硝酸，加热可溶于浓硫酸中。 Ta：溶于氢氟酸和硝酸中，与碱熔融生成钽酸盐，在加热浓硫酸时钽才能作用。

无纺布化学溶解法

无纺布生产厂家　ｈｔｔｐ：／／ｗｗｗ．ｆｌｗｆｂ．ｃｏｍ无纺布化学溶解法该法是根据各种无纺布纤维在不同试剂中的溶解性能的差异来鉴别无纺布纤维。它适用于各种纺织无纺布纤维,特别是合成无纺布纤维,包括染色无纺布纤维或混合成分的无纺布纤维、纱线与织物。此外,溶解法还广泛用于混纺产品中的无纺布纤维含量分析。当待鉴别的试样是纱线或织物时,则需从织物中抽出经、纬纱,然后将纱线分离成单无纺布纤维。为了快速有效地鉴别出无纺布纤维种类,可先用显微镜观察,再用燃烧法复验,如果是合成无纺布纤维则可直接用化学溶解法,对于某些疑难的无纺布纤维,则需采用系统鉴别法。对于单一成分的无纺布纤维,鉴别时可将少量待鉴别的无纺布纤维放入试管中,选择并注入某种溶剂,用玻璃棒搅动,观察无纺布纤维在溶液中的溶解情况,如:溶解、微溶解、部分溶解和不溶解等。如果是混合成分的无纺布纤维或无纺布纤维量极少,则可在显微镜载物台上放上具有凹面的载玻片,然后在凹面处放入试样,滴上溶剂,盖上盖玻片,直接在显微镜中观测,根据不同的溶解情况,判别无纺布纤维类别。由于溶剂的浓度和加热温度不同,对无纺布纤维的溶解性能表现不一,因此在用溶解法鉴别无纺布纤维时,应严格控制溶剂的浓度和加热温度,同时也要注意无纺布纤维在溶

剂中的溶解速度。常用无纺布纤维的化学溶解性能见表4-5。无纺布着色法该法是根据不同无纺布纤维对某种着色剂呈色反应的不同来鉴别无纺布纤维。它适用于未染色无纺布纤维、纯纺纱线和纯纺织物。鉴别无纺布纤维的着色剂有多种。本试验采用碘—碘化钾溶液和1号着色剂。1.碘—碘化钾溶液将碘20g溶解于100mL的碘化钾饱和溶液中,把无纺布纤维浸入溶液中0.5～1min,取出后水洗干净,根据着色不同,判别无纺布纤维品种。

多肽溶解方法和步骤

多肽溶解方法和步骤(Peptide dissolving protocol) 没有绝对理想的一种溶剂可以做到既能溶解所有多肽，又能保持它们的完整性并且与生物学检测相一致。因此，不得不尝试一系列强溶剂直到多肽溶解，对有溶解困难的多肽，下列方法也许有所帮助。第一步总的来说，先用无菌水或者稀醋酸(0.1%)将多肽溶解到一个较高浓度下作为储存溶液，而不是直接配置到检测浓度。等需要用的时候再把这个储备溶液用缓冲Buffer配制到需要浓度。比如一条多肽要溶解成1mg/ml的PBS buffer中，我们需要先将多肽溶解成2mg/ml 的储备溶液，然后在使用前，先移取100ul的10*PBS buffer，再加入400ul的无菌水，最后加入500ul的2mg/ml储备液。千万不要直接用Buffer缓冲液来溶解多肽，因为很多肽在高盐浓度下溶解度是下降的，而且如果发生不溶情况，去除这些盐和有机试剂是很困难的一件事。如果多肽溶解过程中出现可见颗粒始终无法分散到水相中，可以用超声的办法来破碎。不过超声只能加速溶解，并不能起到改善溶解性的效果。

第二步溶解前先审视一下多肽序列，如果多肽中下列氨基酸(Ala，Phe，Ile，Leu，Met，Pro，Val，Trp，Tyr，Cys)占比比较高，这条多肽基本上是难溶的。另外，要注意计算一下序列中含有多少正价基团(Lys，Arg，His和N端)和负价基团(Asp，Glu和C端)，在中性条件下，最后的净价是正是负？价态为正的，在溶解时可以用稀醋酸调节pH到酸性，价态为负的，在溶解时可以用稀氨水调节pH到碱性。如果这样仍不能溶解，可以考虑冻干去除溶剂后变成用强有机溶剂来溶解。第三步如果你的序列在任何pH下都基本不带电荷，或者说你的序列中疏水性氨基酸含量超过50%，甚至更高，前面两步基本上是多余的，直接考虑加入少量乙腈，乙醇，DMF或者DMSO 来溶解，甚至可以用盐酸胍和脲来分散多肽。这些方法溶解多肽的浓度取决于你最终生物检测需要。如果已经知道一条多肽在水相中溶解不是太好，而最终使用却必须在水相，可以考虑全部用醋酸或者DMF来溶解，然后缓慢加水来稀释，这样有机溶剂有助于多肽分散到水相中。多肽溶液的储存问题溶解的多肽的保质期是比较有限的，特别是含有C，M，W，N和Q的多肽，为了延长保存时间，使用无菌水，保持适当酸性(pH5-6)，还有分装冷冻在-20℃或者更低是建议采用的方法。另外，一定要避免反复冻融，这个对多肽的损伤最大。 A Strategy for Dissolving Small Sets of Peptides The kind of individual treatment described above starts to become impractical when handling larger numbers of peptides, say 10 or more. Although exceptions can be found to the success of any generalised procedure, a recommended strategy for redissolving greater numbers of peptides with varied properties is outlined below. 1.Add 0.1% acetic acid/water to give a target peptide concentration of 1-5mg/mL, and sonicate. 2. To any insoluble peptides add pure acetic acid to bring the concentration of acetic acid to 10%(v/v), and sonicate. 3.To any peptides still insoluble add acetonitrile to 20%(v/v), and sonicate. 4.Lyophilise any remaining insoluble peptides to remove the water, acetic acid, and acetonitrile. To the solid, add neat DMF dropwise until the peptide dissolves. Dilute this solution slowly with water to give approximately 10%(v/v) DMF. If the peptide precipitates at any stage during this step, stop adding water and add a little more DMF until the peptide redissolves. Such peptides may be too insoluble in water to be used at concentrations equal to the others in the set. 5.Dilute each solubilized peptide with the solvent found to be effective for it, to bring the stock solutions to the same peptide concentration. This simplifies calculations and subsequent handling. Further dilutions, as needed for the bioassay, can be made in the