comparison of different methods to measure contact angles of soil colloids

Journal of Colloid and Interface Science328(2008)

299–307

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Journal of Colloid and Interface Science

https://www.wendangku.net/doc/4718352933.html,/locate/jcis

Comparison of different methods to measure contact angles of soil colloids Jianying Shang a,Markus Flury a,b,?,James B.Harsh a,Richard L.Zollars c

a Department of Crop and Soil Sciences,Center for Multiphase Environmental Research,Washington State University,Pullman,WA99164,USA

b Department of Biological Systems Engineering,Washington State University,Pullman,WA99164,USA

c Department of Chemical Engineering,Washington State University,Pullman,WA99164,USA

a r t i c l e i n f o a

b s t r a

c t

Article history:

Received29July2008

Accepted12September2008 Available online20September2008

Keywords:

Colloids

Contact angle

Silicates

Clay

Wilhelmy plate

Thin-layer wicking

Sessile drop We compared?ve different methods,static sessile drop,dynamic sessile drop,Wilhelmy plate,thin-layer wicking,and column wicking,to determine the contact angle of colloids typical for soils and sediments.The colloids(smectite,kaolinite,illite,goethite,hematite)were chosen to represent1:1and 2:1layered aluminosilicate clays and sesquioxides,and were either obtained in pure form or synthesized in our laboratory.Colloids were deposited as thin?lms on glass slides,and then used for contact angle measurements using three different test liquids(water,formamide,diiodomethane).The colloidal ?lms could be categorized into three types:(1)?lms without pores and with polar–liquid interactions (smectite),(2)?lms with pores and with polar–liquid interactions(kaolinite,illite,goethite),and(3)?lms without pores and no polar–liquid interactions(hematite).The static and dynamic sessile drop methods yielded the most consistent contact angles.For porous?lms,the contact angles decreased with time,and we consider the initial contact angle to be the most accurate.The differences in contact angles among the different methods were large and varied considerably:the most consistent contact angles were obtained for kaolinite with water,and illite with diiodomethane(contact angles were within3?);but mostly the differences ranged from10?to40?among the different methods.The thin-layer and column wicking methods were the least consistent methods.

?2008Elsevier Inc.All rights reserved.

1.Introduction

The most common methods to determine contact angles are the sessile or pendant drop and the Wilhelmy plate methods.For porous materials,the wicking or capillary rise method is often used[1].For spherical particles,methods have been developed to determine contact angles based on force measurements[2,3], confocal microscopy[4],and?lm trapping[5].The contact angle of colloidal particles,however,is di?cult to measure because the small particle size(<2μm in diameter)poses considerable chal-lenges with existing contact angle measurement methods.

Different methods have been described in the literature to de-termine contact angles of colloids.The sessile drop method can be used to measure static and dynamic contact angles of col-loids.As the sessile drop method requires a?at surface upon which a liquid drop can be placed,colloids are often deposited as a?lm onto a microscope slide or?lter paper[6–10].Smooth ?lms have been made with synthetic colloids,such as Latex micro-spheres[11],mineral colloids,such as smectites and hematite[9,

*Corresponding author at:Department of Crop and Soil Sciences,Center for Mul-tiphase Environmental Research,Washington State University,Pullman,WA99164, USA.Fax:+15093358674.

E-mail address:?ury@https://www.wendangku.net/doc/4718352933.html,(M.Flury).12],bacteria,such as Pseudomonas cepacia3N3A,Arthrobacter sp., Escherichia coli[13,14],and viruses,such as hepatitis A[15].Spher-ical,monodisperse particles,like microspheres are often used with the sessile drop method[11].Among soil colloids,smectites are particularly suitable for the sessile drop method,because these clays are swelling,and form a water impermeable surface[9].If the colloidal?lm is porous,then the liquid drop will penetrate into the?lm,and as a consequence the contact angle changes with time[9,16].Kaolinite,for instance,forms a porous?lm,into which water readily in?ltrates[9].

The sessile drop method has also been used to determine con-tact angles for soil particles.Bachmann and coworkers[17–19] used double-sided adhesive tape to mount a layer of powdered or sieved soil particles on a glass microscope slide.They deter-mined static contact angles for different soil types,varying in texture,mineral and organic matter composition,and geographic origin[19].

The Wilhelmy plate method is commonly used for materials with a well-de?ned wetting length,so that the contact angle can be calculated from the measured capillary force.The Wilhelmy plate method has been used to determine contact angles of gold colloids[20]and soil materials[19,21],where the particles were deposited or glued to a?at plate,which was then used as the Wil-helmy plate.

0021-9797/$–see front matter?2008Elsevier Inc.All rights reserved. doi:10.1016/j.jcis.2008.09.039

300J.Shang et al./Journal of Colloid and Interface Science328(2008)299–307

Table1

Characteristics of colloids.

Sample Particle

diameter a

(nm)Electrophoretic

mobility a

(μm s?1)/(V cm?1)

ζpotential b

(mV)

Particle shape c

Ca-smectite(SAz1)1069±198?1.12±0.01?14.2±0.1Irregular thin?akes Ca-kaolinite(KGa1b)1280±43?0.24±0.01?3.0±0.1Hexagonal platy

Ca-illite(No.36)915±181?1.58±0.05?20.1±0.6Irregular platy Goethite1814±382.10±0.0426.6±0.6Acicular

Hematite146±12.77±0.0235.2±0.3Spherical

±denotes one standard deviation.

a Measured by dynamic light scattering at pH6.0and0.1mM CaCl

2electrolyte background.

b Calculated from the von Smoluchowski equation.

c Determine

d by electron microscopy(SEM and TEM).

Table2

Density,viscosity,air–liquid surface tensionγL,and surface-tension components of test liquids at20?C.[γLW

L

:Lifshitz–van der Waals component(apolar);γ+L:electron-acceptor component(polar);γ?L:electron-donor component(polar)].

Liquid Density

(kg m?3)Dyn.viscosity

(N s m?2)

γL

(mJ m?2)

γLW

L

(mJ m?2)

γ+

L

(mJ m?2)

γ?

L

(mJ m?2)

Hexane663a0.00029a18.418.400 Water9980.0010072.821.825.525.5 Formamide1130a0.00376a58.039.02.2839.6 Diiodomethane3320a0.00280a50.850.800 Surface tensions and surface tension components are from van Oss[8].

a From J.T.Baker and Acros Organic.

For powdered or porous materials,contact angles are often de-termined with the column wicking method[8].In this method,the speed of the capillary rise into the porous medium is measured, from which the contact angle can be determined.For successful use of the column wicking method,the geometry of the porous material should remain constant during the capillary rise.How-ever,soil colloids,such as clay minerals,tend to cluster or shrink and swell,causing the pore structure to change.

To prevent this problem,colloidal particles can be deposited on a?at surface,forming a rigid thin layer of porous material [16,22].This method is known as thin-layer wicking[16].It has been used for a variety of particles,such as illite[16],kaolinite [9],attapulgite[9],talc[16,23],hydrotalcite[24],hematite[12], dolomite[23],calcite[23],basalt[25],limestone[25],silica[26,27], and feldspar[28].Costanzo et al.[12]have shown that for cubic hematite particles,thin-layer wicking yields identical contact an-gles as the sessile drop method.

More recently,contact angle methods based on?lm and gel trapping[5,29],atomic force microscopy[3,30,31],and scanning confocal microscopy[4]have been developed.These methods are particularly useful for spherical particles in the micrometer size range,but less suitable for soil colloids,which have irregular shapes.

The determination of contact angles for soil colloids remains challenging,and no ideal method has yet been described.It is likely that different methods are optimal for different types of colloids.The objective of this paper was,therefore,to compare dif-ferent methods to determine contact angles of soil colloids.We used the sessile drop,Wilhelmy plate,column wicking,and thin-layer wicking methods to determine contact angles of?ve major types of soil colloids(swelling and non-swelling aluminosilicate clays,and(hydr)oxides).We discuss advantages and disadvantages of the different methods,and make recommendations on the opti-mal methods for speci?c colloids.

2.Materials and methods

2.1.Soil colloids

We used?ve typical soil colloids:three aluminosilicate clays and two(hydr)oxides(Table1).Arizona smectite(SAz1)and Geor-gia kaolinite(KGa1b)were obtained from the Clay Minerals Repos-itory(University of Missouri),and illite(No.36,Morris,Illinois) was obtained from Ward’s Natural Science(Rochester,NY).All the clays(smectite,kaolinite,illite),as received from the suppli-ers,were fractionated by gravity sedimentation to obtain parti-cles smaller than2μm in diameter.Hematite and goethite were synthesized in our laboratory following Schwertmann and Cor-nell[32].

The fractionated clay minerals were treated with H2O2to re-move organic matter and the citrate-dithionite method was used to remove iron oxides.Then,to prevent Al3+precipitation on the clay surfaces,the pH of the clay suspensions was lowered to about4by titration with0.1M HCl.The suspensions were shaken for3h,and the supernatant was decanted after centrifu-gation.This procedure was repeated three times.Finally,the clay suspensions were washed with deionized water.Deionized water was added,equilibrated for3h,and decanted after centrifuga-tion.This washing procedure was repeated until the suspensions reached pH 6.Finally,the clay minerals were made homoionic and Ca-saturated by washing with0.5M CaCl2,and dialyzed with deionized water until free from chloride[33,34].All colloids were stored in concentrated suspensions at room temperature un-til use.

Average hydrodynamic particle size and electrophoretic mobil-ity were measured by dynamic light scattering using a Zetasizer 3000HAS(Malvern Instruments Ltd.,Malvern,UK).The particle shapes were determined by scanning and transmission electron microscopy(Hitachi S520SEM,JEOL1200EX TEM).Selected prop-erties of the colloids are shown in Table1.

2.2.Test liquids

Polar and apolar liquids were used for the contact angle mea-surements(Table2):double deionized water(electrical conductiv-ity0.58μS/cm,E-pure,Barnstead),formamide(99.5%purity,from Acros Organics,Morris Plains,NJ),diiodomethane(99%purity,from Acros Organics,Morris Plains,NJ),and hexane(100%purity,J.T. Baker,Phillipsburg,NJ).Hexane was used as the low energy liq-uid with contact angle of0degree,and was used to obtain the capillary constant for the wicking methods.

J.Shang et al./Journal of Colloid and Interface Science328(2008)299–307301

2.3.Sessile drop method(static and dynamic)

For the sessile drop method,a microscope cover glass slide (2.2cm×2.2cm),cleaned with acetone and deionized water,was coated with colloids following the procedure described by Wu[9]. For the coating,concentrated colloid stock suspensions were?rst diluted with deionized water to a concentration of about1–2% wt/vol,and stirred with a magnetic stir bar for several hours.Then, 1.5mL suspension was placed on the microscope slide,evaporated for two days under laminar air?ow,and?nally dried in an oven at 105?C for12h.Glass slides were kept horizontal during the drying process.

The contact angles were determined using a goniometer(Drop Shape Analysis System,DSA100,Krüss GmbH,Hamburg,Germany), equipped with an environmental chamber and a microsyringe steel needle of0.5-mm diameter.The environmental chamber helped to minimize evaporation.For static contact angle measurements,the syringe needle was positioned0.2mm from the surface of the col-loidal?lm,and a drop of the test liquid(2μL)was dispensed at a rate1.75μL s?1.After dispensing,the drop shape was monitored with a digital camera for20s,and contact angle,drop diameter, and volume were recorded.To determine the contact angle,the drop contour was mathematically described by the Young–Laplace equation using DSA100,and the contact angle was determined as the slope of the contour line at the three-phase contact point.For dynamic contact angle measurements,the drop volume was con-tinuously increased and then decreased as contact angles were recorded.We used a liquid dispensation rate of5μL min?1to increase the drop volume from0to5μL(advancing contact an-gle),and then reversed the?ow at the same rate to decrease the drop volume again(receding contact angle).The contact angle was taken as the average angle after the contact angle vs time curve had reached a plateau.

2.4.Wilhelmy plate method

For the Wilhelmy plate method,we coated a cleaned micro-scope cover glass on both sides with colloids.A1.5-mL drop of3% wt/vol colloid suspension was placed on the glass slides and evap-orated for12h under laminar air?ow.Then,the slide was turned over and the other side was coated with the same procedure.The slide was dried for two days under laminar?ow and then heated in an oven at105?C for12h.With this procedure,the slide was completely covered with a thin?lm of colloids.

The contact angles were determined using a tensiometer(K100, Krüss GmbH,Hamburg,Germany).The wetted length of the coated slides was measured by a digital micrometer caliper(precision 0.01mm).The slide was suspended from the electronic microbal-ance(precision1μg)and moved in and out of the test liquids at a speed of1mm min?1.The force acting on the balance was con-tinuously measured.Advancing and receding contact angles were obtained from immersion and emersion,respectively.The contact angle was calculated according to cosθ=(F?F b)/(PγL),where F is the measured vertical force(N),F b is the buoyancy force(N), P is the wetted length(m),andγL is the surface tension of the test liquid(J m?2).The wetting length was measured with the caliper for each colloid-covered slide.The colloidal?lm remained stable on the glass slides during the contact time with the liquids(mea-surements lasted10min).

2.5.Thin-layer wicking method

For the thin-layer wicking method,we prepared thin?lms of colloids on a glass slide(2.4cm×4cm),using the same procedure as described for the Wilhelmy plate method.Because the slide was larger than the ones used for the Wilhelmy plate method,we used a3mL drop of colloid suspension.

The capillary constant was determined with hexane as the test ?uid.Before the hexane measurements,the coated slides were equilibrated in a glass container with saturated hexane vapor for one hour to equalize the spreading pressure[9].For the wicking, the slides were vertically dipped to a depth of5mm into the test liquids contained in a sealed cylindrical glass container to prevent evaporation.As soon as the slide was immersed into the liquid,the wicking height was recorded with a video camera(iSight,Apple Inc.).Recording was stopped when the wicking height was2cm. The Washburn equation was used to calculate contact angles[35]:

x2=

R effγL cosθ

2η

t(1)

where x is the wicking distance(m)in the porous layer,t is time(s),R eff is the effective pore radius(m)of the interparticle capillaries in the porous layer,γL is the surface tension of test liq-uid(J m?2),andηis the liquid viscosity(N s m?2).

2.6.Column wicking method

For the column wicking method,colloid suspensions were dried,ground into powders,and passed through sieves to ob-tain aggregates between106and250μm in diameter.Spherical glass beads(diameter of120μm)were used as standards.The sample holder was an aluminum tube with an inner diameter of 12mm(Krüss GmbH,Hamburg,Germany).A30-μm mesh mem-brane was placed into the sample holder to prevent the sample powder from falling out.Two grams of dry powder were placed into the sample holder with manual tapping(several times)to ob-tain uniform packing of the aggregates.The packing densities were 1.11g cm?3for smectite,0.93g cm?3for kaolinite, 1.00g cm?3 for illite,0.50g cm?3for goethite,and1.00g cm?3for hematite; the differences arose because of different particle densities,sizes, and shapes.After packing,the holder was placed onto the elec-tronic balance of the tensiometer.The weight gain of the sample holder after contact with test liquids was recorded.The modi-?ed Washburn equation was used to calculate contact angles[36]: w2=ctρ2γL cosθ/η,where w is the weight increase of the col-umn(kg),ρis the liquid density(kg m?3),and c is the capillary constant(m5).The capillary constant c was determined using hex-ane as the test?uid.

2.7.Sample storage,measurement replication,and data reporting

After sample preparation as described for the individual meth-ods above,the samples were stored in a desiccator until use for the contact angle measurements.Samples were taken out from the desiccator and used immediately.The relative humidity in the at-mosphere during the measurements was33%;except for the thin-layer wicking method,which was performed in a sealed cylinder, and the vapor pressure was therefore close to saturation.

All measurements were replicated5times,except the ten-siometer measurements(Wilhelmy plate and column wicking method),which were replicated3times.Data are reported as means and standard deviations of the replicates.Statistical differ-ences were analyzed at the5%con?dence level with a t-test.

3.Results and discussion

3.1.Colloid?lms

The thin colloid?lms prepared by deposition of colloids on the glass slides are shown in Fig.1.The electron micrographs show that surface roughness varied among the?lms.Smectite,kaolinite,

302J.Shang et al./Journal of Colloid and Interface Science328(2008)

299–307

Fig.1.Scanning electron micrographs of the?lm surfaces:(a)smectite,(b)kaolinite,(c)illite,(d)goethite,and(e)hematite.

illite,and goethite?lms all had considerable roughness,whereas

the hematite surface appeared smooth at the scale of the micro-

graphs.The smooth surface obtained for hematite was because

of the small and spherical particle size of the hematite colloids

(Table1).Kaolinite,illite,and goethite surfaces show also the pres-

ence of pores.

3.2.Sessile drop method(static)

Fig.2shows the contact angles,drop diameters,and drop vol-

umes determined as a function of time after the liquid drop was

placed onto the colloid?lm.Only the data for smectite,kaolinite,

and hematite are shown;illite and goethite patterns were similar

to kaolinite,and are therefore not shown.Table3shows contact

angles at three time intervals for all colloids.

For smectite,contact angles of water and formamide decreased

and drop diameters increased with time,whereas the drop vol-

umes remained constant(Fig.2).Contact angles,drop diameters,

and drop volumes of diiodomethane remained constant.The con-

stant drop volume indicates that there was no penetration of liquid

into the colloid?lm.Smectite swells in contact with water and in

the process seals the?lm surface[9].The decreasing contact an-

gles of the polar liquids,water and formamide,may be explained

by hydration[37]and polar(acid–base)interactions[38].

For kaolinite the liquid drops in?ltrated into the pores of the

colloid?lm,as indicated by the decrease in drop volume(Fig.2).

As the drop volume decreased,the drop diameter for water and

formamide increased,and the contact angle decreased.The in-

crease in drop diameter was caused by two processes:(1)polar

(acid–base)interactions between the solid and the polar liquids,

and(2)drop imbibition into the pores of the colloid?lm.The

former process is similar to what was observed for smectite.The

latter process,however,causes false contact angle readings,as the

shape of the liquid–gas interface changes because of the imbi-

bition.Correct contact angle readings should therefore be done

at0s,i.e.,before imbibition begins.The use of a digital goniome-

ter,such as the Krüss Drop Shape Analysis System,allows to deter-

mine the contact angle immediately when the drop is placed on

the substrate,so that accurate readings at0s can be made.For di-

iodomethane,the drop volume also decreased,but at a much lower

rate than compared to water and formamide.The colloid?lm im-

bibed the diiodomethane,but the imbibition was slow because of

the high?uid viscosity.Illite and goethite showed very similar be-

havior to kaolinite(Table3).

Contact angles for kaolinite and smectite with water were

reported in the literature.Reported values for the sessile drop

method range from17.4?to34?and21.8?to42.5?for kaolinite

and smectite,respectively[9,39–42].

For hematite,contact angles,drop diameters,and drop volumes

remained constant during the20-s measurement period(Fig.2).

This indicates that there were no interactions or imbibition of

liquid into the colloid?lm.We believe that this was because of

the spherical shape of the hematite particle,which formed a non-

porous?lm with a periodical surface roughness.Contact angles for

hematite reported in the literature vary considerably.This is likely

due to different types of hematite used in different studies.Val-

ues reported for cuboid hematite by Costanzo[12]are generally

smaller than our values.

Based on the experimental results,we can distinguish three

types of mechanisms during contact angle measurements with soil

colloids.For swelling?lms,like smectite,the colloid?lm seals it-

self when in contact with a polar liquid,but acid–base interactions

can cause the drop shape to change with time.The contact an-

gle change with time re?ects the modi?cation of the surface with

time.For non-swelling,porous?lms,such as kaolinite,illite,and

goethite,the drop shape changes because of both acid–base inter-

J.Shang et al./Journal of Colloid and Interface Science328(2008)299–307

303

Fig.2.Contact angles,drop diameters,and drop volumes as a function of time determined with static sessile drop method.Error bars(only shown for contact angles)indicate standard deviations of?ve measurements.

Table3

Contact angles of subsurface colloids determined using static sessile drop method.

Subsurface colloids Time

(s)

Contact angle

Water

(degree)

Formamide

(degree)

Diiodomethane

(degree)

Ca-smectite055.7±1.431.2±0.638.3±1.2

1044.5±0.923.2±0.938.3±1.1

2041.4±0.921.2±0.838.3±1.2

Ca-kaolinite027.8±0.413.7±0.921.9±1.3

1020.8±0.87.4±1.317.1±0.9

2017.8±0.66.5±1.215.3±0.5

Ca-illite043.3±0.321.1±0.730.8±1.4

1031.9±1.117.4±1.830.0±1.6

2029.3±1.316.8±1.529.6±1.6 Goethite022.8±1.824.1±1.019.4±0.4

100±015.3±3.012.8±0.1

200±00±08.1±0.4 Hematite046.9±2.318.5±1.725.0±0.8

1046.5±2.418.5±1.825.5±1.0

2046.4±2.418.5±1.825.4±1.1

±denotes one standard deviation of5replicates.

actions and imbibition,thereby causing false contact angle read-ings after the initial drop has been put on the colloid?lm surface. Because of interactions and imbibition,the most accurate contact angle should be the initial contact angle.For a non-swelling,non-porous?lms,such as hematite,the drop shape remains stable over time.

3.3.Sessile drop method(dynamic)

The dynamic sessile drop method can provide advancing and receding contact angles as a function of time.We again only show the data for smectite,kaolinite,and hematite,as illite and goethite showed similar behavior as kaolinite(Fig.3).The dashed lines in the?gure separate increasing from decreasing drop volume,as controlled by the liquid supply syringe.

For smectite,as the drop volume of water and formamide increased,the contact angles initially decreased and reached a plateau(Fig.3a).This plateau represents the mean advancing con-tact angle[43].For diiodomethane,the contact angle was constant because there were no interactions with the solid surface.When the drop volume was decreased after60s,the drop diameters for formamide still increased,and then decreased.Receding contact angles decreased for all three liquids,and did not reach a constant value.For water and diiodomethane,the drop diameter remained constant,indicating a non-slip boundary at the air–liquid–solid in-terface[44],which will cause the contact angle to continuously decrease as?uid is withdrawn from the drop.

For kaolinite,the advancing contact angles were fairly constant for the three liquids(Fig.3b).The diameters of the liquid drop in-creased when the drop volume increased,and remained constant for a few seconds after?ow was reversed,and then decreased quickly.The colloid?lm imbibed all three liquids,but the rate of imbibition was much smaller than the rate of drop volume increase,therefore,the imbibition had negligible effect,and the advancing contact angles remained constant.

For hematite,the drop diameters for water and formamide re-mained initially constant when the drop volume was increased, but the contact angles increased at a high rate(Fig.3c).When the drop size exceeded a critical limit,the drop diameter jumped to a new position,and remained constant again.This led to a typi-cal slip/stick pattern of the advancing contact angle[44–46].The slip/stick pattern was bounded by a lower and upper critical con-tact angle,and the range was larger for water than for formamide. No distinct slip/stick pattern was observed for diiodomethane.The different behavior among the three liquid drops can be explained by their different Bond numbers:the water drop had the small-est Bond number(Bo=37),and could keep its shape better than the formamide drop(Bo=46),and the diiodomethane drop(Bo= 184).

304J.Shang et al./Journal of Colloid and Interface Science 328(2008)

299–307

Fig.3.Dynamic contact angles and drop diameters of test liquids as a function of time determined by the dynamic sessile drop method:(a)smectite,(b)kaolinite (illite and goethite were similar to kaolinite),(c)hematite.Dashed lines separate increasing from decreasing drop volume.

3.4.Wilhelmy plate method

From the Wilhelmy plate method,both advancing and reced-ing contact angles can be obtained by immersion and emersion of the coated colloid ?lms.The forces measured as a function of im-mersion depth for complete immersion–emersion loops were used to construct force-distance curves.Only the linear portions of the force curves were used to calculate the contact angles.The force curves show a distinct contact angle hysteresis,with the advanc-ing contact angles always larger than the receding ones (Table 4).The largest hysteresis was observed for smectite and hematite with water.We attribute this pronounced contact angle hysteresis to swelling behavior (smectite)and surface roughness (hematite).Hematite has the most pronounced surface roughness in the sense of a periodic arrangement of its spherical particles,leading to both acute and obtuse angles,which causes pronounced contact angle hysteresis.

For kaolinite,illite,and goethite,the receding contact angles were zero for all liquids (Table 4).Zero-degree receding contact angles were also reported by Bachmann et al.[19],who measured contact angles of soil particles (diameter <0.063or 2mm)with the Wilhelmy plate method.The zero-degree contact angles are

J.Shang et al./Journal of Colloid and Interface Science328(2008)299–307305

Table4

Contact angles of test liquids for subsurface colloids using static sessile drop,dy-

namic sessile drop,Wilhelmy plate,and thin-layer wicking methods.

Subsurface colloids

Contact angles(degree)

W ater F ormamide Diiodomethane Static sessile drop method(equilibrium contact angle)

Ca-smectite55.7±1.4A31.2±0.6A38.3±1.2A Ca-kaolinite27.8±0.4A13.7±0.9A21.9±1.3A Ca-illite43.3±1.4A21.1±0.7A30.8±1.4A Goethite22.8±1.9A24.1±1.0A19.4±0.4A Hematite46.9±2.3A18.5±1.7A25.0±0.8A Dynamic sessile drop method(advancing contact angle)

Ca-smectite41.9±2.5B17.2±1.4B46.9±0.7B Ca-kaolinite26.2±2.0A14.9±3.6A,B10.8±1.9B Ca-illite24.0±3.2B13.8±1.6B32.4±3.2A Goethite25.0±2.9A41.2±4.8B13.8±0.8B Hematite42.5±11.4A35.4±8.3B26.4±1.6A Wilhelmy plate method(advancing contact angle)

Ca-smectite57.1±2.5A34.7±2.1A50.9±0.6B,D Ca-kaolinite27.3±1.3A11.1±0.9A20.8±1.9A Ca-illite30.0±0.4C20.0

±1.7A30.6±2.0A Goethite14.2±2.4B17.8±1.4C8.7±2.3B Hematite71.7±2.0B42.3±1.0C35.5±0.6B

Wilhelmy plate method(receding contact angle)

Ca-smectite9.9±2.3C 5.3±1.0C25.6±1.7C Ca-kaolinite0B0C0C

Ca-illite0D0C0B

Goethite0C0D0C Hematite32.3±1.1C 5.8±0.7D23.4±0.4C

Thin-layer wicking method(advancing contact angle)

Ca-kaolinite29.3±2.2A19.8±0.3B52.0±3.1D Ca-illite56.8±3.4E39.1±5.5D34.2±4.9A Goethite34.1±3.4D20.9±1.8A46.7±2.9D ±denotes one standard deviation of5replicates(except for Wilhelmy plate method,where3replicates were used).Letters(A,B,C,D,E)denote statistical difference column-wise for identical colloids:if letters are different between two methods,then there is a signi?cant difference at the5%con?dence level between the methods.

likely caused by imbibition of liquid into the porous?lms or ag-gregates during plate immersion.The Wilhelmy plate method has

successfully been used to determine contact angles for other types of colloidal and porous materials,such as gold colloids[20]and soil particles[19,21].

The Wilhelmy plate method generally leads to an underesti-mation of the advancing contact angle when the plate surface is rough,because the effective plate perimeter is larger than that de-termined by a caliper[47].For our colloids,we cannot quantify the magnitude of this error,because we do not have a quantitative measure of the surface roughness.

3.5.Thin-layer wicking method

We chose kaolinite,illite,and goethite as the samples for the thin-layer wicking clay,because the?lms formed by these colloids have microporous characteristics(Fig.1).Smectite and hematite ?lms,which swell and have no microporosity,respectively,can-not be used for the thin-layer wicking.Results for kaolinite,illite, and goethite are shown in Fig.4and Table4.

The experimental data follow the theoretical trend given by Eq.(1)(Fig.4),indicating that the thin-layer wicking method was suited to calculate the contact angles.The effective pore sizes R eff of kaolinite,illite,and goethite were233,173,and387nm,which are all smaller than the particle diameters(Table1).This is a con-sequence of the platy and rodlike particle shape of the colloids, which upon deposition orient themselves in a thin?lm,causing the pore size to become smaller than the particle size[24].To show that the glass slide itself did not affect the liquid wicking speed,we peeled off the thin colloidal?lm from the glass slide Fig.4.Wicking distance squared versus time for different test liquids using thin-layer wicking:(a)kaolinite,(b)illite,(c)goethite.The lines are linear trendlines of the form x2=at,where a is a?tting parameter given as a=(R effγL cosθ)/(2η). Error bars indicate standard deviations of three measurements.

(this could only be done for illite,the other colloidal?lms broke apart when attempting to peel them off).The wicking results with the illite?lm alone were identical to the ones with the illite?lm on the glass slide.This con?rmed that the glass slide itself did not affect the measurement.

The contact angles obtained from the thin-layer wicking method (Table4)are different than those reported in the literature.For kaolinite and the thin-layer wicking method,Wu[9]reported con-tact angles of46.1?for water,27.2?for formamide,and34.5?for diiodomethane.For illite and goethite,we did not?nd literature data.The values reported by Wu[9]are larger than ours,likely because Wu[9]did not pretreat their kaolinite(no removal of or-ganic matter and iron oxides).

3.6.Column wicking method

Fig.5a shows the results for three replicates of the glass bead measurements with hexane to check the method performance. Three stages can be distinguished in the weight-time curves[48]: in stage1,at very short times,the bottom boundary of the sample holder affects the measurements;in stage2,interparticle pores are ?lled,and a linear increase of the weight-time curve is obtained; in stage3,the pore space is either completely?lled,resulting in a

306J.Shang et al./Journal of Colloid and Interface Science 328(2008)

299–307

Fig.5.Capillary rise curves,wicking weight versus time for different test liquids using the column wicking method:(a)glass beads in hexane (reproducibility),(b)glass beads,(c)smectite,(d)kaolinite,(e)illite,and (f)goethite.

cease of the weight gain,or intraparticle pores begin to ?ll,result-ing in a non-linear weight-time response.For our glass beads,no intraparticle pores were present,and we obtained an ideal weight-time response for hexane (Fig.5a)as well as for the other ?uids (Fig.5b).

For the soil colloids,however,most of the time no distinct stage 2could be identi?ed (Figs.5c–5f ),and therefore,no con-tact angles could be calculated.The pore structure of the packed soil colloids changed as the ?uid was imbibed,thereby,invalidating the assumptions inherent in the Washburn equation.Colloids dis-persed in water and formamide and,in addition,smectite swelled.Thin-layer wicking,on the other hand,was better suited for con-tact angle measurements because the colloids on the plates formed a more rigid porous structure,and did not easily disperse [1].

Column wicking data for natural hematite data reported in the literature for water (contact angle =46?)[49]were very similar to our sessile drop data of 46.9?.Nonetheless,the column wicking method should be used with caution.In addition to the change in pore structure,the column wicking method has the disadvantage that it requires the validity of the Young equation.This require-ment may not be ful?lled for all liquid–solid combinations.The same potential shortcoming regarding the Young equation applies also for the thin-layer wicking https://www.wendangku.net/doc/4718352933.html,parison of contact angles

The contact angle measurements are affected by many factors (e.g.,temperature,relative humidity,solid surface roughness,sur-faces preparation,sample pretreatment).It is therefore not sur-prising that a large variation of contact angles for soil colloids is reported in the literature.

The contact angles obtained from the different methods in our study are summarized in Table 4.The data show that there were considerable differences in the contact angles determined using the different methods.The best agreements among the different methods were obtained with kaolinite (except for diiodomethane).For water,the static and advancing contact angles with kaolinite were within 3?for the different methods,and no signi?cant dif-ferences were observed (Table 4).For formamide,the static and advancing contact angles with kaolinite were within 9?and,except for the thin-layer wicking,the angles were again not statistically https://www.wendangku.net/doc/4718352933.html,rger differences were observed for diiodomethane.

The other colloids generally showed large differences among methods,but the differences among the methods and the colloids were not consistent.For instance,for smectite,the static sessile drop and the Wilhelmy plate method (advancing)gave similar con-tact angles with water and formamide;but for illite,goethite,and hematite,these two methods gave signi?cantly different contact angles (Table 4).For illite,goethite,and hematite,no consistent patterns among different methods were observed.Differences in contact angles among the methods ranged from 20?to 33?for wa-ter,20?to 25?for formamide,and 4?to 40?for diiodomethane (Table 4).

The thin-layer wicking method often produced contact an-gles that deviated considerably from those determined from other methods (Table 4).Although thin-layer wicking has been fre-quently used for powders [9,25–27],it appears that for our soil colloids,its suitability is limited.The column-wicking method was also not suited for contact angle measurement;similar observa-tions were reported by others using powdered liposomes [50],mi-croporous membranes [51],and soil materials [19,48].

Contact angles determined with a single method usually showed a standard deviation of up to about 3degrees (Table 4),so the precision of the individual methods was good.However,the inter-method variability was often much larger than the intra-method variability.Thus,whereas the precision of a single method was good,the method may not provide accurate results.The optimal (most accurate)method for a given colloid has to be determined on a case by case basis.

Based on all our measurements,and requiring that at least two methods should give similar contact angles,we can make the following recommendations for water (Table 5).For kaolinite,all methods except column wicking were suitable and gave simi-lar results.For smectite,the static sessile drop and the Wilhelmy plate method are recommended.For illite,all methods gave sig-ni?cantly different results,but dynamic sessile drop and Wilhelmy plate methods gave the most similar contact angles.For goethite and hematite,static and dynamic sessile drop methods are recom-mended.

J.Shang et al./Journal of Colloid and Interface Science328(2008)299–307307

Table5

Recommended contact angle measurement methods for subsurface colloids with

water.

Subsurface colloid Contact angle measurement method

Static

sessile drop

Dynamic

sessile drop

Wilhelmy

plate

Thin-layer

wicking

Column

wicking

Ca-smectite×!×!!

Ca-kaolinite××××!

Ca-illite!××!! Goethite××!!! Hematite××!!!

×denotes recommended method.

!denotes not recommended method.

4.Conclusions

Our results showed that large differences can exist between contact angles of soil colloids measured with different methods. Given the large differences among measurement methods,it is im-portant to report contact angle always together with its detailed measurements methods.Based on our systematic comparison of different methods,we can recommend speci?c methods for typical soil colloids(Table5).

In terms of the contact angles themselves,our data show that soil colloids generally have fairly large contact angles(equilib-rium and advancing):kaolinite and goethite had a contact angle of about25?,smectite40?to50?,illite25?to45?,and hematite45?. There was a pronounced contact angle hysteresis—receding contact angles were10?for smectite,32?for hematite,0?for kaolinite,il-lite,and goethite.Under natural subsurface conditions,colloids are often coated with organic matter,which will make their contact angles larger than the ones reported here.

Acknowledgment

This research was supported in part by the O?ce of Science (BER),US Department of Energy,Grant No.DE-FG02-08ER64660.

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常用介词的用法

分考点1 表示时间的介词 Point 1 at, in, on 的用法 （1）at 的用法 At 表示时间点，用于具体的时刻（几点，正午，午夜，黎明，拂晓，日出，日落等），或把某一时间看作某一时刻的词之前以及某些节假日的词之前。 at 6：00 在6点钟 At noon 在中午 At daybreak 在拂晓 At down 在黎明 At Christmas 在圣诞节 【特别注意】在以下的时间短语中，at 表示时间段。 At dinner time 在（吃）晚饭时 At weekends/ the weekend 在周末 （2）in 的用法 ①表示时间段，与表示较长一段时间的词搭配，如年份，月份，季节，世纪，朝代，还可以用于泛指的上午、下午、傍晚等时间段的词前。 In 2009 在2009年 In April 在四月 In the 1990s 在20世纪90年代 In Tang Dynasty 在唐朝 In the morning在上午 ②后接时间段，用于将来时，表示“在一段时间之后”。 The film will begin in an hour. 电影将于一个小时之后开始。 【特别注意】当时间名词前有this，that，last，next，every，each，some等词修饰时，通常不用任何介词。 This morning 今天上午last year 去年 （3）on 的用法 ①表示在特定的日子、具体的日期、星期几、具体的某一天或某些日子。 On September the first 在9月1号 On National Day 在国庆节 We left the dock on a beautiful afternoon. 我们在一个明媚的下午离开了码头。 ②表示在具体的某一天的上午、下午或晚上（常有前置定语或后置定语修饰）。 On Sunday morning 在星期日的早上 On the night of October 1 在10月1号的晚上 【特别注意】“on +名词或动名词”表示“一...就...”. On my arrival home/ arriving home, I discovered they had gone. 我一到家就发现他们已经离开了。 Point 2 in，after 的用法 In 和after都可以接时间段，表示“在...之后”，但in 常与将来时连用，after 常与过去时连用。 We will meet again in two weeks.

英语介词用法大全

英语介词用法大全 TTA standardization office【TTA 5AB- TTAK 08- TTA 2C】

介词（The Preposition）又叫做前置词，通常置于名词之前。它是一种虚词，不需要重读，在句中不单独作任何句子成分，只表示其后的名词或相当于名词的词语与其他句子成分的关系。中国学生在使用英语进行书面或口头表达时，往往会出现遗漏介词或误用介词的错误，因此各类考试语法的结构部分均有这方面的测试内容。 1. 介词的种类 英语中最常用的介词，按照不同的分类标准可分为以下几类： (1). 简单介词、复合介词和短语介词 ①.简单介词是指单一介词。如： at , in ,of ,by , about , for, from , except , since, near, with 等。②. 复合介词是指由两个简单介词组成的介词。如： Inside, outside , onto, into , throughout, without , as to as for , unpon, except for 等。 ③. 短语介词是指由短语构成的介词。如： In front of , by means o f, on behalf of, in spite of , by way of , in favor of , in regard to 等。 (2). 按词义分类 {1} 表地点（包括动向）的介词。如： About ,above, across, after, along , among, around , at, before, behind, below, beneath, beside, between , beyond ,by, down, from, in, into , near, off, on, over, through, throught, to, towards,, under, up, unpon, with, within , without 等。 {2} 表时间的介词。如： About, after, around , as , at, before , behind , between , by, during, for, from, in, into, of, on, over, past, since, through, throughout, till(until) , to, towards , within 等。 {3} 表除去的介词。如： beside , but, except等。 {4} 表比较的介词。如： As, like, above, over等。 {5} 表反对的介词。如： againt ,with 等。 {6} 表原因、目的的介词。如： for, with, from 等。 {7} 表结果的介词。如： to, with , without 等。 {8} 表手段、方式的介词。如： by, in ,with 等。 {9} 表所属的介词。如： of , with 等。 {10} 表条件的介词。如：

to与for的用法和区别

to与for的用法和区别 一般情况下, to后面常接对象; for后面表示原因与目的为多。 Thank you for helping me. Thanks to all of you. to sb.表示对某人有直接影响比如，食物对某人好或者不好就用to; for表示从意义、价值等间接角度来说，例如对某人而言是重要的，就用for. for和to这两个介词，意义丰富，用法复杂。这里仅就它们主要用法进行比较。 1. 表示各种“目的” 1. What do you study English for? 你为什么要学英语？ 2. She went to france for holiday. 她到法国度假去了。 3. These books are written for pupils. 这些书是为学生些的。 4. hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。 2．对于 1．She has a liking for painting. 她爱好绘画。 2．She had a natural gift for teaching. 她对教学有天赋/ 3．表示赞成同情，用for不用to. 1. Are you for the idea or against it? 你是支持还是反对这个想法？ 2. He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。 3. I felt deeply sorry for my friend who was very ill. 4 for表示因为，由于（常有较活译法） 1 Thank you for coming. 谢谢你来。 2. France is famous for its wines. 法国因酒而出名。 5．当事人对某事的主观看法，对于（某人），对…来说（多和形容词连用）用介词to，不用for.. He said that money was not important to him. 他说钱对他并不重要。 To her it was rather unusual. 对她来说这是相当不寻常的。 They are cruel to animals. 他们对动物很残忍。 6．for和fit, good, bad, useful, suitable 等形容词连用，表示适宜，适合。 Some training will make them fit for the job. 经过一段训练，他们会胜任这项工作的。 Exercises are good for health. 锻炼有益于健康。 Smoking and drinking are bad for health. 抽烟喝酒对健康有害。 You are not suited for the kind of work you are doing. 7. for表示不定式逻辑上的主语，可以用在主语、表语、状语、定语中。 1．It would be best for you to write to him. 2．The simple thing is for him to resign at once. 3．There was nowhere else for me to go. 4．He opened a door and stood aside for her to pass.

英语介词用法详解

英语常用介词用法与辨析 ■表示方位的介词：in, to, on 1. in 表示在某地范围之内。如： Shanghai is/lies in the east of China. 上海在中国的东部。 2. to 表示在某地范围之外。如： Japan is/lies to the east of China. 日本位于中国的东面。 3. on 表示与某地相邻或接壤。如： Mongolia is/lies on the north of China. 蒙古国位于中国北边。 ■表示计量的介词：at, for, by 1. at表示“以……速度”“以……价格”。如： It flies at about 900 kilometers a hour. 它以每小时900公里的速度飞行。 I sold my car at a high price. 我以高价出售了我的汽车。 2. for表示“用……交换，以……为代价”。如： He sold his car for 500 dollars. 他以五百元把车卖了。 注意：at表示单价(price) ，for表示总钱数。 3. by表示“以……计”，后跟度量单位。如： They paid him by the month. 他们按月给他计酬。 Here eggs are sold by weight. 在这里鸡蛋是按重量卖的。 ■表示材料的介词：of, from, in 1. of成品仍可看出原料。如： This box is made of paper. 这个盒子是纸做的。 2. from成品已看不出原料。如： Wine is made from grapes. 葡萄酒是葡萄酿成的。 3. in表示用某种材料或语言。如： Please fill in the form in pencil first. 请先用铅笔填写这个表格。 They talk in English. 他们用英语交谈(from 。 注意：in指用材料，不用冠词；而with指用工具，要用冠词。请比较：draw in penc il/draw with a pencil。 ■表示工具或手段的介词：by, with, on 1. by用某种方式，多用于交通。如by bus乘公共汽车，by e-mail. 通过电子邮件。

with的用法大全

with的用法大全----四级专项训练with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词; 2. with或without-名词/代词+副词; 3. with或without-名词/代词+介词短语; 4. with或without-名词/代词+动词不定式; 5. with或without-名词/代词+分词。 下面分别举例：

1、 She came into the room，with her nose red because of cold.(with+名词+形容词，作伴随状语) 2、 With the meal over ， we all went home.(with+名词+副词，作时间状语) 3、The master was walking up and down with the ruler under his arm。(with+名词+介词短语，作伴随状语。) The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.(with+名词+不定式，作伴随状语) He could not finish it without me to help him.(without+代词 +不定式，作条件状语) 5、She fell asleep with the light burning.(with+名词+现在分词，作伴随状语) 6、Without anything left in the cupboard， she went out to get something to eat.(without+代词+过去分词，作为原因状语) 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件(详见上述例句)。

高中英语45个介词的基本用法

——45个基本介词的用法 1、about 【原始含义】 a-b-out “A在B外面” 【引申含义】 [prep] （1）在…到处，在…各处here and there eg: We wandered about the town for an hour or so. He looked about the room. （2）在…附近next to a place eg. She lives about the office. （3）关于in connection with eg: a book about English study I don’t know what you are talking about. [adv] （1）大约close to eg: We left there about 10 o’clock. It costs about 500 dollars. （2）到处，各处 eg: The children were rushing about in the garden. （3）在附近 eg : There is no food about. 【常见搭配】 作介词时的搭配: 一.动词+(about+名词) （1）arrange (about sth) 安排关于某事（2）argue (about sth) 讨论某事 （3）ask (about sth) 询问关于某事（4）boast (about sb/sth) 吹嘘... （5）care (about sb/sth)关心…,对…感兴趣（6）chat(about sth) 谈论某事（7）complain(about sb/sth) 抱怨… （8）dream (about sb/sth) 梦见某人/某物（9）go (about sth) 着手做...；从事...

with用法归纳

with用法归纳 （1）“用……”表示使用工具，手段等。例如： ①We can walk with our legs and feet. 我们用腿脚行走。 ②He writes with a pencil. 他用铅笔写。 （2）“和……在一起”，表示伴随。例如： ①Can you go to a movie with me? 你能和我一起去看电影'>电影吗？ ②He often goes to the library with Jenny. 他常和詹妮一起去图书馆。 （3）“与……”。例如： I’d like to have a talk with you. 我很想和你说句话。 （4）“关于，对于”，表示一种关系或适应范围。例如： What’s wrong with your watch? 你的手表怎么了？ （5）“带有，具有”。例如： ①He’s a tall kid with short hair. 他是个长着一头短发的高个子小孩。 ②They have no money with them. 他们没带钱。 （6）“在……方面”。例如： Kate helps me with my English. 凯特帮我学英语。 （7）“随着，与……同时”。例如： With these words, he left the room. 说完这些话，他离开了房间。 [解题过程] with结构也称为with复合结构。是由with+复合宾语组成。常在句中做状语，表示谓语动作发生的伴随情况、时间、原因、方式等。其构成有下列几种情形： 1.with+名词(或代词)+现在分词 此时，现在分词和前面的名词或代词是逻辑上的主谓关系。 例如:1)With prices going up so fast, we can't afford luxuries. 由于物价上涨很快，我们买不起高档商品。（原因状语） 2)With the crowds cheering, they drove to the palace. 在人群的欢呼声中，他们驱车来到皇宫。（伴随情况） 2.with+名词(或代词)+过去分词 此时，过去分词和前面的名词或代词是逻辑上的动宾关系。

常用介词用法(for to with of)

For的用法 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。 尽管for 的用法较多，但记住常用的几个就可以了。 to的用法: 一：表示相对，针对 be strange (common, new, familiar, peculiar) to This injection will make you immune to infection. 二：表示对比，比较 1：以-ior结尾的形容词，后接介词to表示比较，如：superior ,inferior,prior,senior,junior 2: 一些本身就含有比较或比拟意思的形容词，如equal，similar，equivalent，analogous A is similar to B in many ways.

介词with的用法大全

介词with的用法大全 With是个介词，基本的意思是“用”，但它也可以协助构成一个极为多采多姿的句型，在句子中起两种作用；副词与形容词。 with在下列结构中起副词作用： 1.“with+宾语+现在分词或短语”，如： (1) This article deals with common social ills, with particular attention being paid to vandalism. 2.“with+宾语+过去分词或短语”，如： (2) With different techniques used, different results can be obtained. (3) The TV mechanic entered the factory with tools carried in both hands. 3.“with+宾语+形容词或短语”，如： (4) With so much water vapour present in the room, some iron-made utensils have become rusty easily. (5) Every night, Helen sleeps with all the windows open. 4.“with+宾语＋介词短语”，如： (6) With the school badge on his shirt, he looks all the more serious. (7) With the security guard near the gate no bad character could do any thing illegal. 5.“with+宾语＋副词虚词”，如： (8) You cannot leave the machine there with electric power on. (9) How can you lock the door with your guests in? 上面五种“with”结构的副词功能，相当普遍，尤其是在科技英语中。 接着谈“with”结构的形容词功能，有下列五种： 一、“with+宾语+现在分词或短语”，如： (10) The body with a constant force acting on it. moves at constant pace. (11) Can you see the huge box with a long handle attaching to it ? 二、“with+宾语+过去分词或短语” (12) Throw away the container with its cover sealed. (13) Atoms with the outer layer filled with electrons do not form compounds. 三、“with+宾语+形容词或短语”，如： (14) Put the documents in the filing container with all the drawers open.

for和to区别

1.表示各种“目的”，用for （1）What do you study English for 你为什么要学英语？ （2）went to france for holiday. 她到法国度假去了。 （3）These books are written for pupils. 这些书是为学生些的。 （4）hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。 2．“对于”用for （1）She has a liking for painting. 她爱好绘画。 （2）She had a natural gift for teaching. 她对教学有天赋/ 3．表示“赞成、同情”，用for （1）Are you for the idea or against it 你是支持还是反对这个想法？ （2）He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。 （3）I felt deeply sorry for my friend who was very ill. 4. 表示“因为，由于”（常有较活译法），用for （1）Thank you for coming. 谢谢你来。

（2）France is famous for its wines. 法国因酒而出名。 5．当事人对某事的主观看法，“对于（某人），对…来说”，（多和形容词连用），用介词to，不用for. （1）He said that money was not important to him. 他说钱对他并不重要。 （2）To her it was rather unusual. 对她来说这是相当不寻常的。 （3）They are cruel to animals. 他们对动物很残忍。 6．和fit, good, bad, useful, suitable 等形容词连用，表示“适宜，适合”，用for。（1）Some training will make them fit for the job. 经过一段训练，他们会胜任这项工作的。 （2）Exercises are good for health. 锻炼有益于健康。 （3）Smoking and drinking are bad for health. 抽烟喝酒对健康有害。 （4）You are not suited for the kind of work you are doing. 7. 表示不定式逻辑上的主语，可以用在主语、表语、状语、定语中。 （1）It would be best for you to write to him. （2） The simple thing is for him to resign at once.

双宾语 to for的用法

1.两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for：(1) 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。 如： 请把那本字典递给我。 正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。 正：She taught us music last year. 正：She taught music to us last year. (2) 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose,prepare, spare 等之后用介词for 。如： 他为我们唱了首英语歌。 正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。 正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes? 正：Can you spare a few minutes for me? 注：有的动词由于搭配和含义的不同，用介词to 或for 都是可能的。如：do sb a favour＝do a favour for sb 帮某人的忙 do sb harm＝do harm to sb 对某人有害

介词at的基本用法

介词at的基本用法： 一、at引导的时间短语通常可表示： 1.在几点几分，例如：at one o’clock(在一点钟) I usually make the bed at one o’clock.. 2.在用餐时间，例如：at lunchtime（在午餐时间） 3.在某个节日，例如：at Christmas 在圣诞节的时候 4.在某个年龄的时候，例如：at the age of 12。在12岁的时候 5.一天中的某段较短的时间，例如：at noon在中午at night在夜里 二、at也可引导地点短语，常用于小地点之前，例如： at the bus stop在汽车站at the butcher’s 在肉店里at school在学校里at home在家里 介词on的基本用法： 一、on可引导地点短语，表示“在…上面”，例如：on the table在桌子上 二、on也可引导时间短语，通常有以下用法： 1.用于“星期”和“月份”中的任何一天之前，例如：On Monday在星期一on April 1st. 2.用于某个“星期几”当天的某段时间，例如：on Monday morning在星期一上午 3.用于具体某一天之前，例如：on that day在那一天On my birthday在我的生日那天 On Christmas day在圣诞节那天 介词in的基本用法： 一、in可引导地点短语，常表示“在…里面”，例如：in the bag在袋子里 二、in引导的时间短于通常有以下用法： 1.在某个世纪，例如：in the 21st century在21世纪 2.在某一年，例如：in 1995在1995年 3.在某一个季节，例如：in spring在春季 4.在某一个月份，例如：in March在三月里 5.在某段时期，例如：in the holidays在假期里 6.在某个持续几天的节日里，例如：in Easter Week在复活周 7.在一天中的某段时间，例如：in the morning在上午（早晨）

初中 英语 介词“with”的用法

介词“with”的用法 1、同, 与, 和, 跟 talk with a friend 与朋友谈话 learn farming with an old peasant 跟老农学习种田 fight [quarrel, argue] with sb. 跟某人打架 [争吵, 辩论] [说明表示动作的词, 表示伴随]随着, 和...同时 change with the temperature 随着温度而变化 increase with years 逐年增加 be up with the dawn 黎明即起 W-these words he left the room. 他说完这些话便离开了房间。2 2、表示使用的工具, 手段 defend the motherland with one s life 用生命保卫祖国 dig with a pick 用镐挖掘 cut meat with a knife 用刀割肉3

3、说明名词, 表示事物的附属部分或所具有的性质]具有; 带有; 加上; 包括...在内 tea with sugar 加糖的茶水 a country with a long history 历史悠久的国家4 4、表示一致]在...一边, 与...一致; 拥护, 有利于 vote with sb. 投票赞成某人 with的复合结构作独立主格,表示伴随情况时，既可用分词的独立结构，也可用with的复合结构： with +名词(代词)+现在分词/过去分词/形容词/副词/不定式/介词短语。例如： He stood there, his hand raised. = He stood there, with his hand raise.他举手着站在那儿。 典型例题 The murderer was brought in, with his hands ___ behind his back A. being tied B. having tied C. to be tied D. tied 答案D. with +名词(代词)+分词+介词短语结构。当分词表示伴随状况时，其主语常常用

双宾语tofor的用法

1. 两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for： (1) 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。 如： 请把那本字典递给我。 正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。 正：She taught us music last year. 正：She taught music to us last year. (2) 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose,prepare, spare 等之后用介词for 。如： 他为我们唱了首英语歌。 正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。 正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes? 正：Can you spare a few minutes for me? 注：有的动词由于搭配和含义的不同，用介词to 或for 都是可能的。如： do sb a favou r do a favour for sb 帮某人的忙 do sb harnn= do harm to sb 对某人有害

高中常见介词的基本用法

介词 介词不能单独作句子成分，而是用来表示名词或代词等和句中其他词的关系，通常放在名词或代词之前，构成介词短语。介词短语作为一个成分在句中可用作定语，表语，状语等。When shall we have the talk on the history of the Party我们何时听党史报告（定语）His elder brother is in the army.他的哥哥在部队。（表语） I went to school at half past seven yesterday.昨天我7：30 上学。（状语） 《 Will you please come along with me跟我一起走好吗（状语） ※同一个汉语词可以译成不同的英语介词。例如： 一幢石头的房子 a house of stone 这个房间的钥匙 the key to this room 明天的票 the ticket for tomorrow 《 （一）About 1．表示地点：在。。。周围；在。。。附近 We took the foreign guests about the campus. 我们带领外宾在校园里各处看看。 2．表示时间：大约。。。；近于。。。时刻前后We left there about six o’clock 我大约在六点左右离开那个地方。 3．表示客体关系：对于；关于；有关。例如：1) I must see him, I’ve heard so much about him 我必须要见他，我听到很多关于他的事情。2) What do you know about China 关于中国你知道些啥 （二）Above 表示位置，职位，数量，年龄等：在。。。上方；在。。。之上；超过。。。 1) Henry’s work is well above the average.亨利的功课大大超过一般水平。 2) A bird is flying above the woods. 一只鸟在树林上飞。 3) The portrait is above the blackboard.一幅肖像挂在黑板的上方。 4) It weighs above five tons. 这东西有5 吨多重。 （三）Across 1．表动作方向/位置：横过；穿过。（在表面）1）The boy helped the old lady across the street. 男孩扶老大娘穿过马路。2) The tree had fallen down across the railway line.树倒啦，横在铁路上。 2．表示地点：在对面；在。。。的另一边。 1）The church is across the river. 教堂在河的对面。 （四）After 1.表示时间或位置：在。。。之后。 1）Please line up one after another. 请一个挨一个排好对。 He goes on working day after day ,week after week without any change. 他继续日复一日地工作，没有丝毫改变。Shut the door after you. 随手关门！ 2．引伸意义：仿照；按照。 Please make sentences after the model. 请照示例造句。 ※（五）Against 1．表示位置：依着；紧靠；撞击；碰着。 1) He rested his bike against the wall.他把自行车靠在墙上。 2) The rain was beating against the windows. 雨敲打着窗户。 2．引伸意义：反对；禁止。 1）Are you for it or against it 你是赞成还是反对 2) Is there a law in this country against spitting right and left 你们国家有没有反对随地吐痰的规定

英语介词with的用法

英语介词with的用法 with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词； 2. with或without-名词/代词+副词； 3. with或without-名词/代词+介词短语； 4. with或without-名词/代词+动词不定式； 5. with或without-名词/代词+分词。 下面分别举例： 1、 She came into the room，with her nose red because of cold.（with+名词+形容词，作伴随状语） 2、 With the meal over ， we all went home.（with+名词+副词，作时间状语） 3、The master was walking up and down with the ruler under his arm。（with+名词+介词短语，作伴随状语。） The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.（with+名词+不定式，作伴随状语） He could not finish it without me to help him.（without+代词 +不定式，作条件状语） 5、She fell asleep with the light burning.（with+名词+现在分词，作伴随状语） 6、Without anything left in the cupboard， she went out to get something to eat.（without+代词+过去分词，作为原因状语）

to和for的用法有什么不同(一)

to和for的用法有什么不同（一） 一、引出间接宾语时的区别 两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for，具体应注意以下三种情况： 1. 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。如： 请把那本字典递给我。 正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。 正：She taught us music last year. 正：She taught music to us last year. 2. 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose, prepare, spare 等之后用介词for 。如： 他为我们唱了首英语歌。 正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。 正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes?

正：Can you spare a few minutes for me? 3. 有的动词由于用法和含义不同，用介词to 或for 都是可能的。如： do sb a favor＝do a favor for sb 帮某人的忙 do sb harm＝do harm to sb 对某人有害 在有的情况下，可能既不用for 也不用to，而用其他的介词。如： play sb a trick＝play a trick on sb 作弄某人 请比较： play sb some folk songs＝play some folk songs for sb 给某人演奏民歌 有时同一个动词，由于用法不同，所搭配的介词也可能不同，如leave sbsth 这一结构，若表示一般意义的为某人留下某物，则用介词for 引出间接宾语，即说leave sth for sb；若表示某人死后遗留下某物，则用介词to 引出间接宾语，即说leave sth to sb。如： Would you like to leave him a message? / Would you like to leave a message for him? 你要不要给他留个话？ Her father left her a large fortune. / Her father left a large fortune to her. 她父亲死后给她留下了一大笔财产。 二、表示目标或方向的区别 两者均可表示目标、目的地、方向等，此时也要根据不同动词分别对待。如： 1. 在come, go, walk, move, fly, ride, drive, march, return 等动词之后通常用介词to 表示目标或目的地。如： He has gone to Shanghai. 他到上海去了。 They walked to a river. 他们走到一条河边。