Investigation of hydrothermally treated controlled porous glasses (CPGs). II. Study of adsorption properties of hydrothermally modified controlled porous glasses

Materials

Chrmistr,~

ad

INVESTIGATION

Physics,

II.

MENDYK and

Faculty

of

13

PROPERTIES

OF HYDRO-

CONTROLLED POROUS GLASSES

A.L.

DAWIDOWICZ

Chemistry,

Lublin

Received

14

STUDY OF ADSORPTION

THERMALLY MODIFIED

20-031

13

OF HYDROTHERMALLY TREATED CONTROLLED POROUS

GLASSES [CPGs ).

E.

24 (1989)

Maria

(Poland

February

Curie-Sklodowska

University,

)

6,

1989,

accepted

March

17,

1989

ABSTRACT The is

mechanism

relatively

meters

of

presence In

the

porous of

It

previous

associated

the

residues

paper

[l]

changes

of

modified

CPGs.

results

investigations.

As

depend

on

temperature

directly process

and

mainly

with

are

connected

the

change

the

The

was

of

of

hydrothermal glasses

the

only

surface

of

are

and

of

has

properties

adsorption

with

treatment

isotherms

duration

the

modified.

adsorption

adsorption

para-

(CPGs)

thermogravimetric

and

not

and

being

the

shown.

materials

on different

temperature

porous with

of

siliceous

sorbent

Influence

deals

the

with

process in

the

of

among others

controlled

work

This

hydrothermally

treatment

depends

structure,

discussed.

retie

hydrothermal

different

on structural been

of

complex.

isotachopho-

properties the

structural

modification

rebuilding

but

chemistry.

INTRODUCTION One

sorbent It

is

adsorption

factors

The

in

absolute

form as

volume)

the

0x4-0584/89/$3.50

of

above

employed

is

adsorption

in the

and

in

surface first

of

form

on

properties

mentioned

isotherms

parameters

i.e.

as

of

on

unit.

more

of

the

significantly

comparable

calculated

many diameter

nature

which

materials are

mass

( shape,

chemical

adsorption

per

depends

structure the

of

an adsorption

isotherms area,

all

characterization

calculated

a graphical adsorption

specific

adsorption

adsorption

often

ability

presented

The such

pore

surface.

vary

parameters

usually

isotherm.

and

the

of

using per

0 Elsevicr Sequoia/Printed in The Netherlands

14

surface

area

curves ted

is

unit.

Thus

dependent

surface

the

mainly

(type

and

amount

adsorption

isotherms

are

silica

properties

in

gel

take

place The

vapour

part

leads

to

( CPGs).

These

silica and

during

first

part

[1J

I

structure

8 h ow not but

of

chemical from

the in

The

paper

I

only

of

silica

with

absolute

hydrothermally

[l].The

means

of

surface

investigations

isotachophoresis

and

the

CPG is

porous

CPGs

surfaces.

of of

the

surface

SirB:Na should

isotherms

differ be

adsorption

reflec-

Isotherms.

for

porous

as described

been

in

simultaneous

conditions have

The

described of

changes

and with In

Initial

their

amounts

absolute

glasses

( 106%)

a203

results

in

water

( 94-99x). of

modification

latter

under

measurements

of

The

sdsorptlon

treated

adsorption

derivatographic

the

with porous

amounts

dissolution

mentioned

of

changes

Si02

modification

related

absolute

contact

of

changes

and

investiga-

comparison

controlled

structure

chemical

Thus

above

the

gel.

network

ones).

deals

the silica

in

The for

the

residual

(mutually

the

in

the

[2-S]. that

composed

geometrical

result

the

previous

form

of

suggest

composition

ted glass

also

changes

These rebuilding

shows

Besides,

that

of

structura.1

treatment

mainly

adsorption

centers).

significant

CPG contains

from

of nature

convenient

changes are

Na20 (0.03-0.5%).

position

chemical

active

paper

structural

different

of

which

this

materials of

and

especially

hydrothermal of

framework

quite

form on the

associated

boron

content

CPG skeleton

part

in

with anelyred

and

on the

obtained

from

by

CPG

as well.

EXPERIMENTAL Materials The type

glasses

glass

Na20,

35% B203

materials glaas

and

materials described Table obtained

I.

[7,8].

in

55% Si02.

In

sorbents,

and

Glass

were

porosity

7% Na20,

leached

with

and

order

transform

the

I

sorbents-

I also

to narrow

following two

8 characterized D=l08

hydrothermally

pert

were

23% B203

As a consequence

C type

Table

of

porous

heated

prepared: glass

controlled

and

into

were

procedure were

of

composed

[iland contains

8 and

types

the

10%

crude

of

Vycor

previously

described

of

materials

by D-484

initial g and

cm3/g.

according conditions

phyeicochemioal

Vycor

and/or

these

fractions

the

VP-O.78

treated under

70% Slop

V p=l .02

These to

the

procedure

presented properties

cm3/g

initial in of

the

15

Methods Specific

surface

described

out

Poland)

with

hydrogen out

at

using

part

in

carried

12O’C.

The

peak

as

for

the

of

surface

teflon

with

-

the

the

acid

fine1

placed

thermel

analysis

Hungary).

The

polyvinyl

was

range

10 dsg/min.

During

correction. was employed

structure

procedure of

at

carried

and

was described

anion

20°C out

on

( SOi

bands

a

with

and a migration

comparing the

the

following

2-amino-2-methyl-i-propanol (AMP),

of

( moviol),

alcohol AMP,

corundum

Mass crucibles

recorded

with

( 0.49)

analyzed

2001000°C

loss

a Q-1500 in

pH = 10.5

acid, in

during

the

prepared

differential

0 derivatograph

air

applying

measurement

pH = 8.95

hydrochloric

investigations.

the

samples

temperature

the

As electrolytes

curve.

O.OlM

ric in

performed

diffusion

home made apparatus

were

O.OlM

and

Thermogravimet

were

carried

t

electrolyte:

samples

proper

mm i.d.)

0.2

calibration

electrolyte:

hydrochloric

- the

in

separation using

purified were

Isotachophoresis The

cm long,

and

calculations

estimation

Calculations

applied

initial

content glasses.

(15

Dried

the

were

Elwro-WrocZaw,

measurements

[9,10]with

performed

100 JIA.

were

isotherm

Isotachophoretic

capillary

results

The

were

measurements (N-504,

detector.

Investigations.

zones)was

mixtures

isotherm

phase.

method

porous

investigations

chromatography

a. mobile

boron

[ 111.

of

gas

adsorption

Isotachophoretic

current

of

profile

as a method

and SiOi2

porosimetric

a thermoconductivity used

elsewhere

and

The adsorption

I.

by means

was

the

area

were

heated

a temperature

TG changes

were

( MOM, in

the

rise

at

observed.

RESULTS AND DISCUSSION As

follows

porous

from

of

be

found

discussed Figures obtained Table constant

and here

of

they

1 and As can

hydrothermal

(SBET,

The date

were

2 present

the in

time(

the

included

)

depend These

in

I

of

ceuses

the glass

increase

a significant

not

cl]. for

C-type

temperature

the on

variations

are

detail

isotherms

treetments

the

except

msinly

In Table

analyzed

Fig.1,

controlled

treatment

modification.

adsorption

5 hrs

in

VP and D)

already

hydrothermal

be seen

modification

of

changes

hydrothermal

I.

Table as

by various I).

structural

material time

in

I,

a result

initial

temperature ten

as

glasses

geometry

Part

samples ( see at

increase

16

in

adsorption

measured

which

by either

Is

evident

polar

or

from

Table I. The physicochemfcal treated porous glasses. Type

Sample

Time

J

PC

8

The time

of

ChrsJCm2/cd

cc:3/g

&

7

60

1.02

484

6

57

0.94

526

3

200

6

46

0.93

610

250

6

23

0.99

2000

5

300

6

0.77

6750

0.78

108 134

2.0 176

2

150

6

107

0.47

3

200

3

82

0.44

184

4

200

6

52

0.39

260

5

200

12

38

0.35

440

6

250

6

0.28

1832

can

( Fig.

treatment

vapour,

the

6.5

be drawn 2).

higher

The

the

observing

longer

the

influence

of

CPG contact

time

the

adsorption

course

of

absolute

it

was

shown [l]

formation

of

the

with

observed.

Using

electron

treatment

microscopy

leads

structure.

to

the

Structural

to

globular

differences should

diameter

V

4

isotherm

like

Mean pore

PO re

volume

150

same conclusions

water

isotherms

hydrothermally

surface area ,SSET

1

C

of

Specific

1 2

adsorption

substances.

properties

Temperature

code

of glass

the

non polar

in

be

chemical

character

Slop

rather

) are

associated

with

likely The

the

CPG hydrothermal globular

( transition

not

properties.

that

secondary

changes

network

adsorption

the

from

to

cause

observed

modification

sponge

so drastic

phenomenon of

the

surface

nature.

As mentioned CPGs in

their

in

the

siliceous

papers

also

showed

bonded

with

them were

concentration edsorption

of

that

these

properties

introduction

structure

centers

proved

possess

surface strong

and boron

adsorption on the

demonstrated

B203

atoms

and

centers surface,

by the

earlier

[12-141,

residues.

Previous

hydroxyl

groups

C14J. The higher the

investigated

higher

the

sorbents.

proper

6 hrs)

adsorption

the

(for

at

The

treated

1.

written

Fig.

I

600

curves.

samples

isotherms

glass

I

400

I

200

hexane

of

of

~

I

400

I

init.

ISO°C

The

and

of

chloroform temperatures

benzene

8

600

200°C

pressure [hPa]

C-type.

hexane,

200

I

250°C

benzene

1

the

on

200

hydrothermal

initial

400

I

and

chloroform

I

treatments

hydrothermally

600

are

1

2.

isotherms

Fig.

E q

z

zl

E

$-’

,

glasses

influence

for

The

200

hexane

of

of

400

C-type.

hydrothermal

600

12hi-s

modification

time

(at

pressure[hPa]

I

600

I

400

I

200

,12hn

benzene

200°C)

I

on

200

the

form

of

adsorption

I

600

I

4.00

12hrs

chloroform

19

The

varying

surface

determines

glasses

the

Table

II

in

sorbent

one

to

hand

causes

layer.

structure

and of

part

the

inner

glasses.

increase

hand

another

properties

presents

the

porous

of

adsorption

is

of

factor

which

hydrothermally

modified

[15].

8203) ted

hydroxylation

The

per

of

the

of

obtained

analysis{

on the of

B203

meter

were

of

surface.

B203

rise

of

results

of

appears,

the

the on

in

conclusions

the

other surface

drawn

from

I.

Table II. (duration

Influence

of

Sulk

B203

6hrs ) on bulk

Glass *

hydrothermal

and

treatment

surface

boron

Surface

temperature

concentration.

boron

concentration

as

B203

concentration

type

WI

c rg/m2J

c rgfgl

B-l

2.66

21.6

B-3

0.99

1752.6

39.1

B-5

0.35

1897.3

948.7

C-l

2.14

c-2

0.06

8.8

0.05

200.1

1.28

1.87

c-4

1.28

1398.8

26.9

C-6

1.07

2187.3

336.5

*

gram

leads

and on the

concentration

confirm

as

investigaper

temperature

concentration

B20S

the

calculated As it

modification

bulk

expressed

surface

amounts

square

drop

boron

and

CPG hydrothermal

significant

The

data

code

cf.

I.

Table

During

rebuilding

residue

is

surface

together

Taking

dissolved into

sequence

of

with

changes

of

time

hydrothemel

of

As the

boron changes

investigation glass

confirm

B of the

of

water

and

the

distribution

skeleton,

the

( sorbed)

deposited

boron on the

Si02.

data

from

adsorption

Table

can

I

and

( Fig.

isotherms

be expected

the

mutual

2),

analogous

concerning

the

treatment. presented the

a different above

a CPG siliceous

in

condensing

account

absolute

of

boron

are

content

structure

conclusions.

surprising, and was Table

the

boron

carried

II

proves

additional

distribution out

in

that

order the

in

to changes

20

are

similar.

that

the

The

temperature remaining The

B203

autoclave

the

of

and

These

analysis

more

than

all

are

in

phenomena

that

water

significant

not

from

is

at

Table the

the

total

C and

B,

hydrothermal

from

which

of

glass

during

corrosion were

502

for

removed

data

modified

20 and

structure,

suggests

boron and

of

CPG hydrothermally

whole

balance

walls

acid

walls.

of

contains in

some amounts

boric

detailed

surface

the

bed and

confirmed traces

observed

II

shows

highest boron

amount

respectively. treatment

located

on the

by crystalites

on the

during

inner

silica

of

autoclave gel

modifi-

cation. Dependences

of

hydrothermally

mass

treated

3 and

4 ) . It

higher

the

temperature

is

mass loss

Figs.

the

200 Fig. tric with

400

losses

on temperature

glasses can

of

during

600

seem to

be concluded the

for

be very

from

hydrothermal

these

initial

and

interesting plots

treatment,

( see

that

the

the

greater

thermoanalysis.

800

1000"c

3. The mass loss v~ temperature increase during thermogravimeinvestigations for glasses of B-type. Curve number compare the sample code from Table I.

Fig.

4.

The

For

these

mass for

;zn;;r;ments) .

groups

adsorbed

water

According fully

porous of

mass loss

or is

comes

it not

to the

glass)

water

is

which

temperature per

number.

of

water

of

from

200-1000°C. per

loss

2 which

m

originated

is

materials III

would

of

above

are

from

the

III

gel,

total

presented

Table

2OO’C.

( silica

samples

be present

only

Physically

concentration

contains

values

column

surface

measured

investigated

The

Another

of

the OH group

Table the

to water

in micropores.

siliceous

8-9umol/m2.

meter.

OH groups

the whole

of

condensation

enclosed

[16,17]

surfaces

about

range

the

mainly

as mass loss

literature

disappeared

square

from

present

increase (derivatographic Curve number conforms with

corresponds

can be that

hydroxylated

number

if

the

The water

hydroxyl

temperature of C-type.

vs.

glasses

samples

evacuation.

in

loss

shows

on the

amounts

in

the

as

a mole

the

surface

OH group

condensation. As results possess

typical

from Table coverage

III,

the

densities

surfaces

of

the

by OH groups.

initial

materials

Some authors

22

suggest

atoms

that, porous

[lS]

are

hydroxylated

last

suggestion

that

the water

X50-200°C hydroxyl

glass

and the loss

cannot

values

but also

strongly

degree,

glasses

only from

III

it

into

of

Mass loss

structure.

code

Theoritically

H-0 content G

* [W]

B-1

groups

L)tmol/g

0.37

3.42

6.84

B-2

0.45

250

4.38

8.76

0.55

305

6.64

13.28

e-4

0.75

417

18.3.

36.2

B-5

1.27

706

353 .o

706.0

C-l

1.5

833

4.73

c-2

1.2

667

6.23

c-4

1.25

694

13.2

26.4

C-6

2.27

1260

194 lo

386 .O

code

cf,

Table

silica

intraglobular adsorption

gels As it

centers,

was observed

ClQ-221

water.

was’confirmed.

9.46 12.46

I.

The same phenomenon treated

OH

ration

[ pmolfm2]

B-3

*

of

assumed

concent

lJmol/m?J

205

above

surface

Table III. Losses of water during tharmogravimetr~c analysis investi of hydroxyl groups 1 theoritically ated CPGs and yroles assumed 9, that can from measured water amounts. Material

the

modified

.condensation

inner

in boron

account

can be concludsd

hydrothermally

from the

anriched

Taking

from Table

in porous

originate

groups

surfaces

to a higher

In such is in

silica

gels

known that the

in the

case

and was explained

examined

they can significantly groups, materials modified by water.

the

the

in

hydrothermally

presence

micropores

case

share

of

by the

beside

are boron

the observed

presence of

of

micropores

very

strong

and hydroxyl adsorption

far

CONCLUSIONS I.

The

hydrothermal

to the increase The higher the tion

the

2. The

stronger

contact

treatment

of

controlled

of adsorption properties temperature and the longer of

adsorption CPG with

properties water

vapour

porosity

glasses

leads

of the material surface. the time of the modificaare.. causes

the

significant

23

enrichment

of

others

these

3.

The

the

final

atoms

obtained

results

should

increase

the

4.

significant

The

and

the

5.

of

the The

suggest

that

water

CPGs.

boron

hydrothermal

the

Among

modification

hydrothermally for

silica of

time

rise.

of

the

treated

gels

amount

and

a consequence

atoms.

properties.

degree.

from

temperature 1 is

the

results

in

in

adsorption

hydroxylation

of

micropores

hydrothermal

surface

higher

literature

conclusion

points

in

surface loss

analogous

formation with

product

result

point

which

glasses to

the

increases

phenomena

described

in

2-4.

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Dawidowicz,

E.

Mendyk

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Kolloidn.

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Oganesian,

Kolloidn.

Nikitin,

Zhurn.,

E.B.

31 ( 1969) A.V.

Baigubekova,

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Kiselev

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Yu.S.

R.

7 W. Hailer, 8 A.L.

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Mendyk,

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end

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Dawidowicz

15 A.L.

Dawidowicz,

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Davydov,

N.

Remasubramanian,

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I.

Choma,

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11 ( 1984)

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Klselev, Wileyy

Shtchepalin, 71 ( 1957)

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18

F.

Janowski

f6r 19

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