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The modification of sucrose chars by permanganate
Materials Chemistry and Physics, 21 (1989)
THE
MODIFICATION
A.S.
Glass
and
Department New
SUCROSE
M.J.D.
of
York,
Received
OF
Low
Chemistry,
N.Y.
507
CHARS
BY
PERMANGANATE
# New
10003
October
501-520
York
University,
4 Washington
Place,
(U.S.A.)
13,
1988;
accepted
November
8,
1988
ABSTRACT Three sucrose-based chars equivalent to low-, medium-, and hightemperature chars were oxidized with aqueous KMn04 solution in order to explore textural changes caused by the oxidation. The reaction caused the chars to become covered with hydrated MnO which was then dissolved with HCl. Some HCl, however, became boun $ to the chars and had to be removed by boiling them in distilled oxidation leads to impure materials water. In general, the KMn04 containing reaction detritus and bound chlorine which must be carefully removed by washing/boiling steps. The oxidation caused the N2 specific surface areas (SSA) of the samples to decrease and The treated samples were thermally changed their porosities. unstable; degassing them in the 200-400°C range increased the before and after oxidation, were also reacted SSAs. The chars, with HCl or NaOH solutions to test their surface acidity; the samples become more acidic in terms of the amounts of base neutralized, but the acid/base titration data are of dubious value because of the retention of HCl by the chars and because the NaOHchar mixtures were cloudy after centrifugation, i.e., the reaction with base caused some reaction detritus to be released. In oxidation does change the texture and general, although the KMn04 the method is a poor one because surface properties of the chars, of its complexity and should be avoided. INTRODUCTION It
is
well
oxidizing as
well
been
known
agent; as
it
inorganic
reviewed
degradation coals;
these
that
has
the
been
materials.
by
Stewart
procedures
using
have
been
workers.
Permanganate
carbons,
although
to
permanganate W:
to
whom
0254-0584/89/$3.50
solutions inquiries
The [l]
should
used be
an
Lee
have
Hayatsu
extent. as
as
The
al.
has
Oxidative
been
used
with
who
cite
used
with
[3], been
decolorizing
empirical
strong organic
reactions
[2].
also
a
with
of
also et
have
is
such
variety by
solutions
lesser is
wide and
by
ion
used
permanganate
reviewed
numerous
a
permanganate
extensively
of
industrial
aqueous test
of
directed. 0 Elsevier Sequoia/Printed
in The Netherlands
the
activity
of
carbons
of
altered
when
of
nature
the
reactants,
its
and
by
a
that
of
(SSA) upon
Mukherjee least,
oxidized
carbon
solutions
Bhattacharya
clear
implication
of
and is
that
Parenthetically,
particles
of
acid
with
black
particles
If then
permanganate alterations should
In
be
been et
products
in
some
+
NaN03
upon
standing
gross
been
the
at
boiled [9].
The
that
small
of
nitric
reaction
hold
[13].
morphological
reported
to
be
experiments had
by
cement
to
areas
substantially
carbons
. [15]
paid about
seems surface
KMn04
some
al
formed as
oxidation in
the
viewed such
contrast,
unit
weight
[8-111.
then
render
the
out
some
in
Possible
results
terms
to
lead
of
to
larger,
oxidized
textural
changes,
changes
to
explore
per
been
in In
properties
activity
have
uncertain.
treatment,
sucrose-derived
were
chemical/adsorptive
comparisons
experiments
permanganate
have
than
been
be brought
result
of
appeared
Voet
acted
which
acidic
together.
a
carbon
sediments
blacks
any
area.
or
organic
have
specific
that,
in
more
decreased
KMn04
view
a permanganate-
to
might
the
mentioned
degradation
channel
be
samples of
there
changes.
that
solutions
that
would
clear
In
with
that
appears
only
that
chemically
[6-141.
find
which
the
different
filtrates
not
carbon
a carbon
reported
demonstrated become
permanganate to
attention
who
with
and
the
of
been
solutions
of
oxidation;
three
has
fibers,
unexpected
little
inthetexture
of
it
permanganate
be
However,
Matsumura,
and
reactions
not
consequently
treatment
were
the
permanganate of
51,
including
with
would
precursor.
to changes
[4,
types,
treated
it
treated
carbons
various
the
view
made
that
textural
and
describe
for
the
unit
on
carbon's of
some
of
the
surface basis
texture we
have
changes results
the
of
would carried
caused obtained
by with
chars.
EXPERIMENTAL
The was
starting
material
commercial
Scientific
Reagent
Co.,
dehydration
has of
experimental be
termed
degassing
FSD, at
by
were and 500°C
NJ.,
been
sucrose
work
FSD
Grade
Fairlawn,
manufacturer,
preparation
or
by
concentrated
at
900°C
the
carbons in --
dry
samples (Fisher
according
to
the
room-temperature acid.
charcoal,
which vacua;
carbon
Charcoal
which,
sulfuric
as-received, other
all
Sugar
700198)
prepared
the
two
Fisher lot
of
were air
was
Samples which prepared then
for will by
slowly
509
bled
into
are
the
preparation
termed
FS5000
equivalent 173.
to
As
they
low-,
were
materials
(distilled
water
with
on
water
Filter-paper dried
The of
with
KMnO4. mixture
was
at
while
FS500
this
left
Mn02
for
of
1
and
filtrate
gave
air-dried
at
are
termed
treatment taken 5M
up
HCl
found with or
the
to
significant
400°C,
oxidized,
with a
weight
HCl
which
presence
of
These
cool, Cl-
in
samples
code,
e.g.,
An
FSP,
stand
Mnt2
have
such
with
the
wash
are
designated
FS500PHB.
HCl
might
samples, washed
prepared
water
For
was by
by to
of
and
soaked
For
400,
letter
by
an
the
at
In
present in
water, The
llO°C.
testing
FS,
Irish
found.
it
8 appended some
500,
retained,
boiled
dried
in and
example,
at were
on
be
carbons samples
was
were
HCl
could
carbonizing
followed the
the
their
remained
and
treatment
HCl
retention
HCl the
NaBi03),
anthracite
by
FS9OOP 36M
until
this
that
HCl
remove
or
ml
retained.
comparison,
3 days,
to
water
had
samples
water,
air-
subjected
order
10
in
percent
percent
for
FS5OOP,
of
an
weight
the The
and
Unfortunately,
[18]
carbonizing 0.72
in
with
were
solid and
Samples
(oxidation
HCl
gram
water,
in
content
of
was
temperature.
subjected
et al --A ash
which
FS9OOP.
acid
to
batches
to
oxidized
complexity
a carbon
2.8
are
solution
with
and
FS900PH.
the
by
and
materials
1.106
the
with
Samples and
and
acid-treated to
for
amounts
1.07,
remove
allowed
left
Blayden
prepared
times
Microfiber
employed
7 days.
FS5OOP
additional
reduce
water four
filtering)
water
room
repeatedly
tests
carbons:
order
was
overnight.
an
at
oxidation.
washed
negative
Similarly,
to
then
llO°C
0.83,
at
the
to
were
treated
gram
of
washed
for
FSP,
were
0.2
was
a sample
order
sample
oxidized
FS500PH,
that
resp..
Ag+.
FS900
FSPH,
by
900°C,
peat
samples
introduces
in
a shaker
FS
during
three
GF/A
all
and
added
overnight.
termed
ml
H2S04
was
on
were
for
samples
93
1.78M
solid
approx.
hr.
ml
stand
are
[16,
the
washed
starting
FS900 of
sample
samples
produced
and
the
and
oxidized
sample
FS500
filtered,
llO°C
carbons
FS900.
7.0
to
then
are
distilled
Whatman
used
These
llO°C.
samples
chars
solutions,
were
with
were
consisting
carbon
treatment
The
FS,
three
with and
fitted
and
stirring,
was
dried
at
each
A half-gram
mixture
air
of
[ll]
aqueous
pre-treated
filters
These
These
high-temperature
with
funnel
FS500,
oxidations
temperature.
throughout),
inert
FS,
solutions
added,
to
a Buchner
as
and
were
in
room resp..
treated
used
(these
designated
be
was
overnight
at
FS9000,
medium-,
to
starting
tube
and
to
FS500
with the and
510
FS900
samples
were
dried.
These
samples
The
N2
BET sample)
sorption
apparatus
instrument
(
apparatus)
was
prior
to adsorption
The
SSAs
0.35.
3 results The 0.1
being
mg)
made
having
made
The
done
at
the
4
or
5
values
SSAs
value
from
by
300, 350,
at P/P,
deviation
the
the
of
3
of the mean
of
was
determined
as follows,
the
mixture
supernatant
or base
been
SSAs,
and
sample.
deviation
The
was
values
or
24 hrs
was
then with
of micromoles
were
the
for
titrated calculated
data. Two
Typically,
to
solution
The mixture
neutralized titration
(weighed
NaOH
to stand
liquid
solution.
had
100 mg
left
temperature.
at room
the
ml
by
of from
or three
trials
yielded
values
results
of 6 X.
and
Although
Solids
is placed
on gaining
oxidation
might
the
pertinent
treatments,
other
affect
method
oxidation
methods
emphasis
texture some
have and
the
of
understanding
the
to describe as these
oxidation wet
some
of the
of the
bearing are
of
a
treated
observations
on the
probably
involving
the
how
utility
useful
the
in
use of
oxidants. first
reduced.
washing
and
which
particular
purple-colored been
sample
shaking
each
data
measure
about
it seems
considering strong
the average
was
250,
The average
0.1273M
Mixtures work
during
of this
to
sample.
of
solution,
permanganate carbons,
was
to degas
AND DISCUSSION
Reaction present
done
the
of
with
same
6 %.
each
weights,
and
isotherm,
sample
an average
RESULTS
from
100
or of base
m*/g
NY). The
Degassing
A
acid
were
isotherms,
desorption
used,
of
a Quantasorb
Syosset,
in
standardized
units
with
immersed
automatic
sample
in
procedures.
and
the
some
was
and
FS900H.
adsorption/desorption
calculated
what
about
centrifuged, acid
(SSA,
measured
Corp.,
of a particular
of
was
HCl
0.1509M with
were
was
acidity
conventional
area was
and
N2 for 14 hrs. at 200,
on the
Usually
portions
(but not boiled),
measurements.
in flowing
3 determinations
+
to measure
pressures
separate
sample
(Quantachrome
used
a sample
below
washed FS500H,
chromatographic-type
keeping
4OOOC.
HCl, FSH,
surface
of each
a
samples
relative
with
are termed
specific
degassed
or
treated
gave
filtering
and
filtrate, The
next
a bright
washing
indicating washing
gave
yellow-colored
of that
FSP not
a clear filtrate.
with all
water
of the
filtrate;
gave MnOi
the
Apparently,
a had
third as the
511
pH
increased,
The
yellow
but
a
some color
pale
over
20
yellow
was
soluble
ethanol
Immersing
FSP
is
placed
and
the test get
the
yellow
in
in
the
on
a
)
solubilized.
after
centrifuged, when
hotplate. and
washings,
filtrate
was
remained
HCl
or
successive
filtrate
dryness not
with
present
residue
this
the
Cl-,
the
That
gave
a
yellow
residue
was
a positive
no
Analogous
brown
water,
test
then
a second
a pale
but The
filtrate, boiled
a second clear.
general,
FS9OOP
samples
samples
with
and
the
held
step
release
washed
the
out
was
for
but
was
of
fairly
expected the
firmly
by
were
also
of
additional
and
flushed
mixtures
the
release
yellowish away.
The
Cl-
detritus nature
of
was
the but
the
gave
FSSOOP
and these and which
also
FS900PH
which
not
filtrate
products
because of
yellow
deposited
HCl and
pale
was
Treating been
However,
FS500PH,
brown
FS900PH
FSP,
mixtures. had
the
of
untreated be
a
was
was pale
until and
with
Cl-
then
a
a
positive
washed for
gave
degradation away.
FSPH,
caused
and
filtrate
water
which
yellow/brown flushed
only
to Mn02
For HCl,
so the sample
FS500PH,
FSPH,
otherwise
and
apparently not
with
but
be
out
washed of
dissolved
release
negative,
samples.
and the
the
filtrate
tested
in
Boiling
was
of
The
positive
washings
in
first
boiling.
which
golden-brown
positive.
Cl-
washed
would HCl
a
mins.
concentrated
boiled
tested
order
the
yellow
other
in
was
water
filtrates for Mn +2 .
washed
latter
boiling
time
tests
be
Cl-
test
with
but
In 20
water.
second
filtrate
which
gave
All
In
to
yellow FS500PH
several
for
the
became
led
also
test but
negative
pale
for
bright
immersed
filtered
clear,
after
with
the
made
were
filtrate
after
the
hydrated
washings.
boiled
FSP
after
been
After
yellow
FS900PH
filtrate,
present
had
obtained.
than
washing
greenish
was
appeared
many
twice
a
when
golden-yellow
darker
was
FS5OOP
obtained.
could
Cl-
in
mixture
filtrate
were
from
this
after
colored
observations
were
yellow.
samples
after and
Cl-
the
positive
was
resulted is obtained
When
water,
was
resulted
and
example,
with
color
HCl
mixture
solution).
remained
filtrate
which
clear
HCl
Cl-
of
The
filtrate
for
concentrated greenish
washed
for
boiling;
was
in
into
solid
rid
water.
the
still
to
(a similarly
the
The
was
( but
soluble
paler
Mn+'.
Mn02
up
became
and
Brown
evaporated
in
mixture
to
When
formed.
filtrate
products paler
tint
washings.
precipitate
for
yellow
became
taken
samples. subsequent
also could
induced then
yellow/brown
be
512
degradation present
products
interest.
mixture
of KMn04
yellow
acid
[20];
and
be bound
Mn+2
would
omitted, samples
forms
would were
at
done the
Texture 200°C
of
are
differential
shown pore
complexes
the
boiling
step
bound chlorine the
value. it
of
[19,
Such
then
Chars
201;
carbon
materials
be released
traces
Figs.
FS isotherm of the
material while
of
samples
degassed
B show
as Type [23],
and macropores,
FS500
isotherms
hysteresis
The
non-microporous
meso-
of
the
the data.
classification
having
IV
products.
parts
a
them
present
can be classified of
the
samples
the
[22] from
those
Type
our
that
l-3;
that
i.e.,
cl.w7
although
BDDT
were
with
of degradation
(DPV) calculated
II
obtained
isotherms
A of
washings
not thorough,
but also degradation
probable
Some
parts
and
results
As it is,
seems
contained
in
and
[13], or were
and
volumes
(a
oxide
[21].
surfaces
samples
washed,
Suqar
of
of non-graphitic
not only
samples
scope reagent
leads to the formation graphitic
oxidation char
the
Brodie's
treatments. if
be of questionable -PHB
H2S04)
by Matsumura
contain
so that
carefully
purified The
as was
beyond
that
decomposable
Mn+2 -organic
that
and
however,
by the
boiling
seem
would
products,
certain
to the modified
by the HCl and/or It
easily
is formed
could
not
and concentrated
or brownish,
mellitic
is
It is known,
and
FS900
having
loops
[24].
are
Type
These
C and
other isotherms are not remarkable. o.oosQ is interesting is that the 2? What 0.W~cI, permanganate/HCl treatment decreased the
N2
uptake
porosity, FS900PH
1
have
Further
changes were
the
amounts
and
porosity
hysteresis 28 32 36 PORE RADIUS, i
Fig. 1. N2 sorption by FS chars.
loops the
Figs.
of
l-3.
to
loops. radii
when remove
N2 adsorbed IV
with
the
the HCl:
increased isotherms
Type
C or
The changes in
of the
E
in the
in the changes
shown
In view
and
isotherms.
occurred
appeared,
Type
the
FS500PH,
II
boiled
are reflected
pore
eliminated
FSPH,
Type
samples
becoming
O-
and
so that
parts nature
of
B of of
513
PORE
Fig. 2. N2 sorption
the
samples
possible
a
pore
it
to
say
FS
to
become
FS500
Table to
I.
In
subsequent
the
and
derived
each
like
does
lengthy not
seem
discussion
justified.
oxidation/HCl/boiling
mesoporous,
than of
decrease
I.
of
those the
treatment
and
the
of
Suffice
treatment
changed
alone with
of
the
caused FS500,
Specific
caused treated
caused
porosities
of
samples. been
Surface
Areas
as
is
4:: 364
to
one
m*/g
caused
of
A
Column
with
0 shows with with
FS,
Chars
B
C
0
PHB
H
2:: 270
the HCl;
PH IIX I77
SSA The
(column
FS900.
Sugar
6).
C),
substantially
only
decrease
in
the
and
increase
remained
treated SSA
a negligible
summarized
treatment
SSAs
a substantial
A treatment
had
are
columns
samples
untreated which
and
data
(compare
fully
samples
adsorption
oxidation/HCl
treatment the
Sample
Es00 FS900
the
the
case,
boiling
values
from
substantially
SSAs
lower
Table
overall
micro-
values
the
and
the
necessarily
by FS900 chars.
FS900.
decrease
but
and
shapes
that
and
SSA
detailed
%
RADIUS,
Fig. 3. N2 sorption
by FS500 chars.
3:: 360
SSA that
a minor
514 The
data
degassed [25]
to
using and
of
at be
FS900
been
should
because
about the
were
it
was
any
additional material.
unstable
The
all as
changes
of
range
and
the
be
FS:
attributed
to The
to
the
and were
SSA
increases of
not
effects
of
of of
FS500D
What
the
each
of
the
increases There
of
changes
of
large
Overall,
the
FS500PHB, similar
Essentially, caused temperature of degassing.
the
and
SSA are
relatively by
FS500PH
attributed of
shown and of
with the
FS900H
be
trends
in SSA
FS900PH.
As
the
of
Note, large
desorption
those
SSA
changes
and
and
however,
samples.
FS900PH to
of were
in
exhibited
the
may
air
relatively
cannot
to
the
change
smaller,
FS900PH
solely
range
pertinent,
FS500H
the
300-350°C
FS900PHB.
changes
and
at
samples
FS500PH
significantly
of can
desorption
similar and
view
300°C
the
to
treated
are
FS500PHB
Fig. 4. Effects
in
and
the
with
in
350-400°C
large
particular,
is
samples
samples
FS900D
is
rather
of
It
occurring
exposed
wetted.
4.
above
FS900
and
initially
is
SSAs
the
had bring
increased.
changes
in
Fig.
FS
destruction
when
to
unexpected, in
FS500
FS500
treated
were
was
portions
in
other
The
limit
which
treated
increases
higher
degassing.
unoxidized
all
that FS500
much
expected
shown
temperatures FS
thought
That
be
been
chosen
change;
to
at
the
and
summation
formed
to
mild
not
are
the
changes
was
FS
4OO'C.
would of
of
dramatic
lesser
species
SSAs
the
was
had
were
It
temperature
temperatures the
charring.
oxygenated
the 400°C
which
exposed
by
used
degassing the
attributed
the
at
FS.
cause
affected
samples
of
onset
below
of
been
FS-derived
degassing
be
already be
samples conditions
would
results
increasing
simply
nature
carbonization
in
with
these
Some
the
nature
not
degassing
that
the
temperature
FS500
apparent
and
conditions having
degassing
obtained
hrs,
with
samples,
prepared:
were 14
degassing
temperatures,
chosen
l-3 for
compatible
higher
highest
Figs.
200°C
by
HCl.
FS500PH,
FS900PHB
the
FS
are
samples.
oxidation/HCl/boiling the
highchars
low-temperature
to
and behave FS
mediummuch
samples.
like
515
Acid/Base tests to
gain
of
the
various
samples
carbons.
Before
pertinent
to
The been
placed
liquid
in
was
in
sample
in
could
suspension
in
be
centrifugation. with
and
of
dubious
value.
keeping
in
II
various given.
Table
It
mind
is
lists
samples; There
II.
are
FS900 FSPHB FS500PHB FS900PHB FS500PHB400 FS900PHB400
In
two
sets
is
were
obtained
black
globules
of
but
of
in
sample of
light
NaOH
brown of
solution
suspensions and
also
mentioned
of of
above, data
to
the
periods
titration
NaOH
Suaar
and
HCl
using in
view
the the
are the
reacted
of
data,
different the
numerical
HCl
reacted
for
the
units
are
Chars
reacted
ymol/g
ymol/m2
ymollg
5500 83 67 1 x 104 300 280 700 -800
190 0.18 0.14 680
-71 390 610 -550 -130 -150 300 1300
-:::
FS900
qualitative.
values
:::
FS
bulk
a
the
that,
chars
differences
of
an
the
or
a
FS500
interesting
of
with
prolonged
of
had
when
resulted
the
samples
supernatant
when
after
view
is
Reactions NaOH
it
liquids
solution,
acid/base
aspect
significant
Acid/Base
by
the
values
who
properties
clear
contrast,
FS900PHB
the
Sample
K500
the
A
interaction
nevertheless
that
The
others
the
oily-appearing,
even
HCl
of
of
centrifuged
clear
In
the
of
aspects
nature
however,
of
centrifugation
brown/black.
retention
quantitative
Table
by
or
that
any
was
NaOH
remained
FS500PHB,
hues
takeup
liquid.
down
and
was
treatment.
data,
Similarly,
some
Similarly,
FSPHB,
various
spun
chemical
acid/base
solution.
solutions,
the
the
to
the
mixture
standardized
formed
work
after
HCl
although
the
in
char
observations.
the
NaOH
samples
acid/base
centrifuge.
the
floating
placed
the
separable
when
centrifugation,
remained was
standardized
laboratory
immersed
after
following
the
titrimetric
sugar
permanganate
measure
the
readily
obtained
conventional were
the
the
to
was
performing
changes
connect
examining
note
mixture
to
by
procedures
in
untreated the
about
serve
similar
and
about
brought
might
used
objective
treated
information
also
have of
the some
tests
The
Titrations
of
ymol/m2 -2.4 0.8 1.2 .37 -0.47 -0.55 0.58 3.2
values
516
of
these,
depending
FS500PHB/FS500 ymol/g
are
the SSA
used
but
results,
Table
less
to become
negative
to become some
values
As
unlikely
the
that
increased
also
samples.
increased
about in the
large
FS and FSPHB FS500
and
FSgOO
with
However,
a quite
up about
2 x 10m4
would
indicate
carboxyls/l 20.5 R2 area it were would would numbers
existence
R2. These
be about
that
and cannot for
OH-
became
it
seems for the
the acidities
of FS500
of
of FS
and FSgOO
by a
before-and-after
there
was
of FS and the
shows
base
a lOOO-fold
FS500
or FSgOO.
consumption
different mole
that
the
data
they
of
per
FS500
1 carboxyl/l
values
because,
units;
These
be accounted
for only correct
and
with
FS, that
be about
in view
high. Again, for
4
of the
by (CH2),COOH,
10 CH2
bore
R2 of surface.
would
are impossibly
FS it is not
surface
is reasonable
is obtained
distribution
per 3 CH2 group.
per m2 in this
per m2 of surface;
be represented
group
of base
involved
that
result
of base
of about
mole
were
a value
are nonsense
1 carboxyl
that
responsible
general
groups
carboxyl
FS could
be one carboxyl
Consequently,
the
of one carboxyl,
taken
with
the acidity
0.16 x 10m6
R2 of surface,
FSPHB,
a
that
carboxyl
used
the
or
increased
initially
up about
which
for
solution). treatment.
suspicion.
acceptable.
Similarly,
such
calculation
1 carboxyl/103
required
washed,
was
4 and those
because
that
a trivial
reaction,
desorbed
copiously
consumption/m2
used
Assuming
thus
as base
more base titrant -solution), suggesting that
comsumption/m2,
suggests
be viewed
of surface. about
base
was
required
treatment
of about
discrepancy
original
oxidation
of material
However,
is misleading,
difference
and
filtrates.
of base
6.
was
been
the oxidation
by a factor
comparison That
of the
In terms
of
had
base
in Table II (in practice,
the original
the dissolution
As expected,
factor
appear
of
data
weight.
acid as well
the
the
of
In view
the filtrate
than by
ratio
acid/base
sample
with
consumed:
material
the
with
the filtrate
than
samples
acidity
react
the
3.6 if units
are used.
per unit
reacted
altered
samples,
neutralized
than
neutralized
acidity-producing
bound.
of ymol/m2
was
were
example, value
to consider
FSgOO
reactant
For
has the
FS could
and
reactivities
Several
rather
that
FS500
the HCl-immersed
the
area
some
titrant
These
units.
5.7 if units
II indicates
but that
(in practice,
the
consumption
it is pertinent
per unit of surface
acidic
on
for NaOH
if
there
FSPHB
there
are unreasonably
high
by surface that
the
acid
uptake
groups. of base
517
involved
merely
equivalent order the
to
of
a reaction
is
too
of
other
degraded
such
degradations
[27
such
as
lime
saturated converted
acids
are
cleaved, In
of
occurred, material acid
of
it
291.
For at
small
is
as
that
the
alkali
FSPHB,
in
is
taken in
up
that
turn
the
even
complex
in
become
alkali,
may
[27
such
-
be 291.
reactions
converted
reacting
are
including
chains
oxidized
and
of
sugars
that
to
of and
products
mild
sugar
an
nature
mixtures
The
suggested
addition
was
fashion;
the
temperature,
attacked
sites,
polysaccharides
in
example, room
acid
indicated; that
are
sugars
F-S, it
base for
reaction.
of
and
of
known
and
prolonged
resulting
FS
is
water
surface
accounted
alkali,
nature
i.e.,
amount
be
mixtures,
upon
the
the
-
and
reactions
by
into
formed and
view
to
However,
are
rapidly
The
high
some
uncertain.
saccharides
hydroxyls
a neutralization.
magnitude
occurrence
these
of
the
with
bulk
surface
groups. view
In would
be
of
a material not
its
the
precursor,
equivalent
which
has
unreasonable
dehydrated, with
rings is
prepared
by
materials [30].
seem
that
work
unstable
and in
of
surface
permanganate
of
be
of
FS
probably
other
in
data
obtained
the
some obtained wet
with
like
such
the were
and
also
FS500PHB400
exists
chars
It low-
as
samples
the
also
oxidation
natural the
elsewhere.
chars,
with
chars
Further,
(see
doubt
manner.
of
oxidized
degassing
A
some
other
and
detail
value.
that
random of
shells,
low-temparature
II),
data
a
and
a variety
almond
i.e.,
moieties,
in
of
dubious
upon
acid/base
and
fructose
described
like
Table
mixture
crosslinked
indicates
much
a
and
titration
acidity
data
partially
converted
temperature
are
4)
a char.
of
bamboo,
will
acid/base
(Fig.
such
low
FS
into
be was
spectra
coal,
data
behaved
FS900PHB400
utility
at
peat,
pyrolizates
degassing
and
as
these
color,
to FS
infrared
and
carbon.'
glucose
with
with
infrared
temperature
changed
oxidized
pyrolyzing
such
Such
would
line
that
preparation,
low-temperature
begun
is
and
broken,
in
of
a 'very
barely
model
partially
That
method
of
about
the
subjected
to
procedures.
CONCLUSIONS Generalities with and
the FS900
decrease. KMn04/HCl
which
various to
samples
aqueous
(b)
emerge
HCl
Subjecting
treatment
caused
from
are
as
the
follows.
solution
caused
each the
N2
SSA
of of
the each
adsorption (a) the
data
Exposing SSA
three sample
FS,
of each samples to
obtained FS500,
sample to
decrease
to the to
a
518
greater
extent
treatment (d)
Boiling
order
the
to remove
caused
their
the colors removal
to
samples brought
together
sample
brought
and
about
about
during
was
a mixture
which
could HCl
carbon
and
of
in
samples these
now
of
the
Subsequent was
sorbed
HCl)
in water fragments
during
a mixture and into
texture.
These
fraction
of
oxidized
about the
the
'clean'
fragment
that
surface
the
groups
Conventional
clean
oxidation
which
were
acid/base in terms
of
(6).
reports
that
adsorptive
properties
samples
were
(4). As
a
samples
upon
relatively
easily
acidity,'
of the carbons
incompletely
were
washed
or
the
samples released
change
of
significant it is
formation such
of (5).
samples,
are of dubious
value.
caused
the
are inconclusive
changes
in
a small
degassing,
oxidation
to change
each some
decomposed.
titrations
permanganate
stage
contained
the
some
bearing
further
mild
caused
samples of
as Cl',
there
treatment
'surface
At this
(3). Boiling
probably
with
HCl to become
(now
caused
titrations
interpreted Prior
and
the
particles
removal
of chlorine
samples
material.
in SSAs of these
probable
fragments.
filtrate,
now
step.
precursor
removal
deposited
oxidized and
the
and
reaction
complexed
the
about
oxidation
of
oxidized
to dissolve
oxidized
structure
were
(2). Treating
oxidized
mixtures,
was
stage
which
brought
when
further
KMn04
Mn02
this
precursor,
Mn02
the
of
some
brought
MnO2.
hydrated
reaction
overall
Hydrated
fragments
some
step.
(1). The its
At
oxidized
out,'
washings
formed
sample
disrupted
removed
and
of the
conclusions.
changes.
hydrated
caused
fragments
in SSA not
if
taken
account.
In general, become of
FS900.
required
was
HCl,
the boiling
particles.
be 'washed
manganese,
into
SSAs
matter
with
the descriptions
textural
solid
the
KMn04/HCl and
was
the
organic
treated
partially
the
changes
samples
However,
some
were
with
on/within
bound.
The
FS500
the oxidized/HCl-treated
increase.
is led to the following
with
(c). of
oxidized/HCl-treated
of the filtrates,
was
Taken each
treatment.
porosities
were --lower than those of the original samples. caused porosity to re-appear. (g) As indicated by
oxidized
one
HCl
the
HCl. (e). Boiling
SSAs
Boiling
the
the
samples
purified (f)
than
eliminated
SSA.
change
more The
the
permanganate
oxidation
'acid,' but the acidity oxidized
samples
in SSA and surface
are
properties
causes
is introduced also upon
the samples
to
at the expense
thermally
unstable
relatively
mild
and
heating,
519
and
are
probably
additional permanganate samples very
large
seems
solid
explain
in
part
while, control
such worst
the
of
it
the
the
of
if
the
the
need
to
would
the
seem
that
to
hardly not
deposition
remove
permanganate
altering
of
probably The
a
treated
view
but
would
of
of
permanganate
work
adequately.
and
that
in
way
means
In
mechanisms,
because
methods
lost
additional
the
rates
carbon
complexity of
deal
reaction
the
be
the
by
temperatures.
encountered
to
order
on/within
the
variables
in
gained
probably
a great
to
introduce be
of
benefits be
elevated
in
worth
might
would at
procedure
required
possible
that
activated number
oxidation be
groups
oxidation
were
any
Also,
mixtures.
acid
the
treatment
be of
a
deposit seems
to
carbons.
ACKNOWLEDGEMENT Support
by
NSF
CHE-8516257
grant
is
gratefully
acknowledged.
REFERENCES
1
R. Stewart, istry,
2
in K.B. Wiberg,
Academic
Press, New York, 1965,
D.G. Lee, in K.B. Wiberg, istry, Academic
3
R. Hayatsu,
(ed.), Oxidation
( ed.),
Press, New York,
in Organic
Chem-
Part A, p. 1.
Oxidation
in Organic
Chem-
Part D, p. 147.
R.G. Scott and R.E. Winans,
(ed.), in Oxidations
in Organic
in W.S.
Chemistry,
Trahanovsky,
Part 0.
Academic
Press, New York, p. 279.
4
W.J. Lyman, in P.N. Cheremisinoff Carbon Adsorption
Handbook,
1980, p, 136; R.G. Rice,
and F. Ellerbusch,
Ann Arbor Science,
G-W.
Miller,
teds.),
MI,
Ann Arbor,
C.M.
Robson,
and W.
Kuo, lot. cit. p. 496.
5
J.W.
Hassler, p. 347.
1951,
Active
6
A. Z. Wassermann,
7
A.S. 426.
8
N.
9
S. Mukherjee News Ed.,
Behrman
M.
Carbon,
Phys.
and
Winslow,
Trans. and
137.
11
B.R.
O.P.
Ind.
J.
Chem.
Indian
J. Oddoux 1727.
Ind.
1962,
NY
223.
Chem..227
Sot., 92
C. Reitzer, 5's. (1962)
Mahajan,
(1930)
Enq.
Electrochem.
J-B. Donnet, F. Hueber, Bull. Sot. Chim. France
Pub., Brooklyn,
Abt.,A149
S. Bhattacharya,
-12 (1949)
and
Chem.
H. Gustafson,
10
Puri
Chemical
(1935)
(1947)
411.
Chem.
Sot.,
and
741.
Ind.
G. Riess,
520
12
A. Banerjee, 267.
B.K. Mazumdar
13
Y. Matsumura,
14
P. Ehrburger and J.B. Donnet, in W. Watt and P.V. Perov, (eds.),
J. Appl.
and A. Lahiri,
Chem.
Nature,193
Biotechnol., 25 (1975)
(1962) 39.
Handbook of composites, North-Holland Pub. Co., New York, Vol. 1, p. 586. 15
A. Voet, J.B. Donnet, (1966) 155.
16
M.J.D. Low
17
C. Morterra
18
H.H. Blayden, H.L. Riley, 180. -62 (1941)
19
A.R. Ubbelehde and F.A. Lewis, Graphite and its Crystal Compounds, Clarendon Press, Oxford, 1960, p. 152.
20
B. Juettner,
21
J. Bradley and G. Van Praagh, J. Chem. Soc.,1938, 1624; Dobbin, J. Am. Chem. Soc.,41 (1919) 934; 6. H. Cartledge W.P. Ericks, J. Am. Chem. .%ic.,58 (1936) 2061.
22
6. Halsey,
23
S. Brunauer, L.S. Deming, W.S. Deming, Chem. Sot.. 62 (1940) 1723.
24
J.H. de Boer, in The Structure and Properties Materials Proc.*"Symp.rRes.hButterworths, -58, p. 68.
25
C. Orr and MacMillan,
26
The Physical Chemistry A.W. Adamson, Wiley, New York, 1967, p. 152.
27
W.W. Pigman and R.M. Goepp, J., Chemistry Carbohydrates, Academic Press, New York,
28
R.D. Guthrie and J. Honeyman, An Introduction to the Chemistry of Carbohydrates, 2nd. edn., Clarendon Press, Oxford, 1965, p. 44.
29
6.0. Aspinall, 1970, p. 30.
30
N. Wang
and and
P.A. Marsh
and
J. Schultz,
Carbon,4,
C. Morterra,
Carbon,21
(1983) 275.
M.J.D. Low,
Carbon,21
(1983) 283.
J. Am. Chem.
J. Phys.
and A. Taylor,
Soc.,59
Chem.,16
J.M. Dalla New York,
(1937)
(1948)
Low,
208.
and
E. Teller, of
L. and
of Surfaces,
data.
J. Am.
Porous
Measurements,
of the 1948, p.
Pergamon, New York,
unpublished
Sot.,
931.
Valla, Fine Particle 1959, p. 176.
Polysaccharides,
and M.J.D.
J. Am. Chem.
2nd. edn.
72.
THE
MODIFICATION
A.S.
Glass
and
Department New
SUCROSE
M.J.D.
of
York,
Received
OF
Low
Chemistry,
N.Y.
507
CHARS
BY
PERMANGANATE
# New
10003
October
501-520
York
University,
4 Washington
Place,
(U.S.A.)
13,
1988;
accepted
November
8,
1988
ABSTRACT Three sucrose-based chars equivalent to low-, medium-, and hightemperature chars were oxidized with aqueous KMn04 solution in order to explore textural changes caused by the oxidation. The reaction caused the chars to become covered with hydrated MnO which was then dissolved with HCl. Some HCl, however, became boun $ to the chars and had to be removed by boiling them in distilled oxidation leads to impure materials water. In general, the KMn04 containing reaction detritus and bound chlorine which must be carefully removed by washing/boiling steps. The oxidation caused the N2 specific surface areas (SSA) of the samples to decrease and The treated samples were thermally changed their porosities. unstable; degassing them in the 200-400°C range increased the before and after oxidation, were also reacted SSAs. The chars, with HCl or NaOH solutions to test their surface acidity; the samples become more acidic in terms of the amounts of base neutralized, but the acid/base titration data are of dubious value because of the retention of HCl by the chars and because the NaOHchar mixtures were cloudy after centrifugation, i.e., the reaction with base caused some reaction detritus to be released. In oxidation does change the texture and general, although the KMn04 the method is a poor one because surface properties of the chars, of its complexity and should be avoided. INTRODUCTION It
is
well
oxidizing as
well
been
known
agent; as
it
inorganic
reviewed
degradation coals;
these
that
has
the
been
materials.
by
Stewart
procedures
using
have
been
workers.
Permanganate
carbons,
although
to
permanganate W:
to
whom
0254-0584/89/$3.50
solutions inquiries
The [l]
should
used be
an
Lee
have
Hayatsu
extent. as
as
The
al.
has
Oxidative
been
used
with
who
cite
used
with
[3], been
decolorizing
empirical
strong organic
reactions
[2].
also
a
with
of
also et
have
is
such
variety by
solutions
lesser is
wide and
by
ion
used
permanganate
reviewed
numerous
a
permanganate
extensively
of
industrial
aqueous test
of
directed. 0 Elsevier Sequoia/Printed
in The Netherlands
the
activity
of
carbons
of
altered
when
of
nature
the
reactants,
its
and
by
a
that
of
(SSA) upon
Mukherjee least,
oxidized
carbon
solutions
Bhattacharya
clear
implication
of
and is
that
Parenthetically,
particles
of
acid
with
black
particles
If then
permanganate alterations should
In
be
been et
products
in
some
+
NaN03
upon
standing
gross
been
the
at
boiled [9].
The
that
small
of
nitric
reaction
hold
[13].
morphological
reported
to
be
experiments had
by
cement
to
areas
substantially
carbons
. [15]
paid about
seems surface
KMn04
some
al
formed as
oxidation in
the
viewed such
contrast,
unit
weight
[8-111.
then
render
the
out
some
in
Possible
results
terms
to
lead
of
to
larger,
oxidized
textural
changes,
changes
to
explore
per
been
in In
properties
activity
have
uncertain.
treatment,
sucrose-derived
were
chemical/adsorptive
comparisons
experiments
permanganate
have
than
been
be brought
result
of
appeared
Voet
acted
which
acidic
together.
a
carbon
sediments
blacks
any
area.
or
organic
have
specific
that,
in
more
decreased
KMn04
view
a permanganate-
to
might
the
mentioned
degradation
channel
be
samples of
there
changes.
that
solutions
that
would
clear
In
with
that
appears
only
that
chemically
[6-141.
find
which
the
different
filtrates
not
carbon
a carbon
reported
demonstrated become
permanganate to
attention
who
with
and
the
of
been
solutions
of
oxidation;
three
has
fibers,
unexpected
little
inthetexture
of
it
permanganate
be
However,
Matsumura,
and
reactions
not
consequently
treatment
were
the
permanganate of
51,
including
with
would
precursor.
to changes
[4,
types,
treated
it
treated
carbons
various
the
view
made
that
textural
and
describe
for
the
unit
on
carbon's of
some
of
the
surface basis
texture we
have
changes results
the
of
would carried
caused obtained
by with
chars.
EXPERIMENTAL
The was
starting
material
commercial
Scientific
Reagent
Co.,
dehydration
has of
experimental be
termed
degassing
FSD, at
by
were and 500°C
NJ.,
been
sucrose
work
FSD
Grade
Fairlawn,
manufacturer,
preparation
or
by
concentrated
at
900°C
the
carbons in --
dry
samples (Fisher
according
to
the
room-temperature acid.
charcoal,
which vacua;
carbon
Charcoal
which,
sulfuric
as-received, other
all
Sugar
700198)
prepared
the
two
Fisher lot
of
were air
was
Samples which prepared then
for will by
slowly
509
bled
into
are
the
preparation
termed
FS5000
equivalent 173.
to
As
they
low-,
were
materials
(distilled
water
with
on
water
Filter-paper dried
The of
with
KMnO4. mixture
was
at
while
FS500
this
left
Mn02
for
of
1
and
filtrate
gave
air-dried
at
are
termed
treatment taken 5M
up
HCl
found with or
the
to
significant
400°C,
oxidized,
with a
weight
HCl
which
presence
of
These
cool, Cl-
in
samples
code,
e.g.,
An
FSP,
stand
Mnt2
have
such
with
the
wash
are
designated
FS500PHB.
HCl
might
samples, washed
prepared
water
For
was by
by to
of
and
soaked
For
400,
letter
by
an
the
at
In
present in
water, The
llO°C.
testing
FS,
Irish
found.
it
8 appended some
500,
retained,
boiled
dried
in and
example,
at were
on
be
carbons samples
was
were
HCl
could
carbonizing
followed the
the
their
remained
and
treatment
HCl
retention
HCl the
NaBi03),
anthracite
by
FS9OOP 36M
until
this
that
HCl
remove
or
ml
retained.
comparison,
3 days,
to
water
had
samples
water,
air-
subjected
order
10
in
percent
percent
for
FS5OOP,
of
an
weight
the The
and
Unfortunately,
[18]
carbonizing 0.72
in
with
were
solid and
Samples
(oxidation
HCl
gram
water,
in
content
of
was
temperature.
subjected
et al --A ash
which
FS9OOP.
acid
to
batches
to
oxidized
complexity
a carbon
2.8
are
solution
with
and
FS900PH.
the
by
and
materials
1.106
the
with
Samples and
and
acid-treated to
for
amounts
1.07,
remove
allowed
left
Blayden
prepared
times
Microfiber
employed
7 days.
FS5OOP
additional
reduce
water four
filtering)
water
room
repeatedly
tests
carbons:
order
was
overnight.
an
at
oxidation.
washed
negative
Similarly,
to
then
llO°C
0.83,
at
the
to
were
treated
gram
of
washed
for
FSP,
were
0.2
was
a sample
order
sample
oxidized
FS500PH,
that
resp..
Ag+.
FS900
FSPH,
by
900°C,
peat
samples
introduces
in
a shaker
FS
during
three
GF/A
all
and
added
overnight.
termed
ml
H2S04
was
on
were
for
samples
93
1.78M
solid
approx.
hr.
ml
stand
are
[16,
the
washed
starting
FS900 of
sample
samples
produced
and
the
and
oxidized
sample
FS500
filtered,
llO°C
carbons
FS900.
7.0
to
then
are
distilled
Whatman
used
These
llO°C.
samples
chars
solutions,
were
with
were
consisting
carbon
treatment
The
FS,
three
with and
fitted
and
stirring,
was
dried
at
each
A half-gram
mixture
air
of
[ll]
aqueous
pre-treated
filters
These
These
high-temperature
with
funnel
FS500,
oxidations
temperature.
throughout),
inert
FS,
solutions
added,
to
a Buchner
as
and
were
in
room resp..
treated
used
(these
designated
be
was
overnight
at
FS9000,
medium-,
to
starting
tube
and
to
FS500
with the and
510
FS900
samples
were
dried.
These
samples
The
N2
BET sample)
sorption
apparatus
instrument
(
apparatus)
was
prior
to adsorption
The
SSAs
0.35.
3 results The 0.1
being
mg)
made
having
made
The
done
at
the
4
or
5
values
SSAs
value
from
by
300, 350,
at P/P,
deviation
the
the
of
3
of the mean
of
was
determined
as follows,
the
mixture
supernatant
or base
been
SSAs,
and
sample.
deviation
The
was
values
or
24 hrs
was
then with
of micromoles
were
the
for
titrated calculated
data. Two
Typically,
to
solution
The mixture
neutralized titration
(weighed
NaOH
to stand
liquid
solution.
had
100 mg
left
temperature.
at room
the
ml
by
of from
or three
trials
yielded
values
results
of 6 X.
and
Although
Solids
is placed
on gaining
oxidation
might
the
pertinent
treatments,
other
affect
method
oxidation
methods
emphasis
texture some
have and
the
of
understanding
the
to describe as these
oxidation wet
some
of the
of the
bearing are
of
a
treated
observations
on the
probably
involving
the
how
utility
useful
the
in
use of
oxidants. first
reduced.
washing
and
which
particular
purple-colored been
sample
shaking
each
data
measure
about
it seems
considering strong
the average
was
250,
The average
0.1273M
Mixtures work
during
of this
to
sample.
of
solution,
permanganate carbons,
was
to degas
AND DISCUSSION
Reaction present
done
the
of
with
same
6 %.
each
weights,
and
isotherm,
sample
an average
RESULTS
from
100
or of base
m*/g
NY). The
Degassing
A
acid
were
isotherms,
desorption
used,
of
a Quantasorb
Syosset,
in
standardized
units
with
immersed
automatic
sample
in
procedures.
and
the
some
was
and
FS900H.
adsorption/desorption
calculated
what
about
centrifuged, acid
(SSA,
measured
Corp.,
of a particular
of
was
HCl
0.1509M with
were
was
acidity
conventional
area was
and
N2 for 14 hrs. at 200,
on the
Usually
portions
(but not boiled),
measurements.
in flowing
3 determinations
+
to measure
pressures
separate
sample
(Quantachrome
used
a sample
below
washed FS500H,
chromatographic-type
keeping
4OOOC.
HCl, FSH,
surface
of each
a
samples
relative
with
are termed
specific
degassed
or
treated
gave
filtering
and
filtrate, The
next
a bright
washing
indicating washing
gave
yellow-colored
of that
FSP not
a clear filtrate.
with all
water
of the
filtrate;
gave MnOi
the
Apparently,
a had
third as the
511
pH
increased,
The
yellow
but
a
some color
pale
over
20
yellow
was
soluble
ethanol
Immersing
FSP
is
placed
and
the test get
the
yellow
in
in
the
on
a
)
solubilized.
after
centrifuged, when
hotplate. and
washings,
filtrate
was
remained
HCl
or
successive
filtrate
dryness not
with
present
residue
this
the
Cl-,
the
That
gave
a
yellow
residue
was
a positive
no
Analogous
brown
water,
test
then
a second
a pale
but The
filtrate, boiled
a second clear.
general,
FS9OOP
samples
samples
with
and
the
held
step
release
washed
the
out
was
for
but
was
of
fairly
expected the
firmly
by
were
also
of
additional
and
flushed
mixtures
the
release
yellowish away.
The
Cl-
detritus nature
of
was
the but
the
gave
FSSOOP
and these and which
also
FS900PH
which
not
filtrate
products
because of
yellow
deposited
HCl and
pale
was
Treating been
However,
FS500PH,
brown
FS900PH
FSP,
mixtures. had
the
of
untreated be
a
was
was pale
until and
with
Cl-
then
a
a
positive
washed for
gave
degradation away.
FSPH,
caused
and
filtrate
water
which
yellow/brown flushed
only
to Mn02
For HCl,
so the sample
FS500PH,
FSPH,
otherwise
and
apparently not
with
but
be
out
washed of
dissolved
release
negative,
samples.
and the
the
filtrate
tested
in
Boiling
was
of
The
positive
washings
in
first
boiling.
which
golden-brown
positive.
Cl-
washed
would HCl
a
mins.
concentrated
boiled
tested
order
the
yellow
other
in
was
water
filtrates for Mn +2 .
washed
latter
boiling
time
tests
be
Cl-
test
with
but
In 20
water.
second
filtrate
which
gave
All
In
to
yellow FS500PH
several
for
the
became
led
also
test but
negative
pale
for
bright
immersed
filtered
clear,
after
with
the
made
were
filtrate
after
the
hydrated
washings.
boiled
FSP
after
been
After
yellow
FS900PH
filtrate,
present
had
obtained.
than
washing
greenish
was
appeared
many
twice
a
when
golden-yellow
darker
was
FS5OOP
obtained.
could
Cl-
in
mixture
filtrate
were
from
this
after
colored
observations
were
yellow.
samples
after and
Cl-
the
positive
was
resulted is obtained
When
water,
was
resulted
and
example,
with
color
HCl
mixture
solution).
remained
filtrate
which
clear
HCl
Cl-
of
The
filtrate
for
concentrated greenish
washed
for
boiling;
was
in
into
solid
rid
water.
the
still
to
(a similarly
the
The
was
( but
soluble
paler
Mn+'.
Mn02
up
became
and
Brown
evaporated
in
mixture
to
When
formed.
filtrate
products paler
tint
washings.
precipitate
for
yellow
became
taken
samples. subsequent
also could
induced then
yellow/brown
be
512
degradation present
products
interest.
mixture
of KMn04
yellow
acid
[20];
and
be bound
Mn+2
would
omitted, samples
forms
would were
at
done the
Texture 200°C
of
are
differential
shown pore
complexes
the
boiling
step
bound chlorine the
value. it
of
[19,
Such
then
Chars
201;
carbon
materials
be released
traces
Figs.
FS isotherm of the
material while
of
samples
degassed
B show
as Type [23],
and macropores,
FS500
isotherms
hysteresis
The
non-microporous
meso-
of
the
the data.
classification
having
IV
products.
parts
a
them
present
can be classified of
the
samples
the
[22] from
those
Type
our
that
l-3;
that
i.e.,
cl.w7
although
BDDT
were
with
of degradation
(DPV) calculated
II
obtained
isotherms
A of
washings
not thorough,
but also degradation
probable
Some
parts
and
results
As it is,
seems
contained
in
and
[13], or were
and
volumes
(a
oxide
[21].
surfaces
samples
washed,
Suqar
of
of non-graphitic
not only
samples
scope reagent
leads to the formation graphitic
oxidation char
the
Brodie's
treatments. if
be of questionable -PHB
H2S04)
by Matsumura
contain
so that
carefully
purified The
as was
beyond
that
decomposable
Mn+2 -organic
that
and
however,
by the
boiling
seem
would
products,
certain
to the modified
by the HCl and/or It
easily
is formed
could
not
and concentrated
or brownish,
mellitic
is
It is known,
and
FS900
having
loops
[24].
are
Type
These
C and
other isotherms are not remarkable. o.oosQ is interesting is that the 2? What 0.W~cI, permanganate/HCl treatment decreased the
N2
uptake
porosity, FS900PH
1
have
Further
changes were
the
amounts
and
porosity
hysteresis 28 32 36 PORE RADIUS, i
Fig. 1. N2 sorption by FS chars.
loops the
Figs.
of
l-3.
to
loops. radii
when remove
N2 adsorbed IV
with
the
the HCl:
increased isotherms
Type
C or
The changes in
of the
E
in the
in the changes
shown
In view
and
isotherms.
occurred
appeared,
Type
the
FS500PH,
II
boiled
are reflected
pore
eliminated
FSPH,
Type
samples
becoming
O-
and
so that
parts nature
of
B of of
513
PORE
Fig. 2. N2 sorption
the
samples
possible
a
pore
it
to
say
FS
to
become
FS500
Table to
I.
In
subsequent
the
and
derived
each
like
does
lengthy not
seem
discussion
justified.
oxidation/HCl/boiling
mesoporous,
than of
decrease
I.
of
those the
treatment
and
the
of
Suffice
treatment
changed
alone with
of
the
caused FS500,
Specific
caused treated
caused
porosities
of
samples. been
Surface
Areas
as
is
4:: 364
to
one
m*/g
caused
of
A
Column
with
0 shows with with
FS,
Chars
B
C
0
PHB
H
2:: 270
the HCl;
PH IIX I77
SSA The
(column
FS900.
Sugar
6).
C),
substantially
only
decrease
in
the
and
increase
remained
treated SSA
a negligible
summarized
treatment
SSAs
a substantial
A treatment
had
are
columns
samples
untreated which
and
data
(compare
fully
samples
adsorption
oxidation/HCl
treatment the
Sample
Es00 FS900
the
the
case,
boiling
values
from
substantially
SSAs
lower
Table
overall
micro-
values
the
and
the
necessarily
by FS900 chars.
FS900.
decrease
but
and
shapes
that
and
SSA
detailed
%
RADIUS,
Fig. 3. N2 sorption
by FS500 chars.
3:: 360
SSA that
a minor
514 The
data
degassed [25]
to
using and
of
at be
FS900
been
should
because
about the
were
it
was
any
additional material.
unstable
The
all as
changes
of
range
and
the
be
FS:
attributed
to The
to
the
and were
SSA
increases of
not
effects
of
of of
FS500D
What
the
each
of
the
increases There
of
changes
of
large
Overall,
the
FS500PHB, similar
Essentially, caused temperature of degassing.
the
and
SSA are
relatively by
FS500PH
attributed of
shown and of
with the
FS900H
be
trends
in SSA
FS900PH.
As
the
of
Note, large
desorption
those
SSA
changes
and
and
however,
samples.
FS900PH to
of were
in
exhibited
the
may
air
relatively
cannot
to
the
change
smaller,
FS900PH
solely
range
pertinent,
FS500H
the
300-350°C
FS900PHB.
changes
and
at
samples
FS500PH
significantly
of can
desorption
similar and
view
300°C
the
to
treated
are
FS500PHB
Fig. 4. Effects
in
and
the
with
in
350-400°C
large
particular,
is
samples
samples
FS900D
is
rather
of
It
occurring
exposed
wetted.
4.
above
FS900
and
initially
is
SSAs
the
had bring
increased.
changes
in
Fig.
FS
destruction
when
to
unexpected, in
FS500
FS500
treated
were
was
portions
in
other
The
limit
which
treated
increases
higher
degassing.
unoxidized
all
that FS500
much
expected
shown
temperatures FS
thought
That
be
been
chosen
change;
to
at
the
and
summation
formed
to
mild
not
are
the
changes
was
FS
4OO'C.
would of
of
dramatic
lesser
species
SSAs
the
was
had
were
It
temperature
temperatures the
charring.
oxygenated
the 400°C
which
exposed
by
used
degassing the
attributed
the
at
FS.
cause
affected
samples
of
onset
below
of
been
FS-derived
degassing
be
already be
samples conditions
would
results
increasing
simply
nature
carbonization
in
with
these
Some
the
nature
not
degassing
that
the
temperature
FS500
apparent
and
conditions having
degassing
obtained
hrs,
with
samples,
prepared:
were 14
degassing
temperatures,
chosen
l-3 for
compatible
higher
highest
Figs.
200°C
by
HCl.
FS500PH,
FS900PHB
the
FS
are
samples.
oxidation/HCl/boiling the
highchars
low-temperature
to
and behave FS
mediummuch
samples.
like
515
Acid/Base tests to
gain
of
the
various
samples
carbons.
Before
pertinent
to
The been
placed
liquid
in
was
in
sample
in
could
suspension
in
be
centrifugation. with
and
of
dubious
value.
keeping
in
II
various given.
Table
It
mind
is
lists
samples; There
II.
are
FS900 FSPHB FS500PHB FS900PHB FS500PHB400 FS900PHB400
In
two
sets
is
were
obtained
black
globules
of
but
of
in
sample of
light
NaOH
brown of
solution
suspensions and
also
mentioned
of of
above, data
to
the
periods
titration
NaOH
Suaar
and
HCl
using in
view
the the
are the
reacted
of
data,
different the
numerical
HCl
reacted
for
the
units
are
Chars
reacted
ymol/g
ymol/m2
ymollg
5500 83 67 1 x 104 300 280 700 -800
190 0.18 0.14 680
-71 390 610 -550 -130 -150 300 1300
-:::
FS900
qualitative.
values
:::
FS
bulk
a
the
that,
chars
differences
of
an
the
or
a
FS500
interesting
of
with
prolonged
of
had
when
resulted
the
samples
supernatant
when
after
view
is
Reactions NaOH
it
liquids
solution,
acid/base
aspect
significant
Acid/Base
by
the
values
who
properties
clear
contrast,
FS900PHB
the
Sample
K500
the
A
interaction
nevertheless
that
The
others
the
oily-appearing,
even
HCl
of
of
centrifuged
clear
In
the
of
aspects
nature
however,
of
centrifugation
brown/black.
retention
quantitative
Table
by
or
that
any
was
NaOH
remained
FS500PHB,
hues
takeup
liquid.
down
and
was
treatment.
data,
Similarly,
some
Similarly,
FSPHB,
various
spun
chemical
acid/base
solution.
solutions,
the
the
to
the
mixture
standardized
formed
work
after
HCl
although
the
in
char
observations.
the
NaOH
samples
acid/base
centrifuge.
the
floating
placed
the
separable
when
centrifugation,
remained was
standardized
laboratory
immersed
after
following
the
titrimetric
sugar
permanganate
measure
the
readily
obtained
conventional were
the
the
to
was
performing
changes
connect
examining
note
mixture
to
by
procedures
in
untreated the
about
serve
similar
and
about
brought
might
used
objective
treated
information
also
have of
the some
tests
The
Titrations
of
ymol/m2 -2.4 0.8 1.2 .37 -0.47 -0.55 0.58 3.2
values
516
of
these,
depending
FS500PHB/FS500 ymol/g
are
the SSA
used
but
results,
Table
less
to become
negative
to become some
values
As
unlikely
the
that
increased
also
samples.
increased
about in the
large
FS and FSPHB FS500
and
FSgOO
with
However,
a quite
up about
2 x 10m4
would
indicate
carboxyls/l 20.5 R2 area it were would would numbers
existence
R2. These
be about
that
and cannot for
OH-
became
it
seems for the
the acidities
of FS500
of
of FS
and FSgOO
by a
before-and-after
there
was
of FS and the
shows
base
a lOOO-fold
FS500
or FSgOO.
consumption
different mole
that
the
data
they
of
per
FS500
1 carboxyl/l
values
because,
units;
These
be accounted
for only correct
and
with
FS, that
be about
in view
high. Again, for
4
of the
by (CH2),COOH,
10 CH2
bore
R2 of surface.
would
are impossibly
FS it is not
surface
is reasonable
is obtained
distribution
per 3 CH2 group.
per m2 in this
per m2 of surface;
be represented
group
of base
involved
that
result
of base
of about
mole
were
a value
are nonsense
1 carboxyl
that
responsible
general
groups
carboxyl
FS could
be one carboxyl
Consequently,
the
of one carboxyl,
taken
with
the acidity
0.16 x 10m6
R2 of surface,
FSPHB,
a
that
carboxyl
used
the
or
increased
initially
up about
which
for
solution). treatment.
suspicion.
acceptable.
Similarly,
such
calculation
1 carboxyl/103
required
washed,
was
4 and those
because
that
a trivial
reaction,
desorbed
copiously
consumption/m2
used
Assuming
thus
as base
more base titrant -solution), suggesting that
comsumption/m2,
suggests
be viewed
of surface. about
base
was
required
treatment
of about
discrepancy
original
oxidation
of material
However,
is misleading,
difference
and
filtrates.
of base
6.
was
been
the oxidation
by a factor
comparison That
of the
In terms
of
had
base
in Table II (in practice,
the original
the dissolution
As expected,
factor
appear
of
data
weight.
acid as well
the
the
of
In view
the filtrate
than by
ratio
acid/base
sample
with
consumed:
material
the
with
the filtrate
than
samples
acidity
react
the
3.6 if units
are used.
per unit
reacted
altered
samples,
neutralized
than
neutralized
acidity-producing
bound.
of ymol/m2
was
were
example, value
to consider
FSgOO
reactant
For
has the
FS could
and
reactivities
Several
rather
that
FS500
the HCl-immersed
the
area
some
titrant
These
units.
5.7 if units
II indicates
but that
(in practice,
the
consumption
it is pertinent
per unit of surface
acidic
on
for NaOH
if
there
FSPHB
there
are unreasonably
high
by surface that
the
acid
uptake
groups. of base
517
involved
merely
equivalent order the
to
of
a reaction
is
too
of
other
degraded
such
degradations
[27
such
as
lime
saturated converted
acids
are
cleaved, In
of
occurred, material acid
of
it
291.
For at
small
is
as
that
the
alkali
FSPHB,
in
is
taken in
up
that
turn
the
even
complex
in
become
alkali,
may
[27
such
-
be 291.
reactions
converted
reacting
are
including
chains
oxidized
and
of
sugars
that
to
of and
products
mild
sugar
an
nature
mixtures
The
suggested
addition
was
fashion;
the
temperature,
attacked
sites,
polysaccharides
in
example, room
acid
indicated; that
are
sugars
F-S, it
base for
reaction.
of
and
of
known
and
prolonged
resulting
FS
is
water
surface
accounted
alkali,
nature
i.e.,
amount
be
mixtures,
upon
the
the
-
and
reactions
by
into
formed and
view
to
However,
are
rapidly
The
high
some
uncertain.
saccharides
hydroxyls
a neutralization.
magnitude
occurrence
these
of
the
with
bulk
surface
groups. view
In would
be
of
a material not
its
the
precursor,
equivalent
which
has
unreasonable
dehydrated, with
rings is
prepared
by
materials [30].
seem
that
work
unstable
and in
of
surface
permanganate
of
be
of
FS
probably
other
in
data
obtained
the
some obtained wet
with
like
such
the were
and
also
FS500PHB400
exists
chars
It low-
as
samples
the
also
oxidation
natural the
elsewhere.
chars,
with
chars
Further,
(see
doubt
manner.
of
oxidized
degassing
A
some
other
and
detail
value.
that
random of
shells,
low-temparature
II),
data
a
and
a variety
almond
i.e.,
moieties,
in
of
dubious
upon
acid/base
and
fructose
described
like
Table
mixture
crosslinked
indicates
much
a
and
titration
acidity
data
partially
converted
temperature
are
4)
a char.
of
bamboo,
will
acid/base
(Fig.
such
low
FS
into
be was
spectra
coal,
data
behaved
FS900PHB400
utility
at
peat,
pyrolizates
degassing
and
as
these
color,
to FS
infrared
and
carbon.'
glucose
with
with
infrared
temperature
changed
oxidized
pyrolyzing
such
Such
would
line
that
preparation,
low-temperature
begun
is
and
broken,
in
of
a 'very
barely
model
partially
That
method
of
about
the
subjected
to
procedures.
CONCLUSIONS Generalities with and
the FS900
decrease. KMn04/HCl
which
various to
samples
aqueous
(b)
emerge
HCl
Subjecting
treatment
caused
from
are
as
the
follows.
solution
caused
each the
N2
SSA
of of
the each
adsorption (a) the
data
Exposing SSA
three sample
FS,
of each samples to
obtained FS500,
sample to
decrease
to the to
a
518
greater
extent
treatment (d)
Boiling
order
the
to remove
caused
their
the colors removal
to
samples brought
together
sample
brought
and
about
about
during
was
a mixture
which
could HCl
carbon
and
of
in
samples these
now
of
the
Subsequent was
sorbed
HCl)
in water fragments
during
a mixture and into
texture.
These
fraction
of
oxidized
about the
the
'clean'
fragment
that
surface
the
groups
Conventional
clean
oxidation
which
were
acid/base in terms
of
(6).
reports
that
adsorptive
properties
samples
were
(4). As
a
samples
upon
relatively
easily
acidity,'
of the carbons
incompletely
were
washed
or
the
samples released
change
of
significant it is
formation such
of (5).
samples,
are of dubious
value.
caused
the
are inconclusive
changes
in
a small
degassing,
oxidation
to change
each some
decomposed.
titrations
permanganate
stage
contained
the
some
bearing
further
mild
caused
samples of
as Cl',
there
treatment
'surface
At this
(3). Boiling
probably
with
HCl to become
(now
caused
titrations
interpreted Prior
and
the
particles
removal
of chlorine
samples
material.
in SSAs of these
probable
fragments.
filtrate,
now
step.
precursor
removal
deposited
oxidized and
the
and
reaction
complexed
the
about
oxidation
of
oxidized
to dissolve
oxidized
structure
were
(2). Treating
oxidized
mixtures,
was
stage
which
brought
when
further
KMn04
Mn02
this
precursor,
Mn02
the
of
some
brought
MnO2.
hydrated
reaction
overall
Hydrated
fragments
some
step.
(1). The its
At
oxidized
out,'
washings
formed
sample
disrupted
removed
and
of the
conclusions.
changes.
hydrated
caused
fragments
in SSA not
if
taken
account.
In general, become of
FS900.
required
was
HCl,
the boiling
particles.
be 'washed
manganese,
into
SSAs
matter
with
the descriptions
textural
solid
the
KMn04/HCl and
was
the
organic
treated
partially
the
changes
samples
However,
some
were
with
on/within
bound.
The
FS500
the oxidized/HCl-treated
increase.
is led to the following
with
(c). of
oxidized/HCl-treated
of the filtrates,
was
Taken each
treatment.
porosities
were --lower than those of the original samples. caused porosity to re-appear. (g) As indicated by
oxidized
one
HCl
the
HCl. (e). Boiling
SSAs
Boiling
the
the
samples
purified (f)
than
eliminated
SSA.
change
more The
the
permanganate
oxidation
'acid,' but the acidity oxidized
samples
in SSA and surface
are
properties
causes
is introduced also upon
the samples
to
at the expense
thermally
unstable
relatively
mild
and
heating,
519
and
are
probably
additional permanganate samples very
large
seems
solid
explain
in
part
while, control
such worst
the
of
it
the
the
of
if
the
the
need
to
would
the
seem
that
to
hardly not
deposition
remove
permanganate
altering
of
probably The
a
treated
view
but
would
of
of
permanganate
work
adequately.
and
that
in
way
means
In
mechanisms,
because
methods
lost
additional
the
rates
carbon
complexity of
deal
reaction
the
be
the
by
temperatures.
encountered
to
order
on/within
the
variables
in
gained
probably
a great
to
introduce be
of
benefits be
elevated
in
worth
might
would at
procedure
required
possible
that
activated number
oxidation be
groups
oxidation
were
any
Also,
mixtures.
acid
the
treatment
be of
a
deposit seems
to
carbons.
ACKNOWLEDGEMENT Support
by
NSF
CHE-8516257
grant
is
gratefully
acknowledged.
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