1. University
of
South
Florida
Investigation of Methods and Processes to Increase
Efficiency for Carbon Activation Processes
Joshua
Dang
ENC
3246
Dr.
Dianne
Donnelly
June
20,
2014

2. 2
Abstract:
The
demand
for
activated
carbon
keeps
growing
while
supply
will
dwindle.
As
a
result
economic
feasibility
of
such
an
important
material
will
become
nonexistent.
Alternative
sources
of
carbon
rich
raw
material
need
to
be
used,
along
with
innovative
methods
of
activating
carbon,
which
currently
is
a
high
energy
and
high
cost
endeavor.
As
a
result,
possible
improvements
could
be
made
to
increase
the
overall
efficiency
of
the
activation
process,
increase
effectiveness
of
activated
carbon
desired
characteristics,
and
decrease
the
detrimental
impacts
to
the
environment.
These
current
improvements
when
applied
together
within
the
process
chain
will
allow
for
greater
stability
of
raw
resources,
make
activated
carbon
pound
for
pound
more
effective,
and
preserve
the
environment.
INTRODUCTION
The
material
known
as
activated
carbon
affects
countless
lives.
The
application
of
this
material
can
be
found
in
products
throughout
household
items,
including
soft
drinks
and
shampoos
to
large-­‐scale
industries
including
removal
of
mercury
from
natural
gas,
and
carbon
dioxide
from
fermentation
processes
[8].
The
reason
to
the
wide
application
of
activated
carbon
is
due
to
molecular
carbons
special
structure
characteristics,
which
has
a
great
capacity
and
affinity
for
impurities.
Activated
carbon
is
not
found
naturally
with
these
characteristics
but
needs
to
be
created
through
an
extended
process.
It
is
said
that
any
carbon
rich
raw
material
can
be
used
as
a
precursor
to
activated
carbon
[1];
however
current
raw
materials
are
mainly
sourced
from
coal
and
wood
[9],
and
are
activated
through
physical
means,
which
require
a
high-­‐energy
input.
These
current
sources
and
methods
present
several
issues
both
economically
and
environmentally.
Activation
of
carbon
is
a
high
energy
and
cost
endeavor;
however
as
research
continues
for
more
sustainable
sources
such
as
agricultural
byproducts,
viable
processing
methods
such
as
chemical
activation,
and
recycling
techniques
such
as
regeneration
of
used
activated
carbon,
the
cost
will
decrease
as
well
as
an
increased
impact
to
preserve
the
environment.
An
investigation
of
the
activated
carbon
process
will
result
in
measures
to
increase
the
overall
efficiency
of
the
activation
process,
increase
effectiveness
of
activated
carbon
desired
characteristics,
and
decrease
detrimental
impacts
to
the
environment.
BACKGROUND
History
The
earliest
use
of
activated
carbon
has
been
lost
in
history
[10].
It
is
believed
that
the
earliest
application
dates
back
to
3750
B.C.
where
activated
carbon
was
used
by
ancient
Hindus
in
India
as
a
process
for
water
filtration
[11].
The
first
documented

3. 3
use
of
activated
carbon
was
found
on
Egyptian
papyrus
dating
back
to
1500
B.C.
as
a
method
to
absorb
unpleasant
odors
[10].
The
desirable
characteristic
of
activated
carbon
have
been
known
for
more
than
one
and
a
half
millennia,
however
its
main
application
today
are
still
targeted
at
fundamentally
similar
organic
impurities.
As
late
as
the
18th
century
sources
of
raw
carbon
were
derived
from
blood
and
animals,
which
were
then
used
to
purify
liquids
[11].
Documented
uses
of
activated
carbon,
which
became
noted
in
medical
journals,
were
a
treatment
for
ingested
poisons
[10].
Early
uses
were
also
for
medicinal
purposes,
and
most
widely
accepted
in
the
19th
century
were
uses
found
in
the
treatment
of
poultices,
sloughing
ulcers,
and
gangrenous
sores
[10].
Some
noticeable
improvement
pertains
to
the
manufacturing
process
the
produces
a
different
shape
and
size
of
activated
carbon.
These
different
shapes
allow
for
longevity
of
the
carbon
purification
performance
as
well
as
improved
shipping
and
handling
durability.
At
the
beginning
of
the
twentieth
century
activated
carbon
was
only
available
in
a
powder
form.
During
the
First
World
War
granular
activated
carbon
was
used
in
gas
mask
to
capture
deadly
organic
gases
[11],
this
granular
processing
eventually
lead
to
the
widespread
manufacturing
of
granular
activated
for
other
applications
such
as
water
treatment,
and
gas
purification.
The
wide
application
and
available
sources
of
activated
carbon
throughout
history
and
until
this
day
is
a
testament
to
the
imperative
usefulness
of
this
material.
Through
activated
carbons
intrinsic
physical
and
chemical
properties
the
usefulness
has
been
experienced
and
applied
to
a
vast
array
of
situations.
Very
prominent
to
this
day
is
the
application
of
activated
carbon
to
purify
both
gaseous
and
aqueous
phases
of
substances
to
prevent
environmental
harm.
Current
Application
Widespread
uses
of
activated
carbon
can
be
found
in
industrial,
pharmaceutical,
water
treatment
processes.
Great
focus
is
put
on
the
protection
of
the
environment
and
the
health
effects
from
emission
of
gases
and
waste
products
in
industrial
and
manufacturing
processes.
These
emissions
include
volatile
organic
compounds
(VOCs)
and
are
known
to
cause
cancer
in
tested
animals
[12].
Activated
carbon
is
vital
in
the
many
processes
that
involve
VOC’s
to
stay
within
EPA
regulation
of
emissions
for
health
concerns.
Impurities
in
an
aqueous
phase
are
also
an
important
consideration
in
many
products.
These
organic
impurities
are
in
the
form
of
chemical
solvents
used
in
production
processes
for
products
such
as
paints
and
household
cleaners
[12].
Activated
carbon
due
to
its
ability
to
conduct
electricity
can
also
be
found
as
a
catalyst
in
many
vital
electronic
components
including
batteries,
supercapacitors,
and
fuel
cells
[7].
A
major
use
of
activated
carbon
is
in
the
purification
of
water
for
human
consumption.
When
using
this
absorbent
in
the
water
purification
process
it
is
layer
after
sand
and
before
chlorination
[11].
The
use
of
activated
carbon
not
only
decreases
bad
odors
and
taste
but
also
removes
harmful
contaminants
found
in
the
water
sources,
such
as
synthetic
organic

4. 4
compounds
(SOC).
These
current
applications
are
a
constant
issue,
as
nations
economical
and
industrial
development
demands
more
activated
carbon
to
continually
produce
quality
products.
Molecular
Characteristics
Activated
carbon
has
a
desired
physical
and
chemical
structure
due
to
the
porosity
and
surface
area
different
to
non-­‐activated
carbon.
The
porosity
describes
the
amount
of
microscopic
cavity
between
carbon
molecules
and
affects
the
total
surface
area
per
unit
mass.
Another
important
aspect
is
the
pore
size,
which
is
due
to
the
process
of
activation
as
well
as
the
raw
source
for
carbon.
Impurities
can
range
from
one
one
thousand
of
a
micron
to
ten
thousand
microns.
To
effectively
capture
these
contaminants
a
correct
pore
size
must
be
used
to
allow
for
proper
mechanical
fit,
which
is
then
preceded
my
chemical
interactions.
Surface
area
is
directly
related
to
the
capacity
to
hold
impurities.
To
achieve
a
high
surface
area
the
pore
structure
must
be
extensive,
in
that
many
channels
are
present
[2].
It
is
evident
that
the
level
of
desired
molecular
characteristics
can
be
altered.
This
provides
a
variable
in
the
effort
to
increase
the
overall
efficiency
of
the
production
of
activated
carbon.
PROCCESSING
RAW
CARBON
Current
and
Alternative
Sources
Current
raw
carbon
sources
as
a
precursor
are
from
coal
and
wood.
In
the
recent
pass,
the
selected
source
must
meet
several
of
the
following
requirements.
It
must
have
the
potential
to
produce
high
quality
activated
carbon,
which
is
a
function
of
the
porosity
and
resulting
surface
area.
It
must
have
large
available
supplies;
this
will
in
effect
lower
the
cost.
And
finally
it
must
have
the
ability
to
be
stored
for
extended
periods
of
time
[3].
Both
coal
and
wood
have
passed
these
conditions
as
leading
sources
for
the
production
of
activated
carbon,
however
an
important
requirement
have
been
dismissed
in
past
decisions.
This
important
neglected
requirement
is
how
does
sourcing
of
this
material
effect
the
environment?
With
130,000
tons
per
year
of
wood
and
100,000
tons
per
year
of
raw
material
being
harvested,
the
impact
to
the
environment
is
one
of
great
magnitude.
Wood
and
coal
are
currently
the
leading
source
for
the
production
of
carbon.
Coal
comes
from
surface
and
underground
mines,
with
the
majority
from
surface
mines
at
sixty
percent
[13].
Coal
is
considered
a
non-­‐renewable
source
due
to
the
time
it
takes
to
create
it.
Estimates
have
said
supplies
of
coal
will
last
only
until
2035
[14].
This
estimates
does
not
take
into
account
the
coal
that
is
too
deep
and
costly
to
mine.
This
presents
an
issue
to
the
economics
of
using
coal
as
a
source.
Alternative
sources
must
be
researched
and
tested
to
keep
supplies
of
raw
carbon
stable.
Without
proper
preparation
a
sudden
decrease
in
supply
will
trigger

5. 5
staggering
price
hikes,
which
will
effect
how
companies
operate,
prices
of
products,
and
could
even
shut
down
industrial
processes
and
slow
the
economy.
Alternative
sources
need
to
meet
all
constraints
previously
set
as
well
as
an
additional
constraint
of
sustainability.
This
will
be
the
basis
to
analyzing
the
potential
of
new
sources.
A
study
on
the
use
of
corncobs
proves
the
economic
feasibility
and
sustainability
of
this
agricultural
waste
byproduct
as
a
potential
source.
In
a
published
article
from
American
Chemical
Science
Journal
the
use
of
corncobs
have
two
main
advantages,
the
first
is
the
wide
availability,
and
second
is
the
intrinsic
thermodynamics
properties
of
corncobs
[15].
There
is
a
vast
amount
of
corncobs
that
are
wasted
in
the
production
of
food
and
ethanol.
A
51%
portion
of
total
U.S.
grown
corn
is
dedicated
to
the
production
of
food
and
ethanol;
within
these
productions
only
the
kernels
are
used
[16].
These
waste
products
can
be
recycled
and
processed
to
into
a
high
value
material
of
activated
carbon.
The
thermodynamic
characteristics
of
corncobs
allows
for
“a
low
carbonization
temperature
compared
to
other
biomass
residues”
[15].
This
allows
for
a
lower
temperature
during
the
activation
stage
where
all
the
undesired
components
existing
within
the
raw
material
are
vaporized.
Vaporization
of
any
material
takes
a
great
amount
of
energy;
this
is
due
to
how
heat
is
distributed
within
a
substance.
The
energy
input
is
converted
into
thermal
energy,
which
then
flows
down
a
gradient
of
temperature
differences.
Only
when
the
gradient
is
at
equilibrium
at
the
boiling
point
of
the
substance
does
vaporization
initiate.
Therefore,
corncobs
with
low
carbonization
temperature
will
allow
for
a
lower
input
of
thermal
energy.
This
material
has
potential
as
an
alternative
source.
The
source
of
municipal
refuse
is
numerous
in
supply.
This
refers
to
solid
waste
consisting
of
everyday
trash
and
garbage.
The
process
to
which
the
raw
refuse
originates
is
through
the
sorting
out
of
glass
and
metal
leaving
a
source
full
of
carbonaceous
material
ready
to
be
activated
[5].
The
desired
characteristic
from
the
municipal
refuse
was
on
the
same
standard
as
those
that
are
from
coal
and
wood
[5].
Pass
considerations
for
using
refuse
have
been
disregarded
due
to
the
cheap
and
highly
available
supplies
of
wood.
The
economics
and
profit
margins
were
the
key
driving
force
to
choosing
less
sustainable
sources.
However
as
supplies
of
coal
and
the
ever-­‐increasing
cost
to
produce
lumber
these
readily
available
waste
sources
will
become
comparatively
economical.
Activation
Methods
Without
an
improvement
to
chemical
and
physical
characteristics
of
the
carbon
precursor,
the
effectiveness
of
carbon
as
an
absorbent
could
be
17
to
25
times
less
absorbent.
The
possible
range
is
due
to
the
source
of
raw
materials
used,
which
is
a
factor
in
the
pore
structure
and
surface
area.
Activation
is
also
crucial
in
creating
certain
structure,
which
have
a
greater
affinity
for
targeted
impurities.
Activation
is
done
either
physically
or
chemically;
however,
both
techniques
have
been
used

6. 6
simultaneously
to
yield
even
higher
absorption
and
adsorption
capacities
[5]
at
the
expense
of
higher
cost.
Figure 1: Processes for chemical and physical activation [5].
In
figure
1
both
physical
and
chemical
process
are
outlined.
A
physical
activation
is
also
referred
to
as
a
thermal
activation,
due
to
required
high
temperature
conditions.
Physical
means
of
activation
generally
required
two
steps,
as
seen
in
above
figure.
The
first
step
is
carbonization.
This
involves
pyrolysis
in
the
absence
of
oxygen,
which
is
the
breakdown
of
the
raw
carbon
rich
organic
matter
[6].
This
is
done
with
a
high-­‐energy
input
to
raise
temperatures
to
a
level
in
which
a
precession
of
vaporization
of
volatile
components
are
possible.
To
achieve
a
condition
without
the
presence
of
oxygen,
inert
gases
are
pumped
into
the
system.
Inert
gases
are
non-­‐reactive
agents;
this
prevents
side
reactions,
which
is
desired
for
the
conservation
of
pure
carbon.
The
result
of
pyrolysis
is
a
reduction
of
raw
material,
but
also
an
increase
in
the
quality
and
purity
of
carbon
atoms
[3].
The
second
stage
is
activation;
this
process
is
carried
out
with
oxygen
or
steam.
The
purpose
of
activation
is
to
increase
the
porosity
of
the
structure
as
well
as
increase
the
surface
area.
High-­‐energy
cost
due
to
high
temperature
processes
is
associated
predominately
with
physical
means
of
activation.
In
contrast
to
a
high
temperature
process,
chemical
means
of
activation
is
a
one
step
process
and
allows
for
carbonization
at
a
significantly
lower
temperature,
as
a
result

7. 7
there
is
a
greater
porous
structure
[7].
However,
chemical
precursors
are
needed,
which
are
typically
an
acid,
or
strong
base
[4].
Raw
materials
are
impregnated
with
the
chemicals,
which
begins
the
process
of
removing
the
impurities
through
dehydration
which
effects
pyrolytic
decomposition
of
impurities.
Chemical
activation
allow
for
less
thermal
energy
to
be
expended,
however
washing
to
remove
the
impregnated
chemicthals
and
drying
are
required
[5].
These
chemicals
are
a
hazard
to
the
environment
if
not
recycled
and
reused.
The
potential
to
recycle
pyrolytic
chemical
present
an
advantage
over
physical
means
of
activation.
The
economics
associated
with
recycle
stream
within
industrial
application
saves
fresh
material,
which
is
directly
associated
with
lower
cost
of
purchasing
these
chemicals.
For
every
unit
of
mass
activated
carbon
is
created
there
is
small
portion
of
chemicals
that
are
required.
The
ability
to
use
the
fraction
of
the
activated
carbon
product
to
remove
the
impurities
of
the
chemical
for
reuse
of
the
chemical
presents
a
possible
solution
to
lower
energy
consumption
within
the
activated
carbon
process.
Taking
into
account
the
large
surface
area
that
is
created
due
to
activation,
only
a
small
portion
of
the
total
product
needs
to
be
used
in
the
recycling
process
of
the
pyrolytic
chemicals;
Overall,
chemical
activation
if
a
more
viable
method
than
physical
activation.
ENERGY
&
ENVIROMENT
Energy
Consumption
Energy
considerations
for
processing
will
be
discussed
starting
from
the
sourcing
of
raw
materials.
The
mining
of
coal
in
itself
is
a
high-­‐energy
process.
The
large
machinery
and
transportation
of
raw
carbon
accounts
for
most
of
the
energy
expenses
in
the
extraction
of
coal.
Its
estimated
that
15%
of
the
production
cost
is
due
to
transportation
and
mining
of
coal
alone
[14].
Energy
consumption
of
wood
as
precursors
also
account
for
a
significant
portion
of
the
production.
Shipping
of
wood
from
less
rural
area
and
overseas
present
significant
fuel
usage.
Temporary
bridges
must
be
built
over
small
rivers
and
streams
to
gain
access
to
depleting
supplies
of
hard
woods.
This
takes
large
equipment
to
get
to
these
areas.
After
the
wood
is
harvested
it
has
to
be
dried,
this
requires
a
kiln,
which
is
a
thermally
insulated
chamber
where
heat
can
be
added
to
evaporate
water
[18].
High-­‐energy
inputs
are
required
with
vaporization
processes.
A
physical
activation
technique
requires
great
amount
of
expended
energy
to
raise
temperature
to
pyrolyze
all
the
undesired
substances.
The
needed
temperature
of
physical
activation
is
on
a
scale
of
magnitude
twice
that
required
of
a
chemical
activation.
High
temperatures
are
needed
in
the
two-­‐step
process
of
carbonization
and
activation,
which
is
approximately
1000˚C
and
700˚
C
for
carbonization
and
activation
processes,
respectively.
It’s
intuitively
known
and
explained
by
the
2nd
law
of
thermodynamics
that
heat
flows
from
high
temperature
to
low
temperatures.
If
a
substance
at
a
lower
temperature
needs
to
be
at
a
state
of
higher
temperature,
energy
from
the
surroundings
must
be
inputted
in
to
the
system.
This
is
the
main

8. 8
reason
to
experienced
high
operational
cost
associated
with
a
physical
activation
process.
Chemical
activation
is
a
more
economical
and
energy
efficient
method
to
physical
activation.
This
method
also
requires
energy
inputs
to
raise
temperature
in
order
to
start
reactions,
however
these
temperature
are
well
below
at
approximately
500
˚C
depending
on
certain
raw
materials.
Another
advantage
of
a
chemical
means
is
the
one
step
process,
which
lowers
cost
of
special
equipment
and
larger
facilities.
For
every
action
there
is
a
reaction,
and
with
energy
consumption
there
is
a
environmental
impact.
Environmental
Effects
of
Activation
Methods
Through
a
physical
means
of
activation
high
temperatures
are
required
for
extended
periods
to
vaporize
impurities
within
the
raw
material.
The
implication
of
this
method
is
a
high-­‐energy
consumption,
and
therefore
high
environmental
effects.
The
method
to
heating
of
the
carbon
precursor
is
done
though
resistance
heat
coil
or
through
the
burning
of
natural
gas
[5].
Both
of
these
heating
techniques
have
detrimental
impacts
on
the
environment.
With
heat
coils,
electricity
is
used.
Electricity
is
produce
mainly
from
nonrenewable
resources,
with
39%
coal,
27%
natural
gas,
and
19%
nuclear.
These
sources
of
energy
pollute
the
environment
with
the
harmful
emissions
such
as
nitrogen
oxide
(NOx),
which
is
known
to
cause
cancer
in
animals,
destroy
natural
environments,
and
affect
the
health
of
the
ecosystem
[17].
A
chemical
means
of
activation
requires
far
less
energy
than
with
thermal
activation.
With
300,000
tons
a
year
of
activated
carbon
produce
solely
for
water
treatment
processes,
a
huge
impact
can
be
clearly
seen
in
small
energy
saving
[5].
A
potential
detrimental
effect
to
the
environment
can
be
seen
in
the
use
of
chemicals
to
pyrolyze
raw
carbon.
Possible
contamination
can
happen
due
to
waste
chemicals
not
being
handled
properly,
however
with
EPA
regulations
it
would
be
rare.
This
case
would
also
be
unlikely
because
it
is
uneconomically
to
waste
high
value
solvents;
a
common
practice
would
be
to
recycle
and
reuse.
Lower
energy
and
use
of
recyclable
solvents,
chemical
activation
is
a
better
for
the
environment.
DISSCUSSION
&
SUMMARY
A
Cost
Effective
and
Sustainable
Model
As
a
result
of
the
investigation
possible
improvements
could
be
made
to
increase
the
overall
efficiency
of
the
activation
process.
A
sustainable
model
dictates
the
use
of
a
recycling
method.
In
figure
2
below,
a
comparison
of
the
main
aspects
of
the
process
is
depicted.
It
all
starts
with
sustainable
sources
those
that
would
have
otherwise
been
wasted
such
as
corncob
and
municipal
refuse
to
list
just
the
few
possibilities.
With
supplies
of
current
carbon
precursors
becoming
scarce,
this
will
provide
the
shift
in
economical
feasibility
of
waste
sources.
The
benefits
of
using

9. 9
waste
byproducts
will
positively
impact
emission
levels,
natural
habitat
preservation,
and
save
natural
resources.
The
energy
saved
from
initial
production
cost
of
equipment,
labor,
and
transportation
will
then
be
decreased
due
to
recycle
of
the
material
from
waste
byproducts.
Next
the
activation
of
carbon
will
be
processed
with
a
chemical
pyrolysis
method.
This
will
provide
significant
lower
thermal
energy
cost
than
current
physical
methods
due
to
chemical
reactions
instead
of
vaporizations.
The
ability
to
recycle
chemical
activating
solvent
will
provide
yet
another
advantage
in
economically
feasibility
and
sustainability.
With
chemical
reactions
the
ability
to
control
precise
characteristics
in
pore
structures
will
help
to
increase
the
effectiveness
of
activated
carbon
for
specific
materials
and
situations.
Figure 2: A comparison of the process chain in the production of activated
carbon. On the left is the how the majority of activated carbon is currently
produced, and on the right is a more efficient process with sustainable
sources and efficient activation methods.

10. 10
Conclusion
The
gap
is
widening
and
the
rising
cost
of
current
sources
is
soaring.
With
resources
becoming
scarce
and
difficult
to
access
the
economics
of
the
production
will
not
allow
current
prices
and
profits.
Following
this
standard
sustainable
and
efficient
model,
supply
shortages
and
environmental
harm
will
be
avoided.
The
ecosystem
as
a
whole
is
being
affected,
but
with
new
highly
efficient
activation
techniques
and
sustainable
sources,
the
detrimental
effect
of
the
destruction
to
forest,
and
natural
reserves
will
be
limited.
With
the
described
cost
effective
and
sustainable
model,
this
guideline
provides
a
path
to
increase
the
overall
efficiency
of
the
activation
process,
increase
effectiveness
of
activated
carbon,
and
decrease
detrimental
impacts
to
the
environment.

11. 11
References:
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PRODUCTION OF ACTIVATED CARBON DERIVED FROM OIL
PALM EMPTY FRUIT BUNCH [Online], 04 ed., Nigeria: Nnamdi
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12. 12
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coal-supplies/

13. 13
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