Energy & Fuels 2007, 21, 3735–3739
3735
Characterization of Activated Carbon Prepared from Chicken
Waste and Coal
Yan Zhang,† Hong Cui,† Riko Ozao,†,‡ Yan Cao,† Bobby I.-T. Chen,† Chia-Wei Wang,†,§ and
Wei-Ping Pan*,†
Institute for Combustion Science and EnVironmental Technology, Western Kentucky UniVersity, Bowling
Green, Kentucky 42101, SONY Institute of Higher Education, Atsugi, Kanagawa, 243-8501, Japan, and
Mingchi UniVersity of Technology, Taipei, Taiwan
ReceiVed June 24, 2007. ReVised Manuscript ReceiVed August 13, 2007
Activated carbons (ACs) were prepared from chicken waste (CW) and coal (E-coal) blended at the ratios of
100:0, 80:20, 50:50, 20:80, and 0:100. The process included carbonization in flowing gaseous nitrogen (300
mL min-1) at ca. 430 °C for 60 min and successive steam activation (0.1 mL min-1 water injection with a
flow of N2 at 100 mL min-1) at 650 °C for 30 min. Chicken waste is low in sulfur content but is high in
volatile matter (∼55 wt %), and ACs with higher specific surface area were more successfully obtained by
mixing with coal. The specific surface area of the CW/Coal blend AC can be estimated by SSABET ) -65.8x2
+ 158x + 168, where SSABET is the specific surface area in m2 g-1 as determined by the BET method using
CO2 as the adsorbent, where x is the coal fraction by weight in the CW/coal blend ranging from 0.0 to 1.0
(e.g., x ) 0.0 signifies the blend contains no coal and x ) 1.0 signifies the blend consists of 100% coal).
Introduction
Activated carbons can be produced from virtually any type
of carbonaceous materials1 such as coconut shell,2 palm shell,3
nut shell,4 olive stones,5 oil-palm stones,6 agricultural wastes,7,8
and many others. The preparation of activated carbon generally
involves two steps: carbonization of the raw material in the
absence of oxygen and activation of the carbonized products
with water and/or CO2. Volatile matters are released in the
carbonization step, and the remaining solid carbon structure is
generally called as char. In the following activation step, char
reacts with activating agents to form activated carbon (AC) with
improved pore structure and surface properties. However, welltailored activated carbon for specific application and having a
* Corresponding author: tel +1-270-745-2272; fax +1-270-745-2221;
e-mail wei-ping.pan@wku.edu.
† Western Kentucky University.
‡ SONY Institute of Higher Education.
§ Mingchi University of Technology.
(1) Marsh, F.; Rodríguez Reinoso, F. ActiVated Carbon; Elsevier
Science: London, 2005.
(2) Laine, J.; Yunes, S. Effect of the Preparation method on the Pore
Size Distribution of Activated carbon from Coconut Shell. Carbon 1992,
30, 601–604.
(3) Daud, W. M. A. W.; Ali, W. S. W.; Salaiman, M. Z. The Effect of
Carbonization Temperature on Pore Development in Palm-Shell-Based
Activated Carbon. Carbon 2000, 38, 1925–1932.
(4) Wang, Z. M.; Kanoh, H.; Kaneko, K.; Lu, G. Q.; Do, D. D. Structure
and surface property changes of macadamia nut-shell char upon activation
and high temperature treatment. Carbon 2002, 40, 1231–1239.
(5) Gonzalez, M. T.; Rodriguez-Reinoso, F.; Garcia, A. N.; Marcilla,
A. CO2 Activation of Olive Stones Carbonized under Different Experimental
Conditions. Carbon 1997, 35, 159–162.
(6) Jia, G.; Lua, A. C. Preparation of Activated Carbons from Oil-PalmStone Chars by Microwave-Induced Carbon Dioxide Activation. Carbon
2000, 38, 1985–1992.
(7) Chang, C. F.; Chang, C. Y.; Tsai, W. T. Effect of burn-off and
activation temperature on preparation of activated carbon from corn cob
agrowaste by CO2 and steam. J. Colloid Interface Sci. 2002, 232, 45–49.
(8) Gergova, K.; Petrov, N.; Eser, S. Adsorption properties and
microstructure of activated carbons produced from agricultural by-products
by steam pyrolysis. Carbon 1994, 32, 693–702.
specific surface area of 500 m2 g-1 or larger cannot be easily
obtained by simply carbonizing the carbonaceous materials or
biomass above, and because of its ready availability and stability
in production, much study has been done on coal for the
industrial production of activated carbon.9–12
In the case of coal-fired power plants, powdered activated
carbon (PAC) is injected upstream of the electrostatic precipitator (ESP) or baghouse to control mercury emission.13 Although
PAC injection has an advantage of high efficiency, it has a
disadvantage of high sorbent cost, partially due to the lack of
PAC recovery from fly ash. Moreover, the AC commonly need
to be impregnated with sulfur, chlorides, bromine, or iodine to
enhance Hg adsorptive capacity.14–18 Thus, the cost and capture
capability of PAC play an important role in the feasibility of
(9) Munõz-Guillena, M. J.; Illań-Goḿez, M. J.; Martiń-Martińez, J. M.;
Linares-Solano, A.; Salinas-Martińez de Lecea, C. Activated Carbons from
Spanish Coal. 1. Two-Stage CO2 Activation. Energy Fuels 1992, 6, 9–15.
(10) Centeno, T. A.; Stoeckli, F. The Oxidation of an Asutrian
Bituminous Coal in Air and Its Influence on Subsequent Activation by
Steam. Carbon 1995, 33, 581–586.
(11) Kovacik, G.; Wong, B.; Furimsky, E. Preparation of Activated
Carbon from Western Canadian High Rank Coals. Fuel Proc. Technol. 1995,
41, 89–99.
(12) Teng, H.; Ho, J.-A.; Hsu, Y.-F.; Hsieh, C.-T. Preparation of
Activated Carbons from Bituminous Coals with CO2. Ind. Eng. Chem. Res.
1996, 35, 4043–4049.
(13) Pavlish, J. H.; Sondreal, E. A.; Mann, M. D.; Olson, E. S.;
Galbreath, K. C.; Laudal, D. L.; Benson, S. A. Application of sorbents for
mercury control for utilities burning lignite coal. Fuel Process. Technol.
2003, 82–89.
(14) Zeng, H.; Jin, F.; Guo, J. Removal of elemental mercury from coal
combustion flue gas by chloride-impregnated activated carbon. Fuel 2004,
83, 143–146.
(15) Granite, E. J.; Pennline, H. W.; Hargis, R. A. Novel Sorbents for
Mercury Removal from Flue Gas. Ind. Eng. Chem. Res. 2000, 39, 1020–
1029.
(16) Korpiel, J. A.; Vidic, R. D. Effect of Sulfur Impregnation Method
on Activated Carbon Uptake of Gas-Phase Mercury. EnViron. Sci. Technol.
1997, 31, 2319–2325.
(17) Vidic, R. D.; Siler, D. P. Vapor-phase elemental mercury adsorption
by activated carbon impregnated with chloride and chelating agents. Carbon
2001, 39, 3–14.
10.1021/ef700358z CCC: $37.00  2007 American Chemical Society
Published on Web 09/28/2007
3736 Energy & Fuels, Vol. 21, No. 6, 2007
Zhang et al.
Table 1. Summary of Proximate Analysis, CHN, S, and Gross Calorific Value of the Samples
sample
moisture
(wt %)
ash (wt %)
volatile matter
(wt %)
C (wt %)
N (wt %)
H (wt %)
O (wt %)
S (wt %)
calorific value
(Btu lb-1)
CW
C8E2
E5C5
E8C2
E-coal
10.6
9.7
8.4
7.1
6.2
26.6
23.2
18.0
12.8
9.4
54.7
50.6
44.5
38.3
34.2
29.1
36.7
48.2
59.6
67.2
3.4
3.0
2.5
1.9
1.5
5.1
5.2
5.3
5.3
5.4
35
30.8
24.4
18.0
13.8
0.8
1.2
1.8
2.4
2.8
5166
6556
8642
10727
12118
the PAC injection technology. A solution for overcoming the
problem of cost is to use an inexpensive material with high
carbon content, such as industrial or agricultural wastes. The
authors have prepared coal-like material from apple pomace19
and also reported on the preparation of chicken waste woodceramics, i.e., a so-called inexpensive c/c composite produced
from plant-originated carbon, which showed good potential of
capturing mercury.20 Recently, chicken waste was characterized
by proximate, absolute, and elemental analyses, and furthermore,
the decomposition in nitrogen and combustion were studied
using evolved gas analysis.21,22 The results also showed that
chicken waste is a raw material candidate for activated carbon;
i.e., it is a carbonaceous material high in calcium content that
may be suitable for providing activated carbon sites to trap
mercury. Furthermore, woodceramics produced from chicken
waste showed selectivity in adsorption behavior, which suggested chicken waste to favor dominance of chemical adsorption.23 However, to the authors’ knowledge, no activated carbon
has been produced from chicken wastes.
Accordingly, the present study is concerned with the preparation of AC from chicken waste (CW) and coal by the
carbonization in a nitrogen atmosphere followed by activation
in a steam atmosphere. The yields, specific surface area, pore
volume, and pore size of the products are determined. The
effects of carbonization and activation temperature on these
properties are also studied. Thermal weight loss behaviors of
char and AC samples were investigated and used to deduce the
formation of char or AC at varied preparation conditions. The
specific surface area is obtained as a function of the CW/coal
blend ratio.
Experimental Section
Sample Preparation. Chicken waste (CW) (below 0.08 mm in
particle size, which was prepared by drying, grinding, and sieving
with 200-mesh sieve21) and high-sulfur coal (E-coal) were used as
the starting material, and CW was blended with coal at different
ratios by weight of 2:8, 5:5, and 8:2 to obtain samples C2E8, C5E5,
and C8E2, respectively. The samples were characterized using the
American Society for Testing and Materials (ASTM) method D5373
for carbon, hydrogen, and nitrogen using a LECO CHN-2000.
Likewise, sulfur was determined instrumentally using a LECO SC(18) Lee, J. L.; Seo, Y. C.; Jurng, J.; Lee, T. G. Removal of gas-phase
elemental mercury by iodine- and chlorine-impregnated activated carbons.
Atmos. EnViron. 2004, 30, 4887–4893.
(19) Ozao, R.; Pan, W.-P.; Whitely, N.; Okabe, T. Coal-like Thermal
Behavior of a Carbon-Based Environmentally Benign New Material:
Woodceramics. Energy Fuels 2004, 18, 638–643.
(20) Ozao, R.; Okabe, T.; Nishimoto, Y.; Cao, Y.; Whitely, N.; Pan,
W.-P. Gas and Mercury Adsorption Properties of Woodceramics Made from
Chicken Waste. Energy Fuels 2005, 19, 1729–1734.
(21) Whitely, N.; Ozao, R.; Cao, Y.; Pan, W.-P. Multi-utilization of
Chicken Litter as a Biomass Source. Part II. Pyrolysis. Energy Fuels 2006,
20, 2666–2671.
(22) Whitely, N.; Ozao, R.; Artiaga, R.; Cao, Y.; Pan, W.-P. Multiutilization of chicken litter as biomass source. Part I. Combustion. Energy
Fuels 2006, 20, 2660–2665.
(23) Ozao, R.; Okabe, T.; Arii, T.; Nishimoto, Y.; Cao, Y.; Whitely,
N.; Pan, W.-P. Gas adsorption properties of woodceramics. Mater. Trans.
2006, 46, 2673–2678.
432 in accordance with ASTM D4239. Instrumental procedures for
proximate analysis were used following the ASTM method D5142
and utilizing a LECO TGA-601. The gross calorific value was
determined using a LECO AC-350 bomb calorimeter following
ASTM D5865. A Rigaku RIX-3001 XRF was used to determine
the major and minor elemental composition following ASTM
D4326.
Preparation of Char and Activated Carbon. The temperatures
for carbonization, preoxidation, or activation of the CW/coal or
char samples were determined in the range between 300 and 550
°C based on the results obtained by TGA runs and kinetic analysis
thereof.21
The experimental setup24 consisted of a 15 in. tube with 13/16
in. inside diameter inserted into an electric furnace. The weighed
sample was put into this tube with quartz wool on both sides. The
tube was heated to the desired temperature by the electric furnace
via a temperature controller.
For carbonization experiments, the weighed sample sat in a 427
°C nitrogen atmosphere for about 60 min. Similarly, the solid
residues were tested on a TGA. On starting the carbonization, the
furnace was set at a desired temperature. One quartz tube was filled
with around 4.0 mg samples and blocked by quartz wool on the
both sides. Before putting the tube into the heated furnace for
carbonization, it was purged first by N2 flow (300 mL min-1) for
around 15 min. After 60 min of carbonization, the tube was drawn
out of the furnace, and gaseous N2 was flown through for cooling.
Finally, char was collected from the cooling tube and weighed.
The liquid products were swept out of the reactor and passed
through a glass condenser immersed in a mixture of ice and water.
However, the condensable and gases fraction were not collected
since the yields were very small.
Thus-prepared char samples were activated by steam following
the same procedure in the same reactor at 650 and 750 °C for 60
min. The water injection rate was 0.1 mL min-1 with a flow of N2
at 100 mL min-1.
For mass production of activated carbon, however, further study
is necessary using a scaled-up furnace using, e.g., a rotary kiln and
the like.
SEM Observation. The texture and pore structure were observed
under a JEOL JSM 5400-LV scanning electron microscope (SEM).
Thermogravimetric Analysis (TGA). To evaluate the thermal
stability properties, about 20 mg each of the samples was subjected
to TGA runs at a heating rate of 20 °C min-1 using a TA
Instruments Hi-resolution TGA 2950 under air (Airgas compressed
air (breathing grade), type I, grade D, 21% O2 certified) at a flow
rate of 60 mL min-1.
X-ray Diffraction (XRD) Analysis. The XRD analysis on the
thus-prepared samples was made using a SCINTAG X’TRA
AA85516 (ThermoARL) X-ray diffractometer equipped with a
Peltier cooled Si solid detector. Monochromatized Cu KR1 (0.150 54
nm) was used as the radiation. Diffraction patterns were collected
at 45 kV–40 mA, at 0.01° step and count time of 0.500 s over a
range of 1.00°–90.00° (2θ), at a step scan rate of 1.20° min-1.
Pore Structure Analysis. Specific surface area based on the
Brunauer–Emmett–Teller model (SSABET) and the adsorption and
desorption isotherms were obtained using nitrogen gas as adsorbate
at 77 K or carbon dioxide gas at 273 K (ASAP 2020 accelerated
surface area and porosimetry analyzer, Micromeritics Instrument
Corp.). The total pore volume, V0, was calculated from the amount
(24) Cui, H.; Cao, Y.; Pan, W.-P. J. Anal. Appl. Pyrolysis 2007, 80,
319–324.
ActiVated Carbon from Chicken Waste and Coal
Energy & Fuels, Vol. 21, No. 6, 2007 3737
Figure 1. TGA curves and derivative weight curves for E-coal, CW,
and their blended samples in a N2 atmosphere at a heating rate of 20
deg min-1.
Table 2. Basic Composition for Char Samples Prepared at
427 °C (Dry Basis)
sample
C, %
H, %
O, %
N, %
S, %
Cl, ppm
ash, %
CW char
C8E2 char
C5E5 char
C2E8char
E-Coal char
28.43
41.10
54.32
67.15
70.91
1.40
1.96
2.45
3.04
3.38
8.76
4.77
5.49
4.89
7.86
2.67
2.62
2.29
1.92
1.73
1.20
1.72
2.07
2.28
2.40
22617
17747
9290
2630
180
57.54
47.84
33.39
20.73
13.71
of gas adsorbed at relative pressure of 0.95, and the specific surface
area, SSABET, was calculated using multipoint BET equation in the
relative pressure range of 0.05–0.35.
Results and Discussion
Sample Description. As described above, E-coal, a sulfurrich coal having particle size below 0.08 mm, was blended with
CW at mixing ratios of 2:8, 5:5, and 8:2 by weight to obtain
mixed samples denoted as E8C2, E5C5, and E2C8, respectively.
The proximate analysis, CHN, S, and gross calorific value of
E-coal and CW are given in Table 1 together with the blended
samples.
Figure 1 shows mass loss profiles for CW/coal samples in a
N2 atmosphere.24 It is found that volatile releasing temperature
is around 300 °C for CW and around 450 °C for coal, at which
point the devolatilization rate reaches its maximum. For blended
samples, two peaks appear near 300 and 450 °C on the DTG
curves. Increasing the coal content in the blending samples
causes the peak around 300 °C to shrink, while the peak around
450 °C increased in size. The blending samples have the both
characteristics of coal and CW, so that more CW content results
more volatile matters emission at low temperature. By TGA,
the cooperation effect was also not found for the mixture of
CW/coal in a N2 atmosphere.
The basic composition of char samples prepared at 427 °C are
listed at Table 2. With increasing CW contents in the blending
samples, ash, N, and Cl contents of char samples increase. It shows
that char samples remain the original characteristics after carbonization either from coal or chicken waste. Less carbon content and
increased ash content indicate that CW char is not a suitable
precursor for activated carbon. However, a certain amount of coal
blended with CW can increase carbon content and decrease ash
content. Increasing coal content also increases the content of S
while decreasing that of Cl.
Specific surface area as obtained according to BET model,
SSABET, of CW, which was 3.90 m2 g-1 as measured at 77 K
Figure 2. (a) SEM photograph of carbonized E-coal (magnification
200×). (b) SEM photograph of carbonized E-coal (magnification
10000×).
using N2 as adsorbate, increased to 7.79 m2 g-1 by carbonization.
However, the SSABET of the char obtained from E-coal decreased
from 8.55 to 0.50 m2 g-1. This is due to insufficient evolution
of volatiles as above described.
The pore structure and size vary depending on the conditions
of activation.25 By using steam as the activating agent for
thermal activation, the porous structure of the char is enhanced
according to the following reaction: C + H2O ) CO + H2.
The activation temperature was determined on the TG and DTG
curves of the carbonized samples obtained by heating in N2 at
427 °C for 60 min. Generally, the reactivity of the char is partly
attributed to the change in surface area and increases with the
O/C ratio of the precursor. Thus, the highest rate of reaction as
observed on DTG curve was 600 °C for blended samples and
around 700 °C for the CW sample.24 Since no great difference
was observed among the temperature conditions of 650 and 750
°C, the activation temperature was set to 650 °C.
Parts a and b of Figure 2 show the SEM photograph at 200×
and 10 000× magnification, respectively, of the activated carbon
obtained from E-coal. Carbonization and activation of coal result
in fine particles that are adhered on the surface of larger particles.
This can be explained by referring again to Figure 1. The coal
pyrolysis occurs rapidly with gas evolution at a higher temperature, thus destroying partially the original coal structure. On
the other hand, volatiles are gradually released at a lower and
wider temperature range. Thus, the sample consists of larger
particles that are partly porous, as shown in the SEM photographs of parts a and b of Figure 3, which are obtained at 200×
(25) Mui, E. L. K.; Ko, D. C. K.; McKay, G. Production of active
carbons from waste tyres––a review. Carbon 2004, 42, 2789–2805.
3738 Energy & Fuels, Vol. 21, No. 6, 2007
Zhang et al.
Figure 5. Adsorption isotherm of N2 on C5E5 at 77 K.
Figure 6. Specific surface area (m2 g-1) (as determined by BET using
N2 as the adsorbent), SSABET, as a function of the coal fraction, x.
Table 3. Specific Surface Area (BET Method Using N2 and CO2
as Adsorbent at 273 K) and Average Pore Diameter of the
Activated Carbons
Figure 3. (a) SEM photograph of carbonized C5E5 (magnification
200×). (b) SEM photograph of carbonized C5E5 (magnification
10 000×).
N2
pore
specific
pore
specific
coal
surface area: diameter surface area: diameter
(nm)
SSABET (m2/g)
(nm)
sample fraction SSABET (m2/g)
CW
C8E2
C5E5
C2E8
E-coal
Figure 4. XRD patterns of the AC samples.
and 10 000× magnification, respectively. Since CW is higher
in volatile content, volatiles are evolved at a lower temperature
than pure coal, and these gases likely form pores with
complicated structure.
Figure 4 shows the XRD patterns of the AC samples. E-coal
and CW both contain silica as the mineral matter (e.g., (101)
diffraction peak observed at 2θ ) 26.6° and (100) at 2θ )
21.0°). CW furthermore has sharp peaks at 2θ ) 28.2°, 31.2°,
40.2°, and 49.9°, which may be attributed to boehmite (alumina
monohydrate) or calcite.
Figure 5 shows an adsorption–desorption isotherm of N2 on
C5E5 at 77 K. The isotherm is typical of type V and exhibits
hystheresis due to filling the pores by capillary condensation in
mesopores.26 Thus, the activated carbon not only has micropores
CO2
0
0.2
0.5
0.8
1
128
203
235
248
250
2.78
2.27
2.23
1.30
1.68
164.2
203.6
230.0
247.0
263.9
1.04
1.27
1.30
1.30
1.35
(pores with internal width of less than 2 nm) but also mesopores
(pores with internal width between 2 and 50 nm). The original
C5E5 had a specific surface area of 4.06 m2 g-1. After
carbonization at 427 °C for 60 min, its surface area remained
almost constant at 3.33 m2 g-1. However, its specific surface
area was dramatically increased to 235 m2 g-1 after activation
at 650 °C for 30 min, which was attributed to the development
of microporous and mesoporous structure. Accordingly, the
average pore diameter increased from the original 8.14 to 14.7
nm by carbonization but decreased to 2.23 nm with the
development of micro- and mesopores.
Table 3 summarizes the pore properties of the activated
carbon samples. The specific surface area of the ACs increase
with increasing E-coal. The AC produced from E-coal consist
of fine particles, as stated above, and this may account for a
larger specific surface area. Furthermore, CW contain additional
mineral matter, and this may partly account for decreasing the
specific surface area of the ACs prepared from CW.
Since CO2 molecules are accessible to micropores having
wedgelike structure, the specific surface area is increased for
(26) Sing, K. S. W.; Everett, D. H.; Haul, R. A.; Moscou, L.; Pierotti,
R. A.; Rouquerol, J.; Siemieniewska, T. Reporting Physisorption data for
gas/solid systems with special reference to the determination of surface
area and porosity. Pure Appl. Chem. 1985, 57, 603–619.
ActiVated Carbon from Chicken Waste and Coal
Energy & Fuels, Vol. 21, No. 6, 2007 3739
m2 g-1. This provides an empirical estimation of SSABET for
CW/coal blend activated carbons according to the following
equation:
(1)
SSABET ) -65.8x2 + 158x + 168
2
-1
where SSABET is the specific surface area in m g
as
determined by BET method using CO2 as the adsorbent, and x
is the coal fraction by weight in the CW/coal blend ranging
from 0.0 to 1.0 (e.g., x ) 0.0 signifies the blend contains no
coal, and x ) 1.0 signifies the blend consists of 100% coal).
Conclusions
2
-1
Figure 7. Specific surface area (m g ) (as determined by BET using
CO2 as the adsorbent), SSABET, as a function of the coal fraction, x.
all the samples by using CO2 as the adsorbent. The pore diameter
as obtained with N2 as the adsorbent is larger for CW but is
smaller for E-coal. However, this trend is reversed in case CO2
is used as the adsorbent. This indicates that pores with
complicated structure is formed in ACs using CW, which may
be beneficial for capturing smaller molecules.
Figure 6 shows the specific surface area (m2 g-1) (as
determined by BET using N2 the adsorbent), SSABET, as a
function of the coal fraction, x. Similarly, Figure 7 shows SSABET
obtained by using CO2 adsorbent as a function of the coal
fraction, x. The values are indicated with an allowance1 of (25
Activated carbons (ACs) were prepared from chicken waste
and coal by carbonization in nitrogen atmosphere at ca. 430 °C
for 60 min and successive steam activation at 650 °C for 30
min. Because chicken waste is low in sulfur content but is high
in volatile matter (∼55 wt %), ACs with higher specific surface
area were more successfully obtained by mixing with coal. The
specific surface area of CW/coal blend AC can be estimated by
SSABET ) -65.8x2 + 158x + 168, where SSABET is the specific
surface area in m2 g-1 as determined by the BET method using
CO2 as the adsorbent, where x is the coal fraction by weight in
the CW/coal blend ranging from 0.0 to 1.0.
Acknowledgment. This work is supported by the USDA-ARS
Project No. 6406-12630-002-02S.
EF700358Z