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Enhanced SO2 and Rhodamine B removal by blending coke-making waste benzene residu e(BR) for pelletized activated coke (PAC) production and mechanisms Yanxia Guo, Jian Niu, Huirong Zhang, Fangqin Cheng, Haibin Wu, and Dapeng Jin Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.9b00956 • Publication Date (Web): 13 May 2019 Downloaded from http://pubs.acs.org on May 13, 2019
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Enhanced SO2 and Rhodamine B removal by blending coke-making waste
2
benzene residue (BR) for pelletized activated coke (PAC) production and
3
mechanisms Yanxia Guo1, Jian Niu1, Huirong Zhang1*, Fangqin Cheng1*, Haibin Wu1,
4
Dapeng Jin2
5 6 7 8 9 10
1State
Environmental Protection Key Laboratory of Efficient Utilization Technology
of Coal Waste Resources, Institute of Resources and Environmental Engineering, Shanxi University, Taiyuan 030006, P. R. China. 2Qinghuannengchuang
Environmental Protection Technology Co., Ltd., Shanxi
University, Taiyuan 030006, P. R. China.
11
Abstract: It is an economical and efficient way to prepare pelletized activated coke
12
(PAC) by utilizing coking by-product (coke powder and benzene residue (BR)). In this
13
work, carbon precursors were prepared at 600 °C by addition of different content of BR
14
(2%, 4%, 6%, 8%) to the mixture of blending coals and coke powder, followed by
15
activation of steam to obtain PAC with high surface and hierarchical porous structure.
16
It was found that BR could adjust PAC’s pore structure, surface chemistry and further
17
influence its adsorption performance. The specific surface area of PAC modified by the
18
addition of 4% BR is up to 782 m2/g, which is 10.3% higher than the unmodified PAC.
19
The regulation mechanism of BR on PAC’s physicochemical structure was proposed.
20
Obvious improvement of SO2 adsorption was also observed, the sulfur capacity of PAC
21
modified by 8% BR is 58.7 mg/g, which is 17.4% higher than unmodified PAC.
22
Moreover, PAC modified by the addition of 4% BR shows that the Rhodamine B (RhB)
23
adsorption the capacity of RhB was up to 109.8 mg/g, which was 32.6% higher than
24
unmodified PAC. Moreover, this research shows that BR is a potentially effective
25
modifier for PAC, not only it could improve the performance of the PAC, but also
26
utilize the coking by-product.
27 28
Key words: Pelletized activated coke (PAC); Benzene residue; Physicochemical
29
structure; Performance
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1. Introduction
2
Comparing Ca-based1 and Si-based porosity material2, 3, pelletized activated coke
3
(PAC) has characteristics of high specific surface area, good mechanical stability, pore
4
structure adjustable and well-developed porous structure, which can effectively adsorb,
5
oxidize and reduction of pollutants. In recent years, it has gained increasing attention
6
in the field of environmental protection, such as prevention and control of air pollution,
7
wastewater treatment, soil protection, and it is becoming indispensable porous material
8
for environmental protection4-6. Moreover, as a catalyst, PAC also has its unique
9
advantages such as pore structure and surface chemical properties can be adjusted to
10
meet the requirements of specific catalysts7. Previous studies8, 9 have shown that PAC
11
can be prepared by special materials for desirable properties.
12
At present, the main issue of PAC for hindering its large-scale application large
13
scale utilization is its low adsorption performance and high cost. Different
14
physicochemical structure is required for different applications10,
15
microporous PAC is favorable for gas phase adsorption, while mesoporous PAC is
16
more suitable for liquid adsorption12. Many researchers13, 14 focus on improving PAC’s
17
performance by improving the specific surface area and adjustment of pore distribution.
18
PAC’s texture and surface chemistry can be optimized by blending different kinds of
19
coal, and the adjustment of the pore structure also can be achieved, which is due to the
20
pore structure of the PAC produced by the different rank of coal has its own
21
characteristics: PAC produced from lignite (low-rank coal) mainly developed
22
mesoporous pores; PAC produced from anthracite (high-rank coal) mainly developed
23
micropore pores14. In our previous research15, a high specific surface area PAC with a
24
hierarchical pore structure was also obtained through the coal blending method.
25
Parameters during preparation are also crucial to PAC’s structure and performance,
26
such as carbonization temperature and burn-off during activation. As for lowering the
27
cost of AC production, solid wastes materials could be used as raw materials, such as
28
scrap tyres16, corn cob17, palm shell18, et al. However, most of these studies used
29
chemical activation method for AC production, which in turn leading to high costs of
30
AC and serious equipment corrosion.
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such as
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Moreover, the by-products from coke-making also could be used as carbon source
2
for PAC producing, such as coke powder, asphalt and benzene residue (BR), for which
3
not only it could utilize the by-products more efficiently, but also enhance the PAC’s
4
performance for flue gas purification. Zheng et al19 blended semi-coke powder into coal
5
to prepare PAC and found semi-coke powder mainly acts as a carbon skeleton. Not only
6
it can narrow the coefficient of char shrinkage and improve the pore structure of PAC,
7
but also it can decrease the shrinkage between the adjacent semi-coke layers and reduce
8
the cracking of PAC, the compressive strength of PAC was also improved. BR is a
9
hazardous waste produced by benzene refining process with a complex composition
10
such as coumarone resin, indene and styrene et al, which is harmful to the environment.
11
At present, in China, most of BR was burnt, only a small part of BR was used as raw
12
material for resin production. Using BR for PAC’s production not only is an
13
environmentally friendly way to utilization the BR but also could lower the cost of PAC.
14
However, to the best of the authors’ knowledge, few literatures regarding the effect of
15
BR on physicochemical structure and performance could be found.
16
Therefore, in this work, in order to investigate that whether BR could be used as a
17
modifier, partially replaces binder or promote PAC’s performance, different content of
18
BR was added to the mixture of coal blending and coke powder, then carbonized under
19
N2 atmosphere and activated by water vapor. SO2 and Rhodamine B (RhB) adsorption
20
tests were carried out for evaluating the PAC’s adsorption performance.
21
2. Materials and methods
22
2.1 Raw materials
23
Yangcheng (Y, anthracite), Xiangyuan (X, lean coal), Fugu (F, weakly caking coal),
24
coke powder (CP) and benzene residue (BR) were used as raw materials, the mixture
25
of asphalt and coal tar act as a binder (B) to prepare PAC. The proximate analysis (GB/T
26
212–2008) and the ultimate analysis measured by an elemental analyzer are shown in
27
Table 1. The ash composition analysis results determined by X-ray fluorescence
28
spectroscopy (XRF) are shown in Table 2.
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Table 1 Proximate and ultimate analysis of raw materials Proximate Analysis (wt. %)
Ultimate Analysis (wt %)
Samples Mad
Vad
Aad
FCad
Cdaf
Hdaf
St,daf
Ndaf
O* daf
Y
1.24
7.02
6.08
85.66
86.60
3.13
0.43
1.24
8.60
X
1.26
13.03
11.52
74.19
91.33
4.16
0.58
1.57
2.35
F
1.57
37.67
12.23
48.53
76.73
5.15
0.46
0.97
16.68
CP
0.66
1.66
14.34
83.34
98.33
0.25
1.01
0.91
--
BR
5.10
50.06
0.70
44.14
83.84
4.51
2.65
3.88
4.12
2
M: moisture; ad: air-dried base; daf: dry and ash-free base; St: total sulfur; A: ash;
3
V: volatile matter; * by difference
4
5
6 7 8
Table 2 Ash composition analyses of raw materials Samples
SiO2
Al2O3
CaO
SO3
Fe2O3
TiO2
MgO
Na2O
K2O
Y
50.50
42.90
2.91
1.61
2.43
1.69
0.74
1.14
0.74
X
44.70
37.20
7.18
4.49
3.13
1.62
0.70
1.13
0.36
F
24.60
9.82
28.00
7.40
6.27
0.39
5.09
0.94
0.13
CP
41.30
30.10
8.33
5.16
7.44
1.23
1.37
1.33
0.55
2.2 Preparation of PACs
Fig. 1 Process of PAC preparation The preparation of PAC is mainly included briquetting, carbonization, activation
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(Fig. 1). Coals, CP and BR were ground below 75 J* then BR with different
2
proportion (2%, 4%, 6%, 8%) was added to the mixtures (Y: X: F: CP: B =70: 10: 15:
3
5: 30) which have shown high specific surface area and hierarchical porous structure
4
according to our previous research15. It should be noticed that too much addition of BR
5
(>8%) would not be applicable due to output limitation in the coke-making factory.
6
Briquettes were prepared at a pressure of 25 MPa for 5 min. The briquettes carbonized
7
at 600 °C with flow rate of 300 mL/min for 60 min under N2 atmosphere, the precursors
8
were crushed to 425–850 J*9 Then 10 g precursor activated in a vertical tubular quartz
9
reactor (35 mm i.d.) with a heating rate of 10 °C/min up to 900 °C for residence of 90
10
min, deionized water with 600 JM?*
was steamed as a activator and carried by N2
11
with flow rate of 60 mL/min. For simplicity, as-prepared PAC was shortened to PAC-
12
X, where X is the percentage of BR addition.
13
In this paper, the carbonization weight loss efficiency (labeled “weight loss”, X1),
14
activation burn-off (labeled “burn-off”, X2) and PAC yields (labeled “yields”, Y)20 are
15
calculated by the following expressions:
16
X1 = (m0 - m1)/m0
(1)
X2 = (10 - m2)/10
(2)
Y = (1 - X1)(1 - X2)
(3)
where X1, X2, Y are weight loss, burn-off and yield, respectively; m0 is the initial
17
weight of briquette; and m1, m2 is the weight of precursors and PACs, respectively.
18
2.3 Analysis and characterization
19
2.3.1 Surface morphology analysis
20
A high-resolution scanning electron microscope (SEM, JSM-7001F) was
21
employed to examine the surface morphology of the samples. The X-ray energy
22
disperses spectra (EDS) of the samples were taken for calculating the chemical
23
composition of inherent minerals.
24
2.3.2 Surface chemistry analysis
25
The actives site of the PAC was analyzed by Boehm titration method21. 1.0 g AC
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1
(
75 J*5 put in a solution (0.1 mol/L NaOH or 0.1 mol/L HCl) 25 mL in the conical
2
flask at room temperature for 48 h. The 10 mL upper clear solution diluted 5 times and
3
titrated with HCl and NaOH. The samples were also investigated by X-ray
4
photoelectron spectroscopy (XPS, ESCALAB 250XI) with Al IQ X-ray at 15 kV and
5
10 mA.
6
2.3.3 Specific surface area and pore structure analysis
7
The specific surface area of the samples was determined by an ASAP2460 analyzer
8
using Brunauer-Emmett-Teller (BET) method (ASAP2460, Micromeritics, Atlanta,
9
USA) after degassing samples at 150 °C for a minimum of 12 h. The specific surface
10
area (SBET) was calculated at P/P0 values between 0.01 and 0.1. The total micropore
11
volume (Vmic) was calculated according to the t-plot method, and the total pore volume
12
(Vtotal) was evaluated at P/P0 of 0.95. The pore size distribution was estimated via the
13
Density Functional Theory (DFT) method.
14
2.3.4 Carbon crystallite structure analysis
15
X-ray diffraction (XRD) analysis was performed on a Bruker D2PHASERX
16
(German) diffractometer using Cu IQ radiation 3R = 0.154184 nm) at the range of 10–
17
80° 3 S5 with 0.01° step and using a counting time of 0.1 s per step. The average
18
crystallite (La) and the average stacking height (Lc) of the crystallite were determined
19
by peak fitting method according to our previous publication22, carbon crystallite
20
structure parameters calculated using the following equations: d 002
/ 2 sin
(4)
002
Lc
0.89 / B002 cos
La
1.84 / B100 cos
N
L c / d 002
002
100
(5) (6) (7)
21
where: RK 54184 nm; B002 and B100 are the full widths at half maximum of the (002)
22
and (100) peaks on the XRD pattern, rad; S002 and S100 are respectively on the XRD
23
spectrum (002) The diffraction angle of the peak and (100) peaks is half angle (°).
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Typical fitting peaks are as follows (Fig. 2): 1000
PAC Y fit peak 4 peak 002 peak baseline
(a) 750
500
250
350 300 250 200
15
2 3
20
25 21
30
35
PAC 100 peak baseline
400 (b)
Intensity (a.u)
1
Intesity (a.u)
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42
45
48
51
21
Fig. 2 Fitting curves of PACs at S of 15°–34°(a) and 38°–50°(b)
4
2.4 Adsorption performance of PACs
5
2.4.1 SO2 dynamic adsorption
6
The SO2 adsorption of PAC was carried out by self-made fixed bed reactor (18 mm
7
i.d.), and the concentration of SO2 was continuously monitored flue gas analyzer
8
(VARIO plus) (Fig. 3). 5 g PAC was put into the reactor for each run. Simulated flue
9
gas (SO2: 1100 ppm, O2: 6.32%, water vapor:10.53%, N2: balance) with total flow rate
10
0.95 L/min was used for the test. The sulfur capacity of PAC was calculated according
11
to Sun et al.23. After 4 parallel tests, the relative error of the test is less than 4%.
12
Adsorption sulfur capacity (q, mg/g) of PAC calculated using the following equations: (8)
q = FC0tq/M t
=
(9)
(1 - C/ C0 )dt 0
13
where F is the total flow rate of simulated flue gas; M is the PAC mass used for the
14
test; tq is the stoichiometric time, 120 min was selected for all the samples’ sulfur
15
capacity calculation; C and C0 are the concentrations of SO2 at the outlet and inlet,
16
respectively.
17
The PAC with highest sulfur capacity was selected for regeneration investigation,
18
the test conditions as follows: temperature: 400 °C; heating rate: 10 °C/min,
19
regeneration duration: 150 min. For simplicity, The PAC after regeneration was shorted
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3. Results and discussion
2
Physicochemical properties are crucial to PAC’s performance, the evolution of pore
3
structure, carbon crystallite structure parameters, surface chemical properties were
4
examined by surface area and porosity analyze, XRD, XPS/Boehm titration and SEM-
5
EDS.
6
3.1 Effect of BR on the texture of PACs and its evolution during preparation
7
3.1.1 Pore structure development
8
The degree of weight loss, burn-off, yield, BET surface area, pore volume and
9
pore size of PACs were summarized in Table 3. It can be found that, with the addition
10
of BR, the degree of weight loss during carbonization procedure slightly increased from
11
20.0 up to 22.2%, which is due to high volatiles of BR (50.06%, Table 1). Activation
12
process, the pore-forming process which can be represented as the degree of burn-off,
13
are jointly controlled by the reactivity of activated gas molecules (water vapor) with
14
carbon atoms and the diffusion properties of gas molecules24, and the process can be
15
summarized as three steps: exposed the unreachable pores, generate the new pores and
16
expanding the existed pores25. BR addition shows a minor effect on burn-off during the
17
activation (from 53.0% increased to 53.9%). According to dubinin theory26, the PAC is
18
composed of hierarchically pores structure with burn-off at a range between 50% and
19
75%. Furthermore, the addition of BR could slightly reduce the PAC yield from 37.6%
20
to 35.9%.
21
The more detailed pore structure parameters including pore size distribution of
22
PACs with different BR proportion modification was also investigated by N2 isotherms
23
adsorption/desorption at –196 °C, as shown in Fig. 4 and Table 3, it can be found that
24
PAC prepared from BR modification is a typical
25
high relative pressure for all samples, indicating that the PACs are microporous
26
dominant material. The hysteresis loop type H1 is caused by capillary condensation
27
happening in mesopores. With the addition of BR increased from 0 to 8 wt.%, the
28
hysteresis loop transferred to lower relative pressure. It also can be found that, with
isotherm adsorption and type IV at
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addition of BR from 0% to 4%, the pore at range of 1–1.4 nm is significantly increased,
2
and the corresponding mesopores of 2–6 nm is also increased. The total surface area
3
increased from 709 m2/g up to 782 m2/g, which increased by 10.3%; the specific surface
4
area of micropore increased from 518 m2/g up to 535 m2/g, which increased by 3.3%.
5
However, with BR addition increased to 8%, the specific surface area decreased. With
6
the addition of BR, the super-micropore 3T%9" nm) and ultra-micropore (0.7–1 nm)
7
changed little, indicating that the BR has minor influence on the formation of super-
8
micropore and ultra-micropore. An explanation is that BR is mainly composed of
9
disordered carbon which has a high reactivity to water vapor, with increasing of the BR
10
addition, the char pores are liberated by gasification with the water vapor, thus promotes
11
the development of micropores. Too much BR addition would eventually lead to the
12
pore structure collapse, resulting in the reduction of the specific surface area. Therefore,
13
BR has a fine adjustment pore structure of PACs.
14
Table 3. The change of parameters during PAC preparation and the PAC’s pore
15
structure parameters Pore structure analysis by BET Weight
Burn-off
Yield
loss (%)
(%)
(%)
Sample
16
SBETa
Smicb
Vtotalc
Vmicd
Vmec+mace
Davef
(m2/g)
(m2/g)
(cm3/g)
(cm3/g)
(cm3/g)
(nm)
PAC
20.0
53.0
37.6
709
518
0.33
0.20
0.13
1.84
PAC-2%
20.3
53.3
37.2
727
539
0.34
0.21
0.13
1.85
PAC-4%
21.1
53.7
36.5
782
535
0.39
0.21
0.18
1.97
PAC-6%
21.6
53.8
36.2
724
534
0.34
0.21
0.13
1.89
PAC-8%
22.2
53.9
35.9
702
510
0.33
0.20
0.13
1.89
a
Surface area, b Micropore Surface area, a, b Surface area was calculated according c
Total pore volume, d Total micropore pore volume,
e
17
to the BET equation,
18
mesopore and macropore pore volume, c, d, e Evaluated by the t-plot method, f Average
19
pore size, calculated using the HK method.
20 21
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1.0
PAC-8% 200
0
0.0 1.0
PAC-6%
200
0
PAC-4%
200 0
PAC-2%
200
0
PAC-8%
0.5
3 dV/dW Pore volume (cm /g·nm)
3 Quantity adsorbed (cm /g STP)
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PAC
200
0 0.0
PAC-6%
0.5 0.0 1.0
PAC-4%
0.5 0.0 1.0
PAC-2%
0.5 0.0 1.0
PAC
0.5 0.0
0.2
0.4
0.6
-10.8 Relative perssure (PP0 )
1.0
0.7 1 2
(a)
1
10
Pore width (nm)
(b)
2
Fig. 4 N2 adsorption/desorption isotherms of PACs (a) and the pore size distribution
3
of PACs from NLDF method (b).
4
3.1.2 Carbon crystalline structure parameters and surface morphology
5
The difference of crystalline structure of the PAC will directly lead to the difference
6
of the pore structure, resulting in the difference of adsorption properties. Studies have
7
shown that the greater the degree of irregularity of the crystalline structure, the lower
8
the degree of graphitization, the better the adsorption performance. To better understand
9
the influence of BR on the nanostructure of PAC, X-ray diffraction (Fig. 5) were
10
conducted and carbon crystalline structure parameters (Table 4) were calculated. Two
11
characteristic diffraction peaks at around S = 25° and 43° are associated with the
12
graphite (002) and (100) plane 3 SK !9!: and 43.4°, respectively)27-29. A weaker
13
diffraction peak 3V band) on the left side of the 002 peak causes the 002 peak to be
14
asymmetrical, indicating that the raw coal contains a large amount of aliphatic
15
compound30. When the peak width of 100 larger, the peak intensity decreases,
16
indicating that the lamellar condensation degree is lower and the lamellar size is
17
smaller30.
18
It can be found from Table 6 that there is no significant change of d002 with addition
19
of BR, La increased from 36.91 Å to 51.71 Å, Lc and N increased from 27.53 Å and
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7.98 to 32.66 Å and 9.50, respectively, which indicates that addition of BR could
2
slightly promote the graphitization. The reason for which is the disordered carbon
3
which has a strong reactivity to water vapor, and it is easier to form a thin and lamellar
4
structure at the initial stage of activation. The thin and lamellar structure is easier to
5
move, which is favorable for the formation of a stacking regular graphite structure at
6
high temperature31. The nanostructure evolution process of PACs with addition of BR
7
is illustrated in Fig.6.
PAC
Intensity (a.u)
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PAC-2% PAC-4%
PAC-6% PAC-8%
8 9
10
20
30
40
21
50
60
70
80
Fig. 5 X-Ray diffraction patterns of PACs
10 11
Fig. 6 Illustration for the influence of BR addition on the nanostructure of PACs.
12
PAC with disorder carbon structure(a), crystallites with several aligned layers(b),
13
and graphitic carbon planes(c)
14 15 16
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Table 4 Carbon crystallite structure parameters of PACs Samples
d002(Å)
La(Å)
Lc(Å)
N
PAC
3.45
36.91
27.53
7.98
PAC-2%
3.44
38.70
27.73
8.08
PAC-4%
3.44
39.45
28.01
8.15
PAC-6%
3.44
45.48
29.45
8.57
PAC-8%
3.44
51.71
32.66
9.50
2
The surface morphology and microstructure of PACs were investigated by a high-
3
resolution scanning electron microscope as showed in Fig. 7. The sample surfaces
4
rough and irregular. Nevertheless, with the addition of BR, the surface of PAC is
5
becoming smooth, this is because of a large amount of liquid tar formation that recreates
6
its smooth surface. The volatiles of BR is high which effectively promotes the
7
formation of liquid tar. Combined with EDS analysis, it can be seen that the content of
8
elements such as Ca and Mg in the PAC with the addition of BR is slightly decreased,
9
and which has a certain regulation effect on the pore structure of PAC32.
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Page 15 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
1
survey spectra of PACs, it can be found that the BR could slightly modify the surface
2
chemistry of PACs. The high-resolution C 1s spectrum is shown in Fig. 8b, which can
3
be fitted by five peaks corresponding to C-C (384.9 eV), C-O (286.5 eV), C=O (287.8
4
eV), COO (288.9 eV), and X6X (291.5 eV). The percentages of functional groups on
5
PACs’ surface are summarized in Fig. 8c and Table 6, from which can be found that
6
the carboxyl group is increased and O/C is decreased with the addition of BR. Previous
7
study has shown that the surface of PAC with low oxygen content exhibits more basic
8
group and anion exchange characteristics35, which favorable for desulfurization.
9
Similarly, the higher the content of C-O complex, the worse the desulfurization ability36.
10
Nevertheless, it should be noticed that XPS is a surface-sensitive quantitative
11
spectroscopic technique and it assesses only a few atomic layers of tested material, the
12
results sometimes could be misrepresented regarding porous solids such as PAC,
13
because it cannot evaluate all surface functional located into pores37.
14
Table 5 The total acid and basic groups on the PACs Sample
PAC
PAC-2%
PAC-4%
PAC-6%
PAC-8%
Total acidic (mmol/g)
0.72
0.75
0.77
0.80
0.80
Total basic (mmol/g)
1.12
1.17
1.18
1.20
1.20
15
ACS Paragon Plus Environment
Energy & Fuels
C(1s)
50.0k 40.0k O(1s)
30.0k
PAC PAC-2% PAC-4% PAC-6% PAC-8%
20.0k
Raw Fitting Background C-C C=O C-O COOH D-D*
(b)
Intensity (a.u)
60.0k (a)
Counts (a.u)
10.0k 0.0
0
200
400 600 800 Binding energy (eV)
1000 280
285 290 295 Binding energy (eV)
60 40 20 0
1
300
PAC PAC-2% PAC-4% PAC-6% PAC-8%
80 (c)
Aton percentage (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 16 of 24
C-C
C-O
C=O
COO
D-D*
2
Fig. 8 XPS survey spectra of PACs (a) and C 1s spectrum of PACs (b) and atomic
3
percentage distribution of the major functional group of PACs (c)
4
Table 6 Results from the deconvolution of X-ray photoelectron spectra (C1s) Binding states of carbon (%)
Atomic ratio (%)
Samples C-C
C-O
C=O
C=O-O
X6X
O/C
PAC
73.15
13.31
1.77
1.66
10.43
33.66
PAC-2%
74.26
13.24
0.95
4.15
9.28
34.80
PAC-4%
74.79
7.59
1.54
5.47
8.76
32.40
PAC-6%
75.16
8.44
1.30
5.93
8.50
30.45
PAC-8%
77.75
3.30
0.64
8.11
5.35
28.01
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1
3.3 The regulation mechanism of BR on the physicochemical structure of PAC
2 3
Fig. 9 Physicochemical structure development mechanism of PAC modified by BR
4
Based on the previous discussion, it can be found that BR plays a regulatory role
5
in the physicochemical structure during PAC preparation as shown in Fig. 9. With the
6
addition of BR, the volatile matter and disordered carbon which make the reaction with
7
water vapor easier and faster increased. During pyrolysis/activation, BR not only
8
promoting graphitization but also enhances the surface area of the PACs. However, as
9
BR proportion increased, the gasification reaction is strengthened continuously, which
10
eventually led to the collapse of the pore structure, resulting in a certain reduction in
11
the surface area. Furthermore, surface carboxyl groups and amounts of actives sites of
12
PACs are increased.
13
3.4 SO2 and Rhodamine B adsorption capability of the PACs
14
3.4.1 SO2 adsorption
(b)
60
55.4
56.7
58.7
52.7 50
50
40
30
15
65
(a) Sulphur capacity (mg/g)
70
Sulphur capacity (mg/g)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
60.7 60
58.7
59.5
PAC-2% PAC-4% PAC-6% PAC-8%
60.5 58.8
58.1 56
55
50
PAC
61.5
R3 R2 R6 R5 R4 R7 R1 8% C%%%%%%%PA AC-8 AC-8 AC-8 AC-8 AC-8 AC-8 AC-8 P P P P P P P
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1
Fig. 10 Sulphur capacities of PACs (a) and regeneration performance of PAC-8% (b)
2
For better evaluation the PACs’ gas phase contaminate removal performance, SO2
3
was selected as a model contaminate, and the sulfur capacity of PACs conducted at 120
4
°C using simulated flue gas are shown in Fig. 10. With the addition of BR, the sulfur
5
capacity of the PAC increased from 50 mg/g to 58.7 mg/g, which is increased by 17.4%.
6
These results are considered to be associated with pore structure and surface chemical
7
properties of the PAC samples, the base actives sites of the micropore of the PAC are
8
beneficial to the SO2 removal33. The desulfurization process can be described as follows:
9
SO2 absorbed into micropore active sites and then reacts with oxygen (adsorption in the
10
micropore O2-active site (AS)) and water vapor (adsorption in the micropore H2O-AS)
11
to form sulfuric acid, then transported to mesopore or macropore for storage.
12
Combining the data in Table 5, with BR addition, the basic active sites increased and
13
the decrease in oxygen content, which further promotes the adsorption rate of the
14
desulfurization. The PAC-8%’s regeneration performance was further evaluated. It can
15
be found that the sulfur capacity shows the trend of first increase then decrease, which
16
is due to newly formed micropore during regeneration before third regeneration. With
17
the round of regeneration increased, the micropore transformed to mesopores and active
18
sites decreased, therefore, its sulfur capacity decreased. After 7 regenerations, the
19
micropore was collapse during desorption of SO2 with reaction: C+H2SO4Y
20
SO2+CO2+H2O.
21 22
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Page 19 of 24
3.4.2 RhB adsorption
120
90
(a) 109.8 89.7 82.8
82.7
79.5
60
30
PAC
PAC-2% PAC-4% PAC-6% PAC-8%
The adsorption amount of RhB (mg/g)
1
The adsorption amount of RhB (mg/g)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
(b) 120
109.8 101.3 100
94.6
90.3
88
85.8
80
60 -R4 -R1 -R5 -R2 -R3 -4% PAC AC-4% AC-4% AC-4% AC-4% AC-4% P P P P P
2 3
Fig. 11 RhB accumulated adsorption capacities of PACs (a) and regeneration
4
performance of PAC-4% (b)
5
RhB adsorption studies are widely used for the evaluation of adsorbents due to
6
which can be viewed as a model for pollution and is an indicator of mesoporosity. Batch
7
adsorption of PACs prepared from different BhR addition were carried out by using 50
8
mg of PAC and 100 ml of 200 mg/L RhB solution and the results are presented in Fig.
9
11. It can be found that the RhB adsorption capacity increased with BR addition below
10
4%, then decreased. The RhB adsorption capacity of PAC-4% shows the best
11
performance of 109.8 mg/g, which was 32.6% higher than that of unmodified PAC of
12
82.8 mg/g, The main contribution of which is the increased mesopores (Table 3),
13
Furthermore, there is no obvious correlation between RhB adsorption capacities and
14
oxygen-containing groups. After PAC-4% regeneration test, RhB accumulated
15
adsorption capacities has slightly decreased, which is mainly caused by incomplete
16
RhB desorption.
17
4. Conclusion
18
In this paper, waste material BR used as a modifier for PAC production, and the
19
effects of BR on the physicochemical structure and adsorption capacity of PAC have
20
systematically investigated. The main conclusions can be drawn as follows:
21
1. PAC with hierarchically porous structure can be obtained by the addition of BR.
22
The specific surface area of PAC modified by 4% BR is up to 782 m2/g, which was
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1
10.3% higher than that of unmodified PAC. In particular, the increase of actives sites
2
of PACs enhances the adsorption capacity for SO2. PAC-8% exhibits higher sulfur
3
capacity up to 58.7 mg/g, which is 17.4% higher than that of unmodified PAC. PAC-4%
4
BR has the best performance for RhB adsorption with capacity up to 109.8 mg/g, which
5
was 32.6% higher than that of unmodified PAC.
6
2. The regulation mechanism of BR on the physicochemical structure of PAC was
7
discussed: BR’s addition makes the reaction of carbon with water vapor easier and
8
faster. During pyrolysis/activation, BR not only promoting graphitization but also
9
enhances the surface area of the PACs. However, over-dosed BR will eventually lead
10
to the collapse of the pore structure, resulting in a certain reduction in the surface area.
11
3. Coke-making waste materials such as BR could be used as a potential raw
12
material/modifier for PAC production, it is a more practical and applicable approach to
13
tailor the pores in PACs on the industrial scale through adjusting BR’s addition.
14
Acknowledgment:
15 16 17
This research was supported by the National Key R&D Plan (2016YFE0131100) and National Natural Science Foundation of China (U1810209, 21808130). References
18
1.
Yuran, L. I.; Haiying, Q. I.; Jing, W., SO2 capture and attrition characteristics of a
19
CaO/bio-based sorbent. Fuel 2012, 93, (1), 258-263.
20
2.
21
for flue gas clean up. Fuel Processing Technology 2010, 91, (10), 1175-1197.
22
3.
23
Removal from Flue Gas Streams by Solid Adsorbents: A Review of Current Challenges
24
and Future Directions. Energy Fuels 2015, 29, (9), 5467-5486.
25
4.
26
functionalization of carbon. Journal of the American Chemical Society 2013, 135, (3),
27
1110-1116.
Yan, L.; Bisson, T. M.; Yang, H.; Xu, Z., Recent developments in novel sorbents
Rezaei, F.; Rownaghi, A. A.; Monjezi, S.; Lively, R. P.; Jones, C. W., SOx/NOx
Stenehjem, E. D.; Ziatdinov, V. R.; Stack, T. D.; Chidsey, C. E., Gas-phase azide
ACS Paragon Plus Environment
Page 20 of 24
Page 21 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
1
5.
Low, B. T.; Tai, S. C., Carbon molecular sieve membranes derived from pseudo-
2
interpenetrating polymer networks for gas separation and carbon capture. Carbon 2011,
3
49, (6), 2104-2112.
4
6.
5
carbons for SO2 adsorption by CO2 and steam activation. J. Taiwan Inst. Chem. Eng.
6
2012, 43, (1), 112-119.
7
7.
8
Pyrolusite-Modified Activated Coke by Blending Method for Flue Gas Desulfurization.
9
Energy & Fuels 2017, 31, (4) 4556-4564.
Zhu, Y.; Gao, J.; Li, Y.; Sun, F.; Gao, J.; Wu, S.; Qin, Y., Preparation of activated
Yang, L.; Jiang, X.; Jiang, W.; Wang, P.; Jin, Y., Cyclic Regeneration of
10
8.
Gad, H. M. H.; El-Sayed, A. A., Activated carbon from agricultural by-products
11
for the removal of Rhodamine-B from aqueous solution. Journal of Hazardous
12
Materials 2009, 168, (2), 1070-1081.
13
9.
14
Adsorption of Rhodamine-B from aqueous solution using treated rice husk-based
15
activated carbon. Colloids & Surfaces A Physicochemical & Engineering Aspects 2014,
16
446, (446), 1-7.
17
10. Shen, W.; Zheng, J.; Qin, Z.; Wang, J., Preparation of mesoporous carbon from
18
commercial activated carbon with steam activation in the presence of cerium oxide.
19
Journal of Colloid & Interface Science 2003, 264, (2), 467-473.
20
11. Zheng, Y.; Liu, L.; Zhang, Y.; Liang, J.; Wang, J.; Zhang, Z.; Wang, X., Activated
21
Semi-coke in SO2 Removal from Flue Gas: Selection of Activation Methodology and
22
Desulfurization Mechanism Study. Energy & Fuels 2013, 27, (6), 3080-3089.
23
12. Zhang Duoying; Zhang WeiGuang; Miao Shumei; Zhao Xiaoyu; Zhang Xiancheng,
24
Bacterial Community and Function of Biological Activated Carbon Filter in Drinking
25
Water Treatment. Biomedical & Environmental Sciences 2011, 24, (2), 122-131.
26
13. Yang, L.; Huang, T.; Jiang, X.; Li, J.; Jiang, W., The effects of metal oxide blended
27
activated coke on flue gas desulphurization. RSC Adv. 2016, 6, (60), 55135-55143.
28
14. Coetzee, S.; Neomagus, H. W. J. P.; Bunt, J. R.; Everson, R. C., Improved
29
reactivity of large coal particles by K2CO3 addition during steam gasification. Fuel
30
Processing Technology 2013, 114, (3), 75-80.
Ding, L.; Zou, B.; Gao, W.; Liu, Q.; Wang, Z.; Guo, Y.; Wang, X.; Liu, Y.,
ACS Paragon Plus Environment
Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
1
15. Jia, J.; Zhang, H.; Pan, Z.; Guo, Y.; Cheng, F., Research on the correlation between
2
specific surface area and iodine adsorption value of coal-based activated carbon. Clean
3
Coal Technology 2018.
4
16. Sun, J.; Brady, T. A.; Rood, M. J.; Lehmann, C. M.; Rostam-Abadi, M.; Lizzio, A.
5
A. J. E.; fuels, Adsorbed natural gas storage with activated carbons made from Illinois
6
coals and scrap tires. 1997, 11, (2), 316-322.
7
17. Tsai, W.-T.; Chang, C.; Lee, S. J. B. T., A low cost adsorbent from agricultural
8
waste corn cob by zinc chloride activation. 1998, 64, (3), 211-217.
9
18. Lim, W.; Srinivasakannan, C.; Balasubramanian, N. J. J. o. A.; Pyrolysis, A.,
10
Activation of palm shells by phosphoric acid impregnation for high yielding activated
11
carbon. 2010, 88, (2), 181-186.
12
19. Shui, H. F.; Lin, C. H.; Zhang, M.; Wang, Z. C.; Zheng, M. D., Comparison of the
13
associative structure of two different types of rich coals and their coking properties.
14
Fuel 2010, 89, (7), 1647-1653.
15
20. Wang, Y.-L.; Zhu, S.-H.; Gao, M.-Q.; Yang, Z.-R.; Yan, L.-J.; Bai, Y.-H.; Li, F.,
16
A study of char gasification in H2O and CO2 mixtures: Role of inherent minerals in the
17
coal. Fuel Process. Technol. 2016, 141, 9-15.
18
21. Boehm, H. P., Some aspects of the surface chemistry of carbon blacks and other
19
carbons. Carbon 1994, 32, (5), 759-769.
20
22. Zhang, H.; Bai, J.; Li, W.; Cheng, F., Comprehensive evaluation of inherent
21
mineral composition and carbon structure parameters on CO2 reactivity of metallurgical
22
coke. Fuel 2019, 235, 647-657.
23
23. Fei, S.; Gao, J.; Xin, L.; Yang, Y.; Wu, S., Controllable nitrogen introduction into
24
porous carbon with porosity retaining for investigating nitrogen doping effect on SO2
25
adsorption. Chemical Engineering Journal 2016, 290, 116-124.
26
24. Murakami, K.; Sato, M.; Tsubouchi, N.; Ohtsuka, Y.; Sugawara, K., Steam
27
gasification of Indonesian subbituminous coal with calcium carbonate as a catalyst raw
28
material. Fuel Processing Technology 2015, 129, (129), 91-97.
29
25. Maneerung, T.; Liew, J.; Dai, Y.; Kawi, S.; Chong, C.; Wang, C. H., Activated
30
carbon derived from carbon residue from biomass gasification and its application for ACS Paragon Plus Environment
Page 22 of 24
Page 23 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Energy & Fuels
1
dye adsorption: Kinetics, isotherms and thermodynamic studies. Bioresource
2
Technology 2016, 200, 350-359.
3
26. Pande, A. R., Catalytic gasification of active charcoal by carbon dioxide: influence
4
of type of catalyst and carbon particle size. Fuel 1992, 71, (11), 1299-1302.
5
27. Takagi, H.; Maruyama, K.; Yoshizawa, N.; Yamada, Y.; Sato, Y., XRD analysis
6
of carbon stacking structure in coal during heat treatment. Fuel 2004, 83, (17–18),
7
2427-2433.
8
28. Wu, S.; Jing, G.; Xiao, Z.; Wu, Y.; Gao, J., Variation of carbon crystalline
9
structures and CO2 gasification reactivity of Shenfu coal chars at elevated temperatures.
10
Energy Fuels 2008, 22, (1), 199-206.
11
29. Zhou, Z.; Bouwman, W. G.; Schut, H.; Pappas, C., Interpretation of X-ray
12
diffraction patterns of (nuclear) graphite. Carbon 2014, 69, 17-24.
13
30. Nanako, S.; Kyung Jin, L.; Jin, M.; Seong-Hwa, H.; Isao, M.; Bai, A.; Kiyoshi, Y.;
14
Jyongsik, J.; Seong-Ho, Y., Pore structure analysis of activated carbon fiber by
15
microdomain-based model. Langmuir the Acs Journal of Surfaces & Colloids 2009, 25,
16
(13), 7631.
17
31. Rhim, Y. R.; Zhang, D.; Fairbrother, D. H.; Wepasnick, K. A.; Livi, K. J.; Bodnar,
18
R. J.; Nagle, D. C., Changes in electrical and microstructural properties of
19
microcrystalline cellulose as function of carbonization temperature. Carbon 2010, 48,
20
(4), 1012-1024.
21
32. Sadighzadeh, A.; Asiabi, P. A.; Bavand, A.; Hamidi, A. A.; Ghoranneviss, M.;
22
Elahi, A. S., Carbonization, Impregnation and Activation Synthesis for Sulfur Dioxide
23
Adsorbent Capacity of Carbon. Journal of Inorganic & Organometallic Polymers &
24
Materials 2015, 25, (6), 1-5.
25
33. Davini, P., Adsorption of sulphur dioxide on thermally treated active carbon. Fuel
26
1989, 68, (2), 145-148.
27
34. Tan, Z.; Qiu, J.; Xiang, J.; Zeng, H., Adsorptive Removal of SO2 from Coal
28
Burning by Bamboo Charcoal. International Symposium on Coal Combustion. 2011,
29
441-446.
30
35. Kisamori, S.; Kuroda, K.; Kawano, S.; Mochida, I.; Matsumura, Y.; Yoshikawa, ACS Paragon Plus Environment
Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
1
M., Oxidative Removal of SO2 and Recovery of H2SO4 over Poly (acrylonitrile)-Based
2
Active Carbon Fiber. Energy & Fuels 1994, 8, (6), 1337-1340.
3
36. Lizzio, A. A.; Debarr, J. A., Mechanism of SO2 Removal by Carbon. Energy &
4
Fuels 1997, 11, (2), 284-291.
5
37. Kaneko, K., Chapter 4–Surface and Hidden Surface-controlled Carbon Alloys.
6
Carbon Alloys 2003, 57-81.
7
ACS Paragon Plus Environment
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