Electronic Supplementary Information composite …Electronic Supplementary Information Environmental...
Transcript of Electronic Supplementary Information composite …Electronic Supplementary Information Environmental...
Electronic Supplementary Information
Environmental performances of hydrochar-derived magnetic carbon
composite affected by its carbonaceous precursor
Xiangdong Zhu, Feng Qian, Yuchen Liu, Shicheng Zhang*, Jianmin Chen
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of
Environmental Science and Engineering, Fudan University, Shanghai 200433, China
* Corresponding author.
Tel/fax: +86-21-65642297;
E-mail address: [email protected].
Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2015
Fig. S1. HTC temperature and pressure variations as a function of reaction time during the HTC
process.
0 20 40 60 80 100
40
80
120
160
200
240
280
Time (min)
Tem
pera
ture
(o C)
160 oC
0123456789
Pres
sure
(Mpa
)
0 20 40 60 80 100
40
80
120
160
200
240
280
0123456789
200 oC
Tem
pera
ture
(o C)
Pres
sure
(Mpa
)
Time (min)
0 20 40 60 80 100
40
80
120
160
200
240
280240 oC
Tem
pera
ture
(o C)
Pres
sure
(Mpa
)
Time (min)
0123456789
0 20 40 60 80 100
40
80
120
160
200
240
280
0123456789
270 oC
Pres
sure
(Mpa
)
Tem
pera
ture
(o C)
Time (min)
0 20 40 60 80 100
40
80
120
160
200
240
280 300 oC
Tem
pera
ture
(o C)
0123456789
Time (min)
Pres
sure
(Mpa
)
Fig. S2. FTIR spectra for the hydrochar produced at different HTC temperatures.
Abundant FT-IR peaks for hydrochar materials were found, they were similar and different only
in the intensity of some peaks, suggesting that the functional group compositions was not greatly
changed during the HTC reaction. The aromatic C (1616 cm-1) was observed, and the peak
intensity increased with peak temperature of HTC reaction increase, indicating increasing
thermal recalcitrance of hydrochar samples. The hydrochar materials also had the adsorption
bands at 2927 and 2840 cm-1, which were attributed to stretching vibration of aliphatic C-H. The
peak at 1742 cm-1 was assigned to C=O groups, resulted from the acid group (C-OOH).
Obviously, the peaks (2927, 2840 and 1742 cm-1) increased with processing HTC reaction,
indicating that these aliphatic carbons are mainly produced from the HTC reaction. The band at
1512 cm-1 represented the C=C stretching vibration. The peak at 1461 cm-1 was assigned to C-H
deformation vibration. The peak located at 1112 cm-1 was attributed to the C-O stretching
vibration.
4000 3500 3000 2500 2000 1500 1000 500
H-300
H-270
H-240
H-200
Tran
smitt
ance
(%, a
rbita
ry u
nits
)
Wavenumber (cm-1)
1616
H-160
2927 2840
1742 1512
1461
1112
Text S1
As shown in Fig. 1b, the DTG curves contained two general regions of weight loss. The first
region of weight loss was found from 300 to 350°C, resulting from the thermal oxidation of
residual cellulose, hemicellulose and low-boiling products derived from the HTC process. The
second region of weight loss was observed above 400°C, due to the thermal oxidation of the
more recalcitrant organic substances with the structure of lignin or thermally produced
carbonized/aromatic compounds.1 Obviously, the weight loss of hydrochar samples derived from
higher HTC temperatures were focused toward much higher temperatures. Such differences
indicated that hydrochar samples produced at higher peak temperatures would be more
recalcitrant, which was consistent with the qualitative assessment of R50 for those hydrochar
samples.
Fig. S3. Correlations between the yields of magnetic carbon composites and the properties of
hydrochar precursors: R50 index (a), H/C (b) and O/C (c) atomic ratios.
0.36 0.40 0.44 0.48 0.52
4550556065707580
Yiel
d (%
, co
mpo
site)
R50 index
y=201.9x-27.35R2=0.99
a
1.0 1.1 1.2 1.3 1.4 1.5 1.6
4550556065707580
Yiel
d (%
, com
posit
e)
H/C atomic ratio
y=-62.69x+140.8R2=0.98
b
0.2 0.3 0.4 0.5 0.6 0.7
4550556065707580
Yiel
d (%
, com
posit
e)
O/C atomic ratio
y=-69.72x+93.43R2=0.91
c
Fig. S4. Nitrogen adsorption isotherms and pore size distribution for the different hydrochar-
derived magnetic carbon composites.
0.0 0.2 0.4 0.6 0.8 1.0200
250
300
350
400
450
500
MC-300MC-270
MC-240
MC-210
Volu
me
adso
rbed
(cm
3 STP
/g)
P/P0
MC-160a
1 2 3 4 5 6
0.0
0.2
0.4
0.6
0.8
MC-300MC-270
MC-240
MC-200
Pore
size
dist
ribut
ion
(cm
3 /g.n
m)
Pore diameter (nm)
MC-160b
Table S1. Regression equation and correlation coefficient of the porosity of magnetic carbon
composite related to the properties of hydrochar
Hydrochar Properties Regression Equation R2
BET Surface Area = –2862R50 + 2403 0.89Micropore Surface Area = –2951R50 + 2367 0.89
Total Pore Volume = –1.30R50 + 1.17 0.88R50
Micropore Volume = –1.44R50 + 1.16 0.91BET Surface Area = 901H/C + 4.53 0.90
Micropore Surface Area = 944H/C – 125 0.93Total Pore Volume = 0.406H/C + 0.0855 0.87
H/C
Micropore Volume = 0.460H/C – 0.0548 0.95BET Surface Area = 1066O/C + 656 0.95
Micropore Surface Area = 1118O/C + 557 0.98Total Pore Volume = 0.476O/C + 0.380 0.90
O/C
Micropore Volume = 0.541O/C + 0.279 0.99
Fig. S5. XRD patterns of the as-prepared magnetic carbon composites.
10 20 30 40 50 60 70 80
MC-300
MC-270
MC-240
MC-200
aa aaa
Inte
nsity
(arb
itary
uni
ts)
2 Theta (degree)
a
a: -Fe2O3, b: -Fe2O3
b
MC-160
Fig. S6. (a) Hysteresis loop of the as-prepared magnetic carbon composites under 300 K (inset
shows the hysteresis loop of MC-300 sample at ± 200 Oe) and (b) photo of magneto separation
for the as-prepared magnetic carbon composite (MC-270).
b
-20000 -10000 0 10000 20000
-15
-10
-5
0
5
10
15
-4 emu/g
Mag
netiz
atio
n (e
mu/
g)
Magnetic field (Oe)
MC-240MC-160MC-300MC-200MC-270
a
4 emu/g
200 Oe-200 Oe
MC-300
Table S2. Ash and Fe2O3 contents, magnetic property and acid resistance for different hydrochar-
derived magnetic carbon composite
a Ms is saturation magnetization determined at room temperature.
b Fe leaching concentration determined at 2000 mg/L magnetic carbon composite with 24 h
contact time at room temperature.
sample ash (%) Fe2O3 (%) Ms (emu/g) a leaching (mg/L, pH 2) b leaching (mg/L, pH 3) b
MC-160 18.1 15.9 ± 0.66 15.2 0.325 ± 0.003 0.0910 ± 0.001MC-200 15.2 13.7 ± 0.35 14.3 0.419 ± 0.018 0.0685 ± 0.001MC-240 17.4 15.3 ± 0.09 16.3 0.387 ± 0.006 0.131 ± 0.004MC-270 13.2 11.4 ± 0.29 13.6 0.524 ± 0.001 0.153 ± 0.006MC-300 14.2 12.4 ± 0.33 15.0 0.549 ± 0.004 0.149 ± 0.002
Fig. S7. Correlations between the Fe leaching concentration and the porosity of magnetic carbon
composites: BET surface area (a), micropore surface area (b), total pore volume (c) and
micropore volume (d).
900 1000 1100 1200 1300 1400 15000.0
0.1
0.2
0.3
0.4
0.5
0.6
pH=3y=-0.00013x+0.26R2=0.66
Fe
leac
hing
(mg/
L)
BET surface area (m2/g)
pH=2y=-0.00039x+0.88R2=0.93
a
800 900 1000 1100 1200 1300 14000.0
0.1
0.2
0.3
0.4
0.5
0.6
pH=3y=-0.00013x+0.25R2=0.69
Fe le
achi
ng (m
g/L)
Micropore surface area (m2/g)
pH=2y=-0.00038x+0.84R2=0.92
b
0.40 0.45 0.50 0.55 0.60 0.65 0.700.0
0.1
0.2
0.3
0.4
0.5
0.6
pH=3y=-0.27x+0.26R2=0.72
Fe le
achi
ng (m
g/L)
Micropore volume (cm3/g)
pH=2y=-0.78x+0.85R2=0.93
d
0.45 0.50 0.55 0.60 0.65 0.70 0.750.0
0.1
0.2
0.3
0.4
0.5
0.6
pH=3y=-0.28x+0.28R2=0.64
Fe le
achi
ng (m
g/L)
Total pore volume (cm3/g)
pH=2y=-0.83x+0.93R2=0.89
c
Text S2
Adsorption kinetics is the most important characteristic in the representation of pollutants’
uptake rates and adsorption efficiency.2, 3 As shown in Fig. S8a, the adsorption reaction
equilibrium was reached quickly, due to abundant adsorption sites for the ROX molecules. This
is important for highly efficient removal of pollutants in the practical application of as-prepared
magnetic carbon composites.
The pseudo-second-order kinetics equation was used to discuss the adsorption characteristics
of ROX:
22
1 +t e e
t tq k q q
where t is the adsorption time, qt (mg/g) is the ROX uptake at time t, qe (mg/g) is the ROX
uptake at equilibrium, and k2 (g/mg·min) is the rate constant of pseudo-second-order adsorption.
As shown in Table 3, the correlation coefficient was 0.99 for all resultant magnetic carbon
composites, and the pseudo-second-order kinetics equation exhibited a good fit for ROX
adsorption, as further confirmed b Fig. S8b.
The changes in ROX adsorption capacity as a function of ROX concentration in the solution at
equilibrium are shown in Fig. S9a. The Langmuir model was used to fit the adsorption data:
e e
e m m
1C Cq bq q
where Ce (mg/L) is the equilibrium concentration of the ROX in the solution, qm (mg/g) is the
maximum adsorption capacity, and b (L/mg) is the Langmuir constant.
The linear forms of the Langmuir equation for the adsorption data were shown in Fig. S9b. As
shown in Table 3 a high regression coefficient (0.99) for all cases revealed that Langmuir
equation was well fitted to the adsorption of ROX. In addition, the as-prepared magnetic carbon
composites exhibited a large adsorption capacity for ROX removal, indicating that this material
can be an excellent candidate for the ROX removal.
Fig. S8. (a) Adsorption of ROX onto as-prepared magnetic carbon composites as a function of
time (ROX initial concentration: 400 mg/L). (b) Pseudo-second-order kinetics for ROX
adsorption onto the as-prepared magnetic carbon composite: markers are experimental data and
lines are the data predicated by the pseudo-second-order kinetics model.
0 200 400 600 800 1000 1200 14000.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
t (min)
t/qt (
g/m
g m
in)
MC-300MC-270MC-240MC-200MC-160
b
0 200 400 600 800 1000 1200 1400
0.50
0.55
0.60
0.65
0.70
0.75
MC-160 MC-200
MC-240MC-270
MC-300
Contact time (min)
C t/C
0 B D F H J
a
Fig. S9. (a) Adsorption isotherms of ROX onto as-prepared magnetic carbon composites. (b)
Linear Langmuir equation for ROX adsorption onto as-prepared magnetic carbon composites:
markers are experimental data and lines are the data predicated by the Langmuir model.
0 50 100 150 200 250 300100
200
300
400
500
600
MC-270
MC-300
MC-240MC-200
q e (
mg/
g)
Ce (mg/L)
MC-160a
0 50 100 150 200 250 3000.00.10.20.30.40.50.60.70.8 MC-300
MC-270MC-240MC-200MC-160
C e/qe (g
/L)
Ce (mg/L)
b
Fig. S10. Correlations between adsorption uptake at equilibrium (qe, obtained from the pseudo-
second-order kinetics equation at an initial ROX concentration of 400 mg/L) and porosity of
magnetic carbon composites: BET surface area (a), micropore surface area (b), total pore volume
(c) and micropore volume (d).
900 1000 1100 1200 1300 1400 1500
390
420
450
480
510
q e (
mg/
g)
BET surface area (m2/g)
y=0.225x+195R2=0.86
a
800 900 1000 1100 1200 1300 1400
390
420
450
480
510
q e (m
g/g)
Micropore surface area (m2/g)
y=0.214x+223R2=0.83
b
0.45 0.50 0.55 0.60 0.65 0.70 0.75
390
420
450
480
510
q e (m
g/g)
Total pore volume (cm3/g)
c
y=501x+152R2=0.89
0.40 0.45 0.50 0.55 0.60 0.65 0.70
390
420
450
480
510
q e (m
g/g)
Micropore volume (cm3/g)
d
y=446x+217R2=0.84
Fig. S11. Correlations between the maximum adsorption capacity (qm, obtained from the
Langmuir equation) and the porosity of magnetic carbon composites: BET surface area (a),
micropore surface area (b), total pore volume (c) and micropore volume (d).
900 1000 1100 1200 1300 1400 1500400
440
480
520
560
600
q m
(mg/
g)
BET surface area (m2/g)
y=0.293x+171R2=0.96
a
800 900 1000 1100 1200 1300 1400400
440
480
520
560
600
q m (m
g/g)
Micropore surface area (m2/g)
y=0.282x+204R2=0.94
b
0.45 0.50 0.55 0.60 0.65 0.70 0.75400
440
480
520
560
600
Total pore volume (cm3/g)
q m (m
g/g) y=642x+121
R2=0.96
c
0.40 0.45 0.50 0.55 0.60 0.65 0.70400
440
480
520
560
600
q m (m
g/g)
Micropore volume (cm3/g)
y=585x+197R2=0.95
d
Fig. S12. Correlations between adsorption uptake at equilibrium (qe, obtained from the pseudo-
second-order kinetics equation at an initial ROX concentration of 400 mg/L) and properties of
hydrochar: R50 index (a), H/C (b) and O/C (c) atomic ratios.
0.36 0.40 0.44 0.48 0.52
390
420
450
480
510
R50 index
q e (m
g/g)
y=-705.7x+762.1R2=0.92
a
1.0 1.1 1.2 1.3 1.4 1.5 1.6
390
420
450
480
510
q e (m
g/g)
H/C atomic ratio
y=216.7x+177.6R2=0.89
b
0.2 0.3 0.4 0.5 0.6 0.7
390
420
450
480
510
q e (m
g/g)
O/C atomic ratio
y=237.6x+342.6R2=0.80
c
References
1 O. R. Harvey, L.-J. Kuo, A. R. Zimmerman, P. Louchouarn, J. E. Amonette and B. E. Herbert, Environ. Sci.
Technol., 2012, 46, 1415-1421.
2 J. Hu, Z. Tong, Z. Hu, G. Chen and T. Chen, J. Colloid Interf. Sci., 2012, 377, 355-361.
3 J.X. Fan, Y.J. Wang, X.D. Cui and D.M. Zhou, J. Soils Sediments, 2013, 13, 344-353.