Carbonaceous Adsorbents:
Design, Fabrication and
Application in Water Treatment
Lunhong Ai
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province,
College of Chemistry and Chemical Engineering, China West Normal University
2010.12.12
Contaminated Rivers and Lakers
Water treatment methods
biological treatment
ion exchange
adsorption
Water Treatment
coagulation/flocculation
membrane filtration
advanced oxidation technology
Available adsorbents
Carbonaceous materials
Nanomaterials
Biomass
Adsorbent
Functional polymer
Clay
Zeolites
Carbonaceous materials for water treatment
Carbon
activated carbon,
carbon black
carbon nanotubes
graphene
1. Fabrication of activated carbon/CoFe2O4 composites
and their application in water treatment
XRD
(c)
TEM
Intensity (a.u.)
SEM
AC/CFO

CFO
20
30
40
50
60
2Theta (degree)
magnetic separation
(d)
texture property
Samples
BET-surface area
(m2 g-1)
Total pore volume
(cm3 g-1)
AC
909
0.47
AC/CFO
463
0.18
L. Ai et al. / Chemical Engineering Journal 156 (2010) 243–249
70
Removal of malachite green (MG)
100
-1
Adsorption capacity (mg g )
Effect of pH
-1
Adsorption capacity (mgg )
50
49
48
47
2
4
6
8
75
50
25
Effect of initial concentration
0
10
0
pH
8
12
16
-1
Equilibrium concentration (mg L )
40
regeneration
-1
-1
Adsorption capacity (mg g )
60
Adsorption capacity (mg g )
4
45
Effect of contact time
30
15
0
30
20
10
0
0
5
10
15
20
Contact time (min)
25
30
1
2
Cycle number
3
2. Adsorption mechanism of methyl orange (MO) and basic
fuchsin (BF) on AC/CFO
L. Ai, et. al. / Desalination 262 (2010) 134–140
adsorption kinetics
Adsorption kinetics
pseudo-first-order model
pseudo-second-order model
Elovich model
※ adsorption kinetics was best described by the pseudo-second-order model
adsorption kinetics
Table 1 Kinetic parameters for adsorption of dyes on AC/CFO
Pseudo-first-order
Pseudo-second-order
Elovich
Dye
qe,exp
(mg g-1)
k1
(min-1)
qe,cal
(mg g-1)
R2
k2
(g mg-1 min-1)
qe,cal
(mg g-1)
R2
a
b
R2
BF
49.88
0.067
6.83
0.9816
0.022
50.53
1
2.241
41.167
0.9624
MO
47.31
0.084
7.15
0.9372
0.026
47.94
0.9999
1.886
39.979
0.9531
adsorption mechanisms
Adsorption mechanisms
intraparticle diffusion
intraparticle diffusion
surface adsorption
surface adsorption
intraparticle diffusion model
※ the adsorption process was controlled by surface adsorption
(boundary-layer effect) and intraparticle diffusion.
adsorption mechanisms
Boyd kinetic model was generally used to determine the actual rate-controlling
step involved in the dye adsorption process.
Boyd model
※ boundary-layer effect mainly governed the rate-limiting
process of dye adsorption on AC/CFO
adsorption isotherms
Adsorption isotherms
Langmuir and Freundlich models
90
BF
100
MO
75
80
qe (mg g )
60
-1
-1
qe (mg g )
60
40
Experimental
Langmuir
Freundlich
20
0
0
5
10
-1
Ce (mg L )
45
30
Experimental
Langmuir
Freundlich
15
15
0
0
5
10
15
20
25
30
-1
Ce (mg L )
※ Dye adsorption behaviors onto AC/CFO could be better represented
by the Langmuir model (R2 > 0.99)
※ Monolayer adsorption capacities of MO and BF determined from
the Langmuir isotherm are 95.8 and 101.0 mg g−1, respectively
adsorption isotherms
Dubinin-Radushkevich (D-R) model
4.6
MO
BF
4.4
4.2
lnqe
4.0
3.8
3.6
3.4
3.2
500
600
700
800
2
900
1000
-2
(kJ mol )
For D-R model, the magnitude of E(mean fren energy) is useful for
estimating the type of adsorption and if this value is between 8
and 16 kJ mol−1, the adsorption proceeds by surface adsorption.
In this study, the E values for MO and BF are calculated to be 11.74
and 12.42 kJ mol−1.
Table 3. Comparison of BF and MO adsorption capacities of various adsorbents
Dye
Adsorbents
Adsorption capacity
(mg g-1)
BF
AC/CFO (in this study)
101.01
Bottom ash
6.39
Deoiled soya
12.03
Jalshakti®
11.7
Industrial sludges
70.4
AC/CFO (in this study)
95.78
Hypercrosslinked polymeric
adsorbent
70.922
Banana peels
21
Orange peels
20.5
Activated Carbon
9.49
Modified sporopollenin
5.23
NH3+-MCM-41
366.57
MO
Acknowledgement
Financial support from the Chemical Synthesis and Pollution
Control Key Laboratory of Sichuan Province and Scientific
Research Start-up Foundation of China West Normal University
(07B005).