carbonaceous adsorbents: design, fabrication and application in water treatment chemical synthesis...
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Carbonaceous Adsorbents: Design, Fabrication and
Application in Water Treatment
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University
Lunhong Ai
2010.12.12
Contaminated Rivers and Lakers
coagulation/flocculationbiological treatment
ion exchange
advanced oxidation technology
membrane filtrationWater Treatment
adsorption
Water treatment methods
Functional polymer
Biomass
Adsorbent
Clay
Carbonaceous materials
Nanomaterials
Zeolites
Available adsorbentsAvailable adsorbents
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
20 30 40 50 60 70
Inte
nsi
ty (a.
u.)
2Theta (degree)
XRDSEM TEM
Samples BET-surface area (m2 g-1)
Total pore volume (cm3 g-1)
AC 909 0.47
AC/CFO 463 0.18
(c)
(d)
magnetic separation texture property
CFO
AC/CFO
L. Ai et al. / Chemical Engineering Journal 156 (2010) 243–249
2 4 6 8 1047
48
49
50
A
dso
rption c
apac
ity
(mgg
-1)
pH 0 4 8 12 16
0
25
50
75
100
A
dso
rption c
apac
ity
(mg g
-1)
Equilibrium concentration (mg L-1)
0 5 10 15 20 25 30
0
15
30
45
60
A
dsorp
tion c
apacity
(mg g
-1)
Contact time (min)
1 2 30
10
20
30
40
Adso
rption c
apac
ity
(mg g
-1)
Cycle number
Effect of pH
Effect of contact time
regeneration
Effect of initial concentration
Removal of malachite green (MG)
2. Adsorption mechanism of methyl orange (MO) and basic fuchsin (BF) on AC/CFO
L. Ai, et. al. / Desalination 262 (2010) 134–140
pseudo-first-order model pseudo-second-order model
Elovich model
adsorption kinetics
※ adsorption kinetics was best described by the pseudo-second-order model
Adsorption kineticsAdsorption kinetics
Table 1 Kinetic parameters for adsorption of dyes on AC/CFO
DyePseudo-first-order Pseudo-second-order Elovich
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 kinetics
※ the adsorption process was controlled by surface adsorption (boundary-layer effect) and intraparticle diffusion.
Adsorption mechanismsAdsorption mechanisms
adsorption mechanisms
intraparticle diffusion model
surface adsorption
intraparticle diffusion
surface adsorption
intraparticle diffusion
※ boundary-layer effect mainly governed the rate-limiting process of dye adsorption on AC/CFO
adsorption mechanisms
Boyd model
Boyd kinetic model was generally used to determine the actual rate-controlling step involved in the dye adsorption process.
0 5 10 150
20
40
60
80
100
Experimental
qe (m
g g
-1)
Ce (mg L-1)
Langmuir Freundlich
BF
0 5 10 15 20 25 300
15
30
45
60
75
90
Experimental
qe (m
g g
-1)
Ce (mg L-1)
Langmuir Freundlich
MO
Adsorption isothermsAdsorption isotherms
※ 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
Langmuir and Freundlich models
500 600 700 800 900 1000
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
MO BF
lnq
e
(kJ 2 mol-2)
Dubinin-Radushkevich (D-R) model
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.
adsorption isotherms
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
MO 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
Financial support from the Chemical Synthesis and Pollution Contr
ol Key Laboratory of Sichuan Province and Scientific Research Star
t-up Foundation of China West Normal University (07B005).
Acknowledgement