carbonaceous adsorbents: design, fabrication and application in water treatment chemical synthesis...

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