231

Chlorobenzenes `CBsPOPs

`129

[1]

410082Zhang Wei Shi Zhou Xu Shunkai (Key Laboratory of Building Safety and Energy Efficiency of the

Ministry of Education, College of Civil Engineering, Hunan University, Changsha 410082)

` `` ` ` ` `

` ` ` `` ` ` ` ` ` ` ` ` ` ` `

` ` ` ` `

Abstract Multiwalled nanotubes (MWNTs) were used as adsorbents to remove trichlorobenzene (TCB) fromwater, and the gravimetric method was adopted to calculate the adsorption isotherm and kinetic curves of TCBonto carbon nanotubes. Experiments demonstrated that it took only 150 minutes for MWNTs adsorbing to reachequilibrium. The adsorption kinetics and isotherm could be well described by using a pseudo-second-ordermodel and Freundlich isotherm, respectively. The thermodynamic parameters such as equilibrium constant(K ), standard free energy changes ( G ), standard enthalpy change ( H ) and standard entropy change ( S )were obtained. It indicated that the TCB adsorption process onto MWNTs was spontaneous and endothermic.The fact that the variation of pH values from 2 to 11 had little effect on the TCB adsorption onto MWNTs sug-gested that H bond between TCB and MWNTs was almost irrelevant. The strong adsorption of TCB onto MWNTsmay result from a coaction of hydrophobic adsorption and electron conjugation between surface of MWNTsand benzene ring of TCB.

Key words: Carbon nanotube Trichlorobenzene (TCB) Persistent organic pollutants (POPs)Adsorption Kinetics Thermodynamics Isotherm

5077806508JJ3103

1973` 2005`

232

[2 12]

1 2 ` 1 2 4 5 `

[8 12]

`3`

2.1` MWNTs

`8`nm `30 m1 2 3 ` 1 2 4 ` 1

3 5 ` `2 2 `4 4 `6 6`AccuStandard Inc `99.9 `2 2

`4 4 `6 6

`BP211D` `GC 14BLRH 250 ZII`

`PTFE` Millipore FHLC`025002.2 MWNTs`

`3 `mol /L ` `MWNTs`MWNTs[13] `1 000`mL` `3`mol/L`

`5`g`MWNTs` `24`h `pH 6 `PTFE` 80

`450 [13]

2.3 `3`

`600`mL` `48`h`12 000`r/min

8.0 0.5 mg/L

`20`mL``MWNTs

`PTFE` `2`mL` `4`mL``30`min` `5`min

`PTFE

ECD `Shimadzu GC 14B``DB 1` J&W Scientific

Inc.`MWNTs` [8]

3.1 pH``T=25 `C0= 8.0

0.5 mg/L `t = 24`h MWNTs` `0.04`g/L``pH` `MWNTs`

`1` `1` pH` `2 11`MWNTs` `3`

3.2 MWNTs``T = 25 `C0= 8.0 0.5

mg/L MWNTs` `0.04`g/L``2`

1 2 3 ` 1 2 4 ` `1 3 5 ``25`min

`150`min`

`MWNTs``MWNTs`

233

`MWNTs`[13]

eet qt

kqqt += 2

1 1

qt t` mg/gk g/ mg minqe mg/g

t/qt t` `3``1

MWNTs``1` `2`

1 2 4 ` 1 2 3 `1 3 5 ` `k `

1 3 5 ` 1 2 3 ` 1 2 4 ``1 2 4 `

`1 3 5 ` 1 2 3 `1 2 4 `

`MWNTs`

3.3 MWNTs``MWNTs`

`4` `FreundlichFreundlich`

R2

0.999 911

1,2,31,2,41,3,5

log Kow

4.113.974.17

k

0.008 360.005 740.018 93

qe

71.9473.5369.93

1 Kow

b 1 2 4 TCB

a 1 2 3 TCB

234

nee KCq1

= 2

K n

Ce mg/Lqe mg/g

Freundlich` `2`

[14]` `3``3` H0 `MWNTs

` 4 ``MWNTs`

G0` S0` `MWNTs`

3.4

[11]` 12 3

pH` `MWNTs``OH `COOH

`H`[15] pH` `2 11`

MWNTs`

3.2`

`0.7`nm`

`4 ` ` 3 ``sp`2` `2`

`4``sp`2` `2`p` [16]

MWNTs``MWNTs`

`6` Long Yang [17]

` MWNTs`2` `MWNTs`

Zhao` `Lu[18]`

`MWNTs`

1 2 4 `

c 1 3 5 TCB

R

0.9910.9630.975

0.9960.9980.983

0.9830.9850.995

1,2,3

1,2,4

1,3,5

T ( )

5 115 125 1

5 115 125 1

5 115 125 1

1/n

0.4160.3990.398

0.3820.2990.334

0.5680.3600.428

LNK

1.9452.0172.161

2.2052.2031.917

2.2572.0121.924

1,2,3

1,2,4

1,3,5

T (K)

298 1288 1278 1

298 1288 1278 1

298 1288 1278 1

G0

18.58717.55116.456

18.70717.56616.701

19.64218.00016.090

H0

13.16513.16513.165

11.13711.13711.137

29.98429.98429.984

S0

[kJ/(mol K)]

0.106 50.106 70.106 6

0.100 10.099 70.100 1

0.166 50.166 60.165 7

235

4.1 MWNTs``1 2 4 `

`73.53`mg/g `150`min``Freundlich`

`pH` `MWNTs`

4.2 MWNTs``1 3 5 ``0.018 93`g/ mg min

MWNTs`

4.3 MWNTs``MWNTs`

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