Comparative Study ofGas Phase Adsorption of Volatile Organic Compounds on Two Types of Activated Carbon

Daekeun Kim, George A Sorial

Department of Civil and Environmental Engineering

University of Cincinnati

The 227th ACS National Meeting, Anaheim, CA, March 28, 2004

2

Introduction

Objective

Adsorption of Single Compounds• Experimental Method• Results

Ternary Adsorption• Experimental Method• Results

Conclusion

OUTLINE

3

INTRODUCTION

• Volatile Organic Compounds (VOCs) : Typical air pollutants

• VOC Control Technology : Carbon adsorption, Liquid scrubbing, Condensation, Catalytic incineration, Biological treatment.

4

INTRODUCTION (cont’d)

• Biofiltration: Typical Biological Treatment ProcessContaminants or odor are removed through a biologically active media (soil, compost, inorganic material)

• Advantages of BiofiltrationEnvironmental friendlyEconomical viable

• Disadvantages of BiofiltrationUnfavorable performance due to shock load &

load fluctuationsClogging of bed due to accumulation of biomass

5

INTRODUCTION (cont’d)

• For yielding consistently high VOC removal efficiency, a novel combined treatment technology is proposed

Adsorption unit + Biofiltration

VOC

Clean air

Nutrient

6

INTRODUCTION (cont’d)

• Adsorption Unit : as a buffer against unexpected operating conditionRequired design capacity for this unit mainly depend on the results of the adsorption experiment.

• Experimental Method of AdsorptionDynamic adsorption columnGravimetric methodConstant volume method

7

OBJECTIVE

• To obtain basic experimental adsorption data of VOCs for designing an adsorption unit.

• For this purpose, gas phase VOC adsorption on two different adsorbents is carried out by using constant volume method

8

ADSORPTION OF

SINGLE COMPOUNDS

9

EXPERIMENTAL METHOD

• AdsorbateTolueneMethyl ethyl ketone (MEK)Methyl isobutyl ketone (MIBK)

• Adsorbent: two types of activated carbonBPL - bituminous baseOVC - coconut base

• Method : Constant volume method

• Analysis : Myers adsorption equation

10

EXPERIMENTAL METHOD (cont’d)

• Experimental Apparatus

Sampling Bag (Tedlar® bag) 6-L Canister

11

EXPERIMENTAL METHOD (cont’d)

Experimental Procedure

1. Carbons are inserted into sampling bag

12

EXPERIMENTAL METHOD (cont’d)

Experimental Procedure

2. Introduce 6-L pure air by using 6-L canister

13

EXPERIMENTAL METHOD (cont’d)

Experimental Procedure

3. Inject gas phase VOC

14

EXPERIMENTAL METHOD (cont’d)

Experimental Procedure

4. GC measurement

15

RESULTSToluene adsorption on BPL

Ce, mmol/L

10-3 10-2

q e, m

mol

/g

10-1

100

101

500 ppmv250 ppmv100 ppmvRegression line99 % Confidence

16

RESULTS – TOLUENE

Ce, mmol/L

10-4 10-3 10-2

qe, m

mol

/g

10-1

100

101

BPL OVC

17

RESULTS - MEK

Ce, mmol/L

10-4 10-3 10-2 10-1

qe, m

mol

/g

10-1

100

101

BPL OVC

18

RESULTS - MIBK

Ce, mmol/L

10-5 10-4 10-3 10-2 10-1

qe, m

mol

/g

10-1

100

101

102

BPL OVC

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RESULTS - Comparison

Ce, mmol/L

0.000 0.003 0.006 0.009 0.012

q e, B

PL

/ q

e, O

VC

0.0

0.5

1.0

1.5

2.0

TolueneMEKMIBK

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TERNARY ADSORPTION

21

EXPERIMENTAL METHOD

• Composition of adsorbateUsing public data of industrial VOCs air emission (U.S.EPA Toxic Release Inventories),Toluene: MEK: MIBK ≈ 6 : 3 : 1 (Toluene is majority)

• Adsorbent of concernBPL (BPL is superior to OVC for toluene adsorption)

• Experimental Method : Constant Volume Method

• Prediction : IAST (Ideal Adsorption Solution Theory)

22

Results - Ternary Adsorption

Ce, mmol/L

10-6 10-5 10-4 10-3 10-2

q e, m

mol

/g

10-2

10-1

100

101

102

Toluene IAST MEKIAST MIBKIAST

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CONCLUSION

Activated carbon BPL and OVC can effectively adsorb Toluene, MEK, and MIBK as single solute and mixture-compounds.

However, BPL was superior to OVC for adsorption of toluene

Myers adsorption equation was found to reliably represent single solute equilibrium data

24

CONCLUSION (cont’d)

IAST predicted well ternary adsorption on activated carbon BPL, but minor compound (MIBK) was underestimated.

Constant volume method is a simple & accurate experimental method for gas phase VOC adsorption for the low concentrations.

25

ACKNOWLEGEMENTS

This research study was supported financially by National Science Foundation (BES-0229135)

Special thanks is given to Dr. George A. Sorialand is extended to my colleagues at Environmental Chemistry Laboratory at University of Cincinnati.

Comparative Study of Gas Phase Adsorption of Volatile Organic Compounds on Two Types of Activated Carbon

Daekeun Kim Department of Civil and Environmental EngineeringUniversity of Cincinnati

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