Phenol Adsorption

Chemosphere 58 (2005) 1049–1070 www.elsevier.com/locate/chemosphere

Adsorption of phenolic compounds by activated carbon—a critical review
´ A. Dabrowski *, P. Podkoscielny, Z. Hubicki, M. Barczak ˛
Faculty of Chemistry, Department of Theoretical Chemistry, Marie Curie-Skłodowska University, pl. Marii Curie-Skłodowskiej 3, 20-031 Lublin, Poland Received 30 July 2003; received in revised form10 September 2004; accepted 15 September 2004

Abstract Adsorption of phenol and its derivatives on activated carbons is considered based on numerous papers related to this issue. Special attention is paid to the effects of carbon surface functionalities, pH of solution and heterogeneity effects that accompany adsorption of phenolic compounds. Moreover, in this paper the most important aspectsare overviewed referring to irreversible adsorption of phenols and impact of different substituents of phenolic compounds on their uptake by activated carbons is considered. Finally, some remarks pertaining to applications of novel adsorbents for phenol adsorption are discussed and illustrated by means of a few examples. Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Adsorption of phenols;Activated carbon; Irreversible adsorption; Activated carbon fibers

1. Introduction Phenolic derivatives belong to a group of common environmental contaminants. The presence of their even low concentrations can be an obstacle to the use (and/or) reuse of water. Phenols cause unpleasant taste and odour of drinking water and can exert negative effects on different biological processes. Most of thesecompounds are recognized as toxic carcinogens. Industrial sources of contaminants such as oil refineries, coal gasification sites, petrochemical units, etc., generate large quantities of phenols. Besides, phenolic derivatives are widely used as intermediates in the synthesis of plastics,

Corresponding author. Tel.: +48 81 537 5605; fax: +48 81 537 5685. E-mail address: dobrow@hermes.umcs.lublin.pl(A. Dabrowski). ˛

*

colours, pesticides, insecticides, etc. Degradation of these substances means the appearance of phenol and its derivatives in the environment. Phenols have weak acidic properties. The basic information concerning phenolic compounds is included in Table 1 (Vidic et al., 1993). Different methods designed to remove phenols have been proposed. Adsorption by activated carbons(ACs) is the best and most frequently used method. Other methods include, aerobic and anaerobic biodegradation, oxidation by ozone, and uptake by ion exchange resins, etc. ACs possess perfect adsorption ability for relatively low-molecular-weight organic compounds such as phenols. They can be manufactured in such a way that a highly fractal material is obtained, which is similarly roughly structuredwith each magnification and with pores of any width. There are two most common physical forms, in which activated carbon (AC) is used, i.e.,

0045-6535/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2004.09.067

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A. Dabrowski et al. / Chemosphere 58 (2005) 1049–1070 ˛

Table 1 Basic information concerning phenol and its derivatives (Vidic etal., 1993) Phenolic compound
OH

Boiling point (°C)

pKa at 25 °C

Aqueous solubility at 25 °C (g lÀ1)

Critical oxidation potential (COP) (Fieser, 1930) (V)

182
OH CH3

9.89

93

1.089

191

10.20

25

1.040

OH

202
CH3

10.01

26

1.080

OH

202
CH3

10.17

23

1.038

OH
CH3

211
CH3

10.58

Not available

0.895

OH
CH2CH3

20710.2

Sparingly soluble

Not available

OH

214
CH2CH3

10.07

Slightly soluble

Not available

OH

218
CH2CH3

10.0

Slightly soluble

Not available

OH
Cl

204

8.52

28

1.094

OH

214
Cl

8.97

26

Not available

OH

220
Cl

9.37

27

1.094

OH
Cl

210
Cl

7.90

4.5

Not available

OH Cl Cl

246
Cl

5.99

28.6...