Photolytical Degradation Products of Pentachlorophenol in Aqueous Solution and Organic Solvent
Maria Pythias B. Espino
Institute of Chemistry, College of Science
University of the Philippines, Diliman, Quezon City, Philippines
The photolytical degradation of pentachlorophenol in water, ethyl alcohol, and ethyl acetate was investigated to provide an understanding of its persistence and the nature of its degradation products. The photodegradation of pentachlorophenol in water was found to be most efficient resulting in complete dechlorination and production of acetic acid, oxalic acid, and chloride ion as final products. The chlorinated degradation products of pentachlorophenol in water (2,3,4,6-tetrachlorophenol; 2,3,5,6-tetrachlorophenol; 2,4,5-trichlorophenol; 2,3,6-trichlorophenol; 2,6-dichlorophenol; dichlorobenzenediol), ethyl alcohol (2,4,6-trichlorophenol; 2,3,6-trichlorophenol; 2,5-dichlorophenol; 2,3-dichlorophenol), and ethyl acetate (2,3,6-trichlorophenol; 2,4-dichlorophenol) were identified. A theoretical determination of the degradation products using density functional theory computations of atomic charge distribution that correlated with the experimental findings of this study is proposed.
The use of ultraviolet (UV) radiation alone or in combination with oxidizing agents and catalysts to degrade chlorophenols has been reported in literature. In general, the addition of catalysts or oxidants enhances the photodegradation process. The efficacy of sulphonated phthalocyanine complexes as catalysts and sensitizers to photodegrade chlorophenols was established by Ozoemena et al. (2001). Pandiyan et al. (2002), Rao et al. (2003), and Kim et al. (2007) used titanium dioxide as catalyst in the photooxidation of chlorophenols. Pandiyan et al. (2002) found that in the presence of titanium dioxide, polychlorinated phenols are more difficult to dechlorinate than monochlorinated phenols. Antonaraki et al. (2002) studied the photolysis of chlorophenols using UV and visible light in combination with hydrogen peroxide or a polyoxometallate catalyst, and related the decomposition rate with the position and number of chlorine atoms in the phenolic ring. They found that a chlorine atom in the meta position accelarates the photodecomposition process. The photochemical decomposition of chlorophenols using UV light and various oxidants such as hydrogen peroxide, ozone or Fenton's reagent involves free radical formation (Benitez et al. 2000; Ghaly et al. 2001).
AKAI N, KUDOH S, TAKAYAGI M, NAKATA M. 2001. Photoreaction mechanisms of 2-chlorophenol and its multiple chloro-substituted derivatives studied by lowtemperature matrix-isolation infrared spectroscopy and density-functional-theory calculations. J Photochem Photobiol A 146: 49-57.
ANTONARAKI S, ANDROUAKI E, DIMOTIKALI D, HISTIA A, PAPACONSTANTINOU E. 2002. Photolytic degradation of all chlorophenols with polyoxometallates and H2 O2 . J Photochem Photobiol A 148: 191-197.
BENITEZ JF, BELTRAN H J, ACERO J, RUBIO F. 2000. Contribution of free radicals to chlorophenols decomposition by several advanced oxidation processes. Chemosphere 41: 1271-77.
BENITEZ JF, ACERO J, REAL F, GARCIA J. 2003. Kinetics of photodegradation and ozonation of pentachlorophenol. Chemosphere 51: 651-662.
BURROWS H, CANLE M, SANTABALLA J, STEENKEN S. 2002. Reaction pathways and mechanisms of photodegradation of pesticides. J Photochem Photobiol B 67: 71-108.
CRESPIN M A, CARDENAS S, GALLEGO M, VALCARCEL M. 1999. Discrimination of structural isomers of chlorinated phenols in waters using gas chromatography-mass spectrometry in the negative chemical ionization mode. J Chromatogr A 830: 165-174.
CZAPLICKA M. 2006. Phototdegradation of chlorophenols in aqueous solution. J Hazard Mater 134: 45-59.
CZAPLICKA M, KACZMARCZYK B. 2006. Infrared study of chlorophenols and products of their photodegradation. Talanta 70: 940-949.
[EPA] Environmental Protection Agency. 1999. Methods 415.1 and 415.2 for Total Organic Carbon in Water. 16 Nov 1999 Revision. http://www.epa.gov/region09/qa/pdfs/415_1dqi.pdf
ESPINO M P, NAKAI S, HOSOMI M. 2006. Degradation of cis-Chlordane in Aqueous Isopropanol, Isopropanol and Hexane by UV Radiation Treatment. Kimika 22: 65-75.
FREIRE P, LABRADOR V, MARTIN J, HAZEN M. 2005. Cytotoxic effects in mammalian Vero cells exposed to pentachlorophenol. Toxicol 210: 37-44.
FRISCH MJ, TRUCKS GW, SCHLEGEL HB, SCUSERIA GE, ROBB MA, CHEESEMAN JR, ZAKREWKSI VG, MONTGOMERY JA, STRATMANN RE, BURANT JC, DAPPRICH S, MILLAM JM, DANIELS AD, KUDIN KN, STRAIN MC, FARKAS O, TOMASI J, BARONE V, COSSI M, CAMMI R, MENNUCCI B, POMELLI C, ADAMO C, CLIFFORD S, OCHTERSKI J, PETERSSON GA, AYALA PY, CUI Q, MOROKUMA K, MALICK DK, RABUCK AD, RAGHAVACHARI K, FORESMAN JB, CIOSLOWSKI J, ORTIZ JV, STEFANOV BB, LIU G, LIASHENKO A, PISKORZ P, KOMAROMI I, GOMPERTS R, MARTIN RL, FOX D J, KEITH T, AL-LAHAM MA, PENG CY, NANAYAKKARA A, GONZALES C, CHALLACOMBE M, GILL PMW, JOHNSON BG, CHEN W, WONG MW, ANDRES JL, HEAD-GORDON M, REPLOGLE, ES, POPLE JA. 1998. Gaussian 98 Revision A.1. Pittsburg, PA: Gaussian, Inc.
GE J, PAN J, FEI Z, WU G, GIESY J. 2007. Concentrations of pentachlorophenol (PCP) in fish and shrimp in Jiangsu Province, China. Chemosphere 69: 164-169.
GHALY M, HARTEL G, MAYER R, HASENEDER R. 2001. Photochemical oxidation of p-chlorophenol by UV/H2 O2 and photo-Fenton process. A comparative study. Water Manag 21: 41-47.
GUNLAZUARDI J, LINDU W. 2005. Photocatalytic degradation of pentachlorophenol in aqueous solution employing immobilized TiO2 supported on titanium metal. J Photochem Photobiol A 173: 51-55.
HIRVONEN A, TRAPIDO M, HENTUNEN J, TARHANEN J. 2000. Formation of hydroxylated and dimeric intermediates during oxidation of chlorinated phenols in aqueous solution. Chemosphere 41: 1211-18.
HONG H, ZHOU H, LUAN T, LAN C. 2005. Residue of pentachlorophenol in freshwater sediments and human breast milk collected from the Pearl River Delta, China. Environ Int 31: 643-649.
HONG J, KIM D, CHEONG C, JUNG S, YOO M, KIM K, KIM T, PARK Y. 2000. Identification of photolytical transformation products of pentachlorophenol in water. Anal Sci 16: 621-626.
HONG P, ZENG Y. 2002. Degradation of pentachlorophenol by ozonation and biodegradability of intermediates. Water Res 36: 4243-54.
KIGUCHI J, KOBAYASHI T, WADA Y, SAITOH K, OGAWA N. 2007. Polychlorinated dibenzo-p-dioxins and dibenzofurans in paddy soils and river sediments in Akita, Japan. Chemosphere 67: 557-573.
KIM J, CHOI K, CHO I, SON H, ZOH K. 2007. Application of microbial toxicity assay for monitoring treatment effectiveness of pentachlorophenol in water using UV photolysis and TiO2 pholocatalysis. J Hazard Mater 148: 281-286.
KIM M, O'KEEFE P. 2000. Photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in aqueous solutions and in organic solvents. Chemosphere 41: 793-800.
MUSSALO-RAUHAMAA H, PYYSALO H, ANTERVO K. 1998. The presence of chlorophenols and their conjugates in Finnish human adipose and liver tissues. Sci Total Environ 83: 161-172.
OZOEMENA K, KUZNETSOVA N, NYOKONG T. 2001. Comparative photosensitised transformation of polychlorophenols with different sulphonated metallocyanine complexes in aqueous medium. J Mol Catal 176: 29-40.
PANDIYAN T, MARTINEZ RO, OROZCO MJ, BURILLO AG, MARTINEZ CM. 2002. Comparison of methods for the photochemical degradation of chlorophenols. J Photochem Photobiol A 146: 149-155.
RAO N, DUBEY A, MOHANTY S, KHARE P, JAIN R, KAUL S. 2003. Photocatalytic degradation of 2-chlorophenol: a study of kinetics, intermediates and biodegradability. J Hazard Mater B101: 301-314.
SANZ JA, PLAZA MM, MARTINEZ SM, PEREZ MC. 1999. Study of photodegradation of the pesticide ethiofencarb in aqueous and nonaqueous media by gas chromatography-mass spectrometry. J Chromatogr A 840: 235-247.
SILVI B, KRYACHKO S, TISHCHENKO O, FUSTER F, NGUYEN M. 2002. Key properties of monohalogen substituted phenols: interpretation in terms of the electron localization function. Mol Phys 100: 1659-75.
SUEGARA J, LEE B, ESPINO M P, NAKAI S, HOSOMI M. 2005. Photodegradation of pentachlorophenol and its degradation pathways predicted using density functional theory. Chemosphere 61: 341-346.
[UNEP] United Nations Environment Programme. 2002. Southeast Asia and South Pacific Regional Report, Regionally Based Assessment of Persistent Toxic Substances. Geneva, Switzerland: UNEP Chemicals. 125p.
[UNEP] United Nations Environment Programme. 20003. Global Report, Regionally Based Assessment of Persistent Toxic Substances, UNEP Chemicals, Geneva, Switzerland: UNEP Chemicals. 207p.
VILLELA I, OLIVEIRA I, SILVA J, HENRIQUES J. 2006. DNA damage and repair in haemolymph cells of golden mussel (Limnoperna fortunei) exposed to environmental contaminants. Mutat Res/Gen Toxicol and Environ Mutagen 605: 78-86.
[WHO] World Health Organization. 1996. Recommended Classification of Pesticides by Hazard and Guidelines to Classification 1996-1997. Geneva, Switzerland: World Health Organization. 54p. http://whqlibdoc.who.int/hq/1996/WHO_ICS_96.3.pdf
YANG S, HAN X, WEI C, CHEN J, YIN D. 2005. The toxic effects of pentachlorophenol in rat Sertoli cells in vitro. Environ Toxicol Pharmacol 20: 182-187.
YIN D, GU Y, LI Y, WANG X, ZHAO Q. 2006. Pentachlorophenol treatment in vivo elevates point mutation rate in zebrafish p53 gene. Mutat Res/Gen Toxicol and Environ Mutagen 609: 92-101.