DEGRADATION of ORGANOCHLORIDE COMPOUNDS by 03 and O3/H202

Home , Organochloride

War. Res. Vol. 31, No. 9, pp. 2387-2391, 1997 1997 ElsevierScience Ltd. All.rightsreserved Pergamon Printed in Great Britain PII: S0043-1354(97)00066-3 0043-1354/97 $17.00 + 0.00

RESEARCH NOTE

DEGRADATION OF ORGANOCHLORIDE COMPOUNDS BY 03 and O3/H202

P. ORMAD *L, S. CORTI~S ~, A. PUIG 2 and J. L. OVELLEIRO ~ ~Department of Chemical Engineering and Environmental Technology, Science Faculty, University of Zaragoza, Pza. San Francisco, s/n 50009-Zaragoza, Spain and :Confederacidn Hidrogr~fica del Ebro. Pa. Sagasta, 28.50006-Zaragoza, Spain

(First receired May 199& accepted in revised form February 1997)

Abstract--This paper presents the results obtained from oxidation with 03 and O3/H20,_ of a residual water coming from the production of dicofoi and tetradifon pesticides, where chlorobenzenes, DDTs and its metabolites and other organochloride compounds were found. The oxidation processes were carried out using ozone (03) in basic medium (pH 9.4) at low dosage (0--1.5 g O~ g-L initial TOC) and in the presence of hydrogen peroxide (H_,O_,), with a 0,5 H_,O_,/O3 molar ratio. During the treatment, many compounds were removed (dichlorobenzophenone, tetradifon, chlorobenzene, trichlorobenzene) and their change in concentration at different ozonation contact time was monitored. Other compounds like DDE remained practically invariable. This study investigated the formation of first ozonation by-products (FOBPs) in the wastewater, specificallychlorophenols, by means of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/electron capture detection (GC/ECD) analysis in terms of the amount of time the 03 has been in contact with the processed sample, o-Chlorophenol, p-chlorophenol, benzenemethanol, n-chlorohydroxibenzaldehyde, n-chlorobenzenemethanol, chlorobenzoic acid, etc., were formed during the treatment, due to the mechanism of fast and non-selectiveoxidation which ozone has through OH radicals, formed by the decomposition of the 03 molecule and accelerated by the presence of H_~O2 in water. ;f~. 1997 Elsevier Science Ltd

Key words--organochloride compounds, pesticides, ozone, hydrogen peroxide, chlorobenzenes, dicofol, tetradifon, by-products, wastewater.

INTRODUCTION For reasons such as these, many studies have Pesticide-synthesis industries generate spillages been made in order to remove these pollutants in which contain many toxic and non-biodegradable drinking and wastewater treatments (Beltran and compounds that remain in the environment even Beltran, 1986). Studies of the last few years have after the waste products have been subjected to a shown that the effective removal of some of these conventional processing system. The production of organochloride compounds from the aqueous the pesticides dicofol and tetradifon generates medium is achieved by using advanced oxidation waste effluents that contain many different processes (Ormad et al., 1994), with ozone (03) at organochloride compounds like the complete series high pH or 03 combined with hydrogen peroxide of chlorobenzenes, DDTs and its metabolites, (H202), where OH radicals are formed in the chlorobenzaldehyde, chlorobenzoic acid, etc., sub- decomposition of Ot in the aqueous medium (Glaze stances usually detected in industrial waste et al., 1987). spillages, many of which are included in List I Ozonation of organic matter can lead to the of the European Council Directive 76/464/EEC production of by-products (Andrews et al, 1993) as future candidates for regulation (EC, 1976). which are suspected to be public health concerns, The maximum contaminant levels for total like aldehydes, phenols, aromatic acids, etc. trichlorobenzene, hexachlorobenzene and DDTs Organic compounds present in the wastewater and its metabolites have been stipulated by the react with ozone in both molecular form and as EU for wastewater and surface water (EC, 1986, hydroxyl radicals to form oxygenated first 1988, 1990). ozonation by-products (FOBPs) (Legube et al., 1981). This study investigated the formation of *Author to whom all correspondence should be addressed FOBPs in the wastewater, specifically chlorophenols, [Tel: (34)-76-76 10 00 ext. 3308; Fax: (34)-76-7611 59]. during the ozonation processes. wn ~19 I 2387 2388 Research Note

MATERIALS AND METHODS Legube et al. (1983), trichlorobenzene by Masten Sample et al., 1993), etc. Rate constants of reaction of O~ with The wastewater used in this study has been taken from a chlorobenzenes, nitrobenzene, benzaldehyde, benzoic factory which produces the organochloride pesticides acid, etc., have been determined by Hoign6 and Bader dicofol and tetradifon. (Fig. 1). (1983a,b). These organochloride compounds exhibit Ozonation low reaction rate constants (Ko~ < 10 M- ' s-J), but Ozonation was carried out using a closed reactor (Fischer their degradation can be effective when ozonation is Model 501) to which 4 litres of residual water was added. performed in the range of very high pH or in the The raw water (pH 9.4; conductivity 13 mS; TOC 1150 mg presence of H20> litre-'; COD 3920mg litre-'; TOX 606mg litre-'; C1- 5815 mg litre -j and ECs0 370.000mg litre -~) was treated Table 1 shows the variation in concentration of with 03 and O3 combined with H,_O., in a H,.Oz/O~ molar four different solutes (M) during the treatment with ratio of 0.5 (Bellamy et al., 1991). ozone or ozone combined with H.,O_,. Approximately In the experiments, the total contact time was 60 rain and 80% of initial chlorobenzene (M~ = 33.4 mgl-~ in the O3 dosage used was 0-1.5 g litre-' (0-1.3 g g-' TOC). wastewater), the raw material of dicofol, was The non-consumed O3 was determined by bubbling the gas through a 2% KI solution that was titrated with sodium degraded after consumption of 0.23 g O21 -~ in both thiosulphate and starch as indicator (Kolthoffand Belchor, treatments. A total disappearance was achieved by 1957). The residual O3 in the aqueous phase was measured using O3/'H20.~ after dosage of 1.51 g 031 ~. by the Indigo colorimetric method (4500-03 B Standard 1,2,4-Trichlorobenzene (I,2,4-TCB), the raw ma- Method (Cleresci et al., 1989). terial of tetradifon, with an initial concentration of Parameter measurements M0 = 0.7 mgl ' in the wastewater, exhibited lower Organic compounds present in aqueous samples collected reactivity towards O~ than chlorobenzene. Using a during the experiments at different ozonation dosages were dosage of 0.23 g 03 litre -~, the elimination of 50 and analysed by means of GC/ECD and GC/MS (US EPA 62% of 1,2,4-TCB was achieved in the treatment of method 625). The chromatography conditions were as follows: mass spectrometer, ITD Finnigan Mat 800; gas 03 and O3/H20.,, respectively. Table 1 shows that chromatograph, HP 5890 and Varian 3300; detector, O3/H202 was more effective than O.~ alone to remove electron capture detector; column, DB-5; splitless, 0.8 rain; 1,2,4-TCB from wastewater. At the end of the injection temperature, 250~C; detection temperature, 350~C; O3/H_,O_, treatment only 7% of initial 1,2,4-TCB temperature program, 60(1)-4-280(10). Other chemical parameters were also measured: chloride remained after the consumption of 1.51 g O~ litre ~. (Standard Method 4500B, Cleresci et al., 1989); One of the final products of the chemical industry, TOC (Standard Method 5310B, Cleresci et al., 1989); COD the pesticide tetradifon (M0 = 0.15 mg litre-J), was (Standard Method 5220B, Cleresci et al., 1989); TOX totally removed (>98%°) with a dosage of 0.23 g O~ (Standard Method 5320, Cleresci et al., 1989); EC~,o litre J in both treatments. (Bioluminescencetest photobacterium phosphoreum; BOE, 1989). Also, dichlorobenzophenone (M~, = 0.16 mg litre ~), the biodegradation by-product of dicofol, was degraded by the two oxidation processes. An RESULTS AND DISCUSSIONS elimination level of 80 and 85% was achieved with a The wastewater coming from the production of dosage of 0.35g 03 litre -~ with 03 and O~/H20> dicofol and tetradifon pesticides was treated at high respectively. Other compounds, like DDTs and their pH with 03 and 03 plus H202, and the results were metabolites, were not oxidized under these exper- compared. imental conditions. The majority of compounds present in the After the two treatments, with an 03 dosage of wastewater were determined by using GC/MS 1.3 g g-~ TOC, the TOC, COD, TOX and chloride analyses (Fig. 2) and they were quantified by concentration remained practically invariable (simi- GC/ECD (the concentration of these compounds was lar results were achieved by Andrews et al., 1993). below the maximum levels established by the The low elimination of TOC, COD and TOX after European legislation). The degradation of some of treatments (< 10%) shows that the compounds have these compounds using 03 has been studied by many been degraded only partially to CO> So, by means of authors: chlorobenzene and nitrobenzene by Lykins GC/MS analysis, many FOBPs were identified: et al. (1986), benzaldehyde and chlorobenzene by benzenemethanol, chlorobenzenemethanol, benzoic

CI-~ SO2-~~ CI

dicofoi tetradifon

Fig. 1. Dicofol and tetradifon. Research Note 2389

CI CI

o clio cl ' o

c! cI

o CI

C~CI pp'dichlorobenzophenone op'dichlorobenzophenone op'DDE

COOl{ COOH

CI ~ SO2~ CI

CI pp'DDE t¢~clifon

cu 3 CH2C~ .~o ~o coox/

Fig. 2. Majority of compounds present in the wastewater. acid (detected by Legube et al. (1983) in the oxidation treatment with 03 at a dosage of 1.19 g 03 litre E, and of benzaldehyde), chlorobenzoic acid, dichloroben- 3.7 mg litre -~ was detected in the O3/H,_O2 treatment zoic acid, nitrobenzaldehyde, chlorohydroxiben- at a dosage of 0.83 g O~ litre t. The maximum zaldehyde, chlorophenol and trichlorophenol concentration of o-chlorophenol detected during (Fig. 3). both treatments was 9.6/~g litre- ~in the O: oxidation The formation of the two isomers of chlorophenol processes. Trichlorophenol only was detected during may be explained by the electrophilic attack of OH treatment with O3/H20,_ at trace levels. radicals in the ortho and para positions of The biotoxicity (measured as EC50) increased chlorobenzene. Chlorophenols have high reaction during the ozonation processes by about 60%. rate constants (Hoignd and Bader, 1983b; Haag and Yao, 1992). Their degradation by 03 has also been CONCLUSIONS studied by Yu-Hwa Yu and Szu-Tsong Hu (1993). The results presented in this paper and those During the present experiments, chlorophenol is obtained previously show the following in the formed; 03 reacts with it simultaneously, destroying treatment by 03 of wastewater containing it (Figs 4 and 5). The initial concentration in the raw organochloride compounds: water of the ortho and para isomers was 4.2 and 7.6/~g litre ~, respectively. The para isomer was 1. The elimination of TOC, COD and TOX was formed faster than the ortho isomer. Approximately very limited (< 10%), using low 03 dosages. 2.0 mg litre ~ of p-chlorophenol was detected in the 2. DDTs and their metabolites remained practi-

Table I. Degradation of compoundsduring ozonalion(M/M~,) Ozone Ozone + H20: O3/TOC (g g ~) O7/TOC (g g ~) Compound 0 0.2 0.6 1.0 0 0.25 0.4 0.7 1.3 (Mono)ehlorobenzene 1.00 0.20 0 15 0.15 1.00 0.03 0.02 0.02 0.01 1.2,4-TCB 1.00 0.50 0A6 0.38 1.00 0.35 0.20 0.12 0.07 Tetradifon 1.00 0.02 0.01 0.00 1.00 0.02 0.01 0.00 0.00 Dichlorobenzophenone 1.00 0.35 0.18 0.02 1.00 0.29 0,14 0.07 0.00 2390 Research Note

[ cl Cl

CHO CH20H ClIO OH COOH

Fig. 3. FOBPs identified during treatment.

cally invariable under these laboratory con- droxybenzaldehyde, n-chlorobenzenemethanol, ditions. chlorobenzoic acid, etc.) were formed during the 3. Chlorobenzene exhibited higher reactivity treatment, due to the mechanism of fast and towards O~ than 1,2,4-TCB. non-selective oxidation which 03 has through 4. The O~/H20_, system appears to be more efficient OH radicals, formed by the decomposition of than the O3/high-pH system to remove the O3 molecule and accelerated by the presence chlorobenzenic compounds under these exper- of H202 in water. The results of this study have imental conditions. shown that the intermediates in the reaction are 5. Tetradifon and dichlorobenzophenone were highly reactive themselves. The concentration of totally oxidized by O3/H202 and O3/high-pH. chlorophenol was decreased at the end of the 6. Hydroxylated FOBPs (o-chlorophenol, p- treatment, above all in the case of oxidation chlorophenol, benzenemethanol, n-chlorohy- with O3/H202. In a first step, 03 attacks

c (ppb) C (ppb) 4000 10.00 -~ O3 ~ o3 9.00 -' • O3÷H202 ! Ir , 03~H202

8.00 3000 - / 7.00 -~

/ ! 6.00 / -1 2000 5.00 - i 4.00 -~

3,00 - 1000 2.00

1.oo -~

0 T ...... , 0.00 0.00i-I 1.00 :2.00 0.00 1.00 2.00 O3/TOC (mglmg) O3/TOC (rag/rag)

Fig. 4. Formation and degradation of p-chlorophenol Fig. 5. Formation and degradation of o-chlorophenol during treatment with O9 and O3/H.,O.,. during treatment with 03 and O3/H.,O2. Research Note 2391

chloroaromatic compounds and chlorophenol is July 1990), modifying annex II of Directive 86/280/ECC concerning maximum values and quality levels for certain formed; in a second step, 03 attacks the dangerous substances included in List 1 of the annex of chlorophenol molecule, destroying it. Directive 76/464/EEC. Diario Oficial de la Comunidad Europea, Number L 291, 14 August. EEC, Brussels. Acknowledgements--The Confederaci6n Hidrogr~ifica del Glaze W. H., Kang J. and Chapin D. C. (1987) The Ebro and Diputaci6n General de Arag6n are acknowledged. chemistry of water treatment processes involving ozone, hydrogen peroxide and ultraviolet radiation. Ozone Sci. Eng. 9, 335-352. REFERENCES Haag W. R. and Yao C. D. (1992) Rate constants for Andrews S. A., Huck P. M. and Coutts R. T. (1993) reaction of hydroxyl radicals with several drinking water Quantitation of ozonation by-products of fractionated contaminants. Era'. Sci. Technol. 26, 1005-1013. aquatic natural organic matter. Worn Wasser 81,151-165. Hoign6 J. and Bader H. (1983a) Rate constants of reactions Bellamy W, D., Hickman G. T., Mueller P. A. and Ziemba of ozone with organic and inorganic compounds in water. N. ( 1991 ) Treatment of VOC-contaminated groundwater I. Non-dissociating organic compounds. War. Res. 17, by hydrogen peroxide and ozone oxidation. Res. J. 173-183. WPCF 63(2), 120-128. Hoign6 J. and Bader H, (1983b) Rate constants of reactions Beltran Novillo F. J. and Beltran de Heredia J. (1986) of ozone with organic and inorganic compounds in water. Tratamiento de aguas con ozono, lng. Quimi. Enoro, 11. Dissociating organic compounds. War. Res. 17, 143-149. 185-194. BOE (1989) Order dated 13th October 1989, which lays Kolthoff I. M, and Belchor R. (1957) Volumetric Analysis. down methods of characterization of dangerous and toxic lnterscience, New York, USA. waste material. Boletin Oficial del Estado no. 270, Legube B, Langlais B, Sohm B. and Dor6 M. (1981) Ministerio de Obras Pfiblicas y Urbanismo, Madrid, Identification of ozonation by-products of aromatic Spain. hydrocarbon micropollutants: effect on chlorination and Cleresci L. D., Greenberg A. E. and Trussell R. R. (eds) biological filtration. Ozone Sci. Eng. 3, 3348. (1989) Standard Methods for the Examination o]" Legube B., Guyon S., Sugimitsu H. and Dor6 M. (1983) Wastewater, 17th edn. American Public Health Associ- Ozonation of some aromatic compounds in aqueous ation, Washington, DC, USA. solution: styrene, benzaldehyde, naphthalene, diethyl- EC (1976) 76/464/EEC. European Council Directive (4 May phthalate; ethyl and chlorobenzenes. Ozone Sci. Eng. 5, 1976) on pollution caused by certain dangerous 151-170, substances discharged into the aquatic environment of Lykins B. W., Koffskey W. E. and Miller R. G. (1986) community. Official Journal No. L 129, 18/05/76, p. 0023; Chemical products and toxicologic effects of disinfection. Greek special edn, Chapter 15, Volume 01, p. 138. EEC, J. Am. War. Works Assoc., Nov, 66-75. Brussels. Masten S. J., Galbraith M. J. and Davies H, R. (1993) EC (1986) 86/280/EEC. European Council Directive (12th Oxidation of trichlorobenzene using advanced oxidation June 1986), modifying annex II of Directive 86/280/ECC processes. In llth Ozone Worm Congress Proceedings, concerning maximum values and quality levels for certain Vol. 2, pp. $20-35. dangerous substances included in List I of the annex of Ormad P., Puig A., Sarasa J., Roche P., Mutuberria S. and Directive 76/464/EEC. Diario Oficial de la Comunidad Ovelleiro J. L. (1994) Ozonation of wastewater resulting Europea, Number L 191, 15 July. EEC, Brussels. from the production of organochloride plaguicides EC (1988) 88/347/EEC. European Council Directive (16th derived from DDT and trichlorobenzene. Ozone Sci. Eng. June 1988), modifying annex II of Directive 86/280/ECC 16, 487-503. concerning maximum values and quality levels for certain Yu-Hwa Yu and Szu-Tsong Hu (1993) The mechanism dangerous substances included in List I of the annex of involved in the preozonation of some chlorophenolic Directive 76/464/EEC. Diario Oficial de la Comunidad compounds. In 1 lth Ozone World Congress Proceedings, Europea, Number L 158, 25 June. EEC, Brussels. Vol. l, pp. $3-11, Jutl Ozone Assoc., Pan American EC (1990) 90/415/EEC. European Council Directive (27th Group. Stamford, CT.