The pathway of the ozonation of 2,4,62trichlorophenol in aqueous solution

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1 Acta Scientiae Circumstantiae Vol. 25,No. 12 Dec., 2005,. 2,4,62 [J ].,2005,25 (12) : PI Yunzheng, WANGJianglong. The pathway of the ozonation of 2,4,62trichlorophenol in aqueous solution [J ]. Acta Scientiae Circumstantiae,2005,25 (12) : [ ] : 2,4,62, 3, : : : : 2,4,62,, 2,4,62.,, 24 mg L - 1,011 mmol L - 1 2,4,62 6 min, 99 %. 2,4,62, 2,4, %., 2,4,62,.,2,4,62,. 2,4,62 O 3 ΠOH :2,4,62 ; ; ; ; : (2005) :X13112 :A The pathway of the ozonation of 2,4,62trichlorophenol in aqueous solution PI Yunzheng, WANGJianglong 3 Laboratory of Environmental Technology, INET, Tsinghua University, Beijing Received 18 July 2005 ; received in revised form 31 August 2005 ; accepted 28 September 2005 Abstract : The reaction mechanism and pathway of the ozonation of 2,4,62trichlorophenol (2,4,62TCP) in aqueous solution were investigated. The removal efficiency and the variation of H 2 O 2, Cl -, formic acid and oxalic acid were studied during the ozonation process. The results showed that when there was no scavenger, the removal efficiency of 0. 1 mmol L - 1 2,4,62TCP could reach 99 % within 6 min by adding 24 mg L - 1 ozone. The reaction of molecular ozone with 2,4,62TCP resulted in the formation of H 2 O 2. The maximal concentration of H 2 O 2 detected during the ozonation could reach % of the original concentration of 2,4,62TCP. The reaction of ozone with H 2 O 2 resulted in generating a lot of OH radicals. Therefore, 2,4,62TCP was destroyed to formic acid and oxalic acid by ozone and OH radicals together. With the inhibition of OH radicals, ozone molecule firstly destroyed 2,4,62TCP to form chlorinated quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,62TCP by ozone and O 3 ΠOH are proposed. Keywords :2,4,62trichlorophenol ; ozone ; hydrogen peroxide ; hydroxyl radicals ; reaction pathway,,,2,4,62, 25,. (,2002).,, ( Glaze et al., 1979). 2,4,62 (Chu et al., 2003), (CJΠT ) 2,4,62, 0101 mg L ,4,62, p, : (No ) ; : (1974 ),,,E2mail : org. cn ; 3 ( ) Foundation item :National Natural Science Foundation of China (No ), China Postdoc Science Foundation Biography :PI Yunzheng (1974 ), male, Ph. D., E2mail : org. cn ; 3 Corresponding author

2 , (, 2003). 2,4,62,, 2,4,62 (, 1995) ; 2,4,62 (, 2003) ; 2,4,62 (, 1999)., 2,4,62. 2,4,62,. OH,, OH.,,, O 3 ΠOH, 2 ( Results) 1 Fig. 1 Experimental setup 211 2,4,62 NaOH 20 mg L - 1 (011 mmol L - 1 ) 2,4,62 ph 715,, 2. 1 ( Experimental section) ph = mmol L - 1 KH 2 PO mmol L - 1 Na 2 HPO (, 2005). 011 g DPD (N, N2 diethyl2p2phenylenediamine,n,n2 2 ) 10 ml (50 mmol L - 1 ) H 2 SO 4 DPD ;10 mg POD (horseradish peroxidase, ) 10 ml POD (Bader et al., 1988)., k OH Πt2buta = mol - 1 L s - 1 (von Gunten, 2003)., 2,4,62. 3, 2,4,62, DPDΠPOD, ph 4. DOC Elementar High TOC.,pH Dionex ,4,62 HP1100 (, 280 nm). DPDΠ POD,,, DPD,, POD, 551 nm UV , ( 2 L) 24 mg L - 1, 27 L h DOC 2,4,6 - Fig. 2 The removal of DOC and 2,4,62trichlorophenol during ozonation 3 Fig. 3 The variation of the concentration of Cl - during ozonation, formate and oxalate

3 12 : 2,4, k OHΠt2buta c t2buta c OH Πk OHΠmax c CTP c OH 4 ph Fig. 4 The variation of hydrogen peroxide and ph during ozonation = Π = 16 2,4,62 16,, 2,4,62. 2,4,62 2,4,62, ,4,62,,, ph, 4,pH. (615 mmol L - 1 ) 2,4,62 ph 715,, 2,4,62,, 5. 6, 2,4,6 - Fig. 6 The changes of 2,4,62TCP and H 2 O 2 during ozonation with the presence of t2butanol 3 ( Discussion) 5 ( ph = 7. 5) 2,4,6 - Fig. 5 The changes of 2,4,62TCP and H 2 O 2 during ozonation with the presence of buffer (ph = 7. 5) 213,., ;, 2,4,62., 2,4, mmol L - 1, 2,4, mmol L ,4,62, 2,4,62 k OHΠmax = mol - 1 L s - 1 ( Hoigne, 1997), k OHΠt2buta c t2buta c OH, 2,4,62 k OHΠTCP c TCP c OH = k OHΠmax c TCP c OH,, 2, 2,4,62. 2 min,2,4, % ; 9 min, 2,4,62, 100 %. 2 DOC. 2 min, DOC 5 % ; 9 min,doc 17 %, 2,4,62 (100 %), 2,4,62 : 2,4,62,, 2,4,62 3, 6 min,, 2,4,62. 3,2,4,62. 6 min,.,, 25 min. ph, ; p Ka = 318, p Ka 1 = 1,, ph.

4 , 6 min, 2215 mol L - 1, 2,4,62 (011 mmol L - 1 ) 2215 %,., HO - 2,HO - 2 k O3 ΠHO - 2 = mol - 1 L s - 1 ( Staehelin et al1, 1985), (OH ). OH,, 10 8 mol - 1 L s mol - 1 L s - 1 ( Haag et al., 1992)., 2,4,62,,2,4,62, ph 715,, 2,4,62 ( 5), 6 min, 2,4,62.,, 6 min, 1912 mol L - 1, 4. 6 min,, 14 min, 0196 mol L - 1. ph, HO - 2,HO - 2,.,pH, HO - 2, 6,, 2,4,62. 6 min,2,4,62 0 mg L min, 3317 mol L ,4,62, 2,4,62, C C, ( Pi et al., 2005).,,,.,.,,3 min,, DPDΠPOD 2 min, DPD, DPD.,,, DPD (, 1999), : ( ) ( ). HPLC 2 min,,, 2,4,62, 7 (a), 2,4,62,,,., 2,4,62, 7 (b). 2,4,62,,., 2,4,62, 7 (b),,. 7 2,4,6 - ( (a) 2,4,6 - ; ( b) O 3 ΠOH 2,4,6 - ) Fig. 7 The pathways of ozonation of 2,4,62trichlorophenol ( (a) Ozone molecule oxidize 2,4,62TCP ; (b) O 3 ΠOH oxidize 2,4,62TCP) 4 ( Conclusions) 1), 2,4,62,, 2,4,62,, 2,4,62,. 2),

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