The efficient removal of 4-chloro-2-nitrophenol (4C2NP) in ultraviolet (UV)/peroxymonosulfate (PMS) oxidation system was investigated. The effects of pH, PMS dosage and concentrations of 4C2NP, chloride and nitrate ions on the degradation efficiency of 4C2NP were evaluated. No significant differences in 4C2NP degradation rate were observed at pH 2.0~5.0, but a further increase in pH value would inhibit the substrate decomposition. In addition, PMS dosage positively correlated with degradation rates of 4C2NP, while 4C2NP concentration had a negative effect. A typical dual effect of chloride concentrations on the 4C2NP degradation kinetics was observed, whereas the increasing concentrations of nitrate showed an indistinctively inhibitory effect on 4C2NP degradation. Dechlorination and denitration were the dominant degradation pathways during the oxidative degradation of 4C2NP, followed by the formation of chloride and nitrate ions. The released chloride from chloro groups would be involved in re-chlorination through radical reactions. Nitro groups released would be oxidized to stable nitrate, preventing re-nitration. Degradation mechanism of 4C2NP in a UV/PMS system was proposed based on intermediates identified.
Rodgers J D, Bunce N J. Treatment methods for the remediation of nitroaromatic explosives[J]. Water Research, 2001,35(9):2101-2111.
[2]
Hofstetter T B, Heijman C G, Haderlein S B, et al. Complete reduction of TNT and other (poly) nitroaromatic compounds under iron-reducing subsurface conditions[J]. Environmental Science & Technology, 1999,33(9):1479-148.
[3]
Dillert R, Brandt M, Fornefett I, et al. Photocatalytic degradation of trinitrotoluene and other nitroaromatic compounds[J]. Chemosphere, 1995,30(12):2333-2341.
[4]
Li Z M, Shea P J, Comfort S D. Nitrotoluene destruction by UV-catalyzed Fenton oxidation[J]. Chemosphere, 1998,36(8):1849-1865.
[5]
Chen W S, Su Y C. Removal of dinitrotoluenes in wastewater by sono-activated persulfate[J]. Ultrasonics Sonochemistry, 2012, 19:921-927.
Jiang J Y, Li Y, Wang G W, et al. Treatment of Acrylic Fiber Polymerization Wastewater by Fenton Method[J]. Research of Environmental Sciences, 2010,23(7):897-901.
[8]
Tekin H, Bilkay O, Ataberk S S, et al. Use of Fenton oxidation to improve the biodegradability of a pharmaceutical wastewater[J]. Journal of Hazardous Materials, 2006,136:258-265.
[9]
Xu L, Yuan R X, Guo Y G, et al. Sulfate radical-induced degradation of 2, 4, 6-trichlorophenol:a de novo formation of chlorinated compounds[J]. Chemical Engineering Journal, 2013, 217:169-173.
[10]
García Einschlag F S, Lopez J, Carlos L, et al. Evaluation of the efficiency of photodegradation of nitroaromatics applying the UV/H2O2 technique[J]. Environmental Science & Technology, 2002,36(18):3936-3944.
[11]
Carlos L, Nichela D, Triszcz J M, et al. Nitration of nitrobenzene in Fenton's processes[J]. Chemosphere, 2010,80:340-345.
[12]
Marvin-Sikkema F D, De Bont J A M. Degradation of nitroaromatic compounds by microorganisms[J]. Applied Microbiology and Biotechnology, 1994,42:499-507.
[13]
Zhou J, Xiao J H, Xiao D X, et al. Transformations of chloro and nitro groups during the peroxymonosulfate-based oxidation of 4-chloro-2-nitrophenol[J]. Chemosphere, 2015,134:446-451.
[14]
Liu X, Zhang T, Zhou Y, et al. Degradation of atenolol by UV/peroxymonosulfate:Kinetics, effect of operational parameters and mechanism[J]. Chemosphere, 2013,93:2717-2724.
[15]
Olmez-Hanci T, Imren C, Kabda?l? I, et al. Application of the UV-C photo-assisted peroxymonosulfate oxidation for the mineralization of dimethyl phthalate in aqueous solutions[J]. Photochemical & Photobiological Sciences, 2011,10:408-413.
[16]
Liang C J, Wang Z S, Bruell C J. Influence of pH on persulfate oxidation of TCE at ambient temperatures[J]. Chemosphere, 2007,66:106-113.
Gao N Y, Hu X H, Deng J, et al. Study on UV-activated persulfate oxidation of carbamazepine in water[J]. J. Huazhong Univ. Sci. &. Tech. (Natural Science Edition), 2013,41(12):117-122.
[19]
Muthukumar M, Selvakumar N. Studies on the effect of inorganic salts on decolouration of acid dye effluents by ozonation[J]. Dyes and Pigments, 2004,62:221-228.
[20]
Luna A J, Chiavone-Filho O, Machulek A, et al. Photo-Fenton oxidation of phenol and organochlorides (2, 4-DCP and 2, 4-D) in aqueous alkaline medium with high chloride concentration[J]. Journal of Environmental Management, 2012,111:10-17.
[21]
Yuan R, Ramjaun S N, Wang Z, et al. Effects of chloride ion on degradation of Acid Orange 7 by sulfate radical-based advanced oxidation process:Implications for formation of chlorinated aromatic compounds[J]. Journal of Hazardous Materials, 2011, 196:173-179.
[22]
Wang Z, Yuan R, Guo Y, et al. Effects of chloride ions on bleaching of azo dyes by Co2+/oxone regent:kinetic analysis[J]. Journal of Hazardous Materials, 2011,190:1083-1087.
[23]
Wine P H, Mauldin III R L, Thorn R P. Kinetics and spectroscopy of the nitrogen oxide radical (NO3) in aqueous ceric nitrate-nitric acid solutions[J]. The Journal of Physical Chemistry, 1988,92:1156-1162.
[24]
Zuo Z H, Katsumura Y, Ueda K, et al. Laser photolysis study on reactions of sulfate radical and nitrate radical with chlorate ion in aqueous solutions Formation and reduction potential of ClO3 radical[J]. Journal of the Chemical Society, Faraday Transactions, 1997,93:533-536.
[25]
Lou X Y, Guo Y G, Xiao D X, et al. Rapid dye degradation with reactive oxidants generated by chloride-induced peroxymonosulfate activation[J]. Environmental Science and Pollution Research, 2013, 20:6317-6323.
[26]
Khan J A, He X, Shah N S, et al. Kinetic and mechanism investigation on the photochemical degradation of atrazine with activated H2O2, S2O8- and HSO5-[J]. Chemical Engineering Journal, 2014,252:393-403.
[27]
Cotton F A, Wilkinson G, Murillo C A, et al. Advanced Inorganic Chemistry; Wiley-Interscience:New York.