Catalytic Activity of Cr(VI) in the Degradation of Phenol by H₂O₂ Under Acidic Conditions

Abstract

Cr(VI) and phenol are toxic contaminants that need to be treated, and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater. In this study, Cr(VI) was used as a novel Fenton-like catalyst in phenol degradation by H₂O₂. In the pH range of 3.0‒11.0, the degradation efficiency of phenol decreased with elevated pH. At pH = 3.0, 100 mg/L phenol was effectively degraded by 2 mmol/L Cr(VI) and 20 mmol/L H₂O₂. At pH = 7.0 and the same conditions as those of pH = 3.0, 79% of 100 mg/L phenol was removed within 6 h, which was an improvement in pH limitation compared with the Fe(II)-mediated Fenton reaction. Quenching experiments indicated that ^·OH generated from the catalysis of H₂O₂ by Cr(V) instead of Cr(VI) was the primary oxidant that degraded phenol. When pyrophosphate was added in the Cr(VI)/H₂O₂ system, complexes with the Cr(V) intermediate rapidly formed and inhibited H₂O₂ decomposition, implying that the decomposition of H₂O₂ to ^·OH was catalyzed by Cr(V) instead of Cr(VI). The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol. TOC and UV analyses suggest that phenol could not be completely oxidized to CO₂ and H₂O, and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids, primarily maleic, formic, acetic, and oxalic acids, and eventually into CO₂ and H₂O. Considering that more than 50% Cr(VI) can also be removed during this process, the Cr(VI)/H₂O₂ system is more appropriate for the simultaneous removal of Cr(VI) and phenol contaminants from industrial wastewater.

Keywords

Cr(VI) / Cr(V) / Phenol / Fenton / Simultaneous degradation

References

[1] Busca G, Berardinelli S, Resini C, et al. Technologies for the removal of phenol from fluid streams: a short review of recent developments. J Hazard Mater, 2008, 160(2–3): 265-288.

[2] Ahmed S, Rasul MG, Martens WN, et al. Heterogeneous photocatalytic degradation of phenols in wastewater: a review on current status and developments. Desalination, 2010, 261(1–2): 3-18.

[3] Kang N, Lee DS, Yoon J. Kinetic modeling of Fenton oxidation of phenol and monochlorophenols. Chemosphere, 2002, 47(9): 915-924.

[4] Andreozzi R, Caprio V, Insola A, et al. Advanced oxidation processes (AOP) for water purification and recovery. Catal Today, 1999, 53(1): 51-59.

[5] Pera-Titus M, García-Molina V, Baños MA, et al. Degradation of chlorophenols by means of advanced oxidation processes: a general review. Appl Catal B, 2004, 47(4): 219-256.

[6] Garrido-Ramírez EG, Theng BKG, Mora ML. Clays and oxide minerals as catalysts and nanocatalysts in Fenton-like reactions—a review. Appl Clay Sci, 2010, 47(3–4): 182-192.

[7] Heckert EG, Seal S, Self WT. Fenton-like reaction catalyzed by the rare earth inner transition metal cerium. Environ Sci Technol, 2008, 42(13): 5014-5019.

[8] Salem IA, El-Maazawi MS. Kinetics and mechanism of color removal of methylene blue with hydrogen peroxide catalyzed by some supported alumina surfaces. Chemosphere, 2000, 41(8): 1173-1180.

[9] Chaliha S, Bhattacharyya KG. Wet oxidative method for removal of 2,4,6-trichlorophenol in water using Fe(III), Co(II), Ni(II) supported MCM41 catalysts. J Hazard Mater, 2008, 150(3): 728-736.

[10] Duarte F, Maldonado-Hódar FJ, Pérez-Cadenas AF, et al. Fenton-like degradation of azo-dye Orange II catalyzed by transition metals on carbon aerogels. Appl Catal B Environ, 2009, 85(3–4): 139-147.

[11] Bokare AD, Choi W. Chromate-induced activation of hydrogen peroxide for oxidative degradation of aqueous organic pollutants. Environ Sci Technol, 2010, 44(19): 7232-7237.

[12] Liu LD, Wang WM, Liu L, et al. Catalytic activities of dissolved and Sch-immobilized Mo in H₂O₂ decomposition: implications for phenol oxidation under acidic conditions. Appl Catal B, 2016, 185: 371-377.

[13] Vander Griend DA, Golden JS, Arrington CA Jr. Kinetics and mechanism of chromate reduction with hydrogen peroxide in base. Inorg Chem, 2002, 41(26): 7042-7048.

[14] Perez-Benito JF, Arias C. A kinetic study of the chromium (VI) hydrogen peroxide reaction: role of the diperoxochromate (VI) intermediates. J Phys Chem A, 1997, 101(26): 4726-4733.

[15] Song H, Liu Y, Xu W, et al. Simultaneous Cr(VI) reduction and phenol degradation in pure cultures of Pseudomonas aeruginosa CCTCC AB91095. Biores Technol, 2009, 100(21): 5079-5084.

[16] Bagchi D, Stohs SJ, Downs BW, et al. Cytotoxicity and oxidative mechanisms of different forms of chromium. Toxicology, 2002, 180(1): 5-22.

[17] Wang Z, Bush RT, Sullivan LA, et al. Simultaneous redox conversion of chromium(VI) and arsenic(III) under acidic conditions. Environ Sci Technol, 2013, 47(12): 6486-6492.

[18] Li Y, Liu LD, Liu L, et al. Efficient oxidation of phenol by persulfate using manganite as a catalyst. J Mol Catal A Chem, 2016, 411: 264-271.

[19] Han X, Wong YS, Wong MH, et al. Biosorption and bioreduction of Cr(VI) by a microalgal isolate, Chlorella miniata. J Hazard Mater, 2007, 146(1–2): 65-72.

[20] Wang WM, Song J, Han X. Schwertmannite as a new Fenton-like catalyst in the oxidation of phenol by H₂O₂. J Hazard Mater, 2013, 262: 412-419.

[21] Kotaś J, Stasicka Z. Chromium occurrence in the environment and methods of its speciation. Environ Pollut, 2000, 107(3): 263-283.

[22] Park D, Yun YS, Park JM. Reduction of hexavalent chromium with the brown seaweed Ecklonia biomass. Environ Sci Technol, 2004, 38(18): 4860-4864.

[23] Pettine M, Campanella L, Millero FJ. Reduction of hexavalent chromium by H₂O₂ in acidic solutions. Environ Sci Technol, 2002, 36(5): 901-907.

[24] Kuznetsova NI, Kuznetsova LI, Likholobov VA. Catalytic properties of Cr-containing heteropolytungstates in H₂O₂ participated reactions: H₂O₂ decomposition and oxidation of unsaturated hydrocarbons with H₂O₂. J Mol Catal A Chem, 1996, 108(3): 135-143.

[25] Zhang L, Lay PA. EPR spectroscopic studies on the formation of chromium(V) peroxo complexes in the reaction of chromium(VI) with hydrogen peroxide. Inorg Chem, 1998, 37: 1729-1733.

[26] Sugden KD, Wetterhahn KE. EPR evidence for chromium(V) binding to phosphate and pyrophosphate: implications for chromium(V) DNA interactions. Inorg Chem, 1996, 35(13): 3727-3728.

[27] Maciel R, Sant’Anna GL Jr, Dezotti M. Phenol removal from high salinity effluents using Fenton’s reagent and photo-Fenton reactions. Chemosphere, 2004, 57(7): 711-719.

[28] De Laat J, Le Truong G, Legube B. A comparative study of the effects of chloride, sulfate and nitrate ions on the rates of decomposition of H₂O₂ and organic compounds by Fe(II)/H₂O₂ and Fe(III)/H₂O₂. Chemosphere, 2004, 55(5): 715-723.

[29] Gallard H, De Laat J. Kinetic modelling of Fe(III)/H₂O₂ oxidation reactions in dilute aqueous solution using atrazine as a model organic compound. Water Res, 2000, 34(12): 3107-3116.

[30] Santos A, Yustos P, Quintanilla A. Route of the catalytic oxidation of phenol in aqueous phase. Appl Catal B Environ, 2002, 39(2): 97-113.

[31] Liu L, Liu H, Zhao YP, et al. Directed synthesis of hierarchical nanostructured TiO₂ catalysts and their morphology-dependent photocatalysis for phenol degradation. Environ Sci Technol, 2008, 42(7): 2342-2348.

[32] Zazo JA, Casas JA, Mohedano AF. Chemical pathway and kinetics of phenol oxidation by Fenton’s reagent. Environ Sci Technol, 2005, 39(23): 9295-9302.