Sonolytic degradation of 2-chlorobiphenyl

Abstract

The sonolytic degradation of 2-chlorobiphenyl was investigated. Mass spectroscopy was used to detect the products of sonolytic degradation of 2-chlorobiphenyl. The results show that the products of sonolytic degradation, such as biphenyl, ethyl benzene, diethylbiphenyl, dibutylbiphenyl, phenol, propylphenol and di-tert-butyl phenol are produced by thermolysis and hydroxyl free radical reactions, in which biphenyl counts for almost 40% (mole fraction) of the mother compound and others are at trace level. Rapid accumulation of chloride ion shows quick dechlorination, and 78% organic chlorine is converted into chloride ion. Free radical scavengers, bicarbonate and carbonate, decrease the reaction rate of sonolytic degradation of 2-chlorobiphenyl significantly, and the pseudo 1st order rate constant of sonolytic degradation of 2-chlorobiphenyl decreases linearly with the natural logarithm of the concentration of the added free radical scavenger, showing that the pyrolysis and hydroxyl free radical reaction are the two major pathways for the sonolytic degradation of 2-chlorobiphenyl, in which the hydroxyl radical concentration is estimated to be 1×10⁻¹⁰mol/L.

Keywords

sonolytic degradation / 2-chlorobiphenyl / pyrolysis / hydroxyl free radical

References

[1] GoskondaS, CatalloW J, JunkT. Sonochemical degradation of aromatic organic pollutants [J]. Waste Management, 2002, 22(3): 351-356

[2] InceN H. Ultrasound as a catalyzer of aqueous reaction systems: the state of the art and environmental applications [J]. Applied Catalysis B: Environmental, 2001, 29(1): 167-176

[3] GonzeE. Wastewater pretreatment with ultrasonic irradiation to reduce toxicity [J]. Chemical Engineering Journal, 1999, 73(1): 93-100

[4] DavydovL. Sonophotocatalytic destruction of organic contaminants in aqueous systems on TiO₂ powders [J]. Applied Catalysis B: Environmental, 2001, 32(1): 95-105

[5] GondrxonN. Degradation of pentachlorophenol aqueous solutions using a continuous flow ultrasonic reactor: experimental performance and modeling [J]. Ultrasonic Sonochemistry, 1999, 5(2): 125-131

[6] HartE J, HengleinA. Sonochemistry of aqueous solutions: H₂-O₂ combustion in cavitation bubbles [J]. J Phys Chem, 1987, 91(4): 3 654-3 656

[7] CastellanosM, RieszR. ESR-spin trapping study on the sonochemistry of liquids in the presence of oxygen: evidence for the superoxide radical anion formation [J]. Ultrasonics Sonochemistry, 2001, 8(1): 17-22

[8] PetrierC, ReverdyG. Sonochemical degradation of phenol in dilute aqueous solutions: comparison of the reaction rates at 20 and 487 kHz [J]. J Phys Chem, 1994, 98(11): 10 514-10 520

[9] PetrierC, ReverdyG. Unexpected frequency effects on the rate of oxidative processes induced by ultrasound [J]. J Am Chem Soc, 1992, 114(8): 3 148-3 150

[10] HengleinH, GutierrezM. Chemical effects of continuous and pulsed ultrasound: a comparative study of polymer degradation and iodide oxidation [J]. J Phys Chem Ref Data, 1990, 19(12): 5 169-5 172

[11] ZhangGuang-ming, HuaTian-xing. Cavitation chemistry of polychlorinated biphenyls: decomposition mechanisms and rates [J]. Environ Sci Technol, 2000, 34: 1 529-1 534

[12] ZhangGuang-ming, HuaTian-xing. Ultrasonic degradation of trichloroacetonitrile, chloropicrin and bromobenzene: design factors and matrix effects [J]. Advances in Environmental Research, 2000, 4: 211-218

[13] BuxtonetG V. Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (OH/O) in aqueous solution [J]. J Phys Chem Ref Data, 1988, 17(2): 513-577