Sonolytic degradation of hazardous organic compounds in aqueous solution

Abstract

Benzene, chlorobenzene, 1,2-, 1,3-, 1,4-dichlorobenzene, biphenyl, and polychlorinated biphenyls such as 2-, 4-chlorobiphenyl and 2,2'-dichlorobiphenyl in aqueous solutions have been subjected to sonolysis with 200 kHz ultrasound at an intensity of 6 W cm-2 under an argon atmosphere. 80-90% of initial amount of these compounds were degraded by 30-60 min of sonication when the initial concentrations were 10-100 mumol l-1. The degradation rate of these compounds increased with increase in their vapor pressures. In all cases of sonolysis of chlorinated organic compounds, an appreciable amount of liberated chloride ion was observed.

Sonochemical Degradation of Chlorinated Phenolic Compounds in Water: Effects of Physicochemical Properties of the Compounds on Degradation

“…The degradation also increases with the increase in chlorine functional groups that enhance reductive degradation as well as thermal fragmentation. Our results are consistent with the general observations that explain the effect of HO• scavenger on organic compound degradation: (a) t-BuOH quickly decomposes by oxidation and/or thermal fragmentation so that there is a limited amount of HO• to degrade the phenolic compounds (Okuno et al 2000), (b) the reaction of t-BuOH with HO• is significantly competitive with that of phenolic compounds at very high t-BuOH concentration, and (c) the degradation of relatively more oxidized PCP is greater than that for phenol and 2,4,6-TCP due to its strong reductive dechlorination activity.…”

“…The log K ow value reflects the rate of sonochemical degradation of these phenolic compounds, which concentrate onto the gas-liquid interface of bubbles during the reaction. Therefore, the accumulated phenolic compound on the gas-liquid interface and/or inside the gas bubble is effectively degraded by direct pyrolysis (Okuno et al 2000) reaction of HO• (Berlan et al 1994) and direct hydrolysis with water molecules (Yim et al 2002).…”

Humic acid and trihalomethane breakdown with potential by-product formations for atmospheric air plasma water treatment

“…Interestingly, the overall removal efficiencies achieved was found to be greatest for CHCL 3 and least for BF. This is attributed to the volatility of THMs [81], where CHCL 3 with vapour pressure of 26.3 kPa could more easily escape and react with the gaseous reactive species than BF at a vapour pressure of 0.6 kPa. Furthermore, the reaction of plasma active species with the sample also depends upon the hydrophobicity.…”

Sonolysis of chlorobenzene in the presence of transition metal salts

“…Shortly, ¤ Tel/Fax: +4021 2248348/+4021 3121601; Email: vinatorum@yahoo.com; mvinator@cco.ro Brought to you by | MIT Libraries Authenticated Download Date | 5/11/18 1:44 AM this means the creation of bubbles within a liquid followed, after several acoustic cycles, by a violent collapse that releases, locally, a tremendous amount of energy in the order of ¹ 5000 K and ¹ 1000 atm temperatures and pressures, respectively [1]. In the last few years the use of sonochemistry as a degradation technique for organic pollutants has blossomed [2,3,4,5,6]. Under ultrasonic irradiation, organic compounds are degraded by two mechanisms: volatile and apolar solutes such as chloroform and chlorobenzene are mainly pyrolyzed in the cavitation [7,8], while polar compounds are oxidized with reactive species formed by dissociation of water in bulk solution [9].…”

“…Chlorinated compounds are common contaminants of water. A series of studies have already been devoted to the sonodegradation of aqueous solution of halo-derivatives as: chlorophenols [10], o-chlorotoluene [11], trichloroethylene [12], dichlorobenzenes [5].…”