Ultrasonic Induced Dehalogenation and Oxidation of 2-, 3-, and 4-Chlorophenol in Air-Equilibrated Aqueous Media. Similarities with Irradiated Semiconductor Particulates

Sonochemical Treatment of Water Polluted by Chlorinated Organocompounds. A Review

“…In addition, acetylene, methane and ethane should be formed along with carbon dioxide. Similar conclusions were reported for atrazine at 20 and 500 kHz [58] and by Serpone et al [57] using 20 kHz ultrasound field, where chlorophenols were nearly quantitatively dechlorinated, with CO 2 as a detected product. At 1.7 MHz, the degradation efficiency decreased to values lower than 20% at lower concentrations, or even 3% at higher concentrations [60].…”

“…In addition, specific studies, such as the evolution of the pH [39] to acidic values, or the correlation of the molecule properties (vapor pressure) with the kinetics of the process and degradation mechanism [13,40,41,42,43] have been reported. Not only aliphatic compounds but also chlorinated aromatic compounds such as chlorotoluenes [ 44 ], chlorobenzenes [ 45 , 46 , 47 , 48 , 49 ] mixtures of chlorobenzene with trichloroethylene [ 50 , 51 , 52 ], p-chlorobenzoic acid [ 53 ], PCBs [ 54 ], chlorophenols [3,35,48,55,56,57,58,59,60,61] and chlorinated pesticides [58,62,63] have also been the subjects of study, providing a wide range of examples from volatile, nonvolatile, hydrophobic and hydrophilic compounds and their respective behaviors. In the following, the general trends of the operational variables reported in literature and those specifically observed for chlorinated compounds are presented.…”

“…Experimentally, some authors have reported no influence in studies carried out with chlorinated compounds such 1,1,1-trichloroetane at concentrations between 0.16 and 1.27 mM [41] or carbon tetrachloride [31]. However, other authors have found an influence not only for volatile [44,47] but also for non-volatile [53,57] halogenated compounds. Yiang et al [49] have detected pseudo-firstorder reaction kinetics with a significant effect of the initial substrate concentration on the decomposition rate of volatile compounds such as chlorobenzenes, although pyrolytic reactions are expected to follow simple first-order kinetics.…”

“…Other chlorinated organocompounds, now non-volatile such as p-chlorobenzoic acid [53], or even highly hydrophobic and non-volatile such as PCBs, have also been studied [54]. Chlorophenols have also been extensively studied [56,57]. Petrier et al [56] have proposed that chlorophenol is degraded with a scheme of radical reactions occurring most probably in the solution, because chloride appears very soon after sonication has been started and CO 2 evolution appears after a lag time.…”

Ultrasonically Enhanced Voltammetric Analysis and Applications: An Overview

“…radicals is higher at 514 kHz than at 20 kHz [49]. The hydroxyl radical has been shown to be responsible for many chemical effects such as the degradation of chlorophenols [54,55] , cyanide [56] and the treatment of waste water [57].…”