Photosonochemical decomposition of aqueous 1,1,1 ‐ trichloroethane

Abstract

This study describes development of 1,1,1-trichloroethane removal from aqueous solutions. The decomposition of aqueous 1,1,1-trichloroethane is more extensive with combined photolysis and sonolysis process than each separately. The extent of decomposition is measured by gas Chromatograph for removal of CCl 3 CH 3 , by a turbidometric procedure for production of chloride ions, and Fourier transform infrared spectroscopy for solid product. The concept is to degrade CCl 3 CH 3 in water flow systems to chloride ions, which are removable by ion-exchange column.

Sonophotocatalytic reactors for wastewater treatment: A critical review

“…This optimum value of the volume of the effluent also depends on the operating conditions of the reactor mainly the magnitude of power supplied (which will decide the rate of generation of free radicals) and the type of the effluent in question (the rate constant for the reaction between the pollutant and free radicals is equally important). Toy et al (1990) obtained better results for the combination techniques at volumes as low as 3 to 4 mL, whereas Chen and Smirniotis (2002) reported that the synergistic effects of using the combination technique are more pronounced at lower volumes of treatment (relative enhancement was 82% at 50 mL, whereas it was 29% for 300 mL). It appears that too much cavitation at lower volumes can be detrimental (for individual operation or the combination technique), possibly attributable to the fact that the density of cavitation bubbles is higher in small volumes, which are continuously in the zone of influence of the transducers and result in relatively larger bubble sizes (ascribed to coalescence) decreasing the collapse intensity (Gogate and Pandit, 2000) and also possibly affecting the UV transmission rates.…”

Photolysis, Sonolysis, and Photosonolysis of Trichloroethane (TCA), Trichloroethylene (TCE), and Tetrachloroethylene (PCE) Without Catalyst

“…Without a catalyst, the additive or synergistic effects of UV and US were reported by Hamdaoui and Naffrechoux (2008), Naffrechoux et al (2003), and Rong et al (2003). Wu et al (2001) and Toy et al (1990) found an enhanced degradation efficiency using UV and US concurrently without a catalyst, although they did not indicate the reactions were either additive or synergistic.…”

“…Rong et al (2003) observed the synergistic effect of UV (260 nm; 0.4 to 2.1 W) and US (500 kHz; 16-24 W) on the decomposition of p-chlorophenol in a batch reactor. Toy et al (1990) observed that the extent of TCA decomposition with UVUS was greater than UV (200-watt Hg) and US (20 kHz) separately in a batch reactor study without a catalyst.…”

“…The theory, mechanisms, and potential usefulness of photosonolysis have been reviewed in the literature (Sato et al 2001;Halmann 1996;Serpone and Pelizzetti 1989). Compared to photolysis and sonolysis, photosonolysis is a newer water treatment technology and has been studied, especially in the removal of organic compounds, during the past two decades (Toy et al 1990; frequently detected groundwater contaminants (Moran et al 2007) and have been found in widespread areas from multiple sources (Fetter 1988). Although efforts have been made, the studies for the applicability of UV, US, and UVUS without a photocatalyst (e.g., TiO 2 ) to groundwater remediation or drinking water decontamination are very limited.…”

Sonochemical reactions: mass transfer and kinetic studies of a solid-liquid system

“…The rate of decon^osition of aqueous 1,1,1-trichloroethane was higher in the presence of both photolysis and sonolysis when con^pared to the use of either technique alone (Toy et al, 1990). When both techniques were used simultaneously, the authors referred to the process as '^photosonochemical".…”