Sonochemical degradation of chlorophenols in water

Abstract

Sonochemical degradation of dilute aqueous solutions of 2-, 3- and 4-chlorophenol and pentachlorophenol has been investigated under air or argon atmosphere. The degradation follows first-order kinetics in the initial state with rates in the range 4.5-6.6 microM min-1 under air and 6.0-7.2 microM min-1 under argon at a concentration of 100 microM of chlorophenols. The rate of OH radical formation from water is 19.8 microM min-1 under argon and 14.7 microM min-1 under air in the same sonolysis conditions. The sonolysis of chlorophenols is effectively inhibited, but not completely, by the addition of t-BuOH, which is known to be an efficient OH radical scavenger in aqueous sonolysis. This suggests that the main degradation of chlorophenols proceeds via reaction with OH radicals; a thermal reaction also occurs, although its contribution is small. The addition of appropriate amounts of Fe(II) ions accelerates the degradation. This is probably due to the regeneration of OH radicals from hydrogen peroxide, which would be formed from recombination of OH radicals and which may contribute a little to the degradation. The ability to inhibit bacterial multiplication of pentachlorophenol decreases with ultrasonic irradiation.

Structural basis for receptor specificity of influenza B virus hemagglutinin

“…Thus, the growth environment of chicken eggs imposes a strong selective pressure on influenza B virus toward losing the glycans at residue 194, with concomitant enhanced affinity for ␣(2,3)-linked sialic acids (40). Interestingly, the gain or loss of a glycosylation site at residue 194 seems to be an effective tool used by naturally occurring influenza B virus to modify its antigenicity (55,56). Similar strategy was also found by egg-adapted influenza A virus (2,40).…”

Ultrasonic cavitation induced degradation of Congo red in aqueous solutions

“…Over the past two decades, sonochemical degradation of organic pollutants in water has been extensively investigated [9][10][11][12][13]. Ultrasonic irradiation provides a way of onsite ·OH generation.…”

Degradation of azo dye acid red B on manganese dioxide in the absence and presence of ultrasonic irradiation

“…The chemical effects of high-intensity ultrasound result primarily from acoustic cavitation: the formation, growth, and implosive collapse of bubbles in liquids [15]. Acoustic cavitation generates sites of locally high temperatures and pressures for short period of time, which give rise to the H 2 O sonolysis with production of radical species (H • , • OH, HOO • ) and direct destruction of solute [9,16,17]. However, little information is available on heterogeneous sonochemical degradation of organic pollutants.…”