Are microbubbles magic or just small? a direct comparison of hydroxyl radical generation between microbubble and conventional bubble ozonation under typical operational conditions

• Application of microbubbles compared directly with conventionally sized bubbled for ozonation. No evidence microbubble collapse causing radical formation was seen. The level •OH-exposure is linked to the effective dose and pH system. Future ozonation system design should focus on those factors deliver •OH based benefits. application water treatment an emerging technology which has been shown significantly enhance gas–liquid contacting processes. When applied ozonation, mass transfer speed extent compound removal conventional bubbling techniques. One explanation as why systems outperform that shrink, spontaneously generate hydroxyl radicals thought removal. This study (mean diameter 37 ?m) bubble 5.4 mm) under identical conditions. experiments were normalised ozone determine whether generated more than 4-chlorobenzoic used probe proportion a given quantified. OH-exposure O 3 -exposure (the R ct ) compare systems. ratio mean c t Microbubble Conventional 0.73, 0.84 1.12 at 6, 7 8 respectively. Statistical assessment showed there no significant difference between found support hypothesis OH. Instead, future designs OH