Sparged but not stirred: Rapid, ADH-NADH oxidase catalyzed deracemization of alcohols in a bubble column

We investigate in detail both the deracemization reaction rate and maximum conversion of (R,S)-1-phenylethanol a bubble column deactivation rates enzymes involved, alcohol dehydrogenase (ADH) NADH oxidase (nox2). Instead predicted ellipsoidal shape bubbles, we observe spherical all our experiments. Calculated values for area-specific mass transfer coefficient kLa sparged, but not stirred, solution ranged from 17 to 87 h?1. find that minimizing air–liquid interface over time results lowest nox2 deactivation. The onset dissociation beyond initial 50 h correlates with tenfold increase observed constant. highest (99%) deracemizing mM was reached shortest (6 h) if large air bubbles (diameter 2.6 mm) at slow flowrates (5 bubbles/s) were employed. A faster flowrate, which delivers more oxygen per unit time, increased resulted slower higher conversions ultimately incomplete (94%). Reaction under sparging 4–8 times than quiescent solution. Lastly, stirring did significantly aid (41% vs 37% after 12 caused enzyme (44 136 half-life solution).