Dittmer, KaylaKaylaDittmerPaschalidis, LeandrosLeandrosPaschalidisNg-Brossard, ChloeChloeNg-BrossardOhde, DanielDanielOhdeLiese, AndreasAndreasLieseSkiborowski, MirkoMirkoSkiborowski2026-06-292026-06-292026-06-25Industrial & Engineering Chemistry Research (in Press): (2026)https://hdl.handle.net/11420/63658Enzymatic biotransformations can offer sustainable alternatives to conventional chemical processes, but their activity often strongly depends on the pH of the reaction solution. The urease-catalyzed hydrolysis of urea provides a mild route for ammonia production; however, this ammonia production inherently increases the pH in a buffer-free system, rapidly decreasing urease activity. In this work, we combine modeling and experiments to develop a buffer-free pH control strategy for the enzymatic hydrolysis of urea that relies on the dissolution of gaseous carbon dioxide (CO₂). CO₂, which is actually a byproduct of enzymatic urea hydrolysis, is deliberately added to regulate the pH and enhance productivity. A kinetic model for urea hydrolysis is coupled with a thermodynamic model of the acid–base equilibria in the aqueous phase to analyze and design the process. Bayesian optimization is applied to calculate the optimal partial pressures for CO₂ in the gas phase to maximize productivity. The resulting concept is successfully demonstrated experimentally, highlighting a practical approach with minimal downstreaming requirements to control pH in enzymatic reactions.en1520-50452026American Chemical Society (ACS)https://creativecommons.org/licenses/by/4.0/Technology::660: Chemistry; Chemical Engineering::660.2: Chemical EngineeringNatural Sciences and Mathematics::572: BiochemistryJournal Articlehttps://doi.org/10.15480/882.1737010.1021/acs.iecr.6c0091210.15480/882.17370