“…However, according to Xu et al and Sordelet et al urea decomposes as follows: While Lv et al describe a hydrolysis reaction of urea in both acidic (, ) and basic environment (, ): and conclude from the initial drop in the reaction pH that the acidic hydrolysis reaction is taking place. However, studies focusing specifically on urea degradation in water conclude that hydrolysis of urea only takes place when specific enzymes are present, and a water assisted NH 3 elimination reaction has a lower activation barrier (): , For the decomposition of NH 4 HCO 3 , too, different reaction equilibria are reported, as shown above in eqs – and below (– and ): The section above makes clear that although the main reaction products of the decomposition reactions of urea and NH 4 HCO 3 are similar, the exact concentrations might differ from one reaction to another, depending on the concentration of reactants added, pH, reaction temperature and duration, and other chemical present (e.g., surfactants). However, since some of the ions are basic (carbonate, ammonium) and others acidic (carbon dioxide) understanding the decomposition reactions is inevitable in understanding the reaction mechanisms of the precipitation and thus for the design of reaction conditions.…”