Homogeneous precipitation by enzyme-catalyzed reactions. 2. Strontium and barium carbonates

Catalytic decomposition of urea by enzyme urease in aqueous strontium and barium chloride solutions was used to rapidly precipitate witherite (BaCO3) and strontianite (SrCO3) particles at room temperature. At the early stages of the process, uniform spheroidal particles were generated, which were shown to consist of nanosized subunits. On continuous aging of the same systems the additionally precipitated alkali earth carbonates grow as whiskers onto original core particles, which eventually fully transform into crystalline rodlike clusters.