Membrane assisted reactive crystallization with multiple interfacial flow regimes for effective mass transfer control

•Two flow regimes were observed in membrane assisted reactive crystallization (MARC).•Reversible transitions between liquid layer and droplet can be achieved on membrane surface.•Controllable mixing and ions diffusion conditions were achieved via MARC.•Crystals with narrow nano/micro size distribution were obtained via MARC. Herein, membrane-assisted reactive crystallization (MARC) with effective interfacial flow regimes was proposed to achieve the effective mass transfer control during reactive crystallization. Three tube-shell side solution systems (EtOH-H2O, Butanol-H2O and H2O-H2O) were chosen to form different flow regimes on the membrane surface, including the microscale liquid layer and the uniform droplets. The fundamental mechanisms of ‘rising and falling tide’ phenomenon, and flexible layer thickness control were uncovered. A force analysis model was established to illustrate the transition behavior of the droplet and liquid layer on the membrane surface. Molecular simulations additionally demonstrated that MARC implemented various ion diffusion conditions in different solution systems. Compared to the conventional reactive crystallization, MARC with multiple flow regimes can achieve effective control of CaCO3 crystal size ranging from 700 nm to 3 μm and obtain uniform size distribution (coefficient of variation less than 15.1 %), which shed light on the advanced material manufacture with reactive crystallization process.