This paper presents the experimental results of liquid-liquid microflows in a coaxial microfluidic device with mass transfer.Three working systems were n-butanol + phosphoric acid(PA) + water,methyl isobutyl ketone(MIBK) + PA + water,30% kerosene in tri-n-butylphosphate(TBP) + PA + water.The direction and intensity of mass transfer were adjusted by adding PA in one of two phases mutual saturated in advance.When PA transferred from the organic phase to the aqueous phase,tiny aqueous droplets may generate inside the organic phase by mass transfer inducement to form a new W/O/W flow pattern directly on some special cases.Once the PA concentration was very high,violent Marangoni effect could be observed to throw part of organic phase out of droplets as tail.The interphase transfer of PA could expand the jetting flow region,in particular for systems with low or medium inter-facial tension and when the mass transfer direction was from the aqueous phase to the organic phase.
This paper reviews recent development and achievements in controllable preparation of nanoparticles, micron spherical and non-spherical particles, using microfluidics. A variety of synthesis strategies are presented and compared, including single-phase and multiphase microflows. The main structures of microfluidic devices and the fundamental principles of microflows for particle preparation are summarized and identified. The controllability of particle size, size distribution, crystal structure, morphology, physical and chemical properties, is examined in terms of the special features of microfluidic reactors. An outlook on opinions and predictions concerning the future development of powder technology with microfluidics is specially provided.
Guangsheng Luo Le Du Yujun Wang Yangcheng Lu Jianhong Xu
This study presents a novel process of in situ surface modification ofCaCO3 nanoparticles using a multiple- orifice dispersion microreactor. CO2/Ca（OH）2 precipitation reaction was employed to prepare CaCO3 nanoparticles with sodium stearate surfactant. Synthesized CaCO3 products were characterized by ther- mogravimetric analysis （TGA）, infra-red （IR）, X-ray diffraction （XRD）, transmission electron microscopy （TEM） and Brunauer-Emmet-Teller analysis （BET）. The effect of various operation parameters on nanopar- ticles and the dosage of sodium stearate were determined. The results showed that the preparation process could be precisely controlled with efficient mass transfer process. The particles were highly hydropho- bic with a contact angle of 117~ and monodisperse with an average size of 30 nm. The adsorptions of sodium stearate and calcium ion on solid particles during the in situ surface modification process were investigated.
