Main content area

Homogeneous and Heterogeneous Nucleation of Potash Alum in Drop-Based Microfluidic Device

Shi, Huanhuan, Xiao, Yan, Huang, Xin, Bao, Ying, Xie, Chuang, Hao, Hongxun
Industrial & engineering chemistry process design and development 2018 v.57 no.38 pp. 12784-12791
alum, cameras, crystals, droplets, filtration, geometry, models, monitoring, oils, polytetrafluoroethylene, probability, process design, silicone, surface tension, viscosity
In this work, homogeneous and heterogeneous nucleation of potash alum were investigated using a drop-based microfluidic device made of a T-junction and transparent Teflon tubes. Monodisperse droplets were formed through the T-junction geometries, and their sizes could be adjusted by changing the velocities and viscosity of solutions and silicone oil. Ideal droplets which acted as independent crystallizers were successfully obtained. By monitoring each droplet using microscope equipped with a high-speed camera, probabilities of droplets without crystals at different time were determined. By applying or not applying filtration to the experimental solutions, both homogeneous and heterogeneous nucleation were observed. Different models were used to correlate the probability data to derive nucleation rates of potash alum under different conditions. The obtained nucleation rates from homogeneous and heterogeneous nucleation were compared and discussed. The nucleation parameters such as interfacial tension under different conditions were also determined and discussed.