Effect of salt addition on the coalescence process of droplets on fiber

Abstract

Fiber coalescence is an economical and effective technology for the treatment of oily wastewater. In this paper, the microscopic coalescence process of salt droplets on the fiber is studied using a high-speed camera and PIV, and the effect of salt on hydrodynamics and morphological evolution is discussed. The results show that the increase of salt concentration leads to a decrease of double layer force, a larger liquid bridge expansion, and a higher capillary wave propagation velocity. When the salt concentration is too high, the capillary wave propagation velocity decreases. A catchment region with a high velocity is formed near the traveling region of the capillary wave, and the velocity can reach 0.03 m/s. The attenuation coefficient of the oscillation process increases with the increase of salt content. By combining fiber and salt, the rate of droplet coalescence can be increased, and the production of secondary droplets can be reduced.