Removal of Particulate Fines from Organic Solvents Using Water as Collector Droplets.

摘要

A PDMS-based microfluidic aspiration device was developed to carry out a systematic study of the capture of particles suspended in an organic liquid by using water as collector droplets. By applying a suitably strong negative pressure at one of the inputs relative to the port delivering the particles, a water drop was trapped at the constriction and then head-on and glancing collisions were implemented between particles and a water drop. The capture efficiency of particles was determined by a multi-particle tracking code developed in MATLAB. Simulations were performed to obtain a measure of particle interaction time with the drop surface. It was observed that at low capillary numbers O (10-4) , hydrodynamic drainage was not the rate limiting step for particle (O(10 mum) ) capture. The possibility of other hydrodynamic or thermodynamic processes such as bridge formation and contact line motion in particle capture, are discussed. The relationship between particle capture efficiency and velocity and radius of the collector droplets was mapped out. This work aims to provide insight into the feasibility of the use of an aqueous phase for collecting and separating fines from bitumen-solvent mixture by obtaining statistical data for particle-drop impingement process. Current methods for the removal of particulates such as centrifugation and solvent evaporation are energy-intensive, and carry potential emission hazards. Removal of fines using a water drop is much more energy efficient than the traditional methods. The device from this study will lead to fundamental investigations that will provide design guidelines for a mixer for effective particle removal in the oil sands industry.