Design, Fabrication, And Characterization Of A Coaxial-Flow Emulsion Device For The Production Of Porous Silica Spheres

Abstract

Silica sol-gel encapsulation of bacteria and enzymes is a proven bioremediation technology but can be limited by the production rate of the silica material. Because lab-scale production techniques were unsuitably slow, a coaxial emulsion device was designed, fabricated, and characterized to create silica spheres at a rapid rate, in a consistent fashion, with control over individual sphere size. Taking inspiration from microfluidics, a coaxial emulsion device was designed with multiple emulsion needles working in parallel and fabricated by machining and modifying commercially-available materials and equipment. The device was characterized in order to identify the range of parameters to produce a desired sphere size and to reduce sphere size distribution. Sphere size and distribution are functions of the gel flow rate, oil flow rate, and needle diameter, and considering dripping and jetting, the two modes of sphere formation.