Novel Membrane Emulsification Method of Producing Highly Uniform Silica Particles Using Inexpensive Silica Sources

Abstract

A membrane emulsification method for production of monodispersed silica-based ion exchange particles through water-in-oil emulsion route is developed. A hydrophobic microsieve membrane with 15 μm pore size and 200 μm pore spacing was used to produce droplets, with a mean size between 65 and 240 μm containing acidified sodium silicate solution (with 4 and 6 wt% SiO₂) in kerosene. After drying, the final silica particles had a mean size in the range between 30 and 70 μm. Coefficient of variation for both the droplets and particles did not exceed 35%. The most uniform particles had a mean diameter of 40 μm and coefficient of variation of 17%. The particles were functionalised with 3-aminopropyltrimethoxysilane and used for chemisorption of Cu(II) from an aqueous solution of CuSO₄ in a continuous flow stirred cell with slotted pore microfiltration membrane. Functionalised silica particles showed a higher binding affinity toward Cu(II) than non-treated silica particles.