Filtration of Elastic Polymers and Spherical Gels through a Silica-Deposited Layer on a Porous Membrane

Takanori Hidane,Hidemi Kitani,Shintaro Morisada,Sachiko Furuta,Hidetaka Kawakita,Keisuke Ohto

doi:10.3390/membranes11010022

Abstract

A 120-nm silica suspension was permeated through a porous polyethylene (PE) hollow-fiber membrane, as was a solution of deformable elastic particles of poly(N-isopropylacrylamide) (PNIPAM) gel and dextran. The amount adsorbed and flux of permeation were analyzed with ordinary differential equations to obtain adsorption coefficients, maximum amounts adsorbed, and pore-narrowing factors. The thickness of the “silica-deposited layer” on the membrane was 1 μm. In a batch adsorption mode, 5.0 mg of PNIPAM gel and 30 mg of dextran were adsorbed on the PE membrane, with no adsorption on the silica. The PE membrane pores were narrowed by a secondary layer of adsorbed PNIPAM gel. When filtered through the silica-deposited layer, PNIPAM gel occupies gaps, resulting in a reduced permeation flux. Dextran passed through the silica-deposited layer and was partially adsorbed on the PE membrane. The modified membrane can control adsorption, filtration, and flux permeation, which leads to dynamic membrane separations.

Highlights

Microfiltration has been used for the separation of cells and microorganisms as well as protein and polysaccharide separations
The 120-nm silica suspension was permeated through the PE membrane for 50 min to form the silica-deposited layer on the membrane pores
The amount of dextran adsorbed on the PE membrane was higher than that of the PNIPAM gel (Figure 3)

Summary

Introduction

Microfiltration has been used for the separation of cells and microorganisms as well as protein and polysaccharide separations. To enhance the separation efficiency, pore regulation was performed by introducing polymers into the membrane and by forming a skin layer of polymers and inorganic materials on the pore surface. These dynamic membranes have a layer of deposited particles and polymers on the pore surfaces [1]. TiO2 and SiO2 particles have been deposited on membrane surfaces for water treatment and emulsion separations [2,3,4,5]. Deposited layers that enable adsorption and filtration can separate particles and molecules by size effects, and by adhesion

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Conclusion