Magnetically Responsive Membranes for Fluid Filtration (and the Synthesis thereof)

Figure 1. The modified membranes with increased fluid velocity led to mixing – which caused the flow to change direction and/or velocity. This change appears as velocity vectors of varying direction and/or length as well as field lines with chaotic (non-parallel) pathways. This mixing reduces membrane colloidal fouling by reducing concentration polarization and deposition of particles onto the membrane surface.

Opportunity

Available for Licensing

IP Status

US Utility Patent: US 9132389

Inventors

At A Glance

Novel approach to reduce concentration polarization and fouling during filtration
Use of magnetically responsive micro-mixing membranes increase the efficiency of the filtration and increases the purity of the effluent
Important tool for separation and reaction engineering – e.g. reverse osmosis, nanofiltration, and ultra filtration

Licensing Director

Mandana Ashouri
Mandana.Ashouri@colostate.edu
970-491-7100

Reference No.: 11-004

Background

Polymer membranes are commonly used as filters for the purification of liquids. However, the performance of membrane filters can be limited by deposition of particulate matter on the membrane surface and concentration polarization, leading to membrane fouling. Fouling decreases membrane performance over time by reducing membrane capacity (throughput) and selectivity (ability to separate components of different types). Although membranes that respond to stimulus (e.g. modification of pH or temperature) have shown increased resistance to fouling, they all suffer from the major disadvantage that the characteristics of the bulk feed must be modified –typically an expensive and time-consuming task that may also degrade the desired product. Accordingly, there is still an unmet commercial need for fouling-resistant membranes that are adaptable to numerous feeds.

Technology Overview

Researchers in the Chemical and Biological Engineering Department at Colorado State University have developed a new type of responsive membrane that utilizes short polymer chains grafted to the surface of the membrane to stir the feed and suppress fouling. An oscillating magnetic field interacts with magnetic nanoparticles bonded to the ends of the polymer chains and induces the mixing at the membrane interface. The extent of stimulation is controllable and can be actuated during filtration without any adjustments of feed properties. Dead-end filtration tests using both DI water and idealized feed solutions have shown a strong magnetic response, exhibiting improved permeability and rejection capability of the membranes.

This magnetically-responsive membrane technology can be used to improve the performance of any membrane filter, including nanofiltration, microfiltration, and ultrafiltration membranes and is suitable for a variety of aqueous (water-based) and non-aqueous feed solutions in either dead-end or transverse configurations. These membranes should be of particular value in the filtration of wastewaters (e.g. naval bilge waters, coal bed methane wastewater) and other aqueous streams, including desalinization and dairy applications. The membranes are also suitable for filtration of non-aqueous solvent systems and recycling of catalysts, dyes and other high-value chemicals.

Features and Benefits

Microfiltration and nanofiltration membranes modified with short polymer chains and magnetic nanoparticles
Alternating magnetic field is applied to induce mixing at membrane surface and reduce fouling.
Reducing fouling improves membrane performance (capacity and selectivity) and membrane lifetime
Because no added chemicals or temperature/pH modifications are required to stimulate membrane, there is no modification of the bulk feed composition and no inadvertent degradation of product.
Application in purification of wastewater streams as well as non-aqueous solvent systems.

Last updated: May 2020

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