Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gel Filled Filter—More than a Pore

25.04.2014

Microgel-based thermoresponsive membranes for water filtration

Filtration using membrane filters is one of the most commonly used separation techniques. Modern developments are aimed at membranes with tailored separation properties as well as switchability. German scientists have now developed a very simple method for the modification of membranes through the inclusion of microgels. In the journal Angewandte Chemie, they introduce hollow-fiber membranes that demonstrate temperature-dependent flow and retention, thanks to thermoresponsive microgels.

The researchers from RWTH Aachen University and DWI—Leibniz Institute for Interactive Materials used commercially available hollow-fiber membranes used for the ultra- and microfiltration of water. Hollow-fiber filters consist of bundles of fibers made of a semipermeable material with a channel on the inside. The walls of the fibers act as the membrane. In order to modify the membranes, a team led by Matthias Wessling simply filtered microgel suspensions through them. This allowed the microgels to become embedded into the porous structure of the membrane.

A gel is a three-dimensional molecular network that is filled with a liquid. Unlike the liquid in a sponge, the liquid in the gel is tightly bound. Microparticles of a gel are called microgels. The researchers used microgels made of polyvinylcaprolactam that are stable to about 32 °C. Above this temperature, the gel structure collapses, letting the water out.

The hollow-fiber membranes used have an asymmetric pore structure with internal diameters of 30 nm (ultrafiltration) to 200 nm (microfiltration) and external diameters of several micrometers. The fibers can be loaded with the microgels either from the outside in or from the inside out. In the first method the gel particles penetrate partway into the pores and the outside is then coated with microgel. In the second method, gel particles are only found on the interior of the pores, but not in those pores that are very narrow. In both types of fibers, the microgel is so firmly adsorbed that it cannot be washed away either during filtration or back flushing.

The permeability of both types is significantly reduced relative to the untreated membrane, because the microgel makes the pores less accessible. Raising the temperature causes the microgel to shrink, increasing the permeability of the membrane; cooling reverses the effect. This switching mechanism could be an important method for an efficient cleaning of the hollow fiber when high flow rates are needed during a backwashing step at low temperatures.

“The modification of conventional hollow-fiber membranes with stimuli-responsive microgels provides a straightforward and versatile route to design functional membranes with new, tailored properties that allow for regulation of the permeability,” says Wessling. “Varying the chemical structures of the microgels allows for the introduction of specific functionalities into membranes, increasing the efficiency and selectivity of separation processes in water treatment and medical technology. We will further develop this versatile platform by fundamental research within the SFB Functional Microgels and Microgel Systems of the German Research Foundation (DFG).”

About the Author

Matthias Wessling is Alexander von Humboldt Professor at RWTH Aachen. His research aims to integrate selective mass transfer and conversion into micro-, meso- and macroscopic systems. In particular, he focusses on systems with functionalities controlled by tailored interfaces. Macroscopic systems are being analyzed, modeled and developed at his chair for Chemical Engineering at RWTH Aachen University (Aachener Verfahrenstechnik). At DWI, Matthias Wessling focuses on micro- and mesoscopic systems which integrate the basic principles of biological systems. The overall aim is to synthesize interactive materials systems inspired by nature.

Author: Matthias Wessling, RWTH Aachen (Germany), http://www.avt.rwth-aachen.de/

Title: Temperature-Modulated Water Filtration Using Microgel-Functionalized Hollow-Fiber Membranes

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201400316

Matthias Wessling | Angewandte Chemie International Edition

Further reports about: Filtration Gel Pore RWTH fibers membrane filters microgels modification permeability structure temperature

More articles from Life Sciences:

nachricht Not of Divided Mind
19.01.2017 | Hertie-Institut für klinische Hirnforschung (HIH)

nachricht CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland

19.01.2017 | Earth Sciences

Not of Divided Mind

19.01.2017 | Life Sciences

Molecule flash mob

19.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>