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 Identifying drug targets for leukaemia
02.05.2016 | The Hong Kong Polytechnic University

nachricht A cell senses its own curves: New research from the MBL Whitman Center
29.04.2016 | Marine Biological Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

Im Focus: New world record for fullerene-free polymer solar cells

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences (CAS). This work is about avoiding costly and unstable fullerenes.

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

Did you know that Heraeus PID lamps have been used in the measurement of air quality at the London airport?

02.05.2016 | Power and Electrical Engineering

Heraeus Noblelight at the Drupa 2016

02.05.2016 | Trade Fair News

Climate-exodus expected in the Middle East and North Africa

02.05.2016 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>