Featured Research

from universities, journals, and other organizations

MIT Develops Filters For Wastewater Treatment, More

Date:
December 12, 2000
Source:
Massachusetts Institute Of Technology
Summary:
Membranes that filter larger materials from others are key to wastewater treatment and a variety of other processes. Yet the membranes currently on the market are often easily clogged. Enter MIT Associate Professor Anne Mayes, who decided that the field was ripe for fresh ideas and has developed a way to not only make better filtration membranes, but also give those membranes additional applications.

Membranes that filter larger materials from others are key to wastewater treatment and a variety of other processes. Yet the membranes currently on the market are often easily clogged.

Enter MIT Associate Professor Anne Mayes, who decided that the field was ripe for fresh ideas and has developed a way to not only make better filtration membranes, but also give those membranes additional applications. For example, her team is modifying the membranes to encourage the attachment of living cells-a key goal of tissue engineering. Professor Mayes is in the Department of Materials Science and Engineering.

BLACK ART

To date, the manufacture of filtration membranes has been something of a "black art," principally using a process known as "immersion precipitation." A concentrated polymer solution is spread on a moving belt, skimmed to a thin and level coating, then immersed in a water-containing bath. There the polymer precipitates out of solution, forming a membrane with a suprisingly ideal structure for filtration: small surface pores, with larger channels in the bulk membrane structure.

Unfortunately, this process leaves a very small number of pores on the surface, and the materials that are sufficiently strong for filtering applications are hydrophobic, or water-repelling. Oil- or protein-containing solutions passed through such filters tend to clog or foul them.

In the wastewater treatment industry, cleaning and replacement costs associated with fouling cost some 47 percent of the total process costs. Granted, further treatments can lead to a fouling-resistant surface, but these extra fabrication steps drive up costs and don't always work well, since they treat only the outer surface of the membrane. The inner surfaces of the membrane channels remain foulant attractors.

POLYMER 'COMBS'

Professor Mayes' novel idea was to mix into the bulk membrane polymer solution a "comb" polymer composed of a hydrophobic backbone lined with short hydrophilic, or water-loving, "bristles."

When the membrane is cast from the mixed polymer solution, the different affinities of the comb and bulk polymers cause the combs to segregate to the membrane surface. Thus the membrane ends up with a hydrophilic outer surface and even a hydrophilic lining on the internal membrane channels.

"It turns out that this works extraordinarily well," said Professor Mayes. The presence of hydrophilic groups on the filtrant-exposed surfaces helps the membrane resist fouling.

What's more, the comb-containing membranes have a larger number of pores on the surface than membranes that don't include the additive. This increases the amount of solution that can be passed through the membranes. And the membranes heal themselves: if damaged by a caustic solution, a comb-containing membrane can be heated at approximately 90 degrees C in water to re-segregate excess combs from the bulk and re-line the damaged surfaces with hydrophilic material.

NEW CHEMISTRIES

Professor Mayes and her students are now working on comb backbones made of different materials in the hope of further adapting their approach to other membrane chemistries.

"We've been branching out in terms of our chemistry," Professor Mayes said. "We've developed a new route for the synthesis of these comb additives, and recently applied for a patent on the materials."

"We have other applications, too," Professor Mayes continued. These include tethering chelating agents to the comb "bristles" to trap heavy metals from a filtrant, and tethering cell-signaling ligands to the bristles to encourage cell attachment to, for instance, a membrane being used as an artificial tissue material. To explore bioengineering possibilities, she has teamed up with Professor Linda Griffith of the Department of Chemical Engineering and the Division of Bioengineering and Environmental Health to show that comb polymer additives modified with the cell-adhesion peptide RGD can be used to modulate cell attachment.

"We wanted to make a system where we could control the spatial distribution of ligands on the surface more specifically. Often cell signaling events require clustering of ligand receptors on the surface of cells, and that's what we hope to induce by mixing comb polymers modified with multiple ligands with those having no ligands." The researchers have demonstrated comb surface segregation in the manufacture of tissue-engineering scaffolds.

Professor Mayes' work is sponsored by the Office of Naval Research, the National Institutes of Health, and the Whitaker Foundation.


Story Source:

The above story is based on materials provided by Massachusetts Institute Of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Massachusetts Institute Of Technology. "MIT Develops Filters For Wastewater Treatment, More." ScienceDaily. ScienceDaily, 12 December 2000. <www.sciencedaily.com/releases/2000/12/001212070858.htm>.
Massachusetts Institute Of Technology. (2000, December 12). MIT Develops Filters For Wastewater Treatment, More. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2000/12/001212070858.htm
Massachusetts Institute Of Technology. "MIT Develops Filters For Wastewater Treatment, More." ScienceDaily. www.sciencedaily.com/releases/2000/12/001212070858.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins