Tag Archives: bisphenol A

Textiles that clean pollution from air and water

I once read that you could tell what colour would be in style by looking at the river in Milan (Italy). It may or may not still be true in Milan but it seems that the practice of using the river for dumping the fashion industry’s wastewater is still current in at least some parts of the world according to a Nov. 10, 2016 news item on Nanowerk featuring Juan Hinestroza’s work on textiles that clear pollution,

A stark and troubling reality helped spur Juan Hinestroza to what he hopes is an important discovery and a step toward cleaner manufacturing.

Hinestroza, associate professor of fiber science and director of undergraduate studies in the College of Human Ecology [Cornell University], has been to several manufacturing facilities around the globe, and he says that there are some areas of the planet in which he could identify what color is in fashion in New York or Paris by simply looking at the color of a nearby river.

“I saw it with my own eyes; it’s very sad,” he said.

Some of these overseas facilities are dumping waste products from textile dying and other processes directly into the air and waterways, making no attempt to mitigate their product’s effect on the environment.

“There are companies that make a great effort to make things in a clean and responsible manner,” he said, “but there are others that don’t.”

Hinestroza is hopeful that a technique developed at Cornell in conjunction with former Cornell chemistry professor Will Dichtel will help industry clean up its act. The group has shown the ability to infuse cotton with a beta-cyclodextrin (BCD) polymer, which acts as a filtration device that works in both water and air.

A Nov. 10, 2016 Cornell University news release by Tom Fleischman provides more detail about the research,

Cotton fabric was functionalized by making it a participant in the polymerization process. The addition of the fiber to the reaction resulted in a unique polymer grafted to the cotton surface.

“One of the limitations of some super-absorbents is that you need to be able to put them into a substrate that can be easily manufactured,” Hinestroza said. “Fibers are perfect for that – fibers are everywhere.”

Scanning electron microscopy showed that the cotton fibers appeared unchanged after the polymerization reaction. And when tested for uptake of pollutants in water (bisphenol A) and air (styrene), the polymerized fibers showed orders of magnitude greater uptakes than that of untreated cotton fabric or commercial absorbents.

Hinestroza pointed to several positives that should make this functionalized fabric technology attractive to industry.

“We’re compatible with existing textile machinery – you wouldn’t have to do a lot of retooling,” he said. “It works on both air and water, and we proved that we can remove the compounds and reuse the fiber over and over again.”

Hinestroza said the adsorption potential of this patent-pending technique could extend to other materials, and be used for respirator masks and filtration media, explosive detection and even food packaging that would detect when the product has gone bad.

And, of course, he hopes it can play a role in a cleaner, more environmentally responsible industrial practices.

“There’s a lot of pollution generation in the manufacture of textiles,” he said. “It’s just fair that we should maybe use the same textiles to clean the mess that we make.”

Here’s a link to and a citation for the paper,

Cotton Fabric Functionalized with a β-Cyclodextrin Polymer Captures Organic Pollutants from Contaminated Air and Water by Diego M. Alzate-Sánchez†, Brian J. Smith, Alaaeddin Alsbaiee, Juan P. Hinestroza, and William R. Dichtel. Chem. Mater., Article ASAP DOI: 10.1021/acs.chemmater.6b03624 Publication Date (Web): October 24, 2016

Copyright © 2016 American Chemical Society

This paper is open access.

One comment, I’m not sure how this solution will benefit the rivers unless they’re thinking that textile manufacturers will filter their waste water through this new fabric.

There is another researcher working on creating textiles that remove air pollution, Tony Ryan at the University of Sheffield (UK). My latest piece about his (and Helen Storey’s) work is a July 28, 2014 posting featuring a detergent that deposits onto the fabric nanoparticles that will clear air pollution. At the time, China was showing serious interest in the product.

Filtration membranes with twice as much ability to remove unwanted materials from water

A March 26, 2015 news item on Nanowerk offers information about a new method for removing pollutants from water and some insight into the situation regarding bisphenol A (BPA) in Europe,

New types of membrane adsorbers remove unwanted particles from water and also, at the same time, dissolved substances such as the hormonally active bis-phenol A or toxic lead. To do this, researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB imbed selective adsorber particles in filtration membranes.

It was not until January 2015 that the European Food Safety Authority (EFSA) lowered the threshold value for bisphenol A in packaging. The hormonally active bulk chemical is among other things a basic material for polycarbonate from which, for example, CDs, plastic tableware or spectacles glasses are manufactured. Due to its chemical structure, bisphenol A is not completely degraded in the biological stages of treatment plants and is discharged into rivers and lakes by the purification facility.

Activated carbon or adsorber materials are already used to remove chemicals, anti-biotics [sic] or heavy metals from waste or process water. However, a disadvantage of these highly porous materials is the long contact time that the pollutants require to diffuse into the pores. So that as many of the harmful substances as possible are captured even in a shorter time, the treatment plants use larger quantities of adsorbers in correspondingly large treatment basins. However, activated carbon can only be regenerated with a high energy input, resulting for the most part in the need to dispose of large quantities of material contaminated with pollutants.

Also, membrane filtration with nanofiltration or reverse osmosis membranes, which can remove the contaminating substances, is not yet cost-effective for the removal of dissolved molecules from high-volume flows such as process or wastewater. Membranes filter the water through their pores when a pressure is built up on one side of the membrane, thus holding back larger molecules and solid particles. But the smaller the membrane pores are, the higher the pressure – and therefore the more energy – that is required to separate the substances from water.

A March 24, 2015 Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) press release, which originated the news item, goes on to describe their team’s new approach,

Researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart have opted for a new approach that combines the advantages of both methods. When manufacturing the membranes they add small, polymeric adsorber particles. The resulting membrane adsorbers can – in addition to their filtration function – adsorptively bind substances dissolved in water. “We make use of the porous structure of the membrane located underneath the separation layer. The pores have a highly specific surface so that as many particles as possible can be imbedded, and they also provide optimum accessibility,” says Dr. Thomas Schiestel, Head of the “Inorganic Interfaces and Membranes” working group at the Fraunhofer IGB.

“Unlike conventional adsorbers, our membrane adsorbers transport the pollutants convectively. This means that, with the water flowing rapidly through the membrane pores, a contact time lasting only a few seconds is sufficient to adsorb pollutants on the particle surface,” says the scientist. Up to 40 percent of the weight of the membrane adsorbers is accounted for by the particles, so their binding capacity is correspondingly high. At the same time the membrane adsorbers can be operated at low pressures. As the membranes can be packed very tightly, very large volumes of water can be treated even with small devices.

Functional adsorber particles

The researchers manufacture the adsorber particles in a one-step, cost-efficient process. In this patented process monomeric components are polymerized with the help of a crosslinking agent to generate 50 to 500 nanometer polymer globules. “Depending on which substances are to be removed from the water, we select the most suitable one from a variety of monomers with differing functional groups,” Schiestel explains. The spectrum here ranges from pyridine, which tends to be hydrophobic, by way of cationic ammonium compounds and includes anionic phosphonates.

Selective removal of pollutants and metals

The researchers were able to show in various tests that the membrane adsorbers remove pollutants very selectively by means of the particles, which are customized for the particular contaminant in question. For example, membrane adsorbers with pyridine groups bind the hydrophobic bisphenol A especially well, whereas those with amino groups adsorb the negatively charged salt of the antibiotic penicillin G.

“The various adsorber particles can even be combined in one membrane. In this way we can remove several micropollutants simultaneously with just one membrane adsorber,” says Schiestel, pointing out a further advantage. Equipped with different functional groups, the membrane adsorbers can also remove toxic heavy metals such as lead or arsenic from the water. Phosphonate membrane adsorbers, for example, adsorb more than 5 grams of lead per square meter of membrane surface area – 40 percent more than a commercially available membrane adsorber.

Cost-effective and regenerable

So that the membrane adsorbers can be used several times, the adsorbed pollutants have to be detached once again from the particles in the membrane. “Membrane adsorbers for bisphenol A can be fully regenerated by a shift of the pH value,” Schiestel explains. The concentrated pollutants can then be disposed off cost-effectively or broken down using suitable oxidative processes.

The regenerability of the membrane adsorbers also makes possible a further application: reutilization of the separated molecules. This additionally makes the technology attractive for recovering valuable precious metals or rare earth metals.

The Fraunhofer IGB is presenting the membrane adsorbers and other innovative technologies for water purification at the “Wasser Berlin International” Trade Fair and Congress from 24th to 27th March 2015 in Berlin. The IGB is in Hall 2.2, Stand 422.

While it’s too late to attend the presentation, here are two links and citations to papers concerning the work,

Removal of micropollutants from water by nanocomposite membrane adsorbers by Klaus Niedergall, Monika Bach, Thomas Hirth, Günter E.M. Tovar, and Thomas Schiestel. Separation and Purification Technology, Volume 131, 27 June 2014 DOI: 10.1016/j.seppur.2014.04.032

Nanostructured Composite Adsorber Membranes for the Reduction of Trace Substances in Water: The Example of Bisphenol A by Klaus Niedergall, Monika Bach, Thomas Schiestel, and Günter E.M. Tovar. Ind. Eng. Chem. Res., 2013, 52 (39), pp 14011–14018 DOI: 10.1021/ie303264r Publication Date (Web): May 16, 2013

Copyright © 2013 American Chemical Society

Both articles are behind a paywall.