Removal of multiple contaminants from water by supported ionic liquid phases

January 13, 2017, Wiley
Credit: Wiley

Fresh, clean water coming directly from the tap is a true luxury. In developing countries, people often have no choice but to use a contaminated river for drinking water. Water filters can help by quickly converting polluted surface or ground water into safe drinking water. In the journal Angewandte Chemie, researchers have now introduced a novel multifunctional composite material that removes inorganic, organic, radioactive, and microbial impurities from water.

Usually, purification involves a series of filters, each designed to remove a single type of impurity. In contrast, this new filter material is an all-rounder. Scientists from the Universities of Ulm (Germany) and Zaragoza (Spain) have now seized upon a relatively new approach for designing materials, which allows molecular components to be assembled into multifunctional composites called SILP materials (supported ionic liquid phases). An ionic liquid is a salt that is melted at room temperature, making it liquid without being dissolved in a solvent. When such an ionic liquid is adsorbed onto a solid substrate it forms a solid with properties that can be selectively tuned through chemical modification.

The researchers led by Scott G. Mitchell and Carsten Streb have now produced the first SILPs based on polyoxometallates (POM). POMs are molecular transition metal-oxygen clusters in which the metal atoms are bridged by oxygen atoms to form a three-dimensional network. For the new filter materials, they selected polyoxotungstate anions. These anions have a binding site which can trap heavy metal ions. The counterions they selected are voluminous tetraalkylammonium cations known for their antimicrobial effect. The resulting ionic liquids are hydrophobic, immiscible with water, and form stable thin layers on surfaces. By using a porous silicon dioxide support, the researchers obtained dry, free-flowing powders that are easy to transport and handle.

In laboratory experiments, the anions of the new composites reliably removed lead, nickel, copper, chromium, and cobalt ions. Radioactive uranium in the form of UO22+ was trapped directly by the silicon dioxide support. Similarly, the water-soluble blue trityl dye commonly used in the textile industry was also removed as a result of the lipophilic character of the ionic liquid. The antimicrobial cations effectively halt the growth of E. coli. bacteria.

The researchers hope that their new "POM-SILP" filter materials will form the basis for the development of contaminant-specific chemically designed filter systems that can be used for the reliable purification of water in remote areas and developing nations, as well as after natural disasters and chemical accidents.

Explore further: Fast, safe solvent for metal decontamination discovered

More information: Sven Herrmann et al. Removal of Multiple Contaminants from Water by Polyoxometalate-Supported Ionic Liquid Phases (POM-SILPs), Angewandte Chemie International Edition (2017). DOI: 10.1002/anie.201611072

Related Stories

Fast, safe solvent for metal decontamination discovered

September 20, 2016

The solvents currently used to remove specific metals from water all have disadvantages: safety risks are high, the process is slow, they are expensive or not very environmentally friendly. Researchers at TU/e have now produced ...

Revolutionary graphene filter could solve water crisis

March 10, 2016

A new type of graphene-based filter could be the key to managing the global water crisis, a study has revealed. The new graphene filter, which has been developed by Monash University and the University of Kentucky, allows ...

Coffee-infused foam removes lead from contaminated water

September 21, 2016

Coffee is one of the most popular drinks in the U.S., which makes for a perky population—but it also creates a lot of used grounds. Scientists now report in the journal ACS Sustainable Chemistry & Engineering an innovative ...

Scientists develope new agents to battle MRSA

March 25, 2009

Experts from Queen's University Belfast have developed new agents to fight MRSA and other hospital-acquired infections that are resistant to antibiotics. The fluids are a class of ionic liquids that not only kill colonies ...

Recommended for you

Producing defectless metal crystals of unprecedented size

October 19, 2018

A research group at the Center for Multidimensional Carbon Materials, within the Institute for Basic Science (IBS), has published an article in Science describing a new method to convert inexpensive polycrystalline metal ...

Nanodiamonds as photocatalysts

October 19, 2018

Climate change is in full swing and will continue unabated as long as CO2 emissions continue. One possible solution is to return CO2 to the energy cycle: CO2 could be processed with water into methanol, a fuel that can be ...

Researchers unfold secret stability of bendy straws

October 18, 2018

Collapsible dog bowls, bendable medical tubes and drinking straws all seem to work on a common principle, snapping into a variety of mechanically stable and useful states. Despite the many applications for such "designer ...

Shining light on the separation of rare earth metals

October 18, 2018

Inside smartphones and computer displays are metals known as the rare earths. Mining and purifying these metals involves waste- and energy-intense processes. Better processes are needed. Previous work has shown that specific ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.