New polymer material offers possibility of cheap, clean drinking water for heavily polluted areas

Achieving affordable clean drinking water for households in polluted areas could be a step closer after Chinese scientists developed a polymer material that can filter three major pollutants – heavy metals, dye and oils – efficiently and cheaply.

In a paper in the latest issue of Scientific Reports, professor Deng Weiqiao and colleagues detailed the capabilities of the material, called perfluorous conjugated microporous polymer, one gram of which can absorb more than 800 micrograms of lead ions.

The same amount of active carbon, the most common material used in family drinking water machines, could remove less than 22 micrograms.

“All other chemical absorbing materials were developed to deal with specific polluting scenarios, such as oil spills. None of them could remove all the three major types of pollutants simultaneously, making it difficult to guarantee drinking water safety in areas with multiple sources of pollutions,” said Deng, researcher with the Chinese Academy of Sciences’ Dalian Institute of Chemical Physics in Liaoning province.

“Our material may find its biggest application in household water filters. Not only does its performance far exceed any material on the market today, but the polymer is reusable. Just bathe it in alcohol and all the pollutants will be removed and it can be reused.”

The polymer’s pollutant absorption capability came from its unique physical structure, according to the paper.

Its surface was super-hydrophobic, meaning it would not bond with water molecules, allowing it to stay dry all the time. Meanwhile, the fluorine atoms in the polymer would pull positively-charged metallic ions towards them due to their high electro-negativity.

The polymer is highly porous has a large surface area for better contact with the water and pollutants.

Deng said more work was underway to bring the material from the labouratory to the factory.

One major challenge was adding the fluorine atoms to the polymer, which involved numerous chemical reactions that took considerable effort to achieve.

A delicate manufacturing process meant the new material would not be really cheap, Deng said.

It would be too expensive, for instance, to be used in waste water treatment plants, which require large quantities absorption materials in large quantity. But it would be an affordable solution to family drinking systems, costing 1,000 to 2,000 yuan (US$160-320), competitive with the prices of mainstream products at present.

Deng said he planned to work with a chemical company on mass production of the polymer. At present the researchers can only produce a few grams of the material in test tubes daily, and their goal was to boost the output to a few hundred tons per year, he said.