Simple cellulose filter thoroughly purifies syringe-injected water

While we've seen quite a few filtration systems for making polluted water drinkable, many are quite complex, or utilize costly materials. By contrast, an experimental new setup simply requires users to inject dirty water through a layer of cellulose.

Developed by scientists from The University of Texas at Austin, the prototype device consists of a roughly hockey-puck-shaped housing, inside of which is a hydrogel film supported by a membrane full of microscopic pores.

The hydrogel is in turn made up of "an intertwined web" of cellulose nanofibers. Cellulose is the most common organic compound on Earth – it can be easily and inexpensively obtained from a wide variety of readily available natural sources, such as plants.

When utilizing the device, users start by drawing water from a stream, lake or somewhere else, using a regular syringe. They then place the end of that syringe in a port on top of the filter, and inject the water into it.

As the water passes through the tiny gaps between the nanofibers, nearly 100% of the suspended-solid particles larger than 10 nanometers are trapped – bacteria and viruses typically exceed that size. As a result, the water which trickles out of the underside of the filter is rendered clean and drinkable. What's more, each filter can be used up to 30 times, and will biodegrade when discarded.

In tests performed so far, syringes as large as 1.5 liters (1.6 quarts) were utilized to collect muddy water, river water and water contaminated with microplastics, all of which were successfully purified using the filter. The scientists are now working on scaling up the technology, so it can treat larger quantities of water in one session.

"The pressing concern of particle-polluted water, particularly in remote and underdeveloped regions where people frequently rely on contaminated water sources for consumption, demands immediate attention and recognition," said the lead scientist, Prof. Guihua Yu. "Our system, with its high efficiency in removing diverse types of particles, offers an attractive yet practical solution in improving freshwater availability."

A paper on the research was recently published in the journal Nature Sustainability.

Source: The University of Texas at Austin