New Material: Nanoparticle Coated Sponge Can Easily And Quickly Remove Heavy Metals From Water

An experimental new sponge can make the process of removing heavy metal pollutants from water easier than before. With only one treatment, the equipment can reduce the polluted water to a safe and drinkable level. Based on two previous studies, scientists at Northwestern University in Illinois are developing this technology.

Researchers began to use a cheap commercially available cellulose sponge and put it into the slurry mixed with manganese gobi stone nanoparticles. Then they take it out, let it dry, and wash it with water to wash away the scattered particles.

The result is a sponge with a high surface area nano particle coating, whose thickness is only tens of nanometers. The choice of manganese doped gobi stone particles is not only because they can absorb lead ions, but also because they are cheap and non-toxic to human body.

When the sponge is immersed in tap water containing more than one millionth of lead, it will seal the lead ion so that it can no longer be detected in the water, which makes the water safe to drink.

More importantly, lead can then be removed from the sponge by rinsing it in weakly acidic water. It is conceivable that these recovered lead can be used for battery and other products, and the washed sponge can be reused to treat more polluted water. It may not be very effective in the subsequent cycle, although it can still remove more than 90% of the lead ions from the sample. 　

Using different types of nanoparticles, scientists can also remove cobalt from water

Scientists have now developed a platform called Nano SCHeMe to guide other teams to select different types of nanoparticles to chelate different types of heavy metals.

"The presence of heavy metals in water supply is a huge public health challenge for the whole world," said Professor Vinayak Dravid, senior author of a paper on the study. "This is a huge problem, and we need a solution that can be easily, effectively and cheaply deployed. This is where our sponge appears. It can clean up pollution and then be reused.".

This paper was recently published in ACS ES&T Water.