While the banana peel has a reputation of just being a slippery hazard, it is actually useful for many things - Ranging from use as a fertilizer to curing warts and even, polishing shoes and silver. Now it turns out, that it can even help remove heavy metals from water.
The discovery was made by Brazilian environmental scientist and banana lover Gustavo Castro. The Sao Paulo University researcher had heard that the most nutritious part of the banana was not the inside, but the seemingly useless skin, and decided to investigate if that was indeed true.
His tests revealed the presence of nitrogen, sulfur and most importantly, organic compounds like carboxylic acids, that have the capability of binding with metals that they come in contact with.
To experiment if the acids in the peels would be effective in polluted water, he and some colleagues dried and minced some banana peels and added them to jars of water obtained from Brazil's Panama River, which is known to contain copper and lead. They also built filters by compressing the peels and then pushed water through them.
Not only did the peels perform better than existing purifiers like silica and carbon, but they also could also, be re-used eleven times before they stopped working! In addition to that, they are low cost, can easily be found all over the world and, leave behind no chemical residue. The only drawback is that they are not effective in killing bacteria.
While Mr. Castro who has published his findings in the American Chemical Society's Journal of Industrial & Engineering Chemistry Research, does not advocate this method for home use given that the amount of metal found in tap water is minuscule, he hopes that it will be adopted in waters located near large manufacturing plants. This is not the first time plant parts have been effective in removing toxins from water. In the past, waste from apples and sugar cane, as well as, coconut fibers and even peanut shells have shown similar qualities.
Resources: gizmag.com, NPR.org