The Intersection of Plants and People
For some twenty years, Dr. Shyam Shukla has been systematically testing natural waste materials to see which ones could remove harmful metals from contaminated drinking water. His goal has been to provide impoverished populations across the globe with a method that will make their water cleaner and healthier to drink. After years of persistence, he and his research team have found a way to do it. Their most recent findings were presented at the 246th National Meeting of the American Chemical Society.
“Initially, the road was rough trying to narrow down the material,” Dr. Shukla says. “And now it sounds so simple, but at one point, it was not.”
In Dr. Shukla’s lab at the University of Lamar in Beaumont, Texas, a long list of materials were tested, including psyllium husk, sawdust, lemon peel, lime peel, onion, garlic, crab shells and candlenut — the fruit of a tree grown in tropical and subtropical areas for food and medicine. What finally worked best to remove metal ions from water is something so prevalent worldwide, and so commonly tossed into waste bins, that the answer is surprising: orange and banana peels, the latter being Dr. Shukla’s most recent discovery.
With the help of researchers Dr. Andrew Gomes and Prof. Alka Shukla, Dr. Shukla found a method that he refers to as “L3 Technology” — low-cost, low-tech, and locally available.
The ingredients needed for the technology are merely saved banana and orange peels, and empty tea bags, or a similar material, such as cloth. Rather than creating a filtering mechanism that must be shipped and distributed to areas where the drinking water is contaminated, the researchers hope to educate the public so that they can independently improve what is so fundamental to their own health.
“They can make their own; they don’t have to depend on me,” Dr. Shukla explains. “They don’t have to look up to us to do anything.”
In the banana study, dried peels from India were ground into a powder, then placed into empty tea bags. The bags were then steeped in water containing harmful metals. The process of clearing out the metals involves a natural interaction in which the metal ions are drawn to the powders, and are adsorbed. Adsorption is when a material adheres to the surface of another material, rather than being absorbed, which would mean it soaked through the entire substance. Grinding the banana peels into a powder creates more surface area for the metal ions to cling to, making the removal of metals even more successful.
As the researchers found, the metal ions are especially attracted to a chemical compound naturally found in many fruits.
“The crucial issue here is the pectin,” says Dr. Gomes. “That is what is responsible for removing the toxic metal.”
Pectin, abundant in both banana and orange peels, is often sold as an ingredient in grocery stores for making fruit jelly, jam, and dessert gelatin.
For the banana peel powder study, the researchers placed metal ions from lead, barium, cadmium, nickel and silver in distilled water. Lead has been shown to not only cause severe neurological damage and kidney disease, but also to affect human reproduction. Cadmium is a toxic metal known to cause serious kidney damage, while barium has the potential to trigger abnormally high blood pressure. Nickel and silver have been linked to health problems in both humans and in lab animals. These particular metals were used in the study because the U.S. Environmental Protection Agency has identified them as hazardous drinking-water contaminants.
After researchers steeped the banana peel powder in a neutral-PH solution of distilled water and metal ions, the results were impressive. Lead was removed from the water by 91 percent, cadmium by 78 percent, barium by 60 percent, silver by 80 percent and nickel by 67 percent. In five to eight minutes, metal ions were removed from 100 mL of water (almost 1/2 U.S. cup) using one tea-bag of powder.
Dr. Shukla says that one highlight of this particular study is how the researchers observed the adsorption of so many metals simultaneously. Like people trying to cram into an elevator with only so much space, the metals will compete with one another to adhere to the fruit powder. If only one metal were present in the water, the percentage results of removal would go up even higher, Dr. Shukla says.
Dr. Shukla and Dr. Gomes, originally from India and from Bangladesh respectively, have seen firsthand the shocking condition of drinking water in poverty-stricken and rural areas.
“My heart bleeds for the people who are in the unfortunate situation to drink water which is essentially killing them,” Dr. Shukla says.
Earlier this year, the World Health Organization (WHO) and UNICEF released their 2013 report on drinking water and sanitation worldwide. While efforts to improve drinking-water sources have made an encouraging impact, the report states that “an estimated 768 million people did not use an improved source for drinking-water in 2011 and 185 million relied on surface water to meet their daily drinking-water needs.”
Because most people around the world understand how to use tea bags and have easy access to them, the method is especially useful to those living in impoverished conditions. They cannot afford to add a technology such as activated charcoal filters to their day-to-day existence. Bananas and oranges are relatively inexpensive and plentiful around the world. Once ground into powder, the peel technology is portable for the many people in India and Asia who rely greatly on trains for transportation.
“So if I’m traveling by train, a journey lasting twenty hours sometimes, I can be carrying the tea bags in my pocket,” says Dr. Shukla.
Wherever water looks suspicious, out come the tea bags, which not only help purify the water, but, according to the researchers, impart a slight, pleasant, fruit taste.
Dr. Shukla and his team are currently working with institutes in India and Bangladesh to begin educating the public about their discovery.
The trio are also studying a photocatalytic process which uses the sun and activating chemicals to quickly kill off bacteria and remove organic compounds. The researchers hope to incorporate this system as “Stage Two” of their program.
As the purity of existing water and also the availability of water become more pressing concerns worldwide, research such as theirs becomes imperative to human life. Removal of metals like lead, known to cause brain damage in children, is a top concern for Shukla.
“Do we want to subject our next generation to such horrors? I do not accept it,” Dr. Shukla says, adding that a solution to the crisis is at hand. “If we have the material, let’s do it.”