Chemist Discovers New Use for Banana Peels

March 16, 2011 – Jen Noelken

Bananas have long been known for health benefits ranging from healthy bones to reducing stress.  More recently, a Brazilian scientist discovered another way the yellow skinned fruit can keep humans and the environment healthy.  A Sao Paulo researcher found banana peels can help extract heavy metal water pollutants. 

Lead, copper and other heavy metals can contaminate waterways from agricultural runoff and industrial waste.  With no surprise, heavy metals can cause health risks for both humans and other species including affects on the brain and nervous system.  Current trends of removing water pollutants rely on silica, cellulose and aluminum oxide to remove heavy metals from water.  However, these techniques carry potential toxic side affects of their own due to the presence of acids.   

Dr. Milena Boniolo, a chemist and recent PhD graduate from Federal University of Sao Carlos, Brazil received the distinct honor of discovering banana peels ability to help purify dirty water.  In an interview with Bloomberg Business Weekly in February 2010, Dr. Boniolo said she loves the idea of green chemistry.  She said giving importance to items before pitching them (such as fruit skins) is vital to solve environmental issues.  With that mind-set, Dr. Boniolo acquired the idea for banana skins after watching a television documentary about the amount of banana peels food industries discard.

Brazilian fast food industries pitch at least four tons of banana peels a week in Sao Paolo alone.  The massive amount of waste got Dr. Boniolo thinking about potential, practical uses for the peels.  With a PhD dissertation looming, she decided to focus her efforts into saving thousands of banana peels from landing in the garbage.  

Bananas are not indigenous to Brazil, but the country is the second largest banana producers after India.  Portuguese settlers brought the fruit to Brazil and since that time banana production has flourished.  A majority of the commercial crop of bananas come from the northeast region of Brazil, followed by the north.  Bananas are the most widely eaten fruit in the country with several varieties offered at local markets.  Banana selections in Brazil are compared to apple selections in North America or Europe. 

Dr. Boniolo experimented with the peels eventually developing a three step formula.  First, the banana skins were placed in pans and left in the sun to dry for about a week.  Next, the dried skins were ground into a fine powder.  After ground, the skins were passed through a sieve to keep particles the same size.  When the banana peels finished processing, the ground peel formula was mixed with contaminated water.  The results proved basic chemistry principles. 

Basic principle of chemistry states that opposites attract.  Banana peels are rich in negatively charged molecules which attract the heavy metal, positively charged water pollutants.  Dr. Boniolo found 5 mg of banana skin powder could clean 100 ml of heavily polluted water.  Her technique worked on removing metals such as cadmium, lead and nickel.  Around 65% of the tested water was decontaminated after 40 minutes.  Repeating the process could purify the water to almost 100%.  The same peel can be used several times and when the peel purification life is over, metals and peels can be separated for recycling.

The research process found the use of banana peels was “20 times more effective than other substances.”  The technique is also much cheaper than traditional methods because of bananas low costs and high availability.  Not to mention the process is much safer for humans and the environment.  Dr. Boniolo stated the use of bananas offer a very cheap and efficient way of removing heavy metal pollution.  Currently, she is looking for partners to expand the process to an industrial scale.  

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