Processing Magazine

Researchers in Singapore develop water treatment method using tomato and apple peels

July 23, 2013

<photocredit>Copyright NUS OCR | Photography by Lionel Lin</photocredit>

A team of researchers from the National University of Singapore (NUS) has developed a water treatment method using the peels of apples and tomatoes.

Ramakrishna Mallampati, a Ph.D. candidate and lead researcher, says he wanted to develop a technique using materials that are easily accessible to address global potable water shortages.

Under the guidance of Associate Professor Suresh Valiyaveettil of the Department of Chemistry at the NUS Faculty of Science, Mallampati evaluated the effectiveness of tomato peel as an adsorbent by using different pollutants. He also studied the structure of the tomato peels to assess their efficiency as biomaterials to remove toxic metal ions and organic pollutants from water. In addition, factors such as the pH, nature and amount of adsorbent used for extraction were considered to establish the optimum conditions under which tomato peel could remove various pollutants from water.

His study revealed that tomato peels can effectively remove different contaminants in water, including dissolved organic and inorganic chemicals, dyes and pesticides, and they can also be used in large scale applications.

Similar to tomato peels, apple peels can also remove a range of dissolved water pollutants through the adsorption process. In order to enhance the ability of apple peels towards extraction of negatively charged pollutants, Mallampati immobilized naturally occurring zirconium oxides onto the surface of apple peels. Zirconium loaded apple peels were found to be able to extract anions such as phosphate, arsenate, arsenite and chromate ions from aqueous solutions. This method of water purification can also be used for large scale applications.

“In the quest of developing single adsorbent for all pollutants in water, we thought easily available and low cost biowaste will be efficient materials," Mallampati told Eco-Business. "We can use these peels for any kind of water but small modifications may require, if necessary.”

The findings were published in the Royal Society of Chemistry journal RSC Advances in September 2012 and in the May 2013 issue of the American Chemical Society journal ACS Applied Materials & Interfaces.