The powder from leaves of the castor oil plant (Ricinus communis) has been successfully used as a filter to remove heavy metals from industrial wastewater. The experiment was carried out at the Biosciences Institute of the Universidade Estadual Paulista (IB-Unesp) in the city of Araraquara. “The castor oil plant is rich in protein, which is why it is used in animal feed. When we analyzed these proteins, we thought about using them as a filter and it ended up working,” says Gustavo Castro, professor at IB-Unesp and coordinator of the study that also included researchers from the Federal University of Mato Grosso do Sul (UFMS). “The plant’s dried ground leaves, after being washed in water and alcohol, were able to adsorb cadmium, lead, mercury, copper and zinc,” explains Castro, who published a scientific article on the experiment in the July 2013 issue of the journal Applied Surface Science. In this case, the adsorption process means that the metals are retained on the castor oil plant leaf surface through a chemical reaction. The new filter’s only requirement is that the pH of the water be six, which is easily achieved through the use of chemicals. Besides being a simple lost-cost material, it can also be re-used up to 18 times, and since it is organic, it is also easy to dispose of.
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