Banana peels have many unexpected uses: polishing silverware, leather shoes, and the leaves of house plants. Gustavo Castro and colleagues, IB-UNESP, São Paulo, Brazil, have now shown that water purification can be added to the list.

Minced banana peel was shown to extract lead and copper ions from water above pH 3. The maximum adsorption capacities for Cu(II) and Pb(II) were 20.97 and 41.44 mg g⁻¹, respectively. These absorption capacities are higher than those of other materials used in metal ion extraction, such as sawdust and expanded perlite. Only modified silicas had higher absorption capacities. Banana peels did not require chemical modification and are cheap, unlike modified silica.

The team believes banana peels could be used to treat water discharged from mining processes, farms, and industrial wastes.

• Banana Peel Applied to the Solid Phase Extraction of Copper and Lead from River Water: Preconcentration of Metal Ions with a Fruit Waste
  R. S. D. Castro, L.Caetano, G. Ferreira, P. M. Padilha, M. J. Saeki, L. F. Zara, M. A. U. Martines, G. R. Castro,
  Ind. Eng. Chem. Res. 2011, 50 (6), 3446–3451.
  DOI: 10.1021/ie101499e