Is That a Banana in Your Water?
Cole Poirier, Eugene Shen
Sir Winston Churchill
Floor Location : M 198 V

Toxic heavy metal overdoses in drinking water are lethal to humans. Chief among the threats are lead and copper, whose overdose symptoms include liver cirrhosis and death. Contaminated water can also carry lethal water-borne diseases, such as malaria and diarrheal disease. Sub-Saharan Africa has the highest rate of malarial and diarrheal deaths, with approximately 1.83 million combined deaths in just 2002. Furthermore, recent industrial development in sub-Saharan Africa has led to more heavy metals leaching into groundwater.rnrnInspired by a paper by Renata Castro, et al. in 2011, who found that banana peels extract heavy metals from water, our purpose was to determine through trials if bananas are a viable alternative to traditional heavy metal water filters. Developing countries in sub-Saharan Africa lack the financial means to buy traditional water filters. However, Uganda and Rwanda have the highest per capita consumption rate of bananas in the world. Bananas are an ubiquitous foodstuff in sub-Saharan Africa; their peels are zero-cost.rnrnBecause lead was too dangerous, we used a commercial aquarium iron supplement containing chelated iron (II) gluconate to pre-concentrate the iron in a fish tank of water. Our iron testing kit used hydroxylammonium chloride to reduce iron (III) to iron (II), and then 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, which creates a magenta-coloured compound with iron (II), allowing us to colorimetrically determine the concentration of iron in a solution.rnrnWe tested for differences in iron concentration based on different (commercial activated carbon vs. banana) filters, the surface area of banana peels, the time the filter is immersed in the solution, and the concentration of bananas/L of solution. We also tested for the concentration of iron/L in fresh water tainted with contaminated banana peels.rnrnOur results indicated that higher banana peel surface area and higher concentration of bananas filtered out more , as expected. However, immersing the filters for a longer amount of time actually increased the concentration of iron in solution. This result was extremely surprising and unexpected.rnThis result could have risen because of unknown chemicals interfering with the iron-banana bond. There also could have been more iron present in the original contaminated water than calculated; we cannot confirm this, because the colorimetric test is only accurate up to 1 mg of iron/L. This discrepancy could have been because tripyridyl triazine bonded to other metals present in tap water.rnrnIf we could rerun this experiment, we would appropriate more precise instruments using atomic absorption spectrometry, allowing multiple trials to be run at once. We would immediately test samples after taking them to avoid atmospheric contamination. We would use purified or distilled water before adding in the iron (II) gluconate to eliminate other metals' interference. Finally, we would run each test at least three times.rnrnNevertheless, banana peel filters did remove a significant amount of iron from contaminated water, and with Castro's results on copper and lead, banana peel filters seem to be a viable alternative to traditional water filters, especially in developing sub-Saharan regions. Our experiment supported our main hypothesis.