Waste water slip up: AAS assesses efficacy of banana peel remediation

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  • Published: Mar 15, 2011
  • Author: David Bradley
  • Channels: Atomic
thumbnail image: Waste water slip up: AAS assesses efficacy of banana peel remediation

Heavy metal slip up

Atomic absorption spectroscopy is being used to assess how well banana peel can filter heavy metals, such as copper, from waste water. Preliminary results look promising and could lead to an ecologically sound method of industrial cleanup that uses a renewable but otherwise wasted source material.

Domestic science folklore has had people using banana skins to clean everything from silverware to leather shoes and even the leaves of pot plants. However, scientists can now add purification of drinking water contaminated with potentially toxic metals, including copper and lead, to the list of uses for this otherwise wasted product. The team has demonstrated that minced banana peel works better as a water purification technology than other more conventional materials.

Gustavo Castro of the Department of Crop Science, Food Technology, and Socioeconomics at the State Public University in Ilha Solteira, Brazil and colleagues Laercio Caetano, Guilherme Ferreira, Pedro Padilha, Margarida Saeki, Luiz Zara, Marco Antonio Martines point out that there are numerous routes by which contaminants can enter waters. Commonly mining processes, runoff from farms, and industrial waste are probably the three most important ways that heavy metals can enter waterways and so have adverse health effects and a detrimental impact on the environment. They explain that current methods for removing heavy metals from water are not only expensive but several of the filtration substances are themselves toxic.

Heavy metal gets under skin

A cheaper and environmentally benign approach has focused on plant waste and other biomass materials, such as coconut fibres and peanut shells, which can apparently mop up harmful compounds and ions found in contaminated water. Castro and colleagues, in work supported by the São Paulo Research Foundation, have investigated whether another plant waste product available in abundance might be useful in waste water cleanup.

Using atomic absorption spectroscopy using an air−acetylene flame and electrothermal atomization in a graphite furnace to analyse samples before and after treatment the team has shown how minced banana peel can quickly chelate lead and copper from water more effectively than many other materials without any preparation other than mincing. They have also shown that the same banana peel filter can be used more than ten times without loss of metal-binding properties. They further point out that the kinetics of copper and lead uptake reach equilibrium within 10 minutes and extraction is favourable at pH 3 and above. Fourier transform infrared spectroscopy showed absorption bands of carboxylic and amine groups in the medium.

The team adds that the same approach for extracting metal ions from untreated river water might also be used in the determination of ionic concentrations.


 

Atomic absorption spectroscopy is being used to assess how well banana peel can filter heavy metals, such as copper, from waste water. Preliminary results look promising and could lead to an ecologically sound method of industrial cleanup that uses a renewable but otherwise wasted source material.

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