How pineapple leaves help clean water and solve crimes

Bienvenu Gael Fouda Mbanga, a research fellow in environmental analytical chemistry at Nelson Mandela University in Gqeberha, Eastern Cape, explains how discarded pineapple leaves can successfully separate toxic copper from industrial wastewater and even assist forensic units.

- Bienvenu Gael Fouda Mbanga

In South Africa, manufacturers of pineapple juice and other pineapple products discard thousands of tons of pineapple leaves every year, with most ending up in dumpsites.

The leaves are seen as agricultural waste and usually treated as useless. However, they can be converted into something that solves real-world problems; a powerful resource for environmental protection and security.

This involves turning them into a special kind of nanoparticle. (Nanoparticles are tiny materials no bigger than 0,0001mm in size.) I'm part of a team of nanomaterial chemists who focus on making new materials from waste like pineapple leaves. We set out to discover if we could turn pineapple leaves into a nanoparticle powder that could adsorb (hold a substance on the surface of a material, forming a thin film) copper from wastewater.

We found that it could. Once the pineapple leafbased nanoparticles had adsorbed the copper, they could be ground into a powder that forensic investigators could use to dust for fingerprints.

Our research filled a gap. It is the first time that an agricultural waste-derived adsorbent made into nanoparticles has been used to soak up heavy metals from water and then be reused in forensic science, at a low cost.

A bonus is that pineapple leaves cost nothing. While some are being turned into disposable diapers and others are left on pineapple fields to compost, most are thrown away on landfills or even burnt on site.

Transforming the waste into a useful product supports the idea of a circular economy: keeping products in use by reusing and regenerating them as much as possible.

Products that clean up the environment and those used in forensic science have traditionally been researched separately. Developing one product that can do both at a low cost is important.