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Plastic Fantastic: turning plastic pollution into cleaning agents

26 February 2018

Bristol Scientists have discovered a way to re-use your plastic waste to breakdown harmful substances in waste water supplies, as described by a paper published in ACS Applied Materials & Interfaces

With the recently released BBC series ‘Blue Planet II’ highlighting the scale of plastic debris (so-called “white pollution”) in the oceans, developing processes to breakdown, recycle or re-use waste plastics is of critical importance. In response to David Attenborough’s series Greenpeace campaigner, Tisha Brown told The Guardian that "decades-long use of almost indestructible materials to make single-use products was bound to lead to problems".

Another pressing environmental problem is the wide range of toxic and hazardous substances, including synthetic dyes, which are continuously being released into industrial wastewaters, mostly due to lack of effective treatment methods. Recent studies have demonstrated that these pollutant dyes are responsible for serious damage to aquatic ecological systems: the development of methods of removing these compounds from industrial effluents is becoming increasingly important.

An international collaboration between Brazilian and British scientists describes a novel method of re-using waste polystyrene, the plastic found in protective packaging and disposable cutlery. The smart new materials can be used to remove harmful synthetic dyes, which are known to be carcinogenic and act as chronic reproductive toxins to humans and animals.

Contaminants, such as dyes, can be broken down by active oxidation processes (AOP), which often involve a heterogeneous (solid-state) photocatalyst in order to turn pollutants into less harmful end products, such as water and carbon dioxide.

This new study, led by Prof Rodrigo J. de Oliveira at Paraíba State University in Brazil and Professor Julian Eastoe of University of Bristol U.K, re-uses waste plastic (poly(styrene)) to form a porous solid, by freezing it in a solution with cyclohexane as solvent (freezing point +6°C). Once the solvent is removed, an expanded solid plastic poly(styrene) foam is left behind. This high-surface area support material can then be coated with photocatalytic nanoparticles, creating a solid-state photocatalyst that can be introduced into contaminated waste water samples to break down dyes such as Rhodamine B.

This research suggests a promising approach to turn some of the vast amounts of plastic white pollution into a resource for ameliorating environmental damage elsewhere in the form of water materials for treatment.

Further information

Conversion of Waste Plastic into Photocatalytic Nanofoams for Environmental Remediation - ACS Applied Materials & Interfaces 

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