Sunlight, Nanoparticles Break Down Pollutants

Endocrine disruptors mimic or block hormones, interfering with humans’ and animals’ reproductive organs, and causing other health problems.

A class of pollutants that negatively affects hormones can be broken down using nanoparticles and sunlight.

The method, developed at the Center for Advanced Materials at the Indian Association for the Cultivation of Science in Kolkata, India, neutralizes bisphenol A (BPA) and other endocrine disruptors. Endocrine disruptors can mimic or block hormones, interfering with the reproductive organs of humans and animals, and causing other health problems.

This chart demonstrates photocatalytic degradation of phenol using an rGO-Ag composite, rGO alone and Ag alone. The control line indicates photolysis without any catalyst. C/C₀ = concentration ratio of endocrine disruptor (at any time with respect to initial concentration); e− = electron; h+ = light generated cationic charge/hole; HO = phenolic functional group present in endocrine disruptor; OH = phenolic functional group present in endocrine disruptor.

The researchers used a reduced graphene oxide composite with silver nanoparticles (rGO-Ag), which can act as an efficient photocatalyst to degrade these pollutants. They developed a large-scale synthesis method for rGO-Ag, enabling them to degrade BPA, phenol and atrazine under UV and visible light.

Earlier approaches to pollutant degradation have worked exclusively with UV light, which makes up just 6 percent of sunlight, whereas visible light makes up 52 percent of the solar spectrum.

The silver nanoparticles “offer visible-light-induced excitation of silver plasmons, and conductive rGO offers efficient charge separation and thus induces oxidative degradation of the organic pollutant,” the researchers reported.

This new technique could be used to break down other harmful organic compounds, according to the researchers.

The work was funded by India’s Department of Science & Technology and was published in Applied Materials & Interfaces (doi: 10.1021/am505677x).