The most commonly accepted definition for a nanomaterial refers to any material that has at least one dimension less than 100 nanometers (nm) in size (e.g., thin films, graphene films), whereas nanoparticles are defined as objects with their three dimensions of less than 100 nm. At this scale the properties and functions of nanostructures often differ drastically from their bulk counterparts.

The reason is that decreasing nanoparticles size causes their surface effects to become more significant due to an increase of surface atoms ratio in the volume fraction. Moreover, the novel properties of nanoparticles are size- but also shape- dependent because the small size often results in higher reactivity since surface atoms make a large contribution to the thermodynamic characteristics of solids. Their high surface area-to-volume ratio, surface tailorability and multifunctionality open a multitude of new possibilities for a wide variety of applications in different fields of science and technology.

Environmental Engineering is not distant to nanotechnology and there is an increasing interest on the use of nanomaterials in environmental remediation. We are investigating the use of nanoparticles for the reduction of metals, nutrients and pesticides in water and, also, for the reduction of Green House Gases (CH4 and N2O) present in air.

We are also using iron nanoparticles to improve the anaerobic digestion process. Specifically we have found that iron nanoparticles can increase biogas production significantly when added to the anaerobic digestion process at a specific concentration and size.

However, the environmental impact of nanomaterials when released to the environment is not well determined. Then, nanotoxicology is arising as a new discipline related to nanotechnology. We are working in the determination of toxicity of different nanoparticles by using methodologies such as seed germination tests, bioluminescent bacteria, aerobic respirometry and anaerobic digestion tests, among others.

Our investigations in this field are partnered with Dr. Victor Puntes [+] from the Institut Català de Nanotecnologia.