Scientists have developed a new photocatalyst that can eliminate almost all organic pollutants present in water, using sunlight as a source of activation. Developed by CSIC, the Autonomous University of Madrid and the University of Castilla la Mancha, it is currently available for industrial partners interested in its development and commercialisation.
Transmission Electron Microscopy (TEM) image of TiO2-FLG 0.5 % hybrid photocatalyst
Photo-oxidation, the destruction of pollutants by the combination of UV-Visible light and a catalyst, is not new. In fact, photo-oxidation occurs naturally in ecosystems, although it is a time-consuming process.
Technology can mimic and accelerate this natural process with heterogeneous photocatalysts. Titanium oxide catalysts have long been used because they are efficient, low cost and stable.
However, the energy of the solar spectrum that can be utilised by titanium dioxide in solar photocatalysis is, in quantitative terms, only around 5%. As an alternative, one of the most widely implemented option is to combine titanium oxide with other materials in order to obtain hybrid catalysts or nanocomposites, which have higher photoefficiency in the UV-visible range of the solar spectrum.
To achieve photocatalysts that can act directly with sunlight, teams from the CSIC's Institute of Catalysis and Petrochemistry (ICP) and the universities of Castilla la Mancha and the Autonomous University of Madrid have joined forces.
After researching new formulas for the synthesis and preparation of photocatalysts, they have produced a hybrid photocatalyst that combines multilayered graphene with titanium oxide nanoparticles, obtained through a specific procedure that increases its efficiency in photocatalytic processes with sunlight.
These photocatalysts can remove almost all organic pollutants from water or transform them into less polluting or inert compounds, such as water or carbon dioxide. They can be applied for waste water control, as in the image above.
This new methodology for the preparation of graphene nanocomposites, decorated with TiO2 nanoparticles by mechanochemical synthesis, provides a more sustainable procedure for the manufacture of hybrid photocatalysts.
The obtention process is simple and sustainable
These photocatalysts can decontaminate water and remove almost all organic pollutants or transform them into less polluting or inert compounds such as water or carbon dioxide. They can be applied, for example, in water purification plants, or in the purification systems of any company where effluent control is required.
Assays with pesticide-type pollutants show that a total organic carbon molar conversion of 57.5% and 82% is achieved after five and nine hours of reaction, respectively.
Studies of the application of the photocatalytic process with pesticide-type pollutants show that a total organic carbon molar conversion of 57.5% and 82% is achieved after five and nine hours of reaction, respectively.
Specifically, all the pesticides studied (the herbicides isoproturon and alachlor, the fungicide pyrimethanil and the insecticide methomyl) were completely eliminated after almost six hours of irradiation (350 minutes).
The process to obtain this hybrid photocatalyst, say its creators, "is simple and sustainable because it starts directly from titanium oxide and graphene nanoparticles; it generates no waste and requires less energy and time than other procedures". The photocatalysts are also easily recovered from the aqueous medium by sedimentation.
Contact:
Sara Junco Corujedo
Deputy Vice-Presidency for
Knowledge Transfer (CSIC)
Tel.: +34 915854633
E-mail: