Green Chemistry and Technology

A revision on the literature on green synthesis of iron-based nanoparticles and their application as nanotechnology for removal of pollutants from soil and water will be presented, highlighting the uncertainties about their chemical identity and effi ciency for removal of pollutants. In addition, the need of further improvement in order to obtain stable nanoparticles of controlled size and morphology, conducive to large-scale synthesis of iron nanoparticles for environmental remediation and hazardous waste treatment applications will be stressed. As a study case, the preparation of iron-based nanoparticles synthesized from iron salts and water extracts (polyphenols) of powdered Yerba mate (Ilex paraguariensis Saint Hilaire) will be described. Yerba mate is highly consumed as an autochthonous tea in Paraguay, Uruguay, Brazil and Argentina. The nanomaterials have been completely characterized by XRD, Raman and Mössbauer spectroscopies and their applicability for Cr(VI) and As(III)/As(V) removal from polluted waters have been tested in laboratory tests with synthetic and real waters from Argentina and compared with other tea extracts such as green tea and commercial zero valent iron nanoparticles. The nanomaterials

are low-cost, nontoxic and can be easily produced at large scale. They can be used for removal of other pollutants (e.g. mercury, uranium, lead, nitrate, halogenated hydrocarbons, pesticides such as 2,4-D, etc.).