Abstract
Metallic iron nanoparticles were synthesized by the hydrazine reduction method in three experimental versions. The average size and particle size distribution obtained by the three versions was determined with a particle size measurement system making use of dynamic light scattering. The presence of the aromatic solvent and anti-caking additive influences the average size and size distribution of the particles. The metallic iron nanoparticles obtained in the three experiments were used in the treatment of waters containing a 6.8 mg/l concentration of hexavalent chromium. Reduction of hexavalent chromium concentrations as well as total chromium, COD and TSS depend on pH and reaction times. Thus, the optimal conditions requires for Cr6+reduction, for obtaining values lower than 0.1 mg/l, are: the pH value of 11, a duration of the process 10 hours. Keywords: nanoparticles, chromium, wastewater, chemical oxygen demand, biochemical oxygen demand