Ricerc@Sapienza

The effect of soil composition on the reduction of hexavalent chromium (Cr(VI)) by zero valent iron nanoparticles was studied. A model was proposed, to investigate both the effect of manganese oxide and the simultaneous effect of manganese dioxide and soil organic matter on the kinetic of Cr(VI) reduction. Fe(0) nanoparticles consumption by the reaction with dissolved oxygen, water and soluble Cr(VI) was taken into account.

This work deals with the treatment of a tannery wastewater by a mixed-iron coated olive stone bio-sorbent particles. Olive stones were used as the support to zero-valent iron and magnetite nanoparticles to develop a new material for the removal of chromium, organic matter and total phenols from the wastewater. The optimal operating conditions were determined in batch reactors, after which the process was scaled-up using fixed-bed columns in series.

The aim of this paper is to show the results obtained by investigating the reduction of hexavalent Chromium [Cr(VI)] by iron nano-particles in aqueous solution, interpreted in light of the particle-grain model. The diffusional and geometric parameters that govern and describe the reacting system were estimated from the evidences deriving from the characterization and the experiments conducted, allowing assumptions based on physical principles. Such procedure rendered the particle-grain model a valid choice for the interpretation of the results obtained.

Uncoated and nano iron-based coated biomass were employed as packing material in lab-scale and large-lab-scale columns for the removal of Cr(VI) from synthetic wastewaters. A remarkable Cr(VI) removal efficiency (up to about 65%) was observed in large-lab-scale configuration, thus allowing to treat notable amounts of effluents volumes (30–70 L, basing on the inlet flow-rate) at fixed bed height of 38 cm and a sorbent mass of 850 g and 790 g of uncoated and coated material, respectively.