Andrei Predescu

Properties of magnetic iron oxides used as materials for wastewater treatment

The paper describes the properties of some nanopowders obtained by coprecipitation and used as adsorbent for wastewater treatment. The Fe3O4 and γ-Fe2O3 nanopowders were obtained using iron salts and NaOH as precipitation agents. D-sorbitol was used to prevent the agglomeration between the nanoparticles. The particle size and distribution were detected using a transmission electron microscopy (TEM) and a scanning electron microscope (SEM) equipped with dispersive analyze system in X radiation energy (EDS). The structure of the iron oxide nanoparticles was characterized by X-ray powder diffraction. Thus, the nanoparticles were characterized and compare in terms of particle size and chemical composition and used for adsorption studies in order to removal hexavalent chromium from waste waters.

Metallurgical Characterization of the Failed Motor Shaft Component from an Electric Surgical Motor used in Orthopedic Surgery

The paper presents the results of research conducted to determine the causes that led to the fracture of a motor shaft component from an electric surgical motor used in orthopedic surgery.The chemical and structural analysis emphasized a structure rich in complex silicate and sulfides inclusions. They form areas of weakness, acting like stress concentrators which induce fatigue shaft breakage. Their high density and non-uniform shape and distribution suggest a non-adequate technology of making and casting of steel, destinated to work in difficult conditions and having an important operational role.

Nano-Iron Oxides Used for Environmental Applications

The paper emphasizes the importance of use the nano-iron oxides as treatment materials for wastewaters decontamination, having in mind the size of these compounds and specific surface area suitable for retaining toxic metals such as chromium or cadmium presented as major pollutants for industrial wastewaters. Also, the magnetic properties of the nano-iron oxides offer the possibility of a fast removal of these from the system, after wastewaters treatment. The obtaining of some core-shell composites with nano-iron oxides as core represent an advantage because of the dissolving tendency of the nano-iron oxides under acidic conditions, the situation being common to the industrial wastewaters.