Recebido em 6/3/03; aceito em 28/4/03 EDTA: THE CHELATING AGENT UNDER ENVIRONMENTAL SCRUTINY. The chelating agent EDTA (ethylenediaminetetraacetic acid) is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is concluded that EDTA behaves as a persistent substance in the environment and that its contribution to heavy metals bioavailability and remobilization processes in the environment is a major concern.

In the final process of the bleached kraft pulp there are some cellulose fibers that are separated from the main fibers stream; these fibers are rejected and considered as a low quality fibers, these fibers are known as rejected fiber (RF). In the present work the potential use of these fibers for Cellulose Nanocrystals (CNCs) synthesis was studied. The physical and chemical properties of synthesized CNCs were characterized through different techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA). Results demonstrate the feasibility of CNCs synthesis with a yield of 28.1% and 36.9%, and crystallinity of 73.5% and 82.7%. Finally, the morphology and synthesis conditions suggest that this industrial reject fiber (RF) could be used as a source for the CNCs production, thus adding value to the kraft process and opening new possibilities for innovation in the pulp industry.

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A surface treatment of metallic samples irradiated by a nitrogen ion beam generated in a co-axial plasma gun is presented. By placing a titanium insert at the end of the inner electrode of the device, a TiN coating was produced on the surface of the sample. X-ray diffraction, scanning electron microscopy, electron probe x-ray micro-analysis and x-ray photoelectron speectroscopy were employed to study the surface of the treated sample. It was found that the main role of the ion beam was to produce a strong pre-heating of the superficial layers of the substrate, thus favouring the diffusion of the impinging particles.

del Libenador 8250, 1429 Buenos Aires and CIC, Pmvincia de Buenos Aim, Argentina Abstrad Oxidation of pure titanium was carried out at mom temperahlre under different oxygen pressures (10-8-10d torr). The kinetics for each pressure was determined. Measured film thicknesses were larger for higher pressures. Deconvolution of m spectra showed mat 'EO was the major oxide present and TI& the minor component. Formation of T i 2 a and Ti305 was also observed.