Susana P. Boeykens

Total reflection X-ray fluorescence polymer spectra: classification by taxonomy statistic tools.

The aim of this work is to explore the use of chemometric tools for the classification of synthetic and natural polymers with a mean molecular weight greater than 10(6). Total Reflection X-Ray Fluorescence (TXRF) spectra were obtained and analyzed in order to retrieve matrix information and to illustrate the calibration procedure. The intensities of the coherent and incoherent scattered peaks were specially selected for this purpose. The polymers studied were aqueous solutions of scleroglucan, polyacrilamide, polyoxyethylene oxide, glucomannan, 2,3,6-tri-o-ethylamylose and xhantan, in concentrations upto 1% (m/m). matlab software was used for numerical calculations. Using a combination of principal component analysis and cluster analysis, the differences in composition of various analyzed polymers can be visualized.

Eutrophication decrease: Phosphate adsorption processes in presence of nitrates

Eutrophication causes aquatic environment degradation as well as serious problems for different purposes of water uses. Phosphorus and nitrogen, mainly as phosphate and nitrate respectively, are considered responsible for eutrophication degradation. The focus of this work was the study of adsorption processes for decreasing phosphate and nitrate concentrations in bi-component aqueous systems. Dolomite and hydroxyapatite were selected as low-cost adsorbents. Obtained results showed that both adsorbents have high capacity for phosphate adsorption which the presence of nitrate does not modify. Hydroxyapatite proved to be the most efficient adsorbent, however, it showed a low percentage of desorption and few possibilities of reuse. Dolomite, on the other hand, allows a desorption of the adsorbed material that favours its reuse.

Low impurities in scleroglucan aqueous systems: Removal processes control by total reflection X-ray fluorescence analysis

ABSTRACT The aim of this work was to use the determination of trace elements by total reflection X-ray fluorescence (TXRF) for the performance study of three final purification methods of polysaccharide systems. TXRF shows two indispensable advantages to accomplish this study: the small quantities of sample required for the analysis and the avoidance of digesting the organic material. Aqueous scleroglucan systems with only impurity traces were studied, from diluted solutions to gels. The most efficient purification process was selected for each range of concentration.

Characterization of trace elements in high viscosity materials by total reflection X-ray spectrometry ☆

Abstract This paper proposes the use of radiation scattered by the sample instead of the internal standard method for quantifying impurities in high viscosity materials using X-ray fluorescence with total reflection geometry. The method has been performed for checking trace elements in gels of polymers. Advantages include no sample preparation and a minimum amount of sample (10 μl). The method is also insensitive to instrumental variations, sample amount and particle size of the sample. The ratio of coherent to incoherent scattering intensities of X-ray was also investigated to estimate the content of C plus O in these polymers.