Nedja Suely Fernandes

Kinetic evaluation of the dehydration of Yb(III) Lu(III) and Y(III) 4-chlorobenzylidenepyruvate by thermogravimetry (TG)

The dehydration kinetic of Yb, Lu and Y 4-chlorobenzylidenepyruvate was studied by using thermogravimetry and the kinetics parameters obtained by Flynn and Wall method suggest that the dehydration step follows a first order mechanism. The activation energies calculated were 103.6, 96.6 and 97.2 kJ/mol and the lifetime considering the temperature of 31 and 101 o C for the dehydration of these compounds were 23, 26, 31 minutes and 0.6, 1.3 and 1.4 seconds, respectively. The results have similar values and suggest that the water is attached in the same way.

Adsorption of erichrome black t from aqueous solution onto expanded perlite modified with orthophenanthroline

Neste estudo foi realizado processo de adsorcao atraves da analise varios parâmetros que influenciam na remocao do corante azo, negro de eriocromo T, a um chamado efluente sintetico ( solucao aquosa do corante), usando como adsorvente a perlita expandida (um aluminossilicato) modificada com ortofenantrolina (uma base de Lewis).

Determinação do teor de cálcio em comprimido à base de lactato de cálcio utilizado no tratamento da osteoporose

The present study utilized thermogravimetry (TG) and optical emission spectrometry with inductively coupled plasma (ICP/OES) to determine the amount of calcium in calcium lactate tablets used in the treatment of osteoporosis. Thermogravimetry results indicated that the decomposition temperature of CaCO3 occurred at 603.9 and 609.4 oC in the samples of calcium lactate and tablets, respectively. The calcium content obtained by TG for the tablets sample showed a similar result to that disclosed by ICP-OES, indicating a value of 8.93% for both techniques.

Scale-up on Electrokinetic Treatment of Polluted Soil with Petroleum: Effect of Operating Conditions

This study investigates the influence of the scale-up of electrokinetic remediation (EKR) approach in carbonaceus soils. The scale-up study was performed in an electrokinetic lab scale (2.55 dm 3 ) by using two graphite electrodes placed in the cathodic and anodic compartments. The solution used was to humidify the soil were Na2SO4 0.1 M and water. A soil polluted (1.5 Kg) with petroleum (ranging from 500 to 2500 ppm) was treated by applying different currents (ranging from 0.5 A to 0.2 A). The effects such as current, pH, conductivity, z-potential and solution were evaluated to understand the better conditions to remove the organic matter from polluted soil. An increase in scale directly influenced the amount of energy supplied to the soil being treated. As a result, electroosmotic and electromigration flows and electric heating are more intense than in previous study performed where a smaller-scale cell was used.

Determination of calcium content in tablets for treatment of osteoporosis using thermogravimetry (TG)

Tablets containing calcium carbonate are widely used in the treatment of osteopenia and osteoporosis. In the present study, the samples (AM-1, AM-2, AM-3) were characterised by Fourier transform infrared absorption spectra, thermogravimetry, differential thermal analysis, differential scanning calorimetry and X-ray diffraction powder patterns. TG curves were used to quantify the percentage of calcium. The results of thermogravimetry were consistent with the data obtained by inductively coupled plasma-optical emission spectroscopy ICP-OES, indicating the possibility that these techniques can be used to determine calcium in tablets containing calcium carbonate.

Electrochemical Oxidation of Oxalic Acid at Different Anode Materials: Applicability of Electroanalysis for Monitoring OA Degradation

The electrochemical oxidation (EO) of oxalic acid (OA) has been studied, in acidic media at Ti/PbO2, highly boron-doped diamond (BDD), Pt and graphite electrodes by applying 60 mAcm−2 of current density. Generally, EO is monitored by chromatography techniques; but the aim of this work is to show the applicability of electroanalysis for detection of OA concentration during its oxidation; by differential pulse voltammetry (DPV) using two different analytical procedures (by analytical curve and by successive addition standard). The results obtained by DPV analysis showed that OA was oxidized at several substrates to CO2 with different results, showing that the performances of the process dramatically depend on the anodic material. Higher removal efficiencies were obtained at Ti/PbO2, graphite and BDD anodes. Finally, DPV analyses were compared with classic titration method achieving a good fit, confidence intervals and limits. The results are described and discussed in the light of the existing literature.

Estudo comparativo entre alguns benzalpiruvatos - fenil substituído de lantanídeos e ítrio no estado sólido

No presente trabalho avaliou-se as etapas de decomposicao termica de alguns compostos de lantanideos (III) e itrio (III), envolvendo diferentes ligantes fenil substituido derivados do benzalpiruvato, utilizando-se a termogravimetria (TG). Uma correlacao foi realizada a partir dos teores dos ions metalicos, comparando-se os resultados obtidos por termogravimetria e titulacao complexometrica com EDTA.