Avaliação de métodos de preparo de amostra para a determinação de halogênios em alumina de alta pureza / Evaluation of sample preparation methods for halogens determination in high-purity alumina

AUTOR(ES)

Lucélia Hoehne

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

08/04/2011

RESUMO

The presence of trace elements in high purity alumina (e.g. halogens) can compromise the final product characteristics. In this work, different sample preparation methods based on alkaline fusion, halogen extraction in water with and without microwave heating, alkaline extraction, microwave-induced combustion and pyrohydrolysis for further halogens determination were evaluated. Bromine and iodine were determined by inductively coupled plasma mass spectrometry (ICP-MS). Chlorine was determined by inductively coupled plasma optical emission spectrometry, ICP-MS, ion chromatography (IC) and ion-selective electrode. Fluorine was determined by IC, ion-selective electrode and molecular absorption spectrometry with graphite furnace vaporization. No statistical difference was observed (ANOVA, 95% confidence level) between microwave induced combustion and pyrohydrolysis results for Br, Cl, F and I. These methods were considered as more suitable for further halogen determination. Relative standard deviations were lower than 18% for all analytes. For microwave induced combustion, the use of microcrystalline cellulose was necessary as a combustion auxiliary for all halogens. Pellets up to 0.5 g of sample (exceptionally for I, 0.2 g) and 0.5 g of microcrystalline cellulose were used, with 6 mL of 50 mmol L-1 (NH4)2CO3 as absorbing solution. For I the use of V2O5 (0.4 g) was also necessary. For pyrohydrolysis, all halogens were extracted with the following conditions: absorbing solution 50 mmol L-1 (NH4)2CO3, 10 min of reaction time, reactor temperature of 950 C and 0.2 L min-1 of compressed air flow-rate.

ASSUNTO(S)

óxido de alumínio halogênicos química analítica quimica

Documentos Relacionados

• Robust control of high-purity distillation column.
• Sensor locations and noise reduction in high-purity batch distillation control loops
• Convenient separation of high-purity C60 from crude fullerene extract by selective complexation with AlCl3.
• Determination of sample size to evaluation of yellow melon hybrids
• "Comparative evaluation of procedures for agroindustrials sample preparation in the determination of inorganic elements by spctrometric techniques"