Numéro de référence
ISO 2369:1972
ISO 2369:1972
© ISO 2024
ISO 2369:1972
Fluorure d'aluminium à usage industriel — Dosage de la silice — Méthode spectrophotométrique au complexe silicomolybdique réduit
Edition 1
1972-12
1972-12
Annulée
Résumé
The method can be applied provided the phosphorus pentoxide content does not exceed 0,02 % (m/m). The principle is based on alkaline fusion of a test portion by means of a mixture of sodium carbonate and boric acid. Solution of the fused mass in excess nitric acid so that the pH of the final solution is between 0,3 and 0,5 after being diluted. Formation, in a suitable aliquot portion, of the (yellow) oxidized silicomolybdic complex under clearly defined conditions of acidity, concentration of reagents, temperature and time. Selective reduction in a high acidity sulphuric acid medium and in the presence of tartaric acid. Spectrophotometric measurement at a wavelength of about 815 nm.