Numéro de référence
ISO 848:1981
ISO 848:1981
© ISO 2024
ISO 848:1981
Acide phosphorique à usage industriel — Dosage du calcium — Méthode titrimétrique
Edition 1
1981-11
1981-11
Annulée
Résumé
The general method is applicable to phosphoric acid not containing polyphosphoric acids and to products having a calcium content equal to or greater than 0.020 % (m/m). In special cases a preliminary hydrolysis of polyphosphoric acids is carried out by prolonged boiling in the presence of hydrochloric acid. Precipitation of calcium as calcium oxalate at pH 4 0.3, filtration of the precipitate, dissolution in hydrochloric acid and re-precipitation under the same operating conditions in order to purify the precipitate. Oxidimetric titration in sulphuric acid solution by means of potassium permanganate. - Cancels and replaces ISO Recommendation R 848-1968.