Abstract
A new analyzer has been developed for automatic sampling and analyzing the acid and ferric ion of the pickling solution of stainless steels.
HNO3 and uncomplexed HF concentrations are determined with the ion selective electrodes after separating metallic ions from solution with the diffusion dialysis utilizing an anion exchange membrane. Fe3+ concentration is determined by the spectrophotometric method after decomposing ferricfluoride ions by Al(NO3)3 solution.
The influence of ions in the pickling solution on the dialysis coefficients of HNO3and HF through the anion exchange membrane is investigated. The apparent effect of higher concentration level of HNO3 is corrected by using a calibration curve made by running the standard solution which has the similar concentration to that of the sample solution.
The correcting method of the coexisting ferric ions for the determination of hydrofluoric acid is developed.
The analytical accuracy (d)obtained by the new analyzer is 2.7 g/l, 0.4 g/l and -2.1 g/l for HNO3 (31-55 g/l), HF (13.1-37.6 g/l) and Fe3+ (11.3-35.3 g/l) respectively.
