Quantitative chemical analysis of pickling solutions by x-ray fluorescence spectrometry

A quantitative analytical method of chlorine and iron in hydrochloric pickling solutions by x-ray spectrometry in atmospheric He mode is proposed. This work is concerned with the replacement of the wet chemical analyses of pickling solutions with rapid and reproducible quantification by an x-ray fluorescence spectrometer. An in-depth investigation was performed to identify the species present in real pickling solutions. X-ray diffraction patterns and semiquantitative results for the pickling solutions provided synthetic standards based on the compositional range of solutions by analyzing the pickling solutions obtained in real processes. Twenty-seven liquid calibration standards were prepared by diluting standard solutions certified by wet chemical analyses for the x-ray fluorescence spectrometry (XRF) calibration curves for Cl and Fe. The suggested method showed satisfactory precision and accuracy in the analysis of pickling solutions. It is possible to estimate the acidities of pickling acid solutions on the basis of the correlation between the HCl concentrations calculated from a simple XRF measurement of total Cl and Fe concentrations and those measured by acid-base titration methods.