Free acid, iron, heavy metals, and chloride contents
were analyzed to characterize the used pickling
liquor. Free acid content was analyzed according to the Standard Method set by ASTM D1067-02. Iron
and heavy metals were analyzed by inductively
coupled plasma optical emission spectrometry (ICPOES)
(Plasma 7000 DV, Perkin Elmer., USA).
Chloride of the pickling liquor was analyzed by ionic
chromatrography (DIONEX, DX-100, USA).