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Abstract
The present work describes a novel method for cadmium preconcentration and separation with microcrystalline phenolphthalein. Phenolphthalein as an extractant modified by crystal violet was originally applied to cadmium extraction from aqueous solution. Cadmium(II) as CdI3 − and CdI4 2− can associate with the cationic crystal violet (CV+) forming water‐insoluble ion‐association complexes (CdI3 −) · (CV+) and (CdI4 2−) · (CV+)2, which are quantitatively adsorbed on microcrystalline phenolphthalein over the pH range from 1.0 to 6.0. All experimental parameters necessary for successful preconcentration and separation have been investigated and optimized. The study shows that common metal ions, such as Zn(II), Fe(II), Co(II), Ni(II), Mn(II), Cr(III) and Al(III), cannot interfere with cadmium extraction in this microcrystalline system by controlling acidity. The extraction can be accomplished in 15 min. The interaction between CdI3 −and CdI4 2− and CV+ plays an important role in the extraction process. The reported method was successfully applied to the preconcentration and separation of cadmium in synthetic samples and real samples with satisfactory results. The results proved that it is an efficient and attractive technique for cadmium preconcentration and separation at trace level.