A selective reagent for the removal and recovery of chromate, molybdate, tungstate, and vanadate from aqueous solution
The objective was to prepare a reagent to remove Cr(VI) ions from wastewater and separate Cr(VI) from other ions that might interfere with its determination. 4-Aminobenzoic acid, (1-(4-pyridinyl)-2-(1-piperdinyl))ethyl ester, was synthesized and tested to determine its ability to selectively precipitate anions. Fifty-seven common anions were tested. The reagent reacted most readily with the oxyanions of Group VIB and vanadium. The precursor alcohol, 1-(4-pyridinyl)-2-(piperidinyl)ethanol, and the unsubstituted benzoate ester, 1-(4-pyridinyl)-2-(piperidinyl)ethyl benzoate, were also tested. Dissolution of the precipitates in a strong base followed by a methylene chloride wash removes the organic reagent and frees the anions for further analysis.