Poly-(4- and 5-acrylamidosalicylic acids). Part IV. Selectivity in the extraction of metal cations from aqueous solution

Abstract

4- and 5-Aminosalicylic acids have been converted into their N-acryloyl derivatives which underwent polymerisation in the presence of sodium and borate ions to give poly-(4- and 5-acrylamidosalicylic acids). These polymers act as solid-state chelating agents capable of selectively extracting specific cations from aqueous solution. Thus the polymers show appreciable selectivity for Fe³⁺ in the pH range 2·0–2·7, and for Cr³⁺, UO₂²⁺, and Cu²⁺ in the pH range 4·5–5·5; nearly 100% of each of these ions was extracted when a stoicheiometric quantity of polymer was used. A maximum of ca. 30% of the ions Ni²⁺, Co²⁺, Zn²⁺, and Mn²⁺ were extracted in the pH range 4·5–6·0. Cd²⁺ was extracted to ca. 50% in the pH range 4·5–5·5.