Preparation of reusable cross-linked amidoxime polyacrylonitrile microspheres and their efficient adsorption of Cu (II) and Pb (II)

Acrylonitrile (AN)-based polymers with fairly active nitrile groups can be modified as an ideal polymer-based adsorbent material. In this contribution, we proposed a "two-solvent system of water and glycerol" strategy to achieve the complete miscibility of monomers and we designed a cross-linked network structure to effectively improve the mechanical strength and reusability of the adsorbent. Morphological and structural characterization of the amidoxime cross-linked polyacrylonitrile microspheres (H-CAN) showed that these particles present a spherical structure with diameter of 200–300 nm, the expected cross-linked structure, and amorphous properties. The adsorption performance of H-CAN was investigated under different conditions of contact time, pH and temperature. The time to reach adsorption equilibrium at pH 7 and temperature 25 °C was 60 min (Cu (II)) and 40 min (Pb (II)), respectively. The results were in accordance with the Langmuir model, which showed the maximum adsorption of 140.33 and 113.13 mg·g−1 for Cu (II) and Pb (II), respectively. Moreover, the adsorption capacity after seven repetitions was 89.5% (Cu (II)) and 91.0% (Pb (II)) of the initial values. Overall, H-CAN has found wide promising applications in wastewater treatment, with the advantages of simple synthesis, mild application conditions, and satisfactory reusability.