Synthesis and adsorption properties of a temperature-sensitive co(II) ion-imprinted composite membrane based on PVDF

Recovery of cobalt from wastewater is a key method for achieving resource sustainability. A novel temperature-sensitive Co(II)-ion-imprinted composite membrane based on polyvinylidene fluoride was synthesised using N-isopropylacrylamide as the temperature-sensitive monomer and diisooctylphosphinic acid as the ligand. The preparation conditions for the imprinted composite membrane were systematically optimised, resulting in an optimal polymer with an adsorption capacity of 938.61 mg·g −1 that achieved adsorption equilibrium in approximately 30 min, outperforming most reported cobalt ion adsorbents. The surface morphologies of the Co(II)-IICM 6 membranes prepared under the optimal conditions were analysed. The results showed that the ionic ligands enabled the polymer particles to grow successfully and uniformly on the membrane surface. The imprinted composite membrane's pore size increased as a result of this expansion, with the specific area increasing from 13.01 m 2 ·g −1 to 16.84 m 2 ·g −1 . The imprinted composite membrane maintained a high adsorption capacity over ten cycles and exhibited excellent selectivity for Co(II) ions in aqueous samples containing Co(II), Ni(II), Cr(III), Cd(II), Cu(II), and Pb(II). These results indicate that the prepared temperature-sensitive imprinted composite membrane is promising for the separation of Co(II) from real water samples.