Synthesis of Magnetic N‐Vinylformamide Grafted Starch and Its Application in Heavy Metals Adsorption

Using cyclohexanone and sodium bromate as initiators, N ‐vinylformamide (NVF) is self‐polymerized and grafted onto the pregelatinized starch (PGS) to form NVF‐starch graft copolymer (SGC). Fe 3 O 4 surface is coated by MnO 2 formed by in situ chemical reaction between KMnO 4 and MnSO 4 to obtain modified nanoparticles (NFs). A novel M‐starch graft copolymer (M‐SGC) is combined from SGC and NFs in aqueous solution by sonication. The structures of SGC, NFs, and M‐SGC are characterized by FTIR, SEM, XRD, BET, and 1 H‐NMR. The adsorption mechanism by M‐SGC is investigated by FTIR and XPS. The results show that M‐SGC has the ability to adsorb Cu 2+ , Ni 2+ , and Cr 2 O 7 2− from aqueous solutions with high efficiency. Cu 2+ and Ni 2+ are removed by amide bond chelation and ion exchange of M‐SGC. The Cr 2 O 7 2− is separated by chelation through turned to trivalent chromium. M‐SGC adsorbs 274.6 mg g −1 Cu 2+ in 3.0 g L −1 copper solution, 8.92 mg g −1 Ni 2+ in 0.5 g L −1 nickel solution, and 36.5 mg g −1 Cr 2 O 7 2− in 1.2 g L −1 potassium dichromate solution. The adsorption experiments of M‐SGC has a good recyclability.