Synthesis and properties of starch grafted acrylamide flocculant for granite scrub tail mud

Granite has been widely used as raw materials to produce various industrial products, accompanied by the generation of a large amount of tail sludge with high water content. To recycle water quickly and reduce environmental pollution, starch grafted acrylamide (Starch-g-AM) was successfully synthesized, which was applied to the flocculation treatment of granite scrub tail mud wastewater. The optimal synthesis conditions of Starch-g-AM were obtained as follows: the initiator concentration was 0.25 % of the total mass of the reactants with the mass ratio of starch to acrylamide monomer of 1:4, the reaction temperature and time were 50 °C and 3 h, respectively. The successful synthesis of Starch-g-AM was confirmed by Fourier transform infrared spectroscopy (FTIR), ¹H NMR spectra, thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and elemental analysis. The flocculation mechanism of Starch-g-AM on tail mud particles was proposed according to the results of optical microscopy images, particle size tests, Zeta potential, and contact angle. Furthermore, the adsorption behavior of Starch-g-AM on the surface of the tail mud was confirmed by Density functional theory (DFT) calculation. Through the flocculation experiment comparison, it was found that the flocculation efficiency of Starch-g-AM was 67.06 % higher than that of the commercially available cationic polyacrylamide.