Synthesis of anion polyacrylamide under UV initiation and its application in removing dioctyl phthalate from water through flocculation process

In this study, a method to remove dioctyl phthalate (DOP) form water was realized through a flocculation process with a novel polyacrylamide flocculant P(AM/AA/AMPS). P(AM/AA/AMPS) was synthesized under ultraviolet (UV) irradiation using acryl amide (AM), acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) with 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50) as photo-initiator. An optimized product was obtained at an intrinsic viscosity of 1.55 × 103 mL g−1, and its structure and morphology were characterized by Fourier transform-infrared spectroscopy (FTIR), magnetic resonance spectrometry (1H NMR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Compared with thermal initiation, UV-initiation was proved to be more effective in promoting surface modification, increasing the polymerization degree, improving thermal stability, and utilizing less synthesis time. The performance of flocculant was evaluated by their ability to remove DOP from water, and a maximum DOP removal efficiency of 82.1% was obtained under optimized conditions. A possible flocculation mechanism for DOP removal from water was further analyzed by evaluation of the floc size and colloid zeta potential of DOP. Results indicated that adsorption and bridging effects are dominant in alkaline or neutral environments, whereas charge neutralization is favored in acidic conditions.