Synthesis of cationic polyacrylamide by low-pressure UV initiation for turbidity water flocculation

•A novel flocculants of PADC was synthesized through low-pressure initiation.•Hydrophobic monomer of CDEA was introduced to synthesis of polyacrylamide.•Intrinsic viscosity and positive charge density of PADC was investigated.•Chemical structures of PADC were characterized and analyzed.•Flocculation performance and mechanism were evaluated and summarized.

This work presents a preparation process and flocculation performance evaluation of a novel cationic polyacrylamide PADC synthesized by low-pressure ultraviolet (UV) initiation. Flocculant of PADC was polymerized with acrylamide (AM), diallyl dimethyl ammonium chloride (DMDAAC) and coconut diethanolamide (CDEA) in homogeneous aqueous solution under the irradiation of low-pressure UV, and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure2959) was used as photo sensitizer. The factors that affect polymerization were investigated; these include monomer concentration, initiator dosage, mass ratio of mAM:mDMDAAC and irradiation time. Structures and morphologies were characterized by Fourier transform-infrared (FTIR) spectroscopy, nuclear magnetic resonance hydrogen (1H NMR) spectra, scanning electron microscope (SEM), and thermo gravimetric and differential thermal analysis (TG-DTA). The flocculation performance was evaluated by removing high turbidity kaolin suspension; flocculation mechanism was also correspondingly analyzed. Experimental results show that the PADC efficiently removes the suspended particles efficiently by charge neutralization and bridging effect in an environment with wide range of pH.

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