Poly-(acryl amine–co-dimethyldiallyl ammonium chloride) graft starch flocculant for cleaning-up of wastewater

Graft starch flocculant (GSF) was synthesized by copolymerization of carboxymethylated soluble starch, acryl amine and dimethyldiallyl ammonium chloride using ceric ammonium nitrate (NH₄)₂Ce(NO₃)₆ as the polymerization initiator. The morphology was observed by scanning electron microscope, the structure was characterized by Fourier transform infrared spectroscopy and the surface area was measured by the Brunauer–Emmett–Teller method. The experimental results showed that the GSF had huge pore volume, high specific area and proper reaction groups, which could enhance its ability to adsorb heavy metal ions. The adsorption behavior was investigated through batch experiments in simulated Cu²⁺and Pb²⁺ ions wastewater, and adsorption characteristics were affected by many factors, such as flocculant concentration, pH of the solution and adsorption time. Finally, the optimal adsorption parameters were gained, with GSF density of 0.024 mg·L⁻¹, pH of 8 and a reaction time of 30 min. Application experiments adequately demonstrated that the removal ratio of Cu²⁺ and Pb²⁺ ions for the local wastewater reached about 50% based on the above optimized condition.