Dual Polydopamine-Anion Polyacrylamide Polymer System for Improved Removal of Nickel Ions and Methylene Blue from Aqueous Solution

In this study, a kind of novel dual flocculants system was prepared by premixing polydopamine (PDA) with anion polyacrylamide (APAM) to remove nickel ions and methylene blue from aqueous solutions. Polydopamine was prepared by oxidant-induced self-polymerization of dopamine. Anion polyacrylamide was synthesized by acrylamide, acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid under ultraviolet irradiation. Various analytical methods were applied to characterize and exhibit the successful synthesize of polydopamine and anion polyacrylamide. The flocculation performance was evaluated and results indicated that chelation reaction and π–π stacking effects of PDA, meanwhile adsorption and bridging effects of APAM for nickel ions and methylene blue molecules removal were dominant in neutral and alkaline condition, whereas charge neutralization of APAM was favored in weak acidic condition. The maximum removal efficiency of nickel ions and methylene blue was 99.2% and 96.7% under the optimum condition, respectively. This work provides a scientific basis and a platform for the application of polydopamine-anion polyacrylamide to remove heavy metal ions and dyes from aqueous environment.