Amine-Functionalized Poly(pyrrole methane)s synthesized from hydrazine for highly selective mercury removal in water

Mercury pollution is becoming an increasingly serious issue in the ecological environment. Herein, two amine-functionalized poly(pyrrole methane)s materials were synthesized from hydrazine for the efficient and selective removal of mercury ions in water. PPDHA and PPD12HA exhibit exceptional adsorption capacities of 1124 and 1080 mg·g^-1 at 298 K, respectively, and achieve rapid adsorption equilibrium within 20 and 45 min, demonstrating their superior performance. Meanwhile, the two amine-functionalized poly(pyrrole methane)s have excellent adsorption selectivity, for distribution coefficient (K_d) values of Hg(II) greater than 5 × 10⁵ mL·g^-1, which is 10³ (α_s) times that of other divalent metal ions. Even after 10 adsorption–desorption cycles, the removal efficiency for 10 mg·L^-1 of Hg(II) remained above 98 %. Additionally, the adsorption mechanism research reveals that amine groups serve as the primary adsorption sites for Hg(II) through infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. This study demonstrates the potential of amine-functionalized poly(pyrrole methane)s synthesized from hydrazine as highly efficient adsorbents for Hg(II) in water, providing a viable approach for further remediation of heavy metal-contaminated wastewater.