Facile synthesis of Melamine-Modified porous organic polymer for mercury (II) removal

In this study, a novel porous organic polymer modified by melamine (MA-POP) was prepared via a post-modification procedure for the Hg²⁺ removal from aqueous solutions. The use of melamine as the rigid crosslinker endowed the polymer with high surface area (669 m² g⁻¹), total pore volume (0.668 mL g⁻¹) and nitrogen content. The material exhibited rapid adsorption kinetic for Hg²⁺, and the adsorption equilibrium can be reached within 10 min. The adsorption progress was more satisfyingly described by the pseudo-second-order kinetic model and the Langmuir isotherm model with a maximum adsorption capacity of 351.6 mg g⁻¹. XPS and FT-IR spectra suggested that the main adsorption mechanism was chelation between nitrogen groups and Hg²⁺. Besides, the adsorbent possessed high adsorption selectivity towards Hg²⁺ in the presence of other eight coexisting metal ions and maintained good adsorption capacity even after five cycles. Therefore, the obtained MA-POP is qualified as a reliable adsorbent for Hg²⁺ removal.