Selective Removal of Iron, Lead, and Copper Metal Ions from Industrial Wastewater by a Novel Cross-Linked Carbazole-Piperazine Copolymer

A novel cross-linked Copolymer (MXM) was synthesized by the polycondensation reaction of 3,6-Diaminocarbazole and piperazine with p-formaldehyde as a cross-linker. The Copolymer was fully characterized by solid¹³ C-NMR and FT-IR. The thermal stability of MXM was investigated by TGA and showed that the Copolymer was stable up to 300^◦ C. The synthesized polyamine was tested for the removal of iron (Fe²⁺), lead (Pb²⁺), and copper (Cu²⁺) ions from aqueous and industrial wastewater solutions. The effect of pH, concentration and time on the adsorption of iron (Fe²⁺), lead (Pb²⁺), and copper (Cu²⁺) ions was investigated. The adsorption of the studied ions from aqueous solutions onto the MXM polymer occurs following the Freundlich isotherm and pseudo-second-order kinetic models. The intraparticle diffusion model showed that the adsorption mechanism is controlled by film diffusion. The regeneration of MXM showed practical reusability with a loss in capacity of 2–5% in the case of Fe²⁺ and Cu²⁺ ions. The molecular simulation investigations revealed similarities between experimental and theoretical calculations. Industrial wastewater treatment revealed the excellent capabilities and design of MXM to be a potential adsorbent for the removal of heavy metal ions.