Unveiling the potential of a functionalized pyrrole-based polymer for efficient cadmium ion removal from wastewater: synthesis, characterization, and performance evaluation

Abstract Cadmium ion Cd 2+ contamination is a major environmental issue caused by industry. Polyarylidene N-hexane pyrrole (PAP h ) and crosslinked polyarylidene N-phenyl pyrrole (PAP D ) were prepared from the previously synthesized polymer (polyarylidene ketone (PAK)) by using the advantage of repeating carbonyl groups at the 1,4 position and reacting it with hexylamine and P-phenylenediamine via the Paal–Knorr reaction. Various methods were used to characterize polymers, such as FT-IR spectroscopy, X-ray diffraction (XRD), thermogravimetry analysis (TGA), UV–visible spectroscopy, scanning electron microscope (SEM), zeta potential, and surface area measurements (BET), revealing successful fabrication, good thermostability, and well-defined microporous structures useful for Cd 2+ adsorption. Optimal adsorption capacities of 55.8 mg g −1 for PAP h and 86.95 mg g −1 for PAP D indicate a significant enhancement in Cd 2+ adsorption via their microporous structures, Cd 2+ adsorption was also investigated in terms of contact time, initial concentration, and pH. A total input concentration of 30 ppm Cd ions, may yield an 84.3% removal rate for PAP h and an 89.2% removal rate for PAP D . The experimental results were well-fit by many models, including pseudo-second-order kinetics (PSO), Freundlich isotherms, intraparticle diffusion, and Langmuir. The varying adsorption performances of the two polymers studied, (PAP h ) and (PAP D ), were found to be derived from their respective chemical structures, which include various functional groups, according to studies conducted on Cd 2+ in an aqueous solution. Cd 2+ adsorption on polymers was considered physisorption; π –cation interactions and surface complexation played significant roles in adsorption. The PAP polymers may be considered promising substitutes and innovative adsorbents to remove Cd 2+ ions from a water solution.