Design of Solution-Processable Cationic Polyelectrolytes as Versatile Adsorbents for Toxic Iodine, Dye, and Pharmaceutical Wastes across Multiple Media.

Rapid industrialization has intensified water pollution, leading to severe environmental and health concerns due to the presence of radioactive waste, synthetic dyes, and pharmaceutical residues. Cationic polyelectrolytes offer an efficient and reusable solution for water purification via ion-exchange and electrostatic interactions. These polyelectrolytes efficiently removed radioactive waste such as iodine (in vapor, aqueous, and organic media), methyl orange dye, and pharmaceutical waste diclofenac, exhibiting high adsorption capacities and fast kinetics (rate constant up to 0.072 mg g-1 min-1 for methyl orange removal by CP-1). Notably, CP-1 showed excellent selectivity even in the presence of a 100-fold excess of competing anions. Density functional theory (DFT) analyses confirmed strong electrostatic interactions between the polyelectrolytes and target pollutants, as well as determined active binding sites with favorable binding energies. Both polyelectrolytes retained high efficiency over five regeneration cycles and demonstrated consistent performance across various water matrices, including seawater, river water, and lake water. Soluble polymers provide a versatile and scalable approach to pollutant removal, due to their ease of processing and compatibility with conventional fabrication methods. Their solubility in organic solvents enables uniform coating on low-cost, abundant substrates such as sand or silica, effectively creating high-performance adsorbents while minimizing polymer usage (2 mg of polymer producing 10 g adsorbent). This simple coating approach-based on polymer dissolution, substrate immersion, and solvent evaporation-yields stable, efficient, and reusable materials, demonstrating pollutant removal efficiencies exceeding 99%. Compared to conventional insoluble porous adsorbents, these polymer-coated systems offer superior cost-effectiveness, scalability, and practicality for large-scale environmental remediation applications. With high adsorption capacity, rapid kinetics, superior selectivity, and easy reusability, these polyelectrolytes represent a promising, cost-effective approach for advanced water purification technologies.