A Quaternary Ammonium-Modified Resin for Selective Perchlorate Removal from Fireworks Wastewater

Perchlorate (ClO₄^-) is difficult to remove efficiently using conventional treatment technologies, such as coagulation and reverse osmosis, due to its high water solubility and exceptional chemical stability. Quaternary ammonium resins have emerged as cost-effective and efficient materials for ClO₄^- removal; therefore, the development of high-performance quaternary ammonium resins is critical for improving ClO₄^- remediation. In this study, a novel resin (PS-QA) was synthesized by aminating poly (vinylbenzyl chloride) with <i>N</i>,<i>N</i>-dimethylethanolamine, and its adsorption performance was systematically compared with that of three internationally recognized commercial ClO₄^- removal resins. Although all four resins exhibited spherical morphologies, the polystyrene backbone exhibited strong hydrophobicity, and the functional group -[R-N⁺(CH₃)₂(C₂H₄OH)]Cl^- possesses good electrophilicity, thereby conferring excellent selectivity toward ClO₄^-. PS-QA exhibited a specific surface area of 19.94 m²/g, an average pore diameter of 32 nm, and a pore volume of 0.157 cm³/g, indicating comparable adsorption performance relative to the commercial counterparts. Its high thermal stability was further demonstrated through thermogravimetric analysis. Adsorption equilibrium was reached within 60 min, and the kinetic performance of PS-QA was comparable to that of the commercial resins. Isotherm analysis showed that ClO₄^- adsorption conformed to the Freundlich model, suggesting a coupled physical-chemical adsorption mechanism. Moreover, PS-QA exhibited both strong resistance to interference in complex water matrices and excellent reusability. After three adsorption-desorption cycles, more than 80% of the adsorption sites remained active. Notably, PS-QA also demonstrated outstanding performance in pilot-scale applications.