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

## TL;DR

A new resin was developed to efficiently and selectively remove perchlorate from fireworks wastewater, outperforming commercial alternatives.

## Contribution

A novel quaternary ammonium resin (PS-QA) was synthesized and shown to have high selectivity and reusability for perchlorate removal.

## Key findings

- PS-QA exhibited comparable adsorption performance to commercial resins with a specific surface area of 19.94 m²/g.
- The resin showed excellent reusability, retaining over 80% activity after three cycles.
- PS-QA demonstrated strong performance in pilot-scale applications and resistance to complex water matrices.

## Abstract

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 N,N-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.