Liquid-Phase Adsorption of Dimethyl Methylphosphonate on Poly(ether imide) and its Metal Hydroxide-Integrated Composites

Understanding the adsorption behavior of dimethyl methylphosphonate (DMMP), a key simulant for some nerve agents, is crucial for developing effective protective measures and ensuring environmental safety against harmful chemical warfare agents. This study systematically explores the liquid-phase adsorption of DMMP over branched poly(ether imide) (Ultem) and its Ce(OH)₄/Zr(OH)₄ metal hydroxide composites. Utilizing UV–visible (UV–vis) spectroscopy, the adsorption process was monitored over time to analyze the interplay between various Ultem-based composites and DMMP molecules. Nonreactive Ultem materials were experimentally identified as suitable adsorbents for liquid-phase DMMP capture, providing a novel avenue for protective filtration technologies. It was found that incorporating 30 wt % Ce(OH)₄ into Ultem yields the highest DMMP uptake, reaching an impressive adsorption capacity of 10.20 mmol g^–1 at room temperature (i.e., 22 ± 1 °C). Furthermore, the 30 wt % Ce(OH)₄-coated Ultem composite demonstrated the fastest kinetic response (0.39 mmol g^–1 min^–1) across all samples. Our results revealed a combined physisorption–chemisorption mechanism for DMMP adsorption over Ultem-based composite adsorbents. After three adsorption–desorption cycles, the Ultem composites retained their >93% efficiency. These findings are significant in revealing the underlying factors that govern DMMP adsorption over Ultem-based materials, offering insights into the role of metal hydroxides in enhancing adsorption properties. This research has implications for the design and development of advanced materials for chemical defense, environmental safety, and industry.