Zirconia-Based Aerogels for Sorption and Degradation of Dimethyl Methylphosphonate

• Published in: Industrial & engineering chemistry research 2020-11, Vol.59 (44), p.19584-19592
• Main Authors: Long, Jeffrey W, Chervin, Christopher N, Balow, Robert B, Jeon, Seokmin, Miller, Joel B, Helms, Maya E, Owrutsky, Jeffrey C, Rolison, Debra R, Fears, Kenan P
• Format: Article
• Language: English
• Subjects: Materials and Interfaces
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.0c02983

Inspired by recent breakthroughs with Zr­(OH)4-type materials that decompose chemical warfare agents (CWAs), we explore aerogel forms of zirconium oxyhydroxide (ZrO x H y ) as reactive sorbents for dimethyl methylphosphonate (DMMP), a common simulant for organophosphorous CWAs. Zirconia gels were synthesized using propylene oxide and aqueous ZrCl4, followed by supercritical-CO2 extraction to yield monolithic ZrO x H y aerogels. Subsequent calcination at temperatures ≥350 °C removes organic byproducts of the epoxide-based synthesis while preserving high specific surface area (up to 234 m2 g–1) and the aerogel-like, cocontinuous pore-solid structure. Infrared (IR) spectroscopy and 1H nuclear magnetic resonance spectroscopy confirm that ZrO x H y aerogels retain a high concentration of surface hydroxyls, even when heated to 600 °C and converted to nanocrystalline cubic/monoclinic ZrO2. We used in situ IR spectroscopy to probe the interactions of DMMP with a series of ZrO x H y aerogel powders, showing that DMMP rapidly decomposes by reacting with the hydroxyl-rich aerogel to form surface-bound Zr–OCH3 and bridging O–P–O species. We compare these results to those of related zirconia-type materials and discuss prospects and advantages of ZrO x H y aerogels for CWA mitigation.