Recoverable amphiphilic polyoxoniobates catalyzing oxidative and hydrolytic decontamination of chemical warfare agent simulants in emulsion

Amphiphilic polyoxoniobates (PONbs), [C_nH_2n+1N(CH₃)₃]₇HNb₆O₁₉ (for 1, n = 14; for 2, n = 16; and for 3, n = 18), were successfully prepared by the electrostatic interaction of hexaniobate anions with quaternary ammoniums containing long alkyl chain, and thoroughly characterized by using various techniques including Fourier transform infrared (FT-IR), ¹H nuclear magnetic resonance (¹H NMR), ¹³C nuclear magnetic resonance (¹³C NMR), thermogravimetric analysis (TGA), and elemental analysis. All three PONbs were used in the emulsion systems to catalytically decontaminate chemical warfare agent simulants and the influences of quaternary ammonium cations, polyanions, and amount of catalyst on the catalytic efficiency have been evaluated. Under optimal conditions, catalyst 3 in emulsion can completely convert both a the nerve agent simulant, diethyl cyanophosphonate (DECP), in 2 h by hydrolysis and a sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES), in 20 min by oxidation using nearly stoichiometric 3% aqueous H₂O₂. Moreover, the amphiphilic catalyst 3 can be simply separated and readily reused for five recycles without obvious losing its activity. To the best of our knowledge, this study represents the first example where the emulsions of PONbs are used in the catalysis.