Optimal SO₂ Uptake from Mixed-MOF Phase-Inverted Composites

The metal–organic frameworks (MOFs) CALF-20 and ZIF-8 were combined into single bead-like structures through phase inversion of poly(styrene-block-ethylene-co-butylene-block-styrene) to make engineered particles for protection against sulfur dioxide (SO2) at a broad range of relative humidity (RH) conditions. CALF-20 provided good protection under dry conditions, while ZIF-8 provided good protection under humid conditions. An optimal ratio of a 50:50 mixture was found to perform approximately twice as good as a broad spectrum activated, impregnated carbon, with SO2 capacities of 0.9 and 2.6 mol/kg under dry and humid conditions, respectively. The mixed-MOF beads also provided good uptake of 2-chloroethyl ethyl sulfide, a chemical warfare agent simulant, under both dry and humid conditions, with the 50:50 mix having loadings of 4.1 and 3.0 mol/kg, respectively, further expanding the potential usefulness of these materials.