Removal of gaseous sulfur and phosphorus compounds by carbon-coated porous magnesium oxide composites

Carbon-coated porous magnesium oxide (MgO/C) composites were synthesized using an aerogel route for removal of dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethyl sulfide (2-CEES) in dry and wet conditions. The sorption capacities of the as-prepared samples for DMMP (0.23μg/mL) and 2-CEES (0.26μg/mL) were evaluated by breakthrough experiments in nitrogen under ambient conditions. MgO/C composites exhibited a decrease in surface area with carbon content (648-723m²/g), but had a higher surface area than MgO. Under dry conditions, the sorption capacities of the MgO/C composite with a low carbon content of 6.39wt% (MgO/C-1; 67.8mg/g for DMMP and 35.3mg/g for 2-CEES) were higher than those of pure MgO and activated carbon (AC). The sorption capacity of MgO/C composites decreased with an increase in carbon content and became even lower than those of MgO and AC. Under humid conditions, the sorption capacities and breakthrough time of pure MgO decreased significantly and became lower than that of AC. In contrast, the sorption capacities of the MgO/C-1 composite for DMMP and 2-CEES under humid conditions remained at about 91 and 86% of those measured under dry conditions, and were higher than those of AC. In addition, the MgO/C composite remained reactive toward 2-CEES even under humid conditions. MgO/C composites were more stable than MgO under humid conditions because of the presence of carbon-coated shells.