Adsorption of DMMP and water vapor on granular activated carbon: An experimental and molecular simulation study

[Display omitted] •The experimental and molecular simulation results show that the influence of water vapor on DMMP adsorption equilibrium is small in the range of relative humidity 0–90%.•The adsorption is mainly driven by van der Waals force, and the adsorption potential energy between DMMP molecules and GAC active sites is much higher than that of water molecules.•The presence of polar functional groups, such as hydroxyl, has a significant effect on the adsorption equilibrium of DMMP.•Molecular dynamics simulations revealed that the presence of water had little effect on the diffusion of DMMP molecules in GAC pores. The adsorption behavior of Dimethyl methylphosphonate (DMMP), as a simulant of sarin nerve agent, especially in the presence of water vapor, is crucial for the design of efficient chemical protection equipment. Experimental results reveal DMMP's adsorption isotherm on granular activated carbon (GAC) as a typical type I. The adsorption process was a spontaneous and exothermic physical adsorption process, and the adsorption mechanism was in accordance with Dubinin's micropore filling theory. In the relative humidity range of 10 % ∼ 90 %, the isotherm remained I-type, and the effect of water vapor on the equilibrium adsorption capacity and apparent adsorption rate was weak. Molecular simulations also show that DMMP adsorption on GAC follows a type I isotherm, primarily driven by van der Waals forces of physical adsorption. The adsorption potential energy between DMMP and GAC surpasses that of water molecules, resulting in negligible effects from water vapor on DMMP adsorption equilibrium. Meanwhile, water molecules had minimal effect on the diffusion of DMMP molecules in the GAC pores, and the positional distribution of DMMP multilayer adsorption was consistent under different relative humidity conditions. Furthermore, the presence of polar functional groups such as hydroxyl groups significantly affects the adsorption equilibrium of DMMP.