Molecular dynamics insights into the adsorption mechanism of acidic gases over iron based metal organic frameworks

Abstract

Amid global environmental challenges, particularly air pollution caused by toxic and acidic gases like H2S, SO2, CO2, and NO2, public health is increasingly at risk. Metal–organic frameworks (MOFs), distinguished by their crystalline structure, high porosity, tunable pore size, and diverse functionalities, hold great promise for mitigating the capture of these harmful pollutants. In this study, molecular simulation calculations were conducted to investigate the adsorption and diffusion mechanisms of the toxic and acidic gases H2S, SO2, CO2, and NO2 on the novel iron carboxylate (III) Metal–Organic Framework, MIL-100(Fe). The adsorption energy and total energy of the systems were calculated for each gas, with negative values indicating successful adsorption of the gas by MIL-100(Fe). The MIL-100(Fe)/H2S system exhibited the most negative total energy, indicating its superior stability among the studied gas–MOF systems. The highest adsorption energy value was observed for H2S gas at -49.28 kcal/mol, indicating a strong interaction between H₂S molecules and the MIL-100(Fe) framework. Additionally, gas permeability and diffusion coefficient calculations revealed a trend of H2S > CO2 > NO2 > SO2, with H2S exhibiting the highest diffusion coefficient of 7.71 Ų/ps, further supporting its stronger interaction with the MIL-100(Fe)’s adsorption sites. These molecular simulation calculations confirm that MIL-100(Fe) is highly effective at adsorbing toxic gases such as H2S, SO2, CO2, and NO2, highlighting its potential as a promising adsorbent for air purification applications.