Effect of Crosslinker Concentration on Polyacrylic Acid Hydrogel for H₂S Adsorption: Molecular Dynamic Simulation...

The safe and efficient removal of hydrogen sulfide (H₂S) from natural gas is essential to prevent environmental hazards and equipment corrosion. This study investigates the influence of crosslinker concentration on the H₂S adsorption performance of tetraethylenepentamine (TEPA) impregnated polyacrylic acid (PAA) hydrogels through a combination of experimental analysis and molecular dynamics (MD) simulations. The synthesized hydrogel samples were experimentally characterized using Fourier-Transform Infrared Spectroscopy (FTIR) to identify the functional groups. MD simulations were performed to optimize and equilibrate the molecular structures. Simulated X-ray diffraction (XRD) patterns were generated to analyze the structural characteristics of the models. Grand Canonical Monte Carlo (GCMC) simulations were used to investigate H₂S adsorption under different temperatures and pressures. The results reveal that increasing the crosslinker concentration reduces the hydrogel's H₂S adsorption capacity (down to 1.5 mmol/g) by limiting available adsorption sites, restricting swelling, and negatively affecting TEPA distribution. Conversely, lower crosslinker concentrations enhance H₂S uptake (up to 3 mmol/g) by promoting polymer chain flexibility and enabling more effective TEPA-H₂S interactions. This integrated experimental and simulation study provides insight into the adsorption mechanisms of H₂S, offering valuable guidance for the development of high-performance amine-impregnated polymer hydrogels for industrial gas purification applications.