Synthesis of Amine‐Functionalized Fly Ash‐Infused Polymeric Hydrogel for <scp>H₂S</scp> Removal and Validation Using Molecular Dynamic Simulation

ABSTRACT Hydrogen sulfide (H 2 S) removal from natural gas is critical due to its toxicity and corrosive nature. Adsorption is one of the most effective methods, but polymeric hydrogels often exhibit limited H 2 S adsorption capacity. To overcome this, an amine‐functionalized fly ash (FA)‐grafted polyacrylic acid (PAA) hydrogel (FA‐ g ‐PAA) was synthesized using 5 wt.% FA via solution polymerization and functionalized with 30 wt.% monoethanolamine (MEA) to enhance H 2 S removal. Physiochemical properties and H 2 S adsorption performance were evaluated using Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, thermogravimetric analysis (TGA), and X‐ray diffraction (XRD). The results confirmed the successful grafting of FA and MEA into the PAA matrix. Due to the grafting of FA, the morphology and surface area of the FA‐ g ‐PAA hydrogel enhanced from 0.04 m 2 /g (pure hydrogel) to 0.8m 2 /g. The breakthrough analysis showed the 30 wt.% MEA‐functionalized FA‐ g ‐PAA hydrogel demonstrated a superior H 2 S adsorption capacity of (2.0 mmol/g), significantly outperforming the nonfunctionalized FA‐ g ‐PAA (1.6 mmol/g) and pure PAA hydrogel (0.08 mmol/g) at room temperature. Molecular dynamics (MD) simulations confirmed the hydrogel model and revealed the synergistic role of FA and MEA in enhancing H 2 S adsorption. Overall, the MEA‐functionalized FA‐ g ‐PAA hydrogel shows efficient H 2 S adsorbent for industrial gas purification applications.