Functionalized Graphene Oxide-Embedded Hydrogels for Adsorptive Removal of Aromatic Hydrocarbons From Aqueous Systems

In this study, a Lasoda hydrogel-based composite incorporating hydroxyl-functionalized graphene oxide (LA-GO-OH) was developed for efficient adsorption of polycyclic aromatic hydrocarbons (PAHs) from aqueous media. Hydroxyl-functionalized graphene oxide (GO) was synthesized via a thermal shock method and integrated into the Lasoda hydrogel through in situ polymerization. Structural and surface characterization using FESEM, EDS, XRD, FTIR, Raman, and XPS confirmed successful composite formation, preservation of hydroxyl functionalities, and graphitic domains. XPS analysis of the composite after adsorption of naphthalene (Nap) and anthracene (Ant) revealed characteristic C 1s binding energies (∼284.78 eV) corresponding to sp²-hybridized aromatic carbon, along with π→π* shake-up satellite features (∼286-289 eV), indicating intact aromatic structures after adsorption. Ant exhibited stronger satellite features than Nap due to greater electronic delocalization. Adsorption studies monitored by UV-visible spectroscopy at λ_max values of 220 nm (Nap) and 375 nm (Ant) demonstrated maximum removal efficiencies of 97% and 94%, with adsorption capacities of 88 and 128 mg g^{- 1}, respectively. Adsorption mainly occurred through π-π interactions between aromatic molecules and graphitic domains. Equilibrium data followed the Langmuir isotherm, kinetics obeyed the pseudo-second-order model (R² = 0.99), and thermodynamic analysis confirmed spontaneous, endothermic, and entropy-driven adsorption.