Gamma irradiation syntheses of poly arginine/acrylamide/nanographene oxide hydrogel for effective removal of hazardous antibiotic waste from its solution

Abstract Removal of the doxycycline antibiotic from waste solutions is essential to preserve the ecosystem. In this study, a highly absorbent, functionalized hydrogel nanocomposite based on arginine and acrylamide was synthesized via gamma irradiation–induced polymerization and crosslinking. Graphene oxide nanoparticles (nGO), prepared by a modified Hummer’s method, were incorporated during the preparation process. The prepared nanocomposite hydrogel exhibited a maximum gelation percentage of about 90 % at an nGO concentration of 0.5 wt% and an irradiation dose of 20–30 kGy, corresponding to a swelling percentage of approximately 2500 %. A new peak at 2770 cm −1 in the FTIR spectrum, attributed to C–H stretching from nGO alkyl chains, confirms the successful incorporation of GO. The morphological properties of the hydrogel surface, examined through SEM, also revealed structural changes due to nGO addition. XRD analysis confirmed the dispersion of nGO and strong interfacial interactions within the hydrogel matrix, and crystallite sizes ranging from 4.20 to 8.66 nm. TEM analysis illustrated that the nGO sheets possessed lateral diameters ranging from about 9.4 to 20.7 nm. The optimum pH for doxycycline adsorption was found to be 7. The adsorption process followed the Freundlich isotherm model, and kinetic analysis revealed that physical adsorption was the dominant mechanism. Thermodynamic parameters confirmed that the adsorption process was exothermic. The prepared nanocomposite hydrogel demonstrated excellent adsorption performance, achieving a maximum doxycycline removal efficiency of 92.8 %, demonstrating its potential application in sustainable wastewater treatment.