¹ Faculty of Science, Suez University, Suez 43221, Egypt;

² Faculty of Science, Islamic University of Madinah, Madinah 42351, Saudi Arabia

* Correspondence: amostafa0004@gmail.com

The development of environmentally sustainable adsorbents with high efficiency and structural stability remains a critical challenge for advanced water treatment technologies. In this study, a green and scalable strategy was employed to fabricate hybrid nanocomposites (NCs) based on copper benzene-1,3,5-tricarboxylate (MOF-199) and graphene oxide (GO) nanosheets. GO was produced via electrochemical exfoliation of recycled graphite rods, while MOF-199 nanoparticles were synthesized using a water-ethanol solvothermal route, avoiding toxic solvents and harsh conditions. Comprehensive structural and surface analyses (XRD, SEM, TEM, FTIR, Raman spectroscopy, EDX, SEM-EDS, and XPS) confirmed the formation of highly crystalline MOF-199 nanoparticles uniformly anchored onto GO sheets through strong interfacial interactions. Nitrogen adsorption–desorption measurements demonstrated that pristine MOF-199 exhibits a predominantly microporous structure with a high BET surface area of approximately 1380 m² g⁻¹ and a total pore volume of 0.82 cm³ g⁻¹. Controlled incorporation of GO enhanced the textural properties, with the optimized MOF-199/GO NCs achieving a BET surface area of ~1450 m² g⁻¹ and a pore volume of ~0.87 cm³ g⁻¹, attributed to improved pore accessibility and the formation of interfacial mesoporosity, whereas excessive GO loading resulted in reduced surface area due to partial pore blockage and GO restacking. Adsorption experiments using methylene blue (MB) as a model contaminant revealed an adsorption capacity increase of ~20–25% for MOF-199/GO NCs compared with pristine MOF-199 at optimal GO contents (9–12 wt.%). Kinetic analysis followed a pseudo-second-order model, while isotherm data were described by Langmuir and Freundlich models, indicating chemisorption on energetically favorable active sites. Spectroscopic evidence from FTIR and XPS after adsorption confirmed strong interactions involving open Cu²⁺ metal sites, oxygen-containing functional groups on GO, and π–π interactions with dye molecules. Overall, this work establishes a clear structure–textural–performance relationship and highlights MOF-199/GO NCs as promising sustainable adsorbents for advanced water purification applications.