A Novel Graphene Oxide/γ-Alumina Hybrid Nano-Adsorbent Integrated into Polyurethane Foam for Adsorption of Industrial Pollutants from Wastewater

This study reports the synthesis, characterization, and wastewater treatment performance of a hybrid nanocomposite based on graphene oxide (GO) and γ-alumina (γ-Al2O3). Functionalization was carried out via silanization using GPTMS for GO and APTES for γ-Al2O3, followed by covalent grafting through epoxy–amine linkage. FTIR spectroscopy confirmed successful grafting, showing Si–O–Si stretching and reduced epoxy ring vibrations. BET analysis indicated that the GO/γ-Al2O3 hybrid (ALGO) preserved a high specific surface area (198.08 m2/g), comparable to commercial γ-Al2O3, demonstrating that GO did not hinder porosity. ALGO was incorporated into polyurethane foam at loadings of 1–5% (ALGO@PU foam) and applied in wastewater treatment. UV-Vis spectroscopy revealed strong affinity for silver ions, evidenced by a decrease in AgNO3 absorbance (~430–600 nm) with increasing AlGO content. Treatment of real industrial wastewater showed significant reductions in chemical oxygen demand (COD), biological oxygen demand (BOD), and turbidity. At 5% loading, COD and BOD decreased from 1162 and 480 mg/L to 64 and 11 mg/L, respectively, while turbidity dropped from >1100 NTU to 1.62 NTU. These results demonstrate that ALGO is a functional adsorbent capable of removing ion metals, and improving water clarity, highlighting its potential for industrial wastewater treatment applications.