Batch Adsorption Kinetics and Isotherm Modeling of Thiocyanate Using Reduced GO-Metal Oxide Nanocomposites.

The elimination of thiocyanate (SCN-), a persistent and hazardous pollutant in industrial effluents, constitutes a significant environmental issue. This study presents the synthesis and deployment of a new nanocomposite of reduced graphene oxide functionalized with metal oxides (rGO-Al2O3/MgO/K2O) for effective SCN- adsorption. The nanocomposite was synthesized by a hydrothermal process and evaluated using FTIR, XRD, XPS, SEM, TEM, EDX, BET, and TGA studies. FTIR and XPS validated effective functionalization and SCN- adsorption via nucleophilic interactions and surface changes. XRD indicated structural modifications during adsorption, whereas SEM/TEM demonstrated morphological transformation from exfoliated rGO sheets to compact, irregular rGO-MOs-SCN structures. EDX and elemental mapping confirmed the inclusion of Al, Mg, K, and SCN- ions. BET analysis revealed a substantial specific surface area of 36.7123 m2/g for rGO-Al2O3/MgO/K2O, promoting improved adsorption. TGA exhibited enhanced thermal stability of the composite, with merely 54.6% weight loss at 600 °C. Batch adsorption tests demonstrated optimum SCN- removal at pH 2.0 and 25 °C, with a maximum removal of 91.4%. The adsorption effectiveness diminished as temperature increased, signifying exothermic activity. The process adhered to Freundlich and Langmuir isotherms, exhibiting correlation coefficients (R 2) between 0.8901 and 0.9882, respectively. Thiocyanate quantification was accomplished by UV-visible spectrophotometry at 460 nm utilizing Fe3+ complexation. This rGO-metal oxide nanocomposite provides an economical, thermally stable, and highly successful solution for thiocyanate remediation in aqueous environments, with significant implications for industrial wastewater treatment and environmental protection.