Efficient dye removal from aqueous solution using a hybrid GA@ZnO-AC nanocomposite

Environmental damage caused by colored effluents poses a threat to the environment, as vast amounts of harmful water contamination are regularly discharged into water sources. The hybrid nanocomposite was successfully synthesized using hydrothermal and thermal treatment methods. A prepared hybrid nanostructure metal composite material, utilizing gallic acid (GA@ZnO-AC), was synthesized and employed for the treatment of methylene blue (MB) in an aqueous environment via adsorption. FTIR, SEM-EDX, BET, and XRD analyses were performed on the hybrid composite. The ZnO, ZnO-AC, and GA@ZnO-AC have a BET surface area of 3.7360, 491.8929, and 467.51 m²/g, pore volume of 0.004039, 0.286580, and 0.247606 cm³/g, and average pore diameter of 4.3240, 2.3304, and 2.1185 nm, respectively. TGA and TEM results indicate that the material is thermally stable due to its phase transition and exhibits a nano-scale shape. The adsorptive performance of nanocomposites ZnO-AC and GA@ZnO-AC for MB removal was significantly influenced by contact time (60 min), temperature (298 K), adsorbent dosage (60 mg (ZnO-AC), 50 mg (GA@ZnO-AC)), and pH (11). The percentage absorbed MB was 98.61% for ZnO-AC and 98.30% for GA@ZnO-AC at their optimum condition. The Langmuir isotherm showed that ZnO-AC and GA@ZnO-AC had the highest adsorption capacities of 153.85 mg/g and 175.44 mg/g, respectively, at 298 K. Isotherm, kinetics, and thermodynamics studies showed that the results fitted the Redlich-Peterson and PSO models, which indicated a spontaneous, feasible, exothermic, and physisorption process. This study presents a low-cost hybrid material that addresses environmental concerns related to the removal of dyes from aqueous media.