Synthesis of g-C 3 N 4 @WO 3 nanocomposites for dye adsorptive removal in water medium: Equilibrium and kinetics studies

In this research, WO3, g-C3N4, and g-C3N4@WO3 nanocomposites were synthesized from Na2WO4.2H2O and urea precusors via the hydrothermal method in a strong acid medium. Physico-chemical characteristics of WO3, g-C3N4, and g-C3N4@WO3 nanocomposites were examined by means of XRD, Raman, FTIR, FE-SEM, BET, and UV-Vis spectroscopy. The produced materials were then applied for studying adsorptive removal of methylene blue (MB) as a model pollutant from aqueous solutions. The results showed that g-C3N4@WO3 nanocomposites were successfully synthesized, with a hexagonal shape and an average crystal size of in the range of 15.4–20.7 nm. The surface area (68.3 m2/g) of g-C3N4@WO3 nanocomposites was 2.37 times higher compared to sole WO3, and g-C3N4@WO3 composites were mesoporous materials with a typical average pore diameter of 4.5 nm. It was revealed that the MB adsorption process occurred extremely quickly, reaching equilibrium after only about 20 min, with a maximum uptake of MB of 190 mg/g which was significantly higher than other adsorbents. The adsorption process was followed the first-order-kinetics model and the adsorbent showed high durability in adsorbing MB, with a slight decline in adsorption efficiency after 4 cycles (from 98.7% to 95.9%). This research provides an easy method for producing high adsorption capacity nanocomposite which can be applied for efficient removal of MB from water.