Green Synthesis of ZSM-5@rGO Composite for Adsorption of Methylene Blue from Aqueous Solution

A green approach was employed to fabricate ZSM-5 zeolite from expanded perlite and reduced graphene oxide (rGO) in the presence of the synthesized ZSM-5 zeolite to produce ZSM-5@rGO composite by one-step synthesis process via hydrothermal treatment. ZSM-5@rGO composites were characterized by various techniques such as scanning electron microscopy (SEM),  X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and N2 desorption–adsorption. The results showed that ZSM-5@rGO composite have a large surface area, uniform distribution and orderly crystal form. Moreover, the synthesized composites were evaluated as an adsorbent for removing cationic dye, methylene blue (MB), from an aqueous solution. The influence of factors on the adsorption, such as adsorption time, adsorbent dosage, initial dye concentration, and pH of solution, were investigated. The results of isothermal adsorption showed that the adsorption process was fit for both Langmuir and Freundlich models, and the highest adsorption capacity of ZSM-5@rGO composite for MB dye was 95.87 mg/g at environment temperature (30 oC). In addition, the study of adsorption kinetics indicated that the adsorption was consistent with the pseudo-second-order kinetic model with correlation coefficients of 0.9962. From these results, it can be confirmed that ZSM-5@rGO composite uses silicoaluminate as economical starting material with relatively high adsorption capacity and removal efficiency, which is a promising application for treating wastewater on a large scale.