Abstract

A novel graphene oxide (GO)/sodium montmorillonite (NaMMT) polymer nanocomposite was synthesized using a simple and environmentally friendly solution-mixing-evaporation technique and characterized using X-ray diffraction (XRD), fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy-dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) analysis. The nanocomposite, as an efficient adsorbent with a surface area of 230 m² g⁻¹, was subsequently applied for the removal of malachite green (MG) dye from real wastewaters and the effects of MG initial concentration, contact time, solution pH, adsorbent dosage, and the solution temperature were thoroughly studied. The nanocomposite exhibited rapid MG adsorption by reaching to an equilibrium in 20 min and the adsorption process followed the pseudo-second-order kinetic model. Isotherm experiments showed good fitting to the Langmuir model, and the highest adsorption capacity of the GO/NaMMT polymer nanocomposite was 1721 mg g^–1 at the temperature of 30 °C (approximately double the capacity of the highest previously reported adsorbent). Thermodynamic investigations disclosed that the process was inherently spontaneous and endothermic. Taken together, the proposed GO/NaMMT polymer nanocomposite, with the excellent properties, such as facile synthesis, cost-effectiveness (over five reusable cycles without any significant loss of its efficiency), effectiveness in real wastewaters, lack of production of secondary pollutions, stable three-dimensional (3D) structure (allow easy handling and separation during application), have high potential to serve as a highly efficient adsorbent for water/wastewaters treatment applications.