High Efficient Removal of Methylene Blue Using Microcrystalline Cellulose/Polyvinyl Alcohol/Expanded Graphite 3D Porous Foam as a “Green” Adsorbent

Abstract The cellulose/polyvinyl alcohol (PVA)/expanded graphite (EG) 3D porous foam, which has wide application prospects in cost-effective dye removal, was prepared by physical crosslinking and foaming technology. The prepared foam material has an obvious 3D network and porous structure, exhibiting excellent removal efficiency for methylene blue (MB) in an aqueous solution. The largest MB adsorption capacity of the foam is 110.81 mg/g. The adsorption process follows the pseudo-2nd order kinetics and the Freundlich isotherm model, indicating that the adsorption process is controlled by active surface sites and the physical adsorption process. Thermodynamic studies have shown that the adsorption process is a spontaneous and exothermic reaction. After five cycles of adsorption experiments, the composite material still exhibited a more than 70% dye removal rate. The results show that cellulose/PVA/EG 3D porous foam is effective, promising, and recyclable adsorbent, which can be used to remove MB from aqueous solutions.