Directly loading graphene oxide into melamine sponge for fast and high-efficiency adsorption of methylene blue

Graphene oxide (GO) is considered as a promising adsorbent for removal of dye pollutants. Herein, to improve the adsorption ability, GO was directly loaded and immobilized in a commercial melamine sponge with a three-dimensional skeleton. Based on the porous, hydrophilic and elastic characteristics of the sponge, GO sheets were sucked into the pores and dispersed throughout the sponge by a facile squeezing-sucking method in GO aqueous suspension. The sucked GO sheets are stably bound to the skeleton by non-covalent bonds, forming a three-dimensional structure and exposing as many functional groups as possible. Such adsorbent showed high competitiveness in adsorption rate and adsorption capacity for methylene blue (MB). The adsorption efficiency for a MB solution could reach ∼95% in 30 s. By optimizing the loading amount of GO and pH of MB solution, the adsorption reached equilibrium within 90 min and the adsorption capacity could reach 260.9 mg·g−1. The adsorption behavior follows a Pseudo-second-order kinetic model and the Langmuir isotherm model. The main adsorption mechanism is a monolayer adsorption process based on electrostatic interactions. The facile loading method and the high adsorption efficiency of the adsorbent will promote the application of GO in low-cost, fast, and highly efficient treatment of dye pollutants.