Realization of of super high adsorption capability of 2D δ-MnO2/GO through intra-particle diffusion

Due to the high specific surface area and unique pore properties, two-dimensional materials (2D) are promising candidates in adsorption. In this work, 2D delta-MnO2 is synthesized through one-step self-assembly and its adsorption properties to methylene blue (MB) are examined. The maximum adsorption amount achieved 267.6 mg/g, it is far high beyond adsorbents reported previously which have similar structures. Considering the unique properties of GO, the prepared 2D MnO2 is combined with GO to enhance the adsorption capacities further. The combined compounds exhibit super high adsorption capabilities and the adsorption amount of 2D delta-MnO2/GO to MB increased to 1432.0 mg/g, which is more than 5 times higher than that of 2D delta-MnO2, the significant increase of adsorption amount is owing to the increase of pore size, which initiates the intra-particle diffusion channel. The adsorption kinetics and adsorption isotherms of 2D MnO2 and 2D delta-MnO2/GO are also analyzed with pseudo-second-order model and Langmuir isotherm model at different equilibrium concentration respectively.