A facile colloidal crystal templating method to produce three-dimensional hierarchical porous graphene-Fe3O4 nanocomposite for the removal of dyes from aqueous solution

Three-dimensional hierarchical porous graphene-Fe3O4 (3D-HPGF) nanocomposite was synthesized through a facile colloidal crystal templating method and used as adsorbent for the removal of organic dyes from aqueous solution. The obtained 3D-HPGF nanocomposite had high specific surface area and three-dimensional hierarchical porous structure. The adsorption behaviors of 3D-HPGF nanocomposite for methylene blue dye in aqueous solution were systematically investigated. Results showed that 3D-HPGF nanocomposite adsorbent exhibited extraordinary adsorption capacities and fast adsorption rates for the removal of organic dye. The excellent adsorption capacities of 3D-HPGF nanocomposite could be attributed to the van der Waals interactions and strong pi-pi interactions between graphene and organic dye. The kinetics and equilibrium adsorptions were well-described by pseudo-second-order kinetic and Langmuir isotherm model, respectively. The thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic in nature. In addition, 3D-HPGF nanocomposite could be easily regenerated for reuse through magnetic separation and ethanol treatment. Due to the excellent adsorption capacity, fast adsorption rate and convenient magnetic separation, the as-prepared 3D-HPGF nanocomposite could be utilized as an efficient, magnetically separable adsorbent for the environmental applications.