Magnetic nanoadsorbents derived from magnetite and graphene oxide for simultaneous adsorption of nickel ion, methylparaben, and reactive black 5

The purpose of this study was to investigate magnetic nanoadsorbents (GO/Fe3O4) derived from magnetite (Fe3O4) and graphene oxide (GO) for simultaneous removal of nickel ion (Ni(II)), methylparaben (MP), and reactive black 5 (RB5). As a result, the maximum adsorption capacity in aqueous solution for Ni(II), MP, and RB5 was 15.5, 20.69, and 63.18 mg g(-1) in single-component system, respectively. The adsorption of Ni(II), MP, and RB5 onto GO/Fe3O4 reveals good agreement with the Langmuir adsorption isotherms and pseudo-second-order model. The adsorption capacity suppressed for MP with increasing RB5 concentration in MP-RB5 binary system. However, the adsorption capacity for Ni(II) almost was not affected with increasing MP and RB5 concentration in binary system. The mechanisms of GO/Fe3O4 for the adsorption of Ni(II), MP, and RB5 are probably dominated by pi-pi interaction, electrostatic attraction, both pi-pi interaction and electrostatic attraction, respectively. The optimum ethanol concentration to desorb methylparaben from GO/Fe3O4 is 95% with a three times adsorption-desorption cycle by the recovery of magnetic force due to the detachment of the shell (graphene). Conclusively, GO/Fe3O4 has good adsorption performance and is easily reused; these are important factors contributing to its potential practical application.