Preparation of surfactant modified magnetic expanded graphite composites and its adsorption properties for ionic dyes

To enhance the surface hydrophilicity, adsorption capacity to various ionic dyes, and recovery efficiency, modified expanded graphite (MEG) was fabricated by surfactant-based intercalating reagent CTAB/KBr modification of expanded graphite (EG). Then magnetic composite adsorbents (Fe3O4/xMEG) were following synthesized with introduction of in-situ formed magnetic Fe3O4 by two different ways. The adsorption of Orange-II on Fe3O4/3MEG-I was evaluated to understand its effectiveness for dyestuff wastewater treatment. The Fe3O4/3MEG-I exhibited a rapid adsorption efficiency (47% within 2 min) and tunable adsorption properties with adjusting MEG amount, the adsorption process fitted better to the Langmuir isotherm and pseudo-second-order kinetic models. The removal efficiencies of a variety of dyes suggested that Fe3O4/3MEG-I could efficiently adsorb both the anionic and cationic dyes under neutral condition. The regeneration and reusability of the adsorbent were investigated in six consecutive adsorption-desorption cycles. Furthermore, Fe3O4/3MEG-I can be readily collected by an external magnet, which make it a promising candidate for dyes effluent treatment in practical application.

Automated summary

Fe3O4/3MEG-I demonstrated rapid adsorption efficiency and tunable adsorption properties through adjusting the amount of MEG. The adsorption process better fitted the Langmuir isotherm and pseudo-second-order kinetic models. It efficiently adsorbed both anionic and cationic dyes under neutral conditions.