Graphene oxide–carbon nanotube-magnetite nanocomposites for efficient arsenic removal from aqueous solutions

Abstract

In this study, graphene oxide–carbon nanotube-magnetite (GO/CNT/Fe₃O₄) nanocomposites were synthesized via a co-precipitation method for wastewater treatment. The obtained results indicated that Fe₃O₄ nanoparticles exhibited a spherical-shaped morphology, with an average diameter of around 20 nm, and decorated the surface of GO and CNTs. The adsorption data fitted well with the Langmuir isothermal model, exhibiting a coefficient of R² > 0.998, and the adsorption kinetics followed the pseudo-second-order model. This indicated that the adsorption mechanism involved surface complexation between adsorbents and As(III) ions rather than electrostatic interactions. The As(III) removal results also indicated that the GO/CNT/Fe₃O₄ nanocomposites exhibited a significantly enhanced adsorption capacity (q_max) of 128.5 mg g⁻¹ compared with those of CNT/Fe₃O₄ (106.3 mg g⁻¹) and GO/Fe₃O₄ (113.9 mg g⁻¹) composites. In addition, GO/CNT/Fe₃O₄ nanocomposites exhibited the highest adsorption efficiency of up to 99.18%. The coexisting ions, such as phosphate and sulfate, showed a negligible influence on the adsorption of As(III) in solutions. The obtained results demonstrated that the GO/CNT/Fe₃O₄ nanocomposites could be promising candidates for the removal of arsenic and other contaminants from aqueous solutions.