Facile One-Pot Synthesis of Novel Spherical Zeolite–Reduced Graphene Oxide Composites for Cationic Dye Adsorption

Zeolite–reduced graphene oxide (zeolite–rGO) composites were first fabricated from halloysite nanotubes (HNTs) by blending with GO via a hydrothermal reaction and then were used as an effective adsorbent for the removal of cationic dyes (methylene blue and malachite green). Zeolite–rGO was presented as having spherical structure with the diameter of 2–2.5 μm. The adsorption behavior of the two cationic dyes was affected by equilibrium time, pH, etc. Additionally, the most appropriate adsorption process of dyes was well-fitted to Langmuir models. It was found that adsorption of dyes was favorable and the maximum adsorption capacity of methylene blue reached 53.3 mg g –1 (48.6 mg g –1 for malachite green). The superior behavior of zeolite–rGO for cationic dye removal from an aqueous solution should be amenable to potential water treatment applications in consideration of zeolite–rGO’s low-cost, abundance in clay minerals, and favorable adsorption processes.