Exploring the interesting interaction between graphene oxide, Aliquat-336 (a room temperature ionic liquid) and chromium(vi) for wastewater treatment

Abstract

We report an interesting interaction between exfoliated graphene oxide (EGO), ionic liquid (IL) Aliquat-336 and hexavalent chromium. Graphene oxide was impregnated with the ionic liquid and the interaction primarily involves electrostatic affinity between the quaternary ammonium cation and surface hydroxyl groups in EGO. The IL-EGO combination functions as an effective adsorbent for hexavalent chromium. The IL-EGO adsorbent acts as a good host in welcoming the incoming guest, hydrochromate anion and several interesting interactions such as cation–π, electrostatic as well as anion–π could be conceptualized in this process. The adsorbent features are ably supported by various physico-chemical characterization techniques and the effect of various analytical parameters affecting the adsorption is examined in detail. A high Langmuir adsorption capacity of 285.71 mg g⁻¹ is augmented by the thermodynamically favourable adsorption process. Kinetic studies confirm the pseudo second order model and furthermore, the process could be upgraded by column study to a sample volume of 1200 mL. Effective regeneration of the adsorbent could be accomplished with ammonium hydroxide and the potential of this novel adsorbent material has been examined in the total removal of chromium from a tannery effluent sample.