Removal of tartrazine dye and mercury present in aqueous solutions using hexamethylenetetramine exfoliated MoS2 nanosheets as adsorbent: a comparison of kinetic and isotherm models

A hydrothermal approach was followed to make highly exfoliated MoS2 nanosheets with hexamethylenetetramine as the exfoliating agent. The synthesized MoS2 nanosheets have a petal-like structure, as evidenced by scanning electron microscopy and transmission electron microscopy. Using this MoS2 nanosheet, various adsorption isotherm and kinetic models were studied to remove contaminants such as tartrazine dye and mercury in the aqueous solutions. The Freundlich isotherm model, which yields the best match, implicates the multilayer adsorption process. In this study, pseudo-first-order kinetics was found to be a good fit indicating the physisorption process for tartrazine dye adsorption and pseudo-second-order kinetics for mercury ion adsorption. Also, it was noticed that MoS2 nanosheets had eliminated 99% of the tartrazine dye and mercury from the aqueous solution within 5 min and 6 h intervals of time, respectively. The maximal adsorption capabilities for tartrazine dye and mercury ions were 41 and 495 mg g(-1), respectively.

Automated summary

A hydrothermal approach was used to synthesize petal-like MoS2 nanosheets with hexamethylenetetramine as the exfoliating agent. The MoS2 nanosheets showed high adsorption capabilities for tartrazine dye and mercury ions, removing 99% of the contaminants within 5 minutes and 6 hours, respectively. The Freundlich isotherm model and pseudo-first-order and pseudo-second-order kinetic models were found to be applicable for the adsorption processes.