Adsorption performance of magnesium/aluminum layered double hydroxide nanoparticles for metronidazole from aqueous solution

Magnesium/aluminum layered double hydroxide (LDH) nanoparticles were synthesized by hydrolyzing urea and used to remove metronidazole (MN) from aqueous solution. The surface morphology images of the LDH nanoparticles showed that the adsorbent surface consisted of hexagonal nanosheets with a diameter of 200-1000 nm. The MN removal efficiency was strongly dependent on the solution pH ranging from 3 to 9. The addition of nitrate, sulfate, and carbonate did not remarkably affect MN adsorption, while hardness slightly improved MN removal efficiency. The adsorption isotherm data could be well described using the Sips equation. The analysis of kinetic data showed that the adsorption of MN onto LDH closely followed the Avrami model and that several kinetic processes may control the rate of sorption. The adsorption process was non-spontaneous and exothermic in nature. The maximum Langmuir adsorption capacity was 62.804 mg/g, demonstrating that LDH is an efficient adsorbent that can be used for the removal of MN compounds.