Thermodynamic Studies on the Removal of Metronidazole Antibiotic by Multi-Walled Carbon Nanotubes

Hossein Azarpira, Yousef Mahda

Abstract

The adsorption of Metronidazole (MNZ) on Multi-Walled Carbon Nanotube (MWCNTs) samples of varying compositions was investigated using a batch adsorption technique. Adsorption studies were carried out for various parameters such as adsorbent dosage, ionic strength and contact time. Adsorption of MNZ onto MWCNTs increased with the increase in the adsorbent dosage and the optimum adsorbent dosage was found to be 0.1 g/L. The equilibrium between the MNZ and the adsorbent in the solution was established within 60 min. The negative value of ΔG◦ showed the spontaneous nature of MNZ adsorption onto MWCNTs. The standard enthalpy and the entropy changes were determined as 4.17 kJ mol−1 and 0.0165 kJ mol−1K−1 respectively. The positive value of ΔH◦ suggested the endothermic nature of adsorption, while positive values of ΔS◦ showed the increasing randomness at the MWCNTs-solution interface during the adsorption.