Application of the Fe3O4-chitosan nano-adsorbent for the adsorption of metronidazole from wastewater: Optimization, kinetic, thermodynamic and equilibrium studies.

The development of adsorbents with high adsorption performance is an effective method of removing metronidazole (MTZ). Therefore, Fe3O4-chitosan nano-adsorbent (CTS-MNPs) was synthesized. The SEM, TEM, FTIR, VSM and BET analyzes were applied to determine the surface morphologies, shape and size, functional groups, magnetic properties, size and volume of CTS-MNPs, respectively. R software using response surface methodology was applied to investigate the composition effect of input factors and output response. The second-order model because of insignificant lack of fit, lower P-value and also higher R2 indicated highly significant for adsorption of MTZ by CTS-MNPs. The predicted optimal conditions with considering the maximum removal efficiency (100%) were calculated for second-order model and were included (pH, 3; CTS-MNPs dosage, 2 g L-1; contact time, 90 min and MTZ concentration, 10 mg L-1). It is found that the experimental findings for the response are in good agreement with model predictions. The results declare MTZ adsorption onto CTS-MNPs involves a multilayer process (Freundlich isotherm model). Also, pseudo-second-order model indicated more appropriate for describing the MTZ adsorption onto the CTS-MNPs. The adsorption thermodynamic revealed an endothermic and spontaneous reaction for the adsorption of MTZ by CTS-MNPs.