Degradation of ciprofloxacin using hematite/MOF nanocomposite as a heterogeneous Fenton-like catalyst: A comparison of composite and core-shell structures.

A novel strategy was described to fabricate hematite-MOF materials with morphologies (core-shell) and (composite) as an efficient peroxymonosulfate (PMS) activator for degrading ciprofloxacin (CIP) antibiotics. First, α-Fe2O3 nanoparticles (NPs) with a size distribution range of 80 nm were prepared by surfactant-assisted reflux method. Then, cobalt-based metal-organic framework (ZIF-67) was grown onto the α-Fe2O3 NPs with ultrasonic and solvothermal method, which can control the nanostructures morphology. The physicochemical properties of these nanostructures were probed by ATR-IR, WA-XRD, FESEM, VSM, TEM, and EDS spectroscopy. The results showed that all the added CIP (20 ppm) antibiotics were completely degraded in 30 min in the α-Fe2O3/ZIF-67 (0.10 g/L) and PMS (0.20 g/L) system with rate constant of 0.130 min-1. To validate the merits of the α-Fe2O3/ZIF-67, α-Fe2O3@ZIF-67 core-shell nanostructures were also applied under similar conditions. The findings demonstrated that Co/Fe species within α-Fe2O3/ZIF-67 composite catalyzed PMS synergistically to the formation of the OH and SO4- and 1O2 for CIP degradation. Furthermore, α-Fe2O3/ZIF-67 showed good recyclability enabling facile separation of the catalyst from reaction mixtures using an external magnet. The current protocol can be a useful criterion in designing various Magnetic-MOF composites with controlled morphologies for environmental remediation.

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.