Elimination of Ofloxacin from Water Media by chitosan/kappa-carrageenan/polyvinyl alcohol/NiFe LDH Nanocomposite Hydrogel

In this study, chitosan/kappa-carrageenan/polyvinyl alcohol-NiFe-layered double hydroxide (CS/KCa/PVA-NiFe LDH) as novel nanocomposite hydrogels were synthesized by freeze and thawing method to eliminate Ofloxacin (OFL) from water media in a batch mode. Solvothermal method was applied to synthesize NiFe LDH nanoparticles. The successful formation of NiFe LDH, CS/KCa/PVA and CS/KCa/PVA-NiFe LDH was confirmed by FTIR, XRD, SEM and TEM analysis. The optimum weight% of these nanoparticles in the hydrogel matrix was obtained 2 wt% and the removal efficiency of CS/KCa/PVA was enhanced from 68.86 to 91.94% by incorporating 2wt.% of NiFe LDH. The swelling study demonstrated that the highest swelling factor was obtained at a pH of 7.4. The highest removal efficiency of CS/KCa/PVA, CS/KCa/PVA-NiFe LDH (1 wt%), and CS/KCa/PVA-NiFe LDH (2 wt%) was obtained to be 68.86, 85.02, and 91.94%, respectively in optimum values of 7, 0.05 g/L, 30 mg/L, 100 min, and 298 K for pH, adsorbent dose, initial concentration, contact time, and temperature, respectively. Kinetic and isotherm data showed high accuracy fitting with pseudo-second-order and Langmuir models, respectively. Based on the outcomes of intraparticle diffusion model, penetration into adsorbents are more effective than film diffusion in OFL removal. The monolayer adsorption capacity of CS/KCa/PVA, CS/KCa/PVA-NiFe LDH (1 wt%), and CS/KCa/PVA-NiFe LDH (2 wt%) was computed to be 37.59, 41.49, and 52.63 mg/g, respectively. Thermodynamic study reveals that OFL removal process by adsorbents has negative variations in Gibbs free energy and enthalpy (-17.55 kJ/mol for CS/KCa/PVA, -35.88 kJ/mol for CS/KCa/PVA-NiFe LDH (1 wt%), and − 49.15 kJ/mol for CS/KCa/PVA-NiFe LDH (2 wt%)) showing spontaneous and exothermic nature of this process. The ad(de)sorption study showed that no significant changes in removal performance were seen up to 4 cycles. Antibacterial activity showed that CS/KCa/PVA-NiFe LDH has uppermost antibacterial activity towards S. aureus compared to E.Coli. Finally, synthesized adsorbents specially CS/KCa/PVA-NiFe LDH (2 wt%) could be applied as efficient adsorbents in wastewater treatment application.