Chitosan nanofibers functionalized by TiO2 nanoparticles for the removal of heavy metal ions

• The novel adsorbents based on chitosan/TiO2 nanofibers were prepared.
• The efficient adsorption of Cu (II) and Pb (II) ions was investigated.
• The equilibrium time for adsorption process was found to be 30 min.
• The adsorption nature for both metal ions was endothermic/spontaneous.
• The nanofibers can be reused repeatedly with a high adsorption capacity.

The chitosan/TiO2 composite nanofibrous adsorbents were developed by two techniques including TiO2 nanoparticles coated chitosan nanofibers (coating method) and electrospinning of chitosan/TiO2 solutions (entrapped method). The potential of prepared nanofibers was investigated for the removal of Pb (II) and Cu (II) ions in a batch system. The nanofibers were characterized by SEM, FTIR and BET analysis. Kinetic and equilibrium studies showed that the experimental data of Pb (II) and Cu (II) ions were best described by pseudo-first-order and Redlich–Peterson isotherm models using the both chitosan/TiO2 nanofibers. The maximum adsorption capacities of Cu (II) and Pb (II) ions using entrapped and coating methods were found to be 710.3, 579.1 and 526.5, 475.5 mg/g at equilibrium time of 30 min and 45 °C, respectively. The reusability studies indicated that the chitosan/TiO2 nanofibers prepared by entrapped method could be reused frequently without significant loss in adsorption performance after five adsorption/desorption cycles. Whereas, lower than 60% of total adsorption in first cycle took place for metal ions sorption using nanofibers prepared by coating method. The sorption studies of metal ions in a binary system revealed that the selectivity of metal sorption using chitosan/TiO2 nanofibrous adsorbent was in order of Cu (II) > Pb (II).

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