Removal of Ni2+ and Cd2+ ions from aqueous solutions using electrospun PVA/zeolite nanofibrous adsorbent

Abstract

Abstract A novel adsorbent based on electrospun polyvinyl alcohol (PVA)/NaX nanozeolite nanocomposite nanofibers was prepared using electrospinning process and its application for the removal of Ni2+ and Cd2+ ions from aqueous solutions was investigated. The prepared composite nanofibers were characterized by FTIR, SEM and BET analysis. The effect of operating parameters including zeolite concentration, contact time, initial concentration of Ni2+ and Cd2+ ions and temperature were studied in a batch system. The adsorption results indicated that the affinity of PVA/zeolite nanofibrous adsorbent for Cd2+ ions sorption was higher than that of Ni2+ ions sorption. The kinetic data of both Ni2+ and Cd2+ ions were found to follow the pseudo-second-order kinetic model and the equilibrium data of both metal ions sorption were well described by Langmuir isotherm model. The maximum monolayer sorption capacities of Ni2+ and Cd2+ were estimated to be 342.8 and 838.7 (mg g−1) in equilibrium time of 60 min at temperature of 45 °C. Evaluation of thermodynamic parameters indicated that the nature of both metal ions sorption by the nanofibrous adsorbent was endothermic and spontaneous at studied conditions. The result of reusability of the PVA/zeolite composite nanofibers after five sorption–desorption cycles provided a promising nanofibrous adsorbent with the higher efficiency for metal ions sorption. The result of simultaneous sorption of Ni2+ and Cd2+ ions by the PVA/zeolite nanofibers was also confirmed that the adsorption of metal ions followed the descending order: Cd2+ > Ni2+ in a binary system.