Removal of heavy metal ions from aqueous solution using amidoxime-functionlized SiO₂/PVA composite nanofibers prepared by sol-gel electrospinning

Amidoxime-functionalized SiO₂/polyvinyl alcohol(SiO₂/PVA) nanofiber adsorbent was prepared by electrospinning technique. The composite SiO₂/PVA nanofibers was analyzed by SEM, FTIR, DSC and TGA.The nanofiber adsorbent was also evaluated for mental ions adsorption capacity.The results indicate that the highest adsorption occurs at pH=6 and the adsorption capacity can be 143.7 mg/g and 125.1 mg/g for Cu²⁺ and Ni²⁺, respectively. The composite SiO₂/PVA nanofibers can remove almost 90% aforementioned ions from aqueous solutions within 50 min. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order kinetic model, the kinetic process is found to fit the pseudo-second-order equation and the adsorption isotherm data fit well the Langmuir isothermal model. Furthermore, HNO₃ is found to be effective in regenerating the adsorbent and 53% of the metal ions are removal from the aqueous even in the fourth regeneration/reuse cycle, which imply that the nanofibers can be suitable for water treatment as adsorbent.