Polyacrylonitrile/clay nanofibrous nanocomposites for efficient adsorption of Cr (VI) ions

This paper highlights the efficient adsorption of Cr (VI) from wastewater using polyacrylonitrile (PAN)/montmorillonite (Mt) and polyacrylonitrile/zinc oxide nanoparticle-modified montmorillonite (ZnO-Mt) nanofibrous nanocomposites as adsorbents. Mt was modified using zinc oxide nanoparticles (ZnO) by an adsorption process. The particle size of ZnO-Mt was found to be 18 ± 2 nm. Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) images showed the presence of ZnO on and within the layers of Mt. Mt and ZnO-Mt were used to prepare PAN/clay nanofibrous nanocomposites which were further used as adsorbents for Cr (VI) ions. X-ray diffraction (XRD) analysis showed that Mt and ZnO-Mt were exfoliated in the PAN nanofibrous matrix. Mt, ZnO-Mt, PAN/Mt and PAN/ZnO-Mt nanofibrous nanocomposites were analyzed as adsorbents for the adsorption of Cr (VI) ions. The effect of pH, concentration, time and amount of adsorbent on the removal of Cr (VI) ions from water were investigated. Adsorption of Cr (VI) ions over the adsorbents follows pseudo-second-order kinetics, and Langmuir and Freundlich isotherms. PAN/ZnO-Mt and PAN/Mt nanofibrous nanocomposites were found to be more effective adsorbents for Cr (VI) ions compared to ZnO-Mt and Mt.