Highly selective and reusable nanoadsorbent based on expansive clay-incorporated polymeric nanofibers for cationic dye adsorption in single and binary systems

Abstract

Fabrication of nanoadsorbents with excellent adsorption capacity, selectivity, easy separation, and superior reusability for removing organic dyes from polluted water remains challenging. In this study, novel expansive clay/polyvinyl alcohol nanofibers (clay/PVA NFs) were fabricated as sheet-membranes using an electrospinning technique. The expansive clay with different ratios (5, 10, and 15 wt%) was incorporated into PVA NFs and comprehensively studied in terms of morphological and physicochemical characteristics. SEM images showed that incorporating the clay by electrospinning resulted in nanofibers with smaller diameters than the neat PVA NFs. The clay/PVA composite possesses high stability in aqueous media and a negatively charged surface at a pH higher than 4.1. The results showed that incorporating clay into PVA NFs improved the adsorption capacity for removal of crystal violet dye (CV) from single and binary systems. The incorporation of 5 % clay into the PVA NFs reduced diameter from 341 to 217 nm and increased its maximum adsorption capacity for the CV dye removal from 48.65 to 121.73 mg/g. The Redlich-Peterson and pseudo-first order models provided the best modeling of the experimental adsorption isotherm and adsorption kinetic data, respectively. The clay/PVA NFs exhibited outstanding reusability, with a removal efficiency for CV dye of 99.34 % after ten cycles of reuse with easily separated after adsorption. In addition, the clay/PVA NFs have good selectivity for separating CV dye from various binary dye systems. The selectivity of the clay/PVA to separate the CV dye from the binary dye systems of CV/methylene blue, CV/Coomassie brilliant blue, and CV /hematoxylin was 88.57 %, 90.92 %, and 97.24 %, respectively. Finally, excellent adsorption performance, good selectivity, high reusability, and ease of separation make clay/PVA NFs a promising adsorbent for CV dye removal from complex wastewater.