Waste-Valorized Nanowebs for Crystal Violet Removal from Water

Lightweight, metal-free, sustainable, and reusable adsorbent materials are of paramount significance in addressing the challenges of wastewater treatment. Accordingly, semi-crystalline nanocellulose (NC) is extracted from tissue paper waste and used to modify polyacrylonitrile (PAN) to produce electrospun nanowebs with strand diameters from ≈180-300 nm. The incorporation of NC into PAN is confirmed by infrared and Raman spectroscopy and X-Ray diffraction. When tested for crystal violet (CV) adsorption, NC-modified PAN (20% NC@PAN) exhibits the highest CV removal capacity, achieving 91-94% removal over three cycles each, demonstrating exceptional recyclability. In contrast, unmodified PAN significantly decreases in CV adsorption capacity (from 59% to 48% in the third cycle), possibly due to an increased (≈36%) nanofiber diameter. The adsorption kinetics, exhibiting pseudo-second order, interparticle (in between nanofibers) diffusion, and Elovich kinetic models emphasize the role of multilayer CV adsorption through reversible chemical interactions. Confocal micro-Raman spectroscopy unveils a multifaceted CV adsorption mechanism, suggesting both surface and multilayer diffusion, with NC-enhancing interactions. These findings demonstrate the potential of NC-modified PAN nanowebs as effective and environmentally sustainable adsorbents for removing CV from aqueous solutions, suggesting promising practical applications.