Regenerated Silk Nanofibers for Robust and Cyclic Adsorption–Desorption on Anionic Dyes

Abstract

In recent years, adsorption-based membranes have been widely investigated to remove and separate textile pollutants. However, cyclic adsorption–desorption to reuse a single adsorbent and clear scientific evidence for the adsorption–desorption mechanism remains challenging. Herein, silk nanofibers were used to assess the adsorption potential for the typical anionic dyes from an aqueous medium, and they show great potential toward the removal of acid dyes from the aqueous solution with an adsorption rate of ∼98% in a 1 min interaction. Further, we measured the filtration proficiency of a silk nanofiber membrane in order to propose a continuous mechanism for the removal of acid blue dye, and a complete rejection was observed with a maximum permeability rate of ∼360 ± 5 L·m–2·h–1. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy studies demonstrate that this fast adsorption occurs due to multiple interactions between the dye molecule and the adsorbent substrate. The as-prepared material also shows remarkable results in desorption. A 50-time cycle exhibits complete adsorption and desorption ability, which not only facilitates high removal aptitude but also produces less solid waste than other conventional adsorbents. Additionally, fluorescent 2-bromo-2-methyl-propionic acid (abbreviated as EtOxPY)-silk nanofibers can facilitate to illustrate a clear adsorption and desorption mechanism. Therefore, the above-prescribed results make electrospun silk nanofibers a suitable choice for removing anionic dyes in real-time applications.

MXene-based nanocomposites: emerging candidates for the removal of antibiotics, dyes, and heavy metal ions

“…[167][168][169] Due to the extensive usage of organic dyes in different industrial sectors mainly caused numerous diseases, including diarrhea, chronic toxicity, carcinogenicity, genotoxicity, and mutagenicity when associated with the aromatic molecular structure. [170][171][172][173] Annually, 8 Â 10 5 tons of synthetic organic dyes are produced worldwide, which causes environmental pollution. 18,129,171,174,175 Various mechanisms have been reported for the effective separation of organic dyes from wastewater using MXene-based membranes.…”

Recent Advances in Graphene Oxide‐Based Membranes for Heavy Metal Ions Separation

“…Additionally, the d-spacing between 2D sheets can be varied according to electrostatic interaction and cation-pi interaction between sheets and metal ions. So, it is difficult to realize the rejection of mono-or multivalent ions when several ions are in the mixed state based on the mechanism of interlayer distance adjustment [8,34].…”

“…These contaminates are mainly classified into three main groups, i.e., organic, biological, and inorganic par-ticles [7]. The organic and biological contaminants are easily degraded [8,9], however, the separation and degradation of inorganic particles, especially heavy metal ions such as arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), mercury (Hg), nickel (Ni), zinc (Zn), etc. are a big challenge for current technologies [10][11][12].…”

Mussel-inspired polydopamine-modified silk nanofibers as an eco-friendly and highly efficient adsorbent for cationic dyes

“…22 Mehdi et al used electrostatic spinning to prepare silk nanofiber membranes for the adsorption of anionic dyes. 23 However, none of these developed adsorbents have used their unique hierarchical nanofiber characteristic. 24 One big hurdle impeding the proper use of these nanofibers is that they are tightly bundled in mulberry silk due to the strong hydrogen bonding interaction and are difficult to split to obtain well-dispersed nanofibers.…”