Ultrafine Cellulose Nanofibers as Efficient Adsorbents for Removal of UO₂²⁺ in Water

Abstract

Ultrafine cellulose nanofibers, 5−10 nm in diameter, were prepared from oxidation of wood pulp using the (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)/NaBr/ NaClO process followed by mechanical treatment. Carboxylate groups on the surface of these nanofibers provide negative charges, which are very effective to adsorb radioactive UO 2 2+ in water, evidenced by static adsorption and high resolution transmission electron microscopy (TEM) measurements. The UO 2 2+ adsorption capability of ultrafine cellulose nanofibers was about 167 mg/g, which is 2−3 times higher than those of typical adsorbents such as montmorillonite, ion imprinted polymer particles, modified silica particles/fibrous membranes, and hydrogels. The high UO 2 2+ adsorption capability can be attributed to the very high surface-to-volume ratio, high surface charge density, and hydrophilicity of ultrafine cellulose nanofibers, which can be used as effective media to remove radioactive metals from radio-nuclear wastewater.

All cellulose electrospun water purification membranes nanotextured using cellulose nanocrystals

“…Our earlier report on a similar system of CA membranes impregnated with 5 wt% chitin nanocrystals (ChNCs) also showed a high flux of 18,000 Lm -2 h -1 bar -1 . In comparison, Ma et al have reported a flux of 5900 Lm -2 h -1 bar -1 for PAN nanofiber mats with a support layer impregnated with cellulose nanocrystals and is lower than our current membrane (Ma et al 2011b).…”

“…(Huang et al 2013;Ma et al 2005;Qin et al 2015). The electrospun fibrous membranes have also shown potential as an excellent support layer for a secondary active surface-by coating individual fiber or by creating a more complete secondary layer of a bilayered composite membrane (Ma et al 2011a, b;Gopi et al 2017) Ma et al (2011b have shown that TEMPO oxidized cellulose nanocrystals with negative functional groups can be used to functionalize electrospun membranes, which provides a route to reject bacteria via size exclusion and reject virus via adsorption. We have also shown that stand-alone and biobased electrospun membranes of cellulose acetate with sufficient mechanical properties and flux for membrane as well as anti-fouling performance can be obtained via impregnation using chitin nanocrystals (Goetz et al 2016).…”

Cellulose Nanomaterials in Water Treatment Technologies

“…For example, the aforementioned UO 2 2+ -sorbing CNFs formed a gel upon binding that facilitates separation of the contaminant-laden CNFs from water. 48 Magnetite nanoparticles can easily be incorporated into the CN structure to allow for controlled collection via magnetic separation. 56 Zhu et al fabricated CNFs with magnetic particles entrapped within the fibers by including Fe 3 O 4 nanoparticles into the growth media of CNF-producing bacteria during the formation of the fibers.…”

Nanocelluloses and their phosphorylated derivatives for selective adsorption of Ag+, Cu2+ and Fe3+ from industrial effluents

“…Therefore, nanocelluloses with the metal-binding groups are ideal candidates for the treatment of high-volume and low-concentration pollutant water. So far, the use of nanoscaled cellulose for water remediation remains a relatively uncharted area in which few extensive studies have been published [15][16][17][18]. We have reported earlier that the sorption capacities of Ag + onto cellulose nanocrystals are higher than those of cellulose nanofibers; being 34 mg/g and 14 mg/g, respectively [17].…”