Symbiotic Aerogel Fibers Made via In-Situ Gelation of Aramid Nanofibers with Polyamidoxime for Uranium Extraction.

Juan Li,Xuetong Zhang,Wei Wang,Jin Wang

doi:10.3390/molecules24091821

Abstract

The uranium reserve in seawater is enormous, but its concentration is extremely low and plenty of interfering ions exist; therefore, it is a great challenge to extract uranium from seawater with high efficiency and high selectivity. In this work, a symbiotic aerogel fiber (i.e., PAO@ANF) based on polyamidoxime (PAO) and aramid nanofiber (ANF) is designed and fabricated via in-situ gelation of ANF with PAO in dimethyl sulfoxide and subsequent freeze-drying of the corresponding fibrous gel precursor. The resulting flexible porous aerogel fiber possesses high specific surface area (up to 165 m2·g−1), excellent hydrophilicity and high tensile strength (up to 4.56 MPa) as determined by BET, contact angle, and stress-strain measurements. The batch adsorption experiments indicate that the PAO@ANF aerogel fibers possess a maximal adsorption capacity of uranium up to 262.5 mg·g−1, and the absorption process is better fitted by the pseudo-second-order kinetics model and Langmuir isotherm model, indicating an adsorption mechanism of the monolayer chemical adsorption. Moreover, the PAO@ANF aerogel fibers exhibit selective adsorption to uranium in the presence of coexisting ions, and they could well maintain good adsorption ability and integrated porous architecture after five cycles of adsorption–desorption process. It would be expected that the symbiotic aerogel fiber could be produced on a large scale and would find promising application in uranium ion extraction from seawater.

Highlights

With the increasing demand for eco-friendly energy, nuclear energy has taken on greater importance as it has the characteristic advantages of higher calorific value, lower greenhouse gas emission [1,2,3] and safer operating technique in comparison with the traditional fossil energy [4,5].Since uranium is the main source in the nuclear industry, efficient and sustainable uranium extraction has attracted increasing interest worldwide [6,7,8,9]
We found that physical gel could be formed by mixing PAO with aramid nanofiber (ANF) in dimethyl sulfoxide (DMSO) possibly due to the incipient-network conformal-growth [32]
ANFs are formed by dispersing commercially available Kevlar fibers in basic DMSO solution [33], ANFs arebe formed by dispersing commercially in basic solution and they could transformed into hydrogel byavailable replacingKevlar

Summary

Introduction

With the increasing demand for eco-friendly energy, nuclear energy has taken on greater importance as it has the characteristic advantages of higher calorific value, lower greenhouse gas emission [1,2,3] and safer operating technique in comparison with the traditional fossil energy [4,5].Since uranium is the main source in the nuclear industry, efficient and sustainable uranium extraction has attracted increasing interest worldwide [6,7,8,9]. By means of a half-wave rectified alternating current electrochemical method, Cui et al developed an approach to extract uranium from seawater with high uranium uptake up to 1932 mg·g−1 [22]. Wang et al reported a mass production of the poly (imide dioxime) nanofiber adsorbent with excellent adsorption capacity of 951 mg·g−1 in uranium spiked natural seawater (8 ppm) [21]. These methods require some additional electrochemical equipment or air pumps, which will increase the cost of the preparation and use of the adsorbent materials to a certain extent

Methods

Results

Conclusion