Preparation of sodium carboxymethyl cellulose/two-dimensional metal carbide composite xerogel by phytic acid crosslinking for uranium recovery

Abstract

Uranium, as a raw material for clean and green energy, is abundant in the oceans. Therefore, uranium recovery from seawater is an important way to solve the problems of energy shortage and environmental pollution. Here, two-dimensional metal carbides (MXene) and sodium carboxymethyl cellulose (CMC) were crosslinked via phytic acid (PA) to prepare a composite xerogel with cross-linked network structure (PA@MCX). The results showed that PA@MCX had excellent wet-state strength (6.92 MPa) and recyclability, which were critical for adsorbent in practical applications. The adsorbent’s adsorption behavior was more aptly characterized by the pseudo-second-order kinetics and Langmuir isotherm model, yielding a theoretical maximum adsorption capacity of 468.5 mg/g. Furthermore, the phosphate groups in the PA@MCX adsorbent exhibited a strong preference for uranium, achieving a ratio of uranium to vanadium adsorption capacity of 6.6 in tests involving competing ions. After five adsorption–desorption cycles, the adsorbent can still maintain a high elution rate of 80.4 % for uranium. This gel-type adsorbent with high strength, easy recovery, considerable adsorption capacity and excellent selectivity will be one of the mainstreams for uranium extraction from seawater in the future.