Nanoscale zero-valent iron intercalated 2D titanium carbides for removal of Cr(VI) in aqueous solution and the mechanistic aspect

MXenes, as new members of the 2D materials group, are regarded as good candidates for heavy metal removal particularly for radioactive metal element because of their high irradiation stability. However, the small interlayer distance and lack of active sites on the surface limit their further application. In this report, nanoscale zero-valent iron has been introduced into the inter-layer structure of alkaline intercalated Ti3C2 (Alk-Ti3C2) and investigated to Cr(VI) removal. The XPS spectra, SEM images, TEM images, and N2 adsorption-desorption isotherms characterizations revealed that the OH groups on the Alk-Ti3C2 surface assisted the introducing of nZVI into the inter-layer of Alk-Ti3C2 and subsequently stabilized the nZVI. The increased active sites of nZVI and extended interlayer space of Alk-Ti3C2 could improve the uptake capacity of Cr(VI) (194.87 mg/g at pH = 2). The highly efficient removal of Cr(VI) was maintained even in the presence of coexisting cations, which showed great potential for real environment remediation. Mechanistic study indicated that the synergistic effects of nZVI and Alk-Ti3C2 nanosheet in nZVI-Alk-Ti3C2 composites are keys for Cr(VI) removal.