Carboxylated chitosan modified alkalization of 2D MXene Ti3C2 and its Cr(VI) removal performance in aqueous solution

In this work, a novel adsorbent for the removal of hexavalent chromium (Cr(VI)) in aqueous solution was successfully prepared by altering the 2D Ti3C2/chitosan composite with disodium ethylenediaminetetraacetate (EDTA·2Na) agent. The successful surface loading of chitosan on Ti3C2 was demonstrated by various characterization methods, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The adsorption of Cr(VI) by Ti3C2-based composite under various circumstances was evaluated using batch adsorption experiments. The adsorption performance of the optimal sample for Cr(VI) was investigated in detail through different influencing factors, and the adsorption process was analyzed by adsorption kinetics and isotherm model. In addition, XPS analysis of adsorbents before and after adsorption showed that some Cr(VI) was reduced to Cr(III) during the whole process, which was conducive to reducing the biological toxicity of Cr(VI). The mechanism analysis showed that the adsorption was mainly electrostatic physical adsorption, supplemented by chemical reduction adsorption. Finally, through the regeneration cycle experiment, it was found that the adsorption rate of Cr(VI) remained above 80% after six repeated adsorptions, indicating that the composite material had good stability and might have certain practical application value in the treatment of Cr(VI)-containing wastewater.