Effective adsorptive removal of heavy metal anion Cr(Ⅵ) and dye cation methylene blue by the novel 2D material TiVCTx MXene

Abstract

With the increasingly serious industrial pollution, the effective removal of heavy metal ions and organic pollutants from wastewater has become a key issue of environmental protection. In this paper, a new MXene material, TiVCTx, was prepared by in situ etching, and its adsorption capacity of heavy metal anion Cr(Ⅵ) and methylene blue (MB) dye cation was studied. The effect of adsorption time, pH values, temperatures, initial concentrations of adsorbent and adsorbate, interfering ions on the Cr(Ⅵ) and MB adsorption of TiVCTx was systematically investigated. It is found that TiVCTx has excellent Cr(Ⅵ) and MB adsorption property, the adsorption capacity can be as high as 600mg/g and 1430mg/g, respectively. The adsorption experiments revealed that the adsorption process of Cr(Ⅵ) conformed to the Langmuir isotherm model and the Pseudo-second-order kinetic model, which indicated that the Cr(Ⅵ) adsorption was a heat-absorbing monolayer chemisorption. In contrast, the adsorption process of MB is in accordance with the Freundlich isotherm model and the Pseudo-second-order kinetic model, suggesting that the MB adsorption was an exothermic multilayer chemisorption. The results of X-ray electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis further confirmed that the reductive adsorption and electrostatic adsorption can account for the outstanding Cr(VI) and MB adsorption capacity of TiVCTx, respectively.