Effect of temperature on methylene blue removal with novel 2D-Magnetism titanium carbide

Highlights: • A novel magnetic MXene nanocomposite was fabricated for MB removal. • The MB adsorption capacity was enhanced at high temperature. • The adsorption mechanism was investigated via microstructure analysis. • Enhanced MB removal was ascribed to Ti site and OH group of magnetic MXene. -- Abstract: In this work, a novel two-dimensional MXene decorated with Fe₃O₄ (2D-MX@Fe₃O₄) had been successfully synthesized via an in-situ growth method. The characteristic of nanomaterials was analyzed as well as the adsorption properties toward methylene blue (cationic dyes, MB) were investigated with various temperatures. The obtained complex 2D-MX@Fe₃O₄ exhibited a typical 2D lamellar structure with superparamagnetic characteristic (20.3 emu·g^-1). Zeta potential measurement revealed a negative charged surface of 2D-MX@Fe₃O₄ at neutral medium, which was favorable for cationic dye removal. Moreover, the removal process presented an excellent decolorization at high temperature with 91.93% (55 °C) compared with other lower temperatures. Adsorption isotherm indicated the removal process of MB fitted well with Freundlich isotherm model at high temperature (40 and 55 °C) whereas Langmuir isotherm for that at low temperature (25 °C). Thermodynamic study indicated an exothermic and chemisorption process for MB removal, further indicating that the increase of temperature could remarkably promote the removal capacity of 2D-MX@Fe₃O₄. In addition, the removal mechanism at high or low temperature was investigated by XRD, FT-IR and XPS techniques. The abundant Ti–OH groups on 2D-MX@Fe₃O₄ surface played a dominant role in enhancing the MB decolorization through hydrogen bonding (Ti–OH⋯N) and electrostatic attraction at high temperature system, while surface adsorption via electrostatic interaction contributed the MB removal process in the case of 25 °C.