Facile preparation of sulfonic groups functionalized Mxenes for efficient removal of methylene blue

Two demensional nanomaterials have attracted increasing research interest for various applications ranging from environmental adsorption, biomedical applications, catalytic degradation and energy storage owing to their high surface areas, facile surface functionalization. In this work, we demonstrated the preparation and environmental adsorption applications of 2D material MXenes through extracting Al layer from Ti3AlC2 in a simpler and safer way. The surface of Ti3C2 was modified with sulfonic groups via aromatic coupling-diazotization. The adsorption behavior and capacity of the Ti3C2 and functionalized Ti3C2 towards methylene blue (MB) were also examined and compared. The successful preparation of Ti3C2 and modified Ti3C2 was characterized by a number of techniques, including scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The influence of different experiment conditions such as contact time, solution temperature, pH and initial MB concentrations on the adsorption behavior towards MB were also examined. The results demonstrated that sulfonic groups functionalized Ti3C2 (named as Ti3C2-SO3H) exhibited superior removal efficiency for MB. The maximum adsorption capacity of Ti3C2-SO3H towards MB is over four folds that of raw materials. The results of kinetics and isotherms studies demonstrated that experimental data were better described by pseudo-first-order model and Langmuir isotherm adsorption model, respectively. The process of MB onto surface of adsorbents was endothermic and spontaneous. Experimental details about pH indicated that the dye adsorption capability is favorable when the aqueous solution is alkaline. Based on the above results, cationic dye molecules were removed effectively by using Ti3C2-SO3H as adsorbent, which promotes the development of Ti3C2-SO3H for wastewater treatment.