Experimental exploring of Ti₃C₂T_x MXene for efficient and deep removal of magnesium in water sample

In this work, the mechanism and behaviour of magnesium adsorption with Ti₃C₂T_x adsorbent is investigated. Ti₃C₂T_x was synthesized by selective exfoliation of Al layer from Ti₃AlC₂ using acidic solutions of HF 40% and 12 M LiF/ 9 M HCl. The effect of the synthesis method on the structure, the interlayer distance, the type and abundance of the functional groups, the bonds formed, the surface area and the volume of the formed cavities were evaluated by X-ray diffraction, scanning electron microscopy, Energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller and fourier transform infrared analyses. The preliminary discontinuous tests of magnesium adsorption with Ti₃C₂F_x and Ti₃C₂(OH)_x in 100 ppm concentration, pH ~ 7.00, ambient temperature and time of 3 h show 182.5 and 99 mg.g^-1 the adsorption intensity, respectively. The difference in adsorption intensity with Ti₃C₂F_x is the result of the extensive tendency of Mg²⁺ to conduct electrochemical reactions with F^- twice as much as OH^- functional groups. By designing the RSM experiment, analytical, qualitative, optimization and modelling of the magnesium adsorption process with Ti₃C₂F_x adsorbent was carried out with the input variables of magnesium concentration, pH, ambient temperature and time. Isothermal modelling shows the agreement of the experimental results with the Langmuir model and endothermic thermodynamic modelling shows the spontaneity of the adsorption reaction. MXene adsorption-desorption with 0.1 M HCl was done in up to 4 steps. The adsorption results show that Ti₃C₂F_x can show up to 15% initial adsorption intensity by maintaining stability in up to 4 adsorption-desorption steps.