• Ultrasound-assisted etching of Ti₃AlC₂ was demonstrated. • The as-prepared Ti₃C₂Tx MXene exhibits an outstanding energy storage stability. • Consequence of ultrasound on synthesis of Ti₃C₂Tx MXene was proposed.

• 85.82% of Al can be removed from Ti₃AlC₂ after 8 h of ultrasonic treatment. • The ultrasonically synthesized sample possesses a high specific area of 21.7 m²/g. • The ultrasonically synthesized sample exhibits a high capacitance of 128.21 F/g. • Capacitive behavior contributes 99% capacitance for the ultrasound treated sample.

The oxidation kinetics of low valence titanium and iron in Ti-bearing blast furnace slag were investigated, the activation energies were calculated, which are 461.1 and 437.3 kJ/mol, respectively. The results illustrate that the oxidation process of Ti³⁺ in the slag is controlled by chemical reactions. However, the chemical reaction between oxygen and iron, between slag and gas, is the determining step of the iron oxidation process. The effects of the isothermal oxidation on the content of Fe₂O₃, Fe_M, FeO, and Fe_T in the slag are discussed. The Fe²⁺ and Ti³⁺ in the molten slag were oxidized at high temperatures. Oxygen affinity of the slag can be described using oxygen capacity. The oxygen capacity of Ti-bearing blast furnace slag was investigated during the dynamic oxidation process, the results indicates that the oxygen capacity of the slag decreased with increasing oxidation time during the dynamic oxidation process.