Authors: Linjie Yi | Hongwei Wang | Xianliang Ren | GaoBin Liu | Hongen Nian | Zhiqin Zheng | Fang Wu
Source: RSC Advances (article, 2024-01-01)
Field: Materials Science — Materials Chemistry

Enhancing Cr(<scp>vi</scp>) removal performance of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> through structural modification by using a spray freezing method Structural modification is expected to be a facile way to enhance the adsorption performance of MXene. In this work, the structural modification of Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was carried out by a spray freezing method, and two kinds of nano-structure (spherical and flaky) of Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> were prepared by adjusting the solution concentration of Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> . Then the Cr(vi) adsorption capacity and removal efficiency of the spherical and flaky Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was investigated, respectively. It is found that flaky Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was produced with a Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> concentration of 3 mg mL<sup>-1</sup>, while spherical Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was obtained with a concentration of 6 mg mL<sup>-1</sup>. The long diameter of flaky Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> is about 8-10 μm, and the specific surface area is 17.81 m<sup>2</sup> g<sup>-1</sup>. While spherical Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> had a diameter of about 1-4 μm and a specific surface area of 17.07 m<sup>2</sup> g<sup>-1</sup>. The optimized structure of flaky and spherical Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> improves the maximum adsorption capacity by 97% and 33%, respectively, compared with the few-layer Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> . The maximum adsorption capacity of flaky Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was 928 mg g<sup>-1</sup>, while that of spherical Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was 626 mg g<sup>-1</sup>. The adsorption capacity of both Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> structures decreased with the increase of pH, and reached the maximum value at pH = 2; meanwhile, the adsorption capacity of both Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> structures increased with the increase of Cr(vi) concentration. The adsorption of Cr(vi) on flaky Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> was very fast, reaching equilibrium in 3 min, while spherical Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> took 5 min. The adsorption of Cr(vi) on both Ti<sub>3</sub>C<sub>2</sub>T <sub><i>x</i></sub> structures belonged to the monolayers, heat-absorbing chemical adsorption, and the diffusion process of Cr(vi) was regulated by the external diffusion and internal diffusion of particles. Its adsorption mechanism was the combination of reductive adsorption and electrostatic adsorption. Adsorption ; Materials science ; Spray drying ; Crystallography ; Analytical Chemistry (journal) ; Chemical engineering ; Nuclear chemistry ; Chemistry ; Chromatography ; Physical chemistry MXene and MAX Phase Materials ; 2D Materials and Applications ; Ferroelectric and Negative Capacitance Devices