Yi Linjie, Wang Hongwei, Ren Xianliang, Liu GaoBin, Nian Hongen, Zheng Zhiqin, Wu Fang
Chongqing Key Laboratory of Interface Physics in Energy Conversion, College of Physics, Chongqing University Chongqing 400044 P. R. China
Qinghai Institute of Salt Lakes, Key Laboratory of Green and High-end Utilization of Salt Lake Resources, Chinese Academy of Sciences Xining Qinghai Province 810008 P. R. China.
RSC Adv. 2024 Sep 5;14(39):28320-28331. doi: 10.1039/d4ra04640d. eCollection 2024 Sep 4.
Structural modification is expected to be a facile way to enhance the adsorption performance of MXene. In this work, the structural modification of TiCT was carried out by a spray freezing method, and two kinds of nano-structure (spherical and flaky) of TiCT were prepared by adjusting the solution concentration of TiCT . Then the Cr(vi) adsorption capacity and removal efficiency of the spherical and flaky TiCT was investigated, respectively. It is found that flaky TiCT was produced with a TiCT concentration of 3 mg mL, while spherical TiCT was obtained with a concentration of 6 mg mL. The long diameter of flaky TiCT is about 8-10 μm, and the specific surface area is 17.81 m g. While spherical TiCT had a diameter of about 1-4 μm and a specific surface area of 17.07 m g. The optimized structure of flaky and spherical TiCT improves the maximum adsorption capacity by 97% and 33%, respectively, compared with the few-layer TiCT . The maximum adsorption capacity of flaky TiCT was 928 mg g, while that of spherical TiCT was 626 mg g. The adsorption capacity of both TiCT structures decreased with the increase of pH, and reached the maximum value at pH = 2; meanwhile, the adsorption capacity of both TiCT structures increased with the increase of Cr(vi) concentration. The adsorption of Cr(vi) on flaky TiCT was very fast, reaching equilibrium in 3 min, while spherical TiCT took 5 min. The adsorption of Cr(vi) on both TiCT 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.
结构修饰有望成为提高MXene吸附性能的一种简便方法。在本工作中，采用喷雾冷冻法对TiCT进行结构修饰，通过调节TiCT的溶液浓度制备了两种纳米结构（球形和片状）的TiCT。然后分别研究了球形和片状TiCT对Cr(Ⅵ)的吸附容量和去除效率。结果发现，当TiCT浓度为3 mg/mL时生成片状TiCT，而浓度为6 mg/mL时得到球形TiCT。片状TiCT的长径约为8 - 10μm，比表面积为17.81 m²/g。而球形TiCT的直径约为1 - 4μm，比表面积为17.07 m²/g。与少层TiCT相比，片状和球形TiCT的优化结构分别将最大吸附容量提高了97%和33%。片状TiCT的最大吸附容量为928 mg/g，而球形TiCT的为626 mg/g。两种TiCT结构的吸附容量均随pH值的升高而降低，在pH = 2时达到最大值；同时，两种TiCT结构的吸附容量均随Cr(Ⅵ)浓度的增加而增加。Cr(Ⅵ)在片状TiCT上的吸附非常快，3分钟达到平衡，而球形TiCT则需要5分钟。Cr(Ⅵ)在两种TiCT结构上的吸附均属于单层吸热化学吸附，Cr(Ⅵ)的扩散过程受颗粒的外部扩散和内部扩散调控。其吸附机理是还原吸附和静电吸附的结合。
