Xing Yujin, Chen Huabin, Liu Sitong, Wang Wenzhong, Liang Yujie, Fu Junli
College of Life and Environmental Science, Minzu University of China, Beijing100081. P. R. China.
School of Science, Minzu University of China, Bejing100081, P. R. China.
Langmuir. 2022 Jun 14;38(23):7346-7356. doi: 10.1021/acs.langmuir.2c00975. Epub 2022 May 30.
Efficient removal of organic dyes from contaminated water has become a great challenge and urgent work due to increasingly serious environmental problems. Here, we have for the first time prepared nanolayer-constructed TiO(OH) microstructures which can present negative charge by deprotonation of the hydroxyl group to efficiently and selectively remove cationic dyes from aqueous solution through electrostatic interaction and an attraction mechanism. The nanolayer-constructed TiO(OH) microstructures achieve a high adsorption capacity of 257 mg g for methylene blue (MB). The adsorption kinetics, thermodynamics, and isotherms of MB over the TiO(OH) microstructures have been studied systemically. The experimental measurements and corresponding analyses demonstrate that the adsorption process of MB on TiO(OH) microstructures follows a kinetic model of pseudo-second-order adsorption, agrees well with the Langmuir isotherm mode, and is a spontaneous and exothermic physisorption. Fourier transform infrared (FT-IR) spectra confirm that the prepared TiO(OH) microstructures possess hydroxyl group which can deprotonate to present negative charge in solution. Further experimental studies evidently demonstrate that the TiO(OH) microstructures also can remove other cationic dyes with positive charge such as basic yellow 1, basic green 4, and crystal violet but cannot adsorb anionic dye of methyl orange (MO) with negative charge in aqueous solution. The measurements for FT-IR spectra and the adsorption of cationic and anionic dyes evidently reveal that the adsorption of cationic dyes over the TiO(OH) microstructures is achieved by the electrostatic interaction and attraction between TiO(OH) and the dye. This work opens a strategy for the design of new absorbents to efficiently remove organic dyes from aqueous solution through an electrostatic attraction-driven adsorption process.
由于环境问题日益严重，从受污染水中有效去除有机染料已成为一项重大挑战和紧迫任务。在此，我们首次制备了纳米层结构的TiO(OH)微结构，其可通过羟基去质子化呈现负电荷，从而通过静电相互作用和吸引机制从水溶液中高效、选择性地去除阳离子染料。纳米层结构的TiO(OH)微结构对亚甲基蓝（MB）的吸附容量高达257 mg g。系统研究了MB在TiO(OH)微结构上的吸附动力学、热力学和等温线。实验测量和相应分析表明，MB在TiO(OH)微结构上的吸附过程遵循准二级吸附动力学模型，与Langmuir等温线模型吻合良好，是一个自发的放热物理吸附过程。傅里叶变换红外（FT-IR）光谱证实，制备的TiO(OH)微结构具有羟基，可去质子化在溶液中呈现负电荷。进一步的实验研究明显表明，TiO(OH)微结构还可去除其他带正电荷的阳离子染料，如碱性黄1、碱性绿4和结晶紫，但不能吸附水溶液中带负电荷的阴离子染料甲基橙（MO）。FT-IR光谱测量以及阳离子和阴离子染料的吸附明显表明，阳离子染料在TiO(OH)微结构上的吸附是通过TiO(OH)与染料之间的静电相互作用和吸引实现的。这项工作为设计新型吸附剂开辟了一种策略，通过静电吸引驱动的吸附过程从水溶液中有效去除有机染料。
