Regulation of the surface area and surface charge property of MOFs by multivariate strategy: Synthesis, characterization, selective dye adsorption and separation

By Tian-tian Li, Yi-Min Liu, Tao Wang, Yingxian Wu, Yongxin He, Rui Yang, Shengquan Zheng. Microporous and Mesoporous Materials, 2018

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Abstract By using multivariate strategy, a series of multivariate UiO-66-type metal−organic frameworks with mixed 1,4-benzendicarboxylic acid (BDC) and 1,2,4,5- benzentetracarboxylic acid (BTC) ligands in different ratio, namely UiO-66-n (COOH)2 (n = 0, 0.25, 0.50, 0.75 and 1), had been successfully prepared. The products were characterized by 1H NMR, powder X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, N2 adsorption-desorption, and zeta potential. It can be observed that with the increase of BTC ratio, the surface area decreases from 1620 to 179 cm3/g, and the zeta potential decreases from 36.11 to −29.78 mV. Therefore, this strategy can effectively regulate the surface area and charge of the frameworks, thereby regulate their adsorption behaviors towards selected dye molecules. In contrast to the pristine UiO-66 that only adsorption anionic dyes, the multivariate MOFs shows an excellent selective dye adsorption to cationic dyes, where the adsorption capacities of MB and RhB on UiO-66-0.25(COOH)2, UiO-66-0.50(COOH)2, and UiO-66-0.75(COOH)2 are 87, 90, 94 mg/g and 84, 47, 46 mg/g, respectively. In addition, the selective adsorption to mixed cationic and anionic dyes (MB and MO) and cationic dyes with different size (MB and RhB) were also achieved by UiO-66-0.25(COOH)2 and UiO-66-0.75(COOH)2, respectively. This adsorption selectively is attribute to the electrostatic attraction between the charged surface of MOFs and the dyes, as well as the surface area of the MOFs.

Subfields: Inorganic Chemistry

View Paper: https://www.semanticscholar.org/paper/52a9034f7c2163d7aaca43c7d88ec2313f973e80