Tuning the adsorption properties of UiO-66 via acetic acid modulation

Abstract

UiO-66 (Universitetet i Oslo) is one of the most known metal-organic frameworks with high hydrothermal stability. In this work, a series of UiO-66 were prepared using acetic acid as a modulator to produce linker defects. Samples were characterized by X-ray powder diffraction, nitrogen adsorption-desorption isotherms, thermogravimetric analysis and adsorptive desulfurization test. Results indicated that increasing the amount of acetic acid to 30% equivalent with respect to terephthalic acid did not have an obvious negative effect on the structure. At the same time, surface area and micropore pore volume are further increased from 988 $$\hbox {m}^{2}$$ /g, 0.34 $$\hbox {cm}^{3}$$ /g to 1424 $$\hbox {m}^{2}$$ /g, 0.54 $$\hbox {cm}^{3}$$ /g. Adsorptive desulfurization performance is also significantly improved from 6.0 mg/g to 7.9 mg/g. So, the linker defects produced by acetic acid can remarkably enhance the adsorption ability. Adsorptive desulfurization kinetics indicates that while indicating the monomolecular layer, chemical adsorption occupies the dominant position, and there is no special chemical force formed between the defects and dibenzothiophene. AcOH can improve the surface area of UiO-66 significantly. UiO-66 prepared with the new method has good adsorption desulfurization ability. The adsorption process can be described by pseudo-first-order kinetic model and Langmuir isotherm.