Novel Isopropoxy Group-Functionalized UiO-66 with a High Hydrogen Chloride Adsorption Capacity

Abstract

In this paper, a novel isopropoxy group-functionalized UiO-66 (UiO-66-IPO) was synthesized by a general strategy and then used as an adsorbent for the removal of hydrogen chloride from aqueous solutions. The as-synthesized product was characterized by X-ray powder diffraction, scanning electron microscopy, thermal gravimetric analysis, N2 adsorption and desorption isotherms, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The adsorbent showed a much higher adsorption capacity of 429.68 mg·g–1 under the initial condition of 1.4 mol·L–1 HCl concentration at 25 °C within a relatively short time (4 h). Adsorption kinetics, isotherms, thermodynamics, regeneration, and the mechanism of hydrogen chloride adsorption on the adsorbent were studied. The results showed that the hydrogen chloride adsorption process reached equilibrium quickly in 4 h, and the adsorption kinetics on UiO-66-IPO was well-described by the pseudo-second-order model. Meanwhile, the Henry isotherm and Freundlich isotherm fitted the experiment data well. The thermodynamic parameters, such as ΔG, ΔH, and ΔS, were determined, and the results indicated that the adsorption process was spontaneously exothermic and entropy decreasing. XPS and FT-IR were conducted to explore the hydrogen chloride adsorption mechanism. The regeneration experiments demonstrated that UiO-66-IPO still exhibited excellent adsorption performance on hydrogen chloride after three cycles.

Recovery of Biomass-Derived Polyols by Pressure Swing Adsorption: Experiments, Simulations, Scale-up Implementation and Economic Analysis

“…The Freundlich parameter 1/ n is the degree of adsorption intensity related to the surface heterogeneity. A value of n > 1 indicates a favorable physisorption process; if n = 1, it is a homogeneous adsorption without interaction among the adsorbates; and if n < 1, it is an unfavorable chemisorption process. , Therefore, the values of n ( n > 1) demonstrated that physical force rather than chemical interaction contributed more to polyols adsorption. With increasing temperature, the values of n gradually decreased and n (EG, 1,2-PG) > n (1,3-PG), indicating that polyol adsorption became more unfavorable with increasing temperature and that molecular sieve 10X preferred adsorption of EG (1,2-PG) rather than 1,3-PG.…”