Abstract
Isostructural zirconium-based metal–organic frameworks (Zr-MOFs) have attracted the attention of researchers because of their remarkable stability at high temperatures and high pressures and their chemical stabilities against acids and bases. Due to this stability, Zr-MOFs can be utilized in adsorption research, and the adsorption performance of a Zr-MOF depends on the pore size and the surroundings of the MOF. In this study, as the dimensions changed and the adsorption was carried out, the Zr-MOF material remained stable, and the adsorption of the best state was achieved at 235 mg/g. Through the simulation of theoretical kinetic models of Zr-MOFs, we initially postulated that the adsorption capacity is proportional to the pore size and that acid orange 7 (AO7) was adsorbed by the MOFs. Afterwards, we verified our hypotheses through a series of Brunauer–Emmett–Teller (BET) data analysis; non-local density function theory (NLDFT) was mainly used to analyze the data. Moreover, we determined that physical adsorption occurs on the surface of the MOFs during the adsorption process, while chemisorption occurs in the form of dye molecules combining with active sites. Ultimately, we concluded that the larger the pore size, the stronger the adsorption capacity, and this contribution casts a new light on the issue of wastewater treatment.
Highlights
The disposal of dye-contaminated wastewater, which is produced by the industrial fabrication of textiles, paints, printed materials, pharmaceuticals, food, hair dyes, leather, electronics, cosmetics, and so on, is one of the most pressing global challenges [1,2,3,4]
We have reported the synthesis of zirconium-based metal–organic frameworks (Zr-Metal–organic frameworks (MOFs)) with hydrochloric acid as the accelerator, which can serve as an efficient method to obtain different apertures of UiO-66 and UiO-67, composed of different lengths of organic ligands in milder conditions (80 ◦C)
The adsorption behavior of the Zr-MOFs on the dye molecules was mainly performed by natural diffusion and was accompanied by chemical adsorption
Summary
The disposal of dye-contaminated wastewater, which is produced by the industrial fabrication of textiles, paints, printed materials, pharmaceuticals, food, hair dyes, leather, electronics, cosmetics, and so on, is one of the most pressing global challenges [1,2,3,4]. In the study of MOFs, the modification of pore size through the manipulation of the structure of the inorganic secondary structure units with different lengths of ligands is currently popular [37]. In this respect, the use of longer ligands can reduce the density of the material and increase the surface area [38], and organic ligands with functional groups can promote various intermolecular interactions with molecular or ionic guests [15]. The absorbance measurements of all the AO7 aqueous solutions were performed on a UV–visible spectrophotometer (TU-1810DSPC, Purkinje General Instrument Co., Ltd., Beijing, China)
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