Synthesis of sulfamic acid supported on Cr-MIL-101 as a heterogeneous acid catalyst and efficient adsorbent for methyl orange dye

Abstract

Typical highly porous metal-organic framework (MOFs) materials based on chromium benzenedicarboxylates (Cr-BDC) were prepared through a one-pot hydrothermal synthesis, and were then modified by loading the appropriate ratio of sulfamic acid (SA) using a simple impregnation technique. Pure and modified MIL-101 was characterized by XRD, TEM, SEM and FT-IR measurements.TEM and SEM measurements confirmed that the MIL-101 particles preserved their regular octahedral structure after loading with different weight contents of sulfamic acid. The total number of acid sites and Brønsted to Lewis acid sites ratio (B/L) were examined using potentiometric titration and pyridine adsorption. The acid strength and surface acidity of SA/MIL-101 gradually increased after the modification of Cr-MIL-101 by sulfamic acid crystals up to 55 wt%, then decreased again. The catalytic performance of the solid catalysts was confirmed in the synthesis of 14-phenyl-14H-dibenzo [a,j] xanthene and 7-hydroxy-4-methyl coumarin. In the two reactions, the sample with 55% sulfamic acid loaded on MIL-101 displayed the highest catalytic activity and acidity. The adsorption behaviors of sulfamic acid loaded on MIL-101 materials for methyl orange (MO) as an anionic dye were studied, and were exceptionally suitable for the Langmuir adsorption isotherm. All loaded adsorbents showed high adsorption capacity for methyl orange at 25 C. The results indicate that the adsorption capacity was modified by changing the amount of sulfamic acid loaded on MIL-101.

Facile fabrication of bimetallic Fe–Mg MOF for the synthesis of xanthenes and removal of heavy metal ions

“…59 Cations adsorption efficiency were signicantly higher for initial concentration up to 150 mg L À1 due to plenty of freely active sites on the adsorbent surface which has been saturated at extremely higher cation concentrations and as a result, the adsorption slowed increases due to the competition between ions for the available binding sites. 8,57 3.4.5. Adsorption isotherms.…”

“…17) and sulfamic acid/Cr-MIL-101. 8 Most of the preparation methods suffer from some drawbacks such as constraints of catalyst reusability, separation of pure products, difficult workup, use of hazardous solvents and prolonged reaction times.…”

“…Recently; MOFs have received great attention in adsorption of heavy metal ions owing to unique structural features that are not found in other porous materials. 8 In general, the elastic and extremely porous structures of MOFs facilitate the diffusion of the guest ions or molecules easily into the bulk structure. Also; both the size and shape of the formed pores help in increasing the selectivity of adsorbing denite ions or molecules.…”

Sulfamic acid incorporated HKUST-1: a highly active catalyst and efficient adsorbent

“…44,45 Every year MOFs gaining interest in removing hazards component from water. [46][47][48] Despite, HKUST-1 gaining interest in the gas phase adsorption, there is little information about its application in removing hazards components from aqueous solutions.…”

Nano-sized titanium-zirconia catalyst modified by sulphate as an efficient catalyst

“…Additionally, rising of the concentration of MB, the less photons reach the surface of catalyst. Consequently, the production of hydroxyl radicals that can attack the pollutants will reduce and the efficiency of photocatalytic decreases [43][44].…”