Metal–Organic Framework UiO-66 as an Efficient Adsorbent for Boron Removal from Aqueous Solution

Abstract

Water-stable metal−organic framework (MOF) UiO-66 was studied in boron removal from water for the first time. XRD, SEM, nitrogen adsorption/desorption isotherms, and thermogravimetric analysis (TG) were employed to confirm the structure. The boron adsorption kinetics, isotherms, thermodynamics, mechanism, and recycling on UiO-66 were further investigated in batch adsorption process. UiO-66 exhibits great adsorption performance of 10.59 mmol• g −1 at 45 °C, and the adsorption process reaches equilibrium rapidly in 1 h. Pseudo-second-order model, intraparticle diffusion, and Boyd model are employed for kinetic analysis. The process is a spontaneous endothermic process controlled by entropy change rather than enthalpy change, which suggests intensive chemisorption. The adsorption capacity does not decrease obviously after four cycles. Characterization on exhausted UiO-66 with 11 B MAS NMR reveals not solely interaction between boric acid and UiO-66. The XPS patterns suggest interaction with an Zr site, which is confirmed by the adsorption simulation with quantum chemistry. Higher boron adsorption capacity than conventional boron removal adsorbents and easy regeneration make UiO-66 a promising agent for boron removal from aqueous solution.

Functionalized Porous Aromatic Frameworks as High‐Performance Adsorbents for the Rapid Removal of Boric Acid from Water

“…Notably, PAF‐1‐NMDG and P2‐NMDG also exhibit high saturation capacities relative to other polymeric boron‐selective adsorbents (see Table S4, Supporting Information). Recently, some inorganic materials such as nitrogen‐doped graphene oxide and metal–organic frameworks have also been shown to exhibit impressive boron capacities—as high as 10.6 mmol g −1 (at 45 °C) for the metal–organic framework UiO‐66. However, these materials undergo significant reductions in boron adsorption capacity after a few regeneration cycles, casting doubt on their long‐term performance.…”

Self‐Assembly of Metal–Organic Frameworks into Monolithic Materials with Highly Controlled Trimodal Pore Structures

“…In this study,a saproof of concept, we focused on Zrbased UiO-66 type MOF,which undergoes sol-gel transition by self-assembly of Zr clusters and terephthalic acid. [11,22,23] TheM OF UiO-66, with the formula [Zr 6 O 4 (OH) 4 (bdc) 6 ] (bdc = 1,4-benzenedicarboxylate), is one of the most important MOFs owing to its high thermal, chemical, and mechanical stabilities, [24,25] and has been increasingly studied for av ariety of applications for example,c atalyst, [26,27] catalyst support, [28,29] adsorbent, [30] gas storage medium, [11] and liquid or gas separation medium. [31,32] We used 2-aminoterephthalic acid (BDC-NH 2 )a so rganic linker to obtain UiO-66-NH 2 because of its good solubility in solvents such as N,Ndimethylformamide (DMF).…”

Evaluation of the Interaction between Borate Ions and Nickel–Aluminum Complex Hydroxide for Purification of Wastewater

“…For contact time studies, 0.1 g of adsorbent was added to 50 mL of a borate ion solution (100 mg/L at pH 10). The suspension was shaken at 100 rpm for 1, 3,5,8,12,16,20,24,36, and 48 h at 25°C. The effect of pH on adsorption was tested by adding 0.1 g of adsorbent to a borate ion solution (50 mL) at 1, 10, 25, 50, 75, and 100 mg/L (pH = 6, 10, and 12).…”

“…1,2) Boron is one of the most important micro-nutrients for humans, animals, and plants, used to promote the transport and metabolism of carbohydrates, for the synthesis of hemicellulose and related cell wall material, in cell growth and division, to build chloroplast structure, and in the formation of basal grains. [3][4][5] However, previous studies have reported that the ingestion of large amounts of boron can affect the central nervous system and the reproductive system in humans. 6,7) Therefore the WHO limited the maximum boron concentration in drinking water to 2.4 ppm in 2011, while some countries set a more stringent standard.…”