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Considering the surface affinity of MOFs and separation advantages of polymer membranes, herein, a one-step interface synthesis strategy is used in the construction of Cu-BTC/PVDF hybrid membranes, in which Cu2+ ions and 1,3,5-benzenetricarboxylic acid (H3BTC) were dissolved in ionized water and n-octanol separately, and polyvinylidene fluoride (PVDF) films were laid at the interface of two immiscible solvents. As a result, Cu-BTC was generated and readily self-assembled inside the PVDF films. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and the Brunauer–Emmett–Teller (BET) method were used to characterize Cu-BTC/PVDF hybrid membranes, and Congo red (CR) was selected as the target dye to evaluate the surface adsorption activity of the hybrid membranes. Batch adsorption tests under various conditions were conducted to optimize the adsorption capacity, adsorption kinetics, isotherms and thermodynamics, which were analyzed to further explore the adsorption behavior. Based on this, the adsorption mechanism was discussed. It is worth noting that because of the π–π stacking interaction and hydrogen bonding, an extraordinary adsorption capacity of CR was achieved, and the good separation advantage and the cyclic adsorption performances endow the resulting Cu-BTC/PVDF hybrid membranes with promising applications in the removal of organic dyes from practical wastewater. [ABSTRACT FROM AUTHOR]

In this work, we used Cu(II) ions, a bis-pyridyl-bis-amide ligand [N,N′-bis(4-pyridinecarboxamide)-1,2-cyclohexane (4-bpah)], and an aromatic dicarboxylic acid [1,4-cyclohexanedicarboxylic acid (H2CHDA)] to construct a 1D binuclear Cu-based complex, namely {[Cu3(4-bpah)(CHDA)3(H2O)]·2H2O}n (1). Moreover, we also developed a facile method to synthesize two monometallic/bimetallic-doped materials which were derived from the Cu complex (C-N-1 and C-V-1, which were doped with nitrogen and vanadium, respectively). The as-synthesized derived materials were fully characterized and the iodine sorption/release capabilities were investigated in detail. We performed iodine adsorption experiments on the two monometallic/bimetallic-doped materials and found that C-N-1 and C-V-1 possess highly efficient adsorption activities for the adsorption of iodine from solution. The C-N-1 and C-V-1 complexes exhibited remarkable adsorption capacities of 1141.60 and 1170.70 mg g−1, respectively, for iodine from a cyclohexane solution. Moreover, the dye adsorption properties of C-N-1 and C-V-1 were also investigated in detail. The obtained C-N-1 and C-V-1 exhibit effective dye uptake performances in water solution. The adsorption of Congo red (CR) on a single metal carbon material C-N-1 doped with heteroatoms reached equilibrium within 240 min and reached an adsorption capacity of 1357.00 mg g−1 and the adsorption capacities of C-V-1 for methylene blue (MB), gentian violet (GV), rhodamine B (RhB), and CR at room temperature were found to be 187.60, 190.60 and 108.10 and 1501.00 mg g−1 in 180 min, respectively. By comparison, we found that doping vanadium could play an important role in the adsorption processes. The adsorption capacity of C-V-1 (containing the vanadium in its structure) was relatively higher than that of C-N-1, which indicated that the introduction of non-noble metals may effectively tune the adsorption kinetics activity and the introduction of noble metals can change the surface electronegativity of porous carbon materials, thus leading to significantly improved adsorption capabilities. [ABSTRACT FROM AUTHOR]

The research on amorphous metal–organic frameworks (aMOFs) is still in its infancy, and designing and constructing aMOFs with functional pores remains a challenge. Two aMOFs based on Co(II) and heterotopic triangular ligands with large conjugated aromatic planes, namely aMOF-1 and aMOF-2, were constructed and characterized by IR, XPS, EA, ICP, XANS and so on. aMOF-1 possesses mesopores, whereas aMOF-2 possesses micropores. The porosity, conjugated aromatic plane and uncoordinated N atoms in the framework allow these aMOFs to adsorb iodine and dyes. The iodine adsorption capacity of aMOF-1 is 3.3 g per g, which is higher than that of aMOF-2 (0.56 g per g), mainly due to the expansion or swelling of aMOF-1 after iodine adsorption. The uptake of cationic dyes by aMOF-2 showed more rapid kinetics and a higher removal rate than that by aMOF-1, mainly due to the difference in the porosity and surface charge. Although the surface charges of aMOF-1 and aMOF-2 are negative, both of them showed significantly faster adsorption kinetics toward anionic dyes, among which methyl orange (MO) and Congo red (CR) can be removed in 5 min. This occurs possibly because the quick adsorption of Na+ ions alters the surface charge of the framework and promotes dye uptake. The adsorption capacities of aMOF-1 for MO and CR reached 921 and 2417 mg g−1, respectively. The correlation data for aMOF-2 are 1042 and 1625 mg g−1, respectively. All adsorption capacities are among the highest compared to many cMOFs. Adsorption in mixed dye solution is found to be charge-dependent, kinetic-dependent, and synergetic in these systems. The porosity, surface charge regulation during adsorption, weak interactions and multiple adsorption processes contribute to the dye adsorption performance. [ABSTRACT FROM AUTHOR]

Five new lanthanide metal–organic frameworks (Ln-MOFs), namely {[Ln(L)]·Cl}n, [Ln = Pr(1), Nd(2), Eu(3), Ho(4), Ce(5)], based on a benzimidazole carboxylic acid ligand [H2L = 2-(2-carboxyphenyl)-1H-benzo[d]imidazole-6-carboxylic acid] were synthesized by a solvothermal method. Ln-MOFs 1–5 have the same two-dimensional layered structures. Interestingly, 1–5 exhibit excellent adsorption performance to anionic dye Congo red (CR), with adsorption capacities of 2724 mg g−1, 2719 mg g−1, 2718 mg g−1, 327 mg g−1, and 2273 mg g−1, respectively. Adsorption kinetics experiments showed that this kind of adsorption belonged to chemisorption; the hydrogen bonding and π–π interactions between the 1–5 host and CR guest molecules resulted in a high adsorption capacity. Luminescence and sensing experiments showed that 5 can be considered a promising multifunctional fluorescent sensor with good reusability and a high sensitivity toward Ag+ and Hg2+ ions, with detection limits of 1.7 × 10−7 and 2.5 × 10−6 M, respectively. [ABSTRACT FROM AUTHOR]