A rational design of layered metal-organic framework towards high-performance adsorption of hazardous organic dye

Interface synthesis of Cu-BTC/PVDF hybrid membranes and their selective adsorption activity toward Congo red

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.

Co-adsorption and Fenton-like oxidation in the efficient removal of methylene blue by MIL-88B@UiO-66 nanoflowers

Development of binary MOF-on-MOF heterostructures is a research hotspot in MOFs chemistry due to the advantages elicited by a closely connected interface, which may endow more abundant functionality and even broader applications in interface chemistry. A MOF-on-MOF heterostructure was constructed by in situ growth of MIL-88B on the outer surface of UiO-66. The resultant MIL-88B@UiO-66 produced had an interesting flower-like morphology composed of MIL-88B (petal) on tetrahedral UiO-66 (core). The MIL-88B@UiO-66 heterostructure showed adsorption and Fenton-like oxidation abilities, with distinctly improved structural stability in aqueous solution compared with that of single MIL-88B. Methylene blue (MB) was selected as the target molecule to evaluate the adsorption and Fenton-like oxidation activities. The efficiency of total removal of MB was studied systematically under various operating conditions and the influencing factors were optimized. The kinetics of adsorption and catalytic oxidation were simulated to explore the interactions between MB and MIL-88B@UiO-66. The mechanisms of enhanced adsorption and Fenton-like oxidation were suggested. The cyclic removal performance and structural stability of MIL-88B@UiO-66 were also determined.

Aminated Multiwalled Carbon Nanotube-Doped Magnetic Flower-like WSe2 Nanosheets for Efficient Adsorption in Acidic Wastewater

The water body environment is related to ecological and human health. Adsorption is an effective means to remove pollutants from water bodies. Currently, the common adsorbents suffer from disadvantages such as structural instability and poor adsorption performance under acidic conditions, which not only affect the adsorption efficiency but also cause secondary pollution of water bodies. In this study, a novel aminated multiwalled carbon nanotube-doped flower-like nanocomposite was designed, where the anionic or neutral groups were protonated under acidic conditions, and it displayed a higher adsorption capacity for dyes by ion exchange, represented by methylene blue (MB) and rhodamine B (RB). WSe₂ in the composite increases its adsorption sites. The adsorption efficiency of pollutants in acidic wastewater was enhanced while avoiding secondary contamination. The synthesized composites showed maximum adsorptions of 27.55 and 27.47 mg/g for MB and RB, respectively. The current work offers a novel approach to treating acidic wastewater.

Three novel Co(II)-based MOFs: Syntheses, structural diversity, and adsorption properties

In this paper, three new cobalt-based metal organic frameworks (MOFs) with different topologies, namely {[Co(HL)(tib)(H2O)]·2H2O}n (1), [Co3(L)2(bibp)4(H2O)2]n (2) and [Co2(L)(bip)(μ3-OH)]n (3) (H3L = 3-(3,5-dicarboxylphenoxy)-6-carboxylpyridine, tib = 1,3,5-tirs(1-imidazolyl)benzene, bibp = 4,4'-bis(imidazolyl)biphenyl,...

Investigation of antimony adsorption on a zirconium-porphyrin-based metal-organic framework

A zirconium-porphyrin based organic framework PCN-222 was employed for investigating the adsorption performance of Sb(III) in aqueous solution. It is proved that the adsorbent has the advantages of rapid adsorption and high capacity. Interestingly, we discover that PCN-222 shows pH-dependent adsorption performance, with higher capacity at pH = 2 and 8 than at pH = 5. According to XPS and FT-IR analyses, an adsorption model of PCN-222 with pH = 2, 5, and 8 is proposed, that is, zirconium clusters combine with antimony at different pH values with bidentate complexes, monodentate complexes, and alkaline monodentate complexes, thus producing an excellent adsorption effect. Moreover, the porphyrin ring is also beneficial for the adsorption of antimony. In addition, PCN-222 shows good regeneration and recycling performance, and it is a promising adsorbent as well as a platform for investigating the removal of Sb(III) in water treatment.