Imparting UiO-66 with fast cation exchange property via sulfonating organic linkers for selective adsorption

Nanoarchitectonics Design Strategy of Metal-Organic Framework and Bio-Metal-Organic Framework Composites for Advanced Wastewater Treatment through Adsorption

Freshwater depletion is an alarm for finding an eco-friendly solution to treat wastewater for drinking and domestic applications. Though several methods like chlorination, filtration, and coagulation-sedimentation are conventionally employed for water treatment, these methods need to be improved as they are not environmentally friendly, rely on chemicals, and are ineffective for all kinds of pollutants. These problems can be addressed by employing an alternative solution that is effective for efficient water treatment and favors commercial aspects. Metal organic frameworks (MOFs), an emerging porous material, possess high stability, pore size tunability, greater surface area, and active sites. These MOFs can be tailored; thus, they can be customized according to the target pollutant. Hence, MOFs can be employed as adsorbents that effectively target different pollutants. Bio-MOFs are a kind of MOFs that are incorporated with biomolecules, which also possess properties of MOFs and are used as a nontoxic adsorbent. In this review, we elaborate on the interaction between MOFs and target pollutants, the role of linkers in the adsorption of contaminants, tailoring strategy that can be employed on MOFs and Bio-MOFs to target specific pollutants, and we also highlight the effect of environmental matrices on adsorption of pollutants by MOFs.

Highly Efficient One-Step Conversion of Fructose to Biofuel 5-Ethoxymethylfurfural Using a UIO-66-SO3H Catalyst

In this study, a novel sulfonic acid-modified catalyst for MOFs (UIO-66-SO3H) was synthesized using chlorosulfonic acid as a sulfonating reagent and first used as efficient heterogeneous catalysts for the one-pot conversion of fructose into biofuel 5-ethoxymethylfurfural (EMF) in a cosolvent free system. The physicochemical properties of this catalyst were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). The characterization demonstrated that the sulfonic acid group was successfully grafted onto the MOF material and did not cause significant changes to its morphology and structure. Furthermore, the effects of catalyst acid amount, reaction temperature, reaction time, and catalyst dosage on reaction results were investigated. The results showed that the conversion of fructose was 99.7% within 1 h at 140°C, while the EMF yield reached 80.4%. This work provides a viable strategy by application of sulfonic acid-based MOFs for the efficient synthesis of potential liquid fuel EMF from renewable biomass.

Pyrene-based sulfonated organic porous materials for rapid adsorption of cationic dyes in water

Porous organic polymers (POP) have gained attention because of their high specific surface area, porosity and their simplicity in synthesis, but for the most part, they are hydrophobic because of their organic backbone, making it difficult to expand their applications. Here, we have obtained poly(pyrene) porous organic polymers (PyPOP) through the polymerization of pyrene monomers catalysed by aluminium trichloride, which is a simple and inexpensive synthesis method. The sulfonated poly(pyrene) porous organic polymers (PyPOP-SO₃H) obtained showed rapid adsorption of cationic dyes, especially malachite green (MG adsorption 1607 mg/g) and methylene blue (MB adsorption 1220 mg/g) in pH = 7 aqueous solution, room temperature. The results show that the Freundlich model is more in line with the adsorption process than the Langmuir model, whether for methylene blue or malachite green. In addition, the PSO kinetic model fits better than PFO kinetic model, whether it is for the adsorption of methylene blue or malachite green. The excellent adsorption performance of PyPOP-SO3H for cationic dyes may be due to the introduction of sulfonic acid groups, which not only increases the specific surface area but also allows better dispersion in water, increasing contact points and adsorption efficiency. This research expands the scope of exploration and application of POP.

Magnetically recyclable core–shell MOF nanoparticles of Fe3O4@PDA@UIO-66-NH2 grafted by organic acids for intensified cationic dye adsorption

The adsorption mechanism towards MB by the two adsorbents is mainly due to IE at lower solution pH and EA at higher solution pH than their pHpzc.

THE SYNTHESIS AND PROPERTIES OF A SODIUM SUPRAMOLECULAR CRYSTAL NETWORK CONSTRUCTED WITH FUNCTIONAL PYRAZINE SULFONIC ACID

Sulfonic acid groups with C_3ν symmetry can coordinate with metal ions to produce multidimensional structures due to their flexible coordination modes. They can also penetrate into supramolecular structures through an intriguing bridging pattern and weak interactions. Herein, a novel heterocyclic sodium sulfonate supramolecular structure, namely [Na(Pyr-SO₃)(H₂O)]_n where Pyr-SO₃H is pyrazine sulfonic acid, is synthesized by utilizing NaBF₄ to coordinate with the P–SO₃H ligand through the solvent evaporation method. The single crystal X-ray diffraction (XRD) data indicate that the as-formed structure belongs to the Pbca space group. Additional properties are characterized by powder XRD, thermal analysis, and solid-state fluorescence. In particular, the introduction of a soft alkali metal ion can coordinate with the oxygen atom of the sulfonate ligand and form a Na–O bridging configuration that can not only significantly improve the pyrazine sulfonic acid ligand coordination ability, but also provide a reference for the extended study of functional sulfonate polymers in the future.

Mesoporous polystyrene-based microspheres with polar functional surface groups synthesized from double emulsion for selective isolation of acetoside

In this study, a series of the functionalized mesoporous polystyrene-based microspheres (FMPMs) with different functional comonomers (acrylamide, AM; ethyleneglycol dimethacrylate, EGDMA; hydroxyethyl methacrylate, HEMA) and ratios of styrene (St) to divinylbenzene (DVB) were designed and synthesized by a double emulsion interface polymerization method. Among them, St and DVB existed in the oil phase, forming the skeleton structure of FMPMs. AM, EGDMA or HEMA in the water phase formed functional layers on the inner and outer surfaces of FMPMs. The experimental results indicated that the optimal functional comonomers and the ratio of St to DVB were AM (provided the hydrophilic -CONH₂ groups) and 1:1, respectively. Thus, A-FMPMs-2 exhibited the highest adsorption capacity of 108.95 ± 8.13 mg/g and the selectivity of 5.14 ± 0.17. These results were attributed to the hydrophilic -CONH₂ groups on A-FMPMs-2, and these groups were beneficial to ACT molecules diffusion driven by concentration gradient, improving the adsorption performance. Furthermore, hydrophilic -CONH₂ groups on the inner and outer surfaces of A-FMPMs-2 acted as hydrophilic sites that had a high-affinity interaction with ACT molecules, thus increasing the adsorption selectivity. In addition, A-FMPMs-2 had the highest specific surface area and largest pore volume, resulting in the highest adsorption capacity and adsorption selectivity. Therefore, the development of adsorbents with adjustable pore structure and a large number of hydrophilic sites will provide a new strategy for selective separation of bioactive components from natural products.