Ce-doped UiO-67 nanocrystals with improved adsorption property for removal of organic dyes

Efficient photocatalytic activity and selective adsorption of UiO-67 (Zr)/g-C3N4 composite toward a mixture of parabens

In this study, UiO-67 (Zr)/g-C3N4 composites (U67N) were synthesized at wt.% ratios of 05:95, 15:85, and 30:70 using the solvothermal method at 80 °C for 24 h followed by calcination at 350 °C. The composites were characterized using UV-Vis diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy-energy-dispersive X-ray spectroscopy, transmission electron microscopy, and nitrogen physisorption analysis. In addition, thermal stability analysis of UiO-67 was conducted using thermogravimetric analysis. The photocatalytic performance of the composites was assessed during the degradation and mineralization of a mixture of methylparaben (MeP) and propylparaben (PrP) under simulated sunlight. The adsorption process of U67N 15:85 was characterized through kinetic studies and adsorption capacity experiments, which were modeled using pseudo-first-order and pseudo-second-order kinetics and Langmuir and Freundlich isotherms, respectively. The influence of pH levels 3, 5, and 7 on the photocatalytic degradation of the mixture was investigated, revealing enhanced degradation and mineralization at pH 3. The U67N composite exhibited dual capability in removing contaminants through adsorption and photocatalytic processes. Among the prepared composites, U67N 15:85 demonstrated the highest photocatalytic activity, achieving removal efficiencies of 96.8% for MeP, 92.5% for PrP, and 45.7% for total organic carbon in 300 kJ/m2 accumulated energy (3 h of reaction time). The detoxification of the effluent was confirmed through acute toxicity evaluation using the Vibrio fischeri method. The oxidation mechanism of the heterojunction formed between UiO-67 (Zr) and g-C3N4 was proposed based on PL analysis, photoelectrochemistry studies (including photocurrent response, Nyquist, and Mott-Schottky analyses), and scavenger assays.

Chitosan as Support Material for Metal-Organic Framework based Catalysts

Turning waste into valuable products is one of the main challenges of the chemical industry. In this work, chitosan (CS), an abundant, low-cost, and non-toxic biopolymer derived from chitin, was reshaped into beads of ~3 mm. Their suitability as a support material for active phase catalyst materials was tested for a zirconium-based Metal-Organic Framework (MOF) with incorporated Pt, namely UiO-67-Pt. Its incorporation was investigated via two procedures: a one-pot synthesis (OPS) and a post-synthetic functionalization (PSF) synthesis method. Scanning electron microscopy (SEM) images show good UiO-67-Pt dispersion throughout the CS beads for the one-pot synthesized material (UiO-67-Pt-OPS@CS). However, this uniform dispersion was not observed for the post-synthetically functionalized material (UiO-67-Pt-PSF@CS). The success of the implementation of UiO-67-Pt was evaluated with ultraviolet-visible and infrared spectroscopy for both composite materials. Thermogravimetric analysis (TGA) reveals higher thermal stabilities for UiO-67-Pt-OPS@CS composite beads in comparison to pure CS beads, but not for UiO-67-Pt-PSF@CS. The study provides valuable insights into the potential of chitosan as a green, bead-shaped support material for MOFs, offering flexibility in their incorporation through different synthesis routes. It further contributes to the broader goal of the sustainable and eco-friendly design of a new generation of catalysts made from waste materials, which will be the topic of future studies.

Progressive Insights into Metal-Organic Frameworks and Metal-Organic Framework-Membrane Composite Systems for Wastewater Management

The sustainable management of wastewater through recycling and utilization stands as a pressing concern in the trajectory of societal advancement. Prioritizing the elimination of diverse organic contaminants is paramount in wastewater treatment, garnering significant attention from researchers worldwide. Emerging metal-organic framework materials (MOFs), bridging organic and inorganic attributes, have surfaced as novel adsorbents, showcasing pivotal potential in wastewater remediation. Nevertheless, challenges like limited water stability, elevated dissolution rates, and inadequate hydrophobicity persist in the context of wastewater treatment. To enhance the performance of MOFs, they can be modified through chemical or physical methods, and combined with membrane materials as additives to create membrane composite materials. These membrane composites, derived from MOFs, exhibit remarkable characteristics including enhanced porosity, adjustable pore dimensions, superior permeability, optimal conductivity, and robust water stability. Their ability to effectively sequester organic compounds has spurred significant research in this field. This paper introduces methods for enhancing the performance of MOFs and explores their potential applications in water treatment. It delves into the detailed design, synthesis strategies, and fabrication of composite membranes using MOFs. Furthermore, it focuses on the application prospects, challenges, and opportunities associated with MOF composite membranes in water treatment.

Smartphone-integrated ratiometric fluorescence sensing platform based on bimetallic metal-organic framework nanowires for anthrax biomarker detection

Developing an intelligent, sensitive, and visual strategy for quickly identifying anthrax biomarkers is crucial for ensuring food safety and preventing disease outbreaks. Herein, a smartphone-integrated ratiometric fluorescent sensing platform based on bimetallic metal-organic framework (Eux/Tb1-x-MOF) nanowires was designed for specific recognition of pyridine-2,6-dicarboxylic acid (DPA, anthrax biomarker). The Eux/Tb1-x-MOF was prepared by coordinating Eu3+ and Tb3+ with BBDC ligands, which exhibited a uniform fibrous morphology and dual-emission fluorescence at 543 and 614 nm. After the introduction of DPA, the red emission at 614 nm displayed obvious fluorescence quenching, while the green emission at 543 nm was gradually enhanced. The ratiometric sensing offered a wide linear equation in the range of 0.06-15 µg/mL and a low detection limit (LOD) of 20.69 ng/mL. Furthermore, a portable smartphone installing the color recognition application can achieve sensitive, real-time, and visual detection of DPA. As a simple and effective smartphone-assisted sensing platform, this work holds admirable promise to broaden the applications in biomarker real-time determinations and other fields.

Efficient removal of organic dyes using electrospun nanofibers with Ce-based UiO-66 MOFs

Cerium-based UiO-66 (Ce-UiO-66) metal-organic frameworks (MOFs) were synthesized via a facile solvothermal method and fully characterized using FTIR, XRD, BET, SEM, EDX, and zeta potential techniques. The synthesized Ce-UiO-66 particles were embedded into an electrospun cross-linked polyvinyl alcohol (PVA)/chitosan (CTS) nanofiber (EPCNF), and then employed to remove organic dyes from water. The adsorption results demonstrated that the adsorption capacities of both anionic (Congo Red (CR), Methyl Orange (MO) and Methyl Red (MR)) and cationic (Methylene Blue (MB)) dyes over the fabricated electrospun nanofibers (ENFs) increased with increasing the loadings of Ce-UiO-66 MOFs. Accordingly, the adsorption performance of EPCNF-10 (containing 10 wt% of Ce-UiO-66 MOFs) adsorbent toward these organic dyes is in the order of CR (102.04 mg/g) > MO (87.71 mg/g) > MR (65.35 mg/g) > MB (34.24 mg/g). Moreover, it was found that the Freundlich isotherm model and the pseudo-second-order kinetic model were appropriate for describing the adsorption behaviors of EPCNF-10 adsorbent toward both anionic and cationic dyes. Thus, it can be proposed that the fabricated EPCNF-10 adsorbent would be effective adsorbent materials for the removal of anionic and cationic dyes from water due to its excellent adsorption performance, facile preparation, good regeneration, and simple separation from aqueous solutions.

Highly sensitive fluorescent quantification of carbendazim by two-dimensional Tb-MOF nanosheets for food safety

Carbendazim (CBZ), a well-known benzimidazole pesticide, is utilized in agriculture to prevent and cure plant diseases caused by fungi. Residual CBZ in food poses serious threat to human health. Herein, a fluorescent two-dimensional terbium-based metal-organic framework (2D Tb-MOF) nanosheet sensor was developed for the rapid and ultrasensitive detection of CBZ. The 2D Tb-MOF nanosheets, prepared with Tb³⁺ ions and 5-borono-1,3-benzenedicarboxylic acid (BBDC) as the precursors, exhibited excellent optical properties. Upon the addition of CBZ, the fluorescence of Tb-MOF nanosheets was quenched because of the inner filter effect (IFE) and dynamic quenching. The fluorescence sensor offered two linear ranges of 0.06-4 and 4-40 µg/mL with a low detection limit of 17.95 ng/mL. Furthermore, the proposed sensing platform was successfully applied to assay CBZ in apples and tea, and satisfactory results were obtained. This study provides an effective alternative strategy for the qualitative and quantitative determination of CBZ to ensure food safety.

Efficient adsorption and photocatalytic degradation of water emerging contaminants through nanoarchitectonics of pore sizes and optical properties of zirconium-based MOFs

Over the past decades, the presence of pharmaceutical emerging contaminants in water bodies is receiving increasing attention due to the high concentration detected from wastewater effluent. Water systems contain a wide range of components coexisting together, which increases the difficulty of removing pollutants from the water. In order to achieve selective photodegradation and to enhance the photocatalytic activity of the photocatalyst on emerging contaminants, a Zr-based metal-organic framework (MOF), termed VNU-1 (VNU represents Vietnam National University) constructed with ditopic linker 1,4-bis(2-[4-carboxyphenyl]ethynyl)benzene (H₂CPEB), with enlarged pore size and ameliorated optical properties, was synthesized and applied in this study. When compared to UiO-66 MOFs, which only had 30% photodegradation of sulfamethoxazole, VNU-1 had 7.5 times higher adsorption and reached 100% photodegradation in 10 min. The tailored pore size of VNU-1 resulted in size-selective properties between small-molecule antibiotics and big-molecule humic acid, and VNU-1 maintained high photodegradation performance after 5 cycles. Based on the toxicity test and the scavenger test, the products after photodegradation had no toxic effect on V. fischeri bacteria, and the superoxide radical (·O₂^-) and holes (h⁺) generated from VNU-1 dominated the photodegradation reaction. These results demonstrate that VNU-1 is a promising photocatalyst and provide a new insight for developing MOF photocatalyst to remove emerging contaminants in the wastewater systems.

Simple synthesis of chitosan/alginate/graphene oxide/UiO-67 amphoteric aerogels: Characterization, adsorption mechanism and application for removal of cationic and anionic dyes from complex dye media

A chitosan/alginate/graphene oxide/UiO-67 (CS/SA/GO/UiO-67) amphoteric aerogel was synthesized successfully. A series of characterization experiments of CS/SA/GO/UiO-67 amphoteric aerogel was performed by SEM, EDS, FT-IR, TGA, XRD, BET, and zeta potential. The competitive adsorption properties of different adsorbents for complex dyes wastewater (MB and CR) at room temperature (298 K) were compared. Langmuir isotherm model predicted that the maximum adsorption quantity of CS/SA/GO/UiO-67 for CR and MB was 1091.61 and 1313.95 mg/g, respectively. The optimum pH values of CS/SA/GO/UiO-67 for the adsorption of CR and MB were 5 and 10, respectively. The kinetic analysis showed that the adsorption of MB and CR on CS/SA/GO/UiO-67 was more suitable for the pseudo-second-order and pseudo-first-order kinetic model, respectively. The isotherm study revealed that the adsorption of MB and CR was consistent with the Langmuir isotherm model. The thermodynamic study demonstrated that the adsorption process of MB and CR was exothermic and spontaneous. FT-IR analysis and zeta potential characterization experiments revealed that the adsorption mechanism of MB and CR on CS/SA/GO/UiO-67 depended on π-π bond, hydrogen bond, and electrostatic attraction. Repeatable experiments showed that the removal rates of MB and CR of CS/SA/GO/UiO-67 after six cycles of adsorption were 67.19 and 60.82 %, respectively.

CuCo Nanoparticle, Pd(II), and l-Proline Trifunctionalized UiO-67 Catalyst for Three-Step Sequential Asymmetric Reactions

Metal-organic frameworks (MOFs) have become a promising support for different active sites to construct multifunctional and heterogeneous catalysts. However, the related investigation mainly focuses on introducing one or two active sites into MOFs and trifunctional catalysts have been very rarely reported. Herein, non-noble CuCo alloy nanoparticles, Pd²⁺, and l-proline, as encapsulated active species, functional organic linkers, and active metal nodes, respectively, were successfully decorated to UiO-67 to construct a chiral trifunctional catalyst by the one-step method, which was further applied to asymmetric three-step sequential oxidation of aromatic alcohols/Suzuki coupling/asymmetric aldol reactions with excellent oxidation and coupling performance (yields up to 95 and 96%, respectively), as well as good enantioselectivities (ee_anti value up to 73%) in asymmetric aldol reactions. The heterogeneous catalyst can be reused at least five times without obvious deactivation due to the strong interaction between the MOFs and the active sites. This work provides an effective strategy to construct multifunctional catalysts via the introduction and combination of three or more of active sites, including encapsulated active species, functional organic linkers, and active metal nodes, into stable MOFs.

Water stable MOFs as emerging class of porous materials for potential environmental applications

Metal-organic frameworks (MOFs) are extensively recognized for their wide applications in a variety of fields such as water purification, adsorption, sensing, catalysis and drug delivery. The fundamental characteristics of the majority of MOFs, such as their structure and shape, are known to be sensitively impacted by water or moisture. As a result, a thorough evaluation of the stability of MOFs in respect to factors linked to these property changes is required. It is quite rare for MOFs in their early stages to have strong water-stability, which is necessary for the commercialization and development of wider applications of this interesting material. Also, numerous applications in presence of water have progressed considerably as a "proof of concept" stage in the past and a growing number of water-stable MOFs (WSMOFs) have been discovered in recent years. This review discusses the variables and processes that affect the aqueous stability of several MOFs, including imidazolate and carboxylate frameworks. Accordingly, this article will assist researchers in accurately evaluating how water affects the stability of MOFs so that effective techniques can be identified for the advancement of water-stable metal-organic frameworks (WSMOFs) and for their effective applications toward a variety of fields.

Enhanced transformation of CO2 over microporous Ce-doped Zr metal-organic frameworks

Metal-organic frameworks (MOF) have been studied extensively for the adsorption and catalytic conversion of CO2. However, previous studies mainly focused on the adsorption capabilities of partially or totally Ce substituted UiO-66, there are few studies focusing on transformation of the structure and catalytic activity of these materials. In this work, a series of Zr/Ce-based MOFs with UiO-66 architecture catalysts were prepared for the conversion of CO2 into value-added dimethyl carbonate (DMC). Owing to the different addition order of the two metals, significantly varied shapes and sizes were observed. Accordingly, the catalytic activity is greatly varied by adding a second metal. The different catalytic activities may arise from the different acid-base properties after Ce doping as well as the morphology and shape changes. Besides, the formation of terminal methoxy (t-OCH3) was found to be the rate limiting step. Finally, the reaction mechanism of CO2 transformation in the presence of a dehydrating agent was proposed.

Zirconium-Based MOFs and Their Biodegradable Polymer Composites for Controlled and Sustainable Delivery of Herbicides

Adsorption and controlled release of agrochemicals has been studied widely using different nanomaterials and a variety of formulations. However, the potential for application of high surface-area metal–organic frameworks (MOFs) for the controlled release of agrochemicals has not been thoroughly explored. Herein, we report controlled and sustainable release of a widely used herbicide (2-methyl-4-chlorophenoxyacetic acid, MCPA) via incorporation in a range of zirconium-based MOFs and their biodegradable polymer composites. Three Zr-based MOFs, viz., UiO-66, UiO-66-NH₂, and UiO-67 were loaded with MCPA either postsynthetically or in situ during synthesis of the MOFs. The MCPA-loaded MOFs were then incorporated into a biodegradable polycaprolactone (PCL) composite membrane. All three MOFs and their PCL composites were thoroughly characterized using FT-IR, TGA, SEM, PXRD, BET, and mass spectrometry. Release of MCPA from each of these MOFs and their PCL composites was then studied in both distilled water and in ethanol for up to 72 h using HPLC. The best performance for MCPA release was observed for the postsynthetically loaded MOFs, with PS-MCPA@UiO-66-NH₂ showing the highest MCPA concentrations in ethanol and water of 0.056 and 0.037 mg/mL, respectively. Enhanced release of MCPA was observed in distilled water when the MOFs were incorporated in PCL. The concentrations of herbicides in the release studies provide us with a range of inhibitory concentrations that can be utilized depending on the crop, making this class of composite materials a promising new route for future agricultural applications.

Determination of five nonsteroidal anti-inflammatory drugs in water by dispersive solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on metal-organic framework composite aerogel

非甾体类抗炎药(NSAIDs)能在环境水体中长期稳定存在,不仅对生物有慢性毒性还能增加病原体的耐药性,开发可靠的测定水样中痕量非甾体抗炎药的分析方法至关重要。该文制备新型金属有机骨架/壳聚糖复合气凝胶材料Co-UiO-67(bpy)/CS分散固相萃取吸附剂,将其用于环境水体中酮洛芬、萘普生、氟比洛芬、双氯芬酸、布洛芬5种非甾体类抗炎药的富集,结合超高效液相色谱-串联质谱法(UPLC-MS/MS),建立了基于金属有机骨架材料(MOFs)复合气凝胶环境水体中药物残留检测的新方法。为获得最佳的萃取效率,对影响萃取效果的主要因素(材料类型、MOFs用量、萃取时间、水样pH值、离子强度、甲酸体积分数、洗脱时间、洗脱剂体积)进行条件考察及优化。优化结果显示,吸附剂5 min内就可实现目标化合物的完全吸附,用总体积为5 mL的1%甲酸甲醇溶液洗脱6 min,目标化合物就能充分解吸。在最优的固相萃取条件下建立分析方法,结果表明,5种非甾体类抗炎药在各自范围内线性关系良好,线性相关系数均大于0.9937,方法的检出限(LOD)和定量限(LOQ)分别为0.32~2.06 ng/L和1.05~6.78 ng/L。在40、250和1500 ng/L 3个加标水平下进行加标回收试验,5种待测物的平均回收率为74.5%~114.1%。日内、日间相对标准偏差分别为1.3%~12.3%和1.3%~11.5%。将该方法用于实际水样的检测,市政污水检测出微量的酮洛芬和氟比洛芬,含量分别为14.52 ng/L和10.05 ng/L。该方法具有良好的灵敏度、准确度和精密度,操作简便,耗时短,为环境水体中痕量非甾体抗炎药富集检测提供了新方法。

Functionally modified metal–organic frameworks for the removal of toxic dyes from wastewater

This review highlights recent advancement in functional modified (FM) MOFs as superior adsorbents for the removal of dyes, classifying them by various modification strategies. The adsorption interactions affected by the FM approach are summarized.

Applications of water-stable metal-organic frameworks in the removal of water pollutants: A review

Because the pollutants produced by human activities have destroyed the ecological balance of natural water environment, and caused severe impact on human life safety and environmental security. Hence the task of water environment restoration is imminent. Metal-organic frameworks (MOFs), structured from organic ligands and inorganic metal ions, are notable for their outstanding crystallinity, diverse structures, large surface areas, adsorption performance, and excellent component tunability. The water stability of MOFs is a key requisite for their possible actual applications in separation, catalysis, adsorption, and other water environment remediation areas because it is necessary to safeguard the integrity of the material structure during utilization. In this article, we comprehensively review state-of-the-art research progress on the promising potential of MOFs as excellent nanomaterials to remove contaminants from the water environment. Firstly, the fundamental characteristics and preparation methods of several typical water-stable MOFs include UiO, MIL, and ZIF are introduced. Then, the removal property and mechanism of heavy metal ions, radionuclide contaminants, drugs, and organic dyes by different MOFs were compared. Finally, the application prospect of MOFs in pollutant remediation prospected. In this review, the synthesis methods and application in water pollutant removal are explored, which provide ways toward the effective use of water-stable MOFs in materials design and environmental remediation.

Stable dual-emissive fluorescin@UiO-67 metal-organic frameworks for visual and ratiometric sensing of Al3+ and ascorbic acid

Encapsulation of fluorophore in metal organic framework (MOF) is an effective method to construct multi-emissive composites. Unfortunately, the small molecules loaded in MOF pores are easy to leak. To overcome this difficulty, fluorescin (FL) is proposed to be encapsulated tightly in the cage of the small tetrahedron of UiO-67, as one of the organic ligands coordinated with the central ion Zr. Finally, stable multi-emission fluorescence was successfully achieved, and Förster resonance energy transfer (FRET) occurred between FL and UiO-67. Ascorbic acid (AA) can dynamically quench the fluorescence of FL@UiO-67 nanoclusters (NCs) through internal filtering effect, photoinduced electron transfer (PET). The detection limit of the probe for AA was as low as 0.20 μM, and the detection range was 0.67 μM-0.36 mM. The probe was further employed to detect Al³⁺ due to the coordination between Al³⁺ and the carboxyl group in the FL@UiO-67 NCs. The detection limit for Al³⁺ was 3.3 nM, and the linear range was 11 nM-5 μM agarose film and test paper were both prepared successfully for visual detection of AA and Al³⁺. This work provides new ideas for low-cost and convenient real-time detection method.

Enhancing toxic gas uptake performance of Zr-based MOF through uncoordinated carboxylate and copper insertion; ammonia adsorption

This study reports the development of a new type of Zr-based MOF by inserting copper and carboxylate into HCl modulated UiO-67 (UiO-67-vac) which gained higher surface area/vacant than UiO-67. Copper was inserted into MOF containing uncoordinated carboxylate group, to create open metal site in the form of -COOCu which called UiO-67-ox-Cu. PXRD, FTIR, BET, SEM, EDS, UV-Vis and XPS were used to characterize the obtained MOFs. As expected, UiO-67-ox-Cu exhibits the highest ammonia capacity (178.3 mg/g) among UiO-67 (104 mg/g) and UiO-67-vac (121 mg/g) at 298 K and 1 bar pressure. In fact, the significant increase in ammonia uptake of UiO-67-ox-Cu is related to the modified binding affinity of -COOCu groups with ammonia. Moreover, UiO-67-vac with the highest surface area showed the hydrogen adsorption capacity of 18.75 mg/g at 77 K, which is comparable or even superior to the previously reported value. Interestingly, adsorption capacities were retained with slight changes around five cycles and three regeneration temperatures, 25, 60 and 120 °C under vacuum pressure which were proved by PXRD after ammonia adsorption/desorption. The good results obtained in the current work clearly show the role of postsynthesis functionalization approach for creation of new metal/active sites into MOFs.

Cerium based UiO-66 MOF as a multipollutant adsorbent for universal water purification

Herein, we demonstrate the use of cerium (Ce)-UiO-66 metal organic framework (MOF) for the removal of a variety of potentially toxic pollutants. The Ce-UiO-66 MOF, with similar framework topologies to Zr-UiO-66, has not been explored for its adsorptive properties in water remediation. The replacement of Zr metal center with Ce yields a MOF that can be synthesized in shorter durations with lesser energy consumptions and with excellent multipollutant adsorption properties. Further, the Ce-UiO-66 MOF was also studied for its adsorption abilities in the binary component system. Interestingly, the adsorbent showed higher adsorption capacities in the presence of other pollutants. Removal studies for other potentially toxic anionic and cationic dyes showed that the Ce-UiO-66 MOF has a wide range of contaminant removal abilities. Investigations of individual adsorption capacities revealed that the Ce-UiO-66 MOF has a maximum adsorption capacity of 793.7 mg/g for congo red (CR), 110 mg/g for methylene blue (MB), 66.1 mg/g for fluoride (F^-), 30 mg/g for Cr⁶⁺ and 485.4 mg/g for the pharmaceutical waste diclofenac sodium (DCF). To imply the practical applications of the Ce-UiO-66 MOF we have also demonstrated an adaptable filter that could separate all the potentially toxic pollutants.

E. coli@UiO-67 composites as a recyclable adsorbent for bisphenol A removal

E. coli@UiO-67 composites were obtained using an effective and simple self-assembly method. The composites showed unique properties as a remarkable and recyclable adsorbent for the efficient removal of bisphenol A (BPA) from water with a high adsorption capacity (402.930 mg g^-1). The increase in pore size is a key factor why E. coli@UiO-67 composites maintained high capacity. The reason might be due to that the composites with large pore sizes and defects could effectively improve mass transport and active molecular metal sites. The adsorption of BPA is a chemisorption process due to the Zr-OH groups in UiO-67 exhibit affinity toward BPA molecules, π-π interaction, and electrostatic attraction. The adsorption efficiency remained at 82.5% after 15 cycles without any remarkable changes in the PXRD patterns of E. coli@UiO-67. Moreover, the use of microorganism-loading MOFs could reduce the cost to at least 50% and minimize secondary pollution through nanoscale MOFs usage reduction. The developed composites have advantages, including low-cost, high adsorption capacity, easy to be separated and regenerated from aqueous solution, a large number of cycles, short adsorption equilibrium time, and stability, showing excellent application prospects. The presented strategy would be a potentially promising way to produce novel MOFs-based adsorbents with high-performance to control environmental pollution from wastewater.

Advanced applications of Zr-based MOFs in the removal of water pollutants

The global water pollution is caused by the increase of industrial and agricultural activities, which have produced various toxic pollutants. Pollutants in water generally consist of metal ions, pharmaceuticals and personal care products (PPCPs), oil spills, organic dyes, and other organic pollutants. Amongst the adsorbents that have been developed to deal with pollutants in water, Zr-based metal-organic frameworks (MOFs) have drawn scientists' great attention due to their excellent stability and adjustable functionalization. Herein, the present review article introduces the synthetic methods of functionalized Zr-based MOFs and summarizes their applications in water pollution treatment. It also clarifies the interactions and removal mechanisms between pollutants and Zr-based MOFs. The use of these MOFs with eminent adsorption ability and recycling performance have been discussed in detail. Zr-based MOFs also face some challenges such as high cost, lack of real water environment applications, selective removal of pollutants, and low ability to remove composite pollutants. Future research should focus on addressing these issues. Although there is still a blank of the practical utility of Zr-based MOFs on a commercial scale, the research reported to date clearly shows that they are very promising materials for the water treatment.

Ratiometric fluorescent sensing carbendazim in fruits and vegetables via its innate fluorescence coupling with UiO-67

A ratiometric fluorescent sensor was facilely fabricated using innate fluorescence of carbendazim (MBC) and fluorescent UiO-67 to sensitively and selectively detect MBC in food matrixes. The innate fluorescence of MBC provided a signal at 311 nm (F₃₁₁), and the fluorescent UiO-67 at 408 nm (F₄₀₈) could recognize MBC through π-π stacking inducing fluorescent quenching relied on photoelectron transfer (PET). The ratio (F₃₁₁/F₄₀₈) of the fluorescence enhancement of MBC and the quenching of UiO-67 linearly responded to the MBC concentrations of 0-47.6 μmol/L with a low limit of detection (LOD) of 3.0 × 10^-3 μmol/L. The reverse response signals of the sensor enhanced the sensitivity toward MBC and presented remarkable anti-interference capability in complex matrices. The as-prepared sensor was applied to detect MBC residues in apple, cucumber and cabbage, obtaining satisfactory accuracy and precision with the recovery of 90.82-103.45% and RSDs of lower than 3.03%.