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• Three phosphate ester-based MOFs (UiO-66-(OPO 3) X) containing different amounts and spatial positions were prepared. • UiO-66-(OPO 3) X can efficiently remove Pb2+ from aqueous solution. • Even at pH = 2 and pH = 3, UiO-66-(OPO 3) X maintains a high removal efficiency of Pb2+. • UiO-66-(OPO 3) X has excellent selectivity and anti-interference ability for Pb2+. • The adsorption mechanism was investigated in detail by experiment combined with DFT. Metal-organic framework (MOF) materials have emerged as promising candidates for treating heavy metal wastewater because of their controllable pore size, high specific surface area, and abundant active sites. Nevertheless, the currently reported MOFs usually require near-neutral environments (pH = 5–6) to achieve efficient removal of Pb2+ and cannot be applied to acidic environments (pH = 2–3). In this work, the structurally stabilized zirconium-based MOF UiO-66 was chosen as the object of study. Three phosphate ester-based MOFs (UiO-66-(OPO 3) X) containing different amounts and spatial positions were designed and prepared by simple chemical modification and used to remove Pb2+. Adsorption experiments showed that they could reach adsorption equilibrium in 30 min with excellent adsorption rate. Owing to the unique ionization ability of the phosphate ester group, UiO-66-(OPO3) X maintains a high removal efficiency of Pb2+ even at pH = 2 and pH = 3. In addition, selectivity and competition experiments demonstrated that UiO-66-(OPO 3) X possessed excellent selectivity and anticompetitive ability towards Pb2+.The excellent regeneration performance demonstrates their value for practical application. Moreover, the adsorption mechanism was investigated in detail by experiment combined with density functional theory (DFT). [ABSTRACT FROM AUTHOR]

• Review explores MOFs' evolving role, strengths, limitations. • MOFs offer promise in removing heavy metals, organics from industrial wastewater. • MOFs exhibit high efficacy in adsorption, removal processes. • Emerging MOFs address limitations of conventional wastewater treatment. • MOFs present customizable properties, structural features for pollution mitigation. The discharge of heavy metal ions and organic pollutants from industrial, agricultural, and domestic activities poses a significant threat to water bodies and ecosystems. The persistence of these contaminants in the environment can lead to water pollution with far-reaching consequences. Human exposure to heavy metals like lead, mercury, and cadmium, as well as organic pollutants including pesticides and industrial chemicals, can result in severe health implications such as neurological disorders, cancer, and reproductive problems. Addressing this challenge requires the effective removal of these pollutants from wastewater, which can be complex and expensive. Conventional treatment methods may fall short, particularly when dealing with low concentrations or intricate mixtures of pollutants. Recently, Metal-Organic Frameworks (MOFs) have emerged as highly promising materials for tackling this issue. With their distinctive structural features and customizable properties, MOFs exhibit remarkable efficacy in adsorption and elimination processes. This review article comprehensively explores the growing significance of MOFs in addressing environmental contamination. We delve into their evolving role, recent advancements, diverse synthesis methods, as well as their strengths and limitations. Furthermore, we highlight the various techniques employed for the characterization of MOFs and their versatile applications as efficient adsorbents for the removal of heavy metal ions and organic pollutants from industrial wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • UiO-66 decorated HAp composites were successfully prepared via solvothermal method. • TC was adsorbed efficiently using 30UiO-66@HAp. • TC adsorption mechanism explained via pH effect and surface charge. • After 7 cycles, TC adsorption was 82.5% and reusability was excellent. Tetracycline (TC) is considered to be one of the commonly preferred antibiotics in the pharmaceutical industry. On the other hand, in order to eliminate the increasing environmental pollution associated with TC, the researchers are studying promising methods for its removal from water. In the present investigation, a novel zirconium metal–organic framework (UiO-66) decorated hydroxyapatite (HAp) composite adsorbent was synthesized by one-pot technique for the removal of TC from water. The proposed composites were prepared by proportioning different quantities by mass (10 %, 30 % and 50 %) of UiO-66 with HAp. The samples were characterized by various analyzes such as XRD, TGA, SEM, FT-IR and BET/N 2. The adsorption process was conformed to the Langmuir isotherm model, which is a monolayer model. HAp and UiO-66@HAp composites were compared on the basis of maximum TC adsorption capacity (q max) and the best q max was obtained as 218.68 mg g−1 for 30UiO-66@HAp composite. Adsorption kinetics was optimized with linear pseudo second order and Elovich models, additionally the equilibrium time was determined as 300 min. Maximum adsorption was reached in the range of pH 4–8 while adsorption efficiency diminished below pH 4. Thermodynamic analysis reveals that TC adsorption is a spontaneous, favourable and endothermic process. The reusability of the 30UiO-66@HAp was perfect and the removal was 82.5 % even after 7 adsorption cycles. It also performed well with TC solutions prepared in different water matrices, with a clear reduction only with increasing HA concentration. It also showed a remarkable potential in the removal of different antibiotics and organic dyes. The synthesised 30UiO-66@HAp exhibited a favorable adsorption capacity and stable operating performance. It is expected to be utilized in the future wastewater treatment processes in industrial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MOF was firstly applied to adsorptive removal of carbazole from bitumen-derived fuel. • Performance of MOF in carbazole adsorption increased with increasing the N sites on MOF. • The adsorption was explained with hydrogen bonding, where carbazole was H-donor. • Calculation supports the beneficial role of amines of MOFs in carbazole adsorption. • Amine-functionalized MOFs can be suggested as an adsorbent for N removal from fuel. The high nitrogen content of bitumen is a major disadvantage because nitrogenous species disturb deep desulfurization and provoke air pollution. Here, denitrogenation of model bitumen-derived fuel (n-octane and toluene mixtures composed of carbazole (CBZ) and dibenzothiophene (DBT)), through selective adsorption of nitrogen-containing compounds (NCCs), was studied firstly using a MOF, MIL-101(Cr) (named M101), especially after functionalization with ethylenediamine (ED) or diethylenetriamine (DETA). The maximum adsorption capacity (Q 0) of M101-DETA for CBZ (per unit BET surface area) was 1.4 and 2.1 times that of M101-ED and M101, respectively, confirming the efficiency of the MOF in CBZ adsorption increased with increasing the number of amino groups on the MOF. This tendency was also observed in the model fuel containing both CBZ and DBT. Moreover, M101-DETA interacted more strongly with CBZ than DBT. All the observed results could be explained mainly with hydrogen bonding that was supported by a computational calculation and XPS analysis. Therefore, amine-functionalized MOFs such as M101-DETA (showing a high maximum adsorption capacity of 277.8 mg of CBZ/g) can be suggested as potential/recyclable materials for effective and selective removal of NCCs from fuels with a high concentration of SCCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cr 2 O 7 2− adsorbed on hydrothermally-synthesized mesoporous ZIF-67 nanoparticles. • Exothermic spontaneous monolayer chemical 2nd-order-kinetics Langmuir adsorption. • Cr(VI)/ZIF-67 adsorption synergism with Cr(VI)/Co(II) oxidation-reduction. • DFT shows adsorption-based H-bonding, van der Waals, π-bonding, Cr N coordination. • DFT shows post-adsorption internal destabilization inside each of Cr 2 O 7 2− & ZIF-67. Metal organic frameworks (MOFs) have attracted great attention due to their unique characteristics and accordingly found their way to a multitude of applications including water remediation. Co-based zeolite imidazole framework (ZIF-67) has recently shown interesting adsorptive decontamination capabilities towards metallic and organic water pollutants. Yet, ZIF-67 adsorption mechanism and stability have not been studied enough. In this study, ZIF-67 nanocrystals (∼40 nm) were synthesized and applied as an adsorbent for Cr 2 O 7 2− from water. The Cr 2 O 7 2−−ZIF-67 adsorption mechanism and both of Cr 2 O 7 2− and ZIF-67 consequent structural changes were investigated by analyzing the elemental composition and oxidation states, the adsorption isotherms, kinetics and thermodynamics, and the optimized quantum computational models. The experimental results fitted well with pseudo-second order and Langmuir models, and gave ΔH° and ΔG° of −86.4 ± 17.6 and 12.8 ± 2.4 kJ/mol, respectively, suggesting exothermic spontaneous monolayer chemical adsorption, with maximum capacity of 370 mg/g. Kinetics also show concurrence surface adsorption with intra-particle diffusion within the micropores. XPS results reveal that both Cr6+ and the less-toxic Cr3+ co-existed in Cr 2 O 7 2−−ZIF-67, whilst the Co3+/Co2+ ratio increased, referring to an oxidation–reduction reaction between Cr and Co. Computational analysis concede that the Cr 2 O 7 2−−ZIF-67 high affinity is based on H-bonding between the Cr 2 O 7 2− oxygens and the imidazole hydrogens, van der Waals attraction between the Cr 2 O 7 2− lone pairs and the imidazole π cloud, the Cr 2 O 7 2−−ZIF-67 electron transfer, and Cr N coordination interaction. However, these computations show that the Cr 2 O 7 2−−ZIF-67 interaction causes internal destabilization within each of Cr 2 O 7 2− and ZIF-67, as Cr 2 O 7 2− tends to dissociate and ZIF-67 integrity weakens. [ABSTRACT FROM AUTHOR]

[Display omitted] • Copper-gallic acid metal organic framework (CuGA MOF) was synthesized for basic red 9 (BR9) removal from aqueous solution. • ANN and PSO were applied to determine output of artificial intelligence (AI). • The ANN model is a robust approach for optimizing synthesize parameters. • CuGA MOF may favorable material for removing contaminants from aqueous solution. The subfield of artificial intelligence (AI) known as machine learning promises to advanced science and technology by enabling better quality, performance, and predictive capabilities. In this research, a new method was proposed to extend the application of AI to optimize the green synthesis of copper-gallic acid metal–organic framework (CuGA MOF) and explore the complex hyperdimensional relationship between the synthesis parameters and the resulting product qualities. The deep learning (DL) method has shown higher accuracy, with a coefficient of determination (R2) of 0.881. Various synthesis conditions, including the molar ratio of NaOH to GA, temperature, and reaction time, were conducted to obtain the optimal yield and crystallinity percentage. The Particle Swarm Optimization (PSO) algorithm suggests inputs of 1.8, 108 °C, and 1.5 h for parameters of the molar ratio of NaOH to GA, temperature, and reaction time, respectively. The optimum results indicate a yield percentage of 60.61 % and a crystallinity percentage of 59.2 %. Furthermore, CuGA MOF was used for basic red 9 (BR9) dye removal from aqueous solutions. The adsorption capacity of this MOF for the removal of BR9 was high, up to 115.08 mg/g. The performance of CuGA 90–2.2 remained high (>90 %) even after 3 adsorption–desorption cycles, making it a promising reusable adsorbent. In addition, the pre-adsorption and post-adsorption of CuGA MOF were characterized by various analytical techniques, including FTIR, XRD, SEM, EDS, and XPS. [ABSTRACT FROM AUTHOR]

• A PTFE-based support was post-synthetically decorated by UiO-66-NH 2 and tannins. • The new bio-based multifunctional membrane used for extraction of Hg(II). • The post-modified PTFE showed higher total mercury uptake (380.6 mg/g). • Polyphenols (tannins) used in this effort were extracted from the green tea. In this study, we have designed and synthesized a porous membrane by functionalizing the polytetrafluoroethylene (PTEF) support with natural biomass polyphenols (tannins) grafted on amino-functionalized UiO-66 metal–organic framework to give a robust, environmentally friendly polyphenol/metal–organic framework/PTFE membrane, namely PPG-UiO-66@PTFE. Then, the nominal solid was used for the efficient extraction of mercury ions from water samples before ICP-Mass measurements. The effects of some parameters such as pH, type, and volume of eluent, eluent, sample flow rate, and co-existent ions were explored and optimized. Under optimum conditions, the limit of detection was obtained at 1.5 ng/L. The results exhibited that the presence of the co-existing ions does not affect the experimental results. The PPG-UiO-66@PTFE demonstrated superior performance compared to individual materials. This bio-based porous membrane had benefits such as a wide linear range, selectivity, renewability, and real applications in laboratory settings. [ABSTRACT FROM AUTHOR]

• A novel metal organic framework porous biochar composite was synthesized. • Removal mechanisms of TC on Zn-BTC@SBC were explored. • The maximum adsorption capacity of Zn-BTC@SBC could reach 125.9 mg/g for TC. • Zn-BTC@SBC exhibited excellent reusability with the elution by NaOH. Overuse of tetracycline (TC) has caused serious damage to aquatic environment. Developing sustainable and efficient removal technologies for TC is of great significance to eliminate its ecological risks. In this study, a novel zinc metal organic framework porous biochar composite (Zn-BTC@SBC) derived from sludge was the first time synthesized and employed for adsorptive removal of TC from water. The adsorption process of TC followed the Elovich and Temkin model and the maximum capacity of Zn-BTC@SBC to adsorb TC was 125.9 mg/g. Characterization analysis demonstrated that the greater adsorption capacity of Zn-BTC@SBC was ascribed to its larger surface area, pore volume and abundant oxygen-containing functional groups. The fitting results showed that both chemisorption and physical adsorption predominated the adsorption process of TC on Zn-BTC@SBC. Further material characterization (FTIR and XPS) and density functional theory (DFT) calculations at the molecular level suggested that the good adsorption performance of Zn-BTC@SBC on TC might be due to chemisorption dominated by oxygen-containing functional groups, which included π-π conjugation, H-bonding and electrostatic interaction. And it was a spontaneous, endothermic and randomness increasing reaction. Both ion species/strength and solution pH significantly affected the adsorption capacity of Zn-BTC@SBC for TC. The natural water samples with complex composition (lake and river water) still showed 71.27–76.37 % of TC adsorbed. The used Zn-BTC@SBC was capable of maintaining its stable adsorption capacity by NaOH regeneration. This study demonstrated that Zn-BTC@SBC was a promising practicability in removal of TC and workable approach for sustainable utilization of sludge. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis and characterization of Sn-MOF. • Adsorption studies of organophosphate pesticide diazinon. • The adsorbents exhibited good reusability for four adsorption/desorption cycles. • Optimized the results via Box-Behnken design. The purpose of this study was to examine the efficiency of a tin-metal organic framework (Sn-MOF) to remove the organophosphate pesticide diazinon (DZ) from water. The results of the experiments conducted were compelling and demonstrated that Sn-MOF is a powerful adsorbent for removing DZ from aqueous solutions. The Sn-MOF was analyzed using various techniques including SEM, XRD, and BET analysis. It showed that the surface area of Sn-MOF is considerable high 897.69.75 m2/g and a significant pore volume of 1.04 cm3/g. Surface characterization was performed to determine the point of zero charge. To investigate the impact of pH levels on adsorption equilibrium, we carried out batch tests. Interestingly, our findings indicate that variations in solution pH have a significant impact on adsorption behavior. The optimum condition to have high adsorption capacity was found at pH 6, dose 0.01 g, and the temperature, as the temperature rises, the adsorption capacity rises because the process of adsorption is endothermic. The efficacy of DZ adsorption on Sn-MOF was extensively evaluated using kinetic models, specifically adhering to the pseudo-second-order model. Additionally, the Langmuir isotherm model was applied to accurately fit the adsorption process. It was observed that the overall process involved a chemisorption mechanism. In order to optimize the parameters such as absorbent dosage, solution pH, temperature, and time, Box-Behnken design (BBD) with Response Surface Methodology (RSM) was employed. Following the instructions, we were able to extract the values of (ΔH°), (ΔS°), and (ΔG°) for DZ, which indicated that the process was endothermic and spontaneous when using Sn-MOF as an adsorbent. The Sn-MOF adsorbent that was synthesized shows remarkable reusability and can be cycled up to five times for adsorption-desorption processes. The newly developed adsorbent's efficiency was evaluated as a proof of concept for purifying wastewater samples on a small scale in a laboratory. Additional study was done to better understand the way that Sn-MOF and DZ interact, and it was suggested that the interaction may occur through various mechanisms, including π-π interaction, pore filling, H-bonding, or electrostatic interaction. The use of Sn-MOF as an adsorbent presents a simple and effective approach for the treatment of industrial wastewater and water filtration. The effectiveness of utilizing Sn-MOF as an adsorbent to remove DZ from wastewater samples has never been demonstrated before, but our study is the first to do so. According to the results, a pH value of 6 is required to achieve the highest adsorption capability of DZ onto Sn-MOF, with a value of 587.39 mg.g−1. [ABSTRACT FROM AUTHOR]

• ► The microstructure of the synthesized Al-MOFs can be controlled by adjusting the ratio of Al to BDC. • ► The maximum adsorption capacity of Al-BDC-10 for phosphorus can reach 100.37 mg P/g. • ► The phosphorus removal mechanism of Al-BDC-10 was studied. The recovery of phosphorus from phosphorus-contaminated water is of great significance to prevent the eutrophication of natural water and overcome the shortage of phosphorus resources. To increase the effectiveness of phosphorus removal from water, aluminum metal–organic frameworks (Al-MOFs) with different microstructures were synthesized in this study by varying the ratio of metal centers (Al) to organic ligands (terephthalic acid, BDC) in the precursor solution. For the precursor solution of a 10:1 M ratio of Al3+ to BDC, the synthesized Al-MOF exhibited the maximum phosphorus adsorption capacity (100.37 mg P/g). The pseudo-second-order kinetic model indicated a better fit for the experimental data obtained from the adsorption of phosphorus onto the synthesized Al-MOFs. The synthesized Al-MOFs appeared highly effective in removing phosphorus from water at an initial pH of 3.0 to 9.0. In addition, phosphorus adsorption onto Al-MOFs is not seriously affected by the presence of coexisting ions in water such as Ca2+, Mg2+, CO 3 2–, HCO 3 –, NO 3 –, and Cl-. After five cycles of adsorption–desorption, the phosphorus recovery efficiency of the synthesized Al-MOFs decreased by only 15%. The phosphorus adsorption onto synthesized Al-MOFs is mainly governed by electrostatic interaction, complexation, and ligand exchange mechanisms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis and characterization of La/Pd-MOF. • Studies adsorption of Triclosan by La/Pd-MOF. • Studying the mechanism of adsorption and rate controlling steps. • Mechanism of interaction. • Optimization the adsorption results using Box-Behnken Design. Utilizing Lanthanum/Palladium -Metal organic framework (La/Pd-MOF), this study sought to analyze the efficacy of removing triclosan (TCS) from aqueous solutions. Through compelling experimentation, we demonstrated that La/Pd-MOF is an effective adsorbent for eliminating TCS from water. Characterization of the material was conducted using SEM, XRD, BET analysis, and surface characterization to determine the point of zero charge. Through batch experiments, we investigated how pH levels impacted adsorption equilibrium. Fascinatingly, our results show that changes in solution pH drastically altered adsorption behavior. The effectiveness of TCS adsorption on La/Pd-MOF was thoroughly examined using kinetic models, adhering to the pseudo-second-order model. Furthermore, Langmuir isotherm model fitted the adsorption process accordingly. It was identified that a chemisorption process was involved in the overall process. To further customize the parameters like absorbent dosage, solution pH, temperature and time, Box-Behnken design (BBD) with Response Surface Methodology (RSM) were implemented. According to the instructions, the (ΔH°), (ΔS°), and (ΔG°) of TCS were endothermically and spontaneously extracted using La/Pd-MOF as an adsorbent. The synthesized La/Pd-MOF adsorbent exhibits remarkable render ability and cyclability for up to five cycles of adsorption–desorption. The effectiveness of the created adsorbent was evaluated as a proof of concept for cleaning wastewater samples at a lab scale. Study the mechanism of interaction between the La/Pd-MOF and TCS as it could be taking place through π-π interaction, pore filling, H-Bonding or electrostatic interaction. The La/Pd-MOF adsorbent provided a straightforward and efficient method for managing industrial effluent and water filtration. Our research indicates that our work is the first to describe how to remove TCS using La/Pd-MOF adsorbent from wastewater samples. The results showed that a maximum adsorption capacity of TCS onto La/Pd-MOF is obtained at a pH value of 6, which is 610.845 mg·g−1. [ABSTRACT FROM AUTHOR]

In this study, CeO 2 nanofibers derived from Ce(1,3,5-BTC)(H 2 O) 6 (Ce-BTC) metal organic frameworks were prepared, and then the affinity of CeO 2 towards 2,4-dichlorophenoxyacetic acid (2,4-D) was investigated. After the Ce-BTC nanoparticles were synthesized by hydrothermal method, the Ce-BTC was calcinated, and CeO 2 nanofibers were obtained. The Ce-BTC and CeO 2 were characterized by SEM, XRD, FTIR and AFM methods, respectively. The adsorption studies of 2,4-D from water with CeO 2 were carried out as batch type. The Langmuir, Freundlich and Sips isotherms were applied to the experimental data. And pseudo second order, intra-particle diffusion and Bangham kinetic models were used for determination of the kinetic mechanism of the adsorption. The maximum adsorption capacity for 2,4-D was found to be 86.16, 95.78 and 84.29 mg/g for each temperature (298, 308 and 318 K), respectively. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks are novel adsorbents that have been widely used in recent years. The main properties of this emerging adsorbent include high specific surface area, significant porosity, regular structure and adjustable cavities. The main objective of this study was ZIF-8 synthesis with cubic structure, functionalization with ethylenediamine and evaluation for arsenic adsorption from aqueous environments. All the experiments were carried out in batch conditions. Main variables including pH, initial arsenic concentration, adsorbent dosage and contact time were evaluated in this work. In this study, Design of Experiment software was used for experimental runs order arrangement and better understanding of the variables effects on the process. The BET results showed that surface area of the synthesized ZIF-8 and ED-ZIF-8 was 910 m 2 /g and 850 m 2 /g, respectively. It was also revealed that before and after functionalization with ethylenediamine, ZIF-8 adsorbent was aminined at about 3 mmol/g. In addition, the findings showed that the arsenic adsorption capacity increased from 72 mg/g to 83.5 mg/g. The best pH for arsenic adsorption was neutral (pH ≈ 7). The co-existing of anions effect showed that bicarbonate, sulfate and chloride had the least inhibition effects on arsenic adsorption. This study showed that application of these class of adsorbents can be seriously addressed in solving some environmental challenges. [ABSTRACT FROM AUTHOR]

Cubic zeolitic imidazolate framework-8 (ZIF-8), a new class of hybrid adsorbent, was synthesized and investigated for phosphorus (P) removal from aqueous solution. A prediction model for P adsorption was developed by performing the experiments according to central composite design. The adsorption model showed that P adsorption is associated directly with time and ZIF-8 dosage and indirectly with initial P concentration. The removal also increased with decrease in pH until reaching the critical pH of about 2.6. The efficiency of P removal under mechanically stirred increased with agitation speed from 100 to 300 rpm. In contrast to high ultrasonic frequency (130 kHz), sonication under 35 kHz provides excellent dispersive mixing and shortened the equilibrium time. Study of coexisting ions showed that P adsorption hindered considerably in the presence of carbonate. Equilibrium studies indicated that P adsorbed onto ZIF-8 in monolayer and the adsorbent has definite localized sites that are energetically identical. The maximum Langmuir sorption capacity of ZIF-8 for P was 38.22 mg/g in the present study. Analysis of experimental data also revealed that the chemosorption is the rate limiting step in P adsorption by ZIF-8. In conclusion, the present report suggest zif-8 as an efficient and fast removal sorbent for P from aqueous solutions. [ABSTRACT FROM AUTHOR]

A thiol-functionalized metal organic framework material (called HS-mSi@MOF-5) was successfully prepared by the thiol modification which taking the silica gel layer as a medium, on the basis of zinc based metal organic framework (MOF-5) synthesized by hydro-thermal method. The novel material was characterized by Fourier transfer infrared spectroscopy, scanning electron microscopy and X-ray powder diffraction. It was also investigated to remove lead and cadmium ions from aqueous solution. In view of adsorption capacity and adsorption rate, HS-mSi@MOF-5 was shown to be a more convenient and effective adsorbent (312.5 mg/g; 65.2 g/mg·min 0.5 ) than unmodified MOF-5 (211 mg/g; 4.2 g/mg·min 0.5 ). Besides, in the hydrostability test, unmodified MOF-5 would leak its own component when present in acid solution, whereas the thiol-functionalized material was stable owing to its synthesis process taking the silica gel layer as a medium. At last, electrostatic attraction and the thiol coordination interaction with potentially toxic metals played vital roles in the adsorption of lead and cadmium ions on HS-mSi@MOF-5. [ABSTRACT FROM AUTHOR]

In this study, a new adsorbent called metal organic framework was used for the removal of fluoride from aqueous solutions. Effects of various parameters such as pH, fluoride initial concentration, contact time, adsorbent dose, and co-existing anions were also evaluated. The central composite design was used to optimize the fluoride adsorption. The Uio-66-amine was characterized by x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) spectra, field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy (EDAX) and Brunauer-Emmett-Teller (BET) surface area and total pore volumes. The isotherm and kinetics models were investigated. The central composite design results showed that pH was the most influential factor in the removal of fluoride with Uio-66-amine. With the increase of fluoride concentration, fluoride adsorption was decreased. The results show that the best local maximum was found to be at the initial solution pH of 7, initial ion concentration of 12.18 mg/L, adsorbent dose of 0.4 g, contact time of 32.4 min, fluoride removal efficiency of 88.14%, and desirability of 1. The maximum adsorption of fluoride was 41.5 mg/L and adsorption data of Uio-66-amine fit well with the pseudo-second order and Langmuir isotherm models. [ABSTRACT FROM AUTHOR]

[Display omitted] • DUT-5 for water remediation with notable chemical stability and cyclability. • High adsorption capacity and stability at different pH with fast MB adsorption. • Strong host-guest interactions by cooperative and different physicochemical interactions. • Presence of π-π stacking, cation-π interactions, and hydrogen bonds. The existence of dyes in water causes environmental and health problems. Thus, a Metal-Organic Framework entitled DUT-5 was explored in the methylene blue adsorption process. DUT-5 showed a high adsorption performance exhibiting a maximum adsorption capacity of 140.66 mg g−1 in a short contact time of 45 min and stability at different pHs from 4 to 8. The adsorption isotherms and kinetic data followed the Temkin and PSO models, respectively, which suggested the involvement of physico-chemical forces in the adsorption process. The thermodynamic study confirmed the exothermic nature of the process. The key to the high adsorption of MB was the relatively strong host-guest interactions by cooperative and different physicochemical interactions, which were elucidated by FTIR, solid-state NMR, and XPS. Moreover, DUT-5 proved to be an exceptional candidate for methylene blue remediation with remarkable chemical stability and cyclability. [ABSTRACT FROM AUTHOR]

• MOF-808 with abundant missing linker defects was prepared. • Defective MOF-808 showed high uranium extraction capacity from natural seawater. • Defective MOF-808 had superior uranium adsorption selectivity over vanadium. • The high affinity of defective MOF-808 towards uranium comes from the increasing accessible Zr-O terminals. Highly effective extraction of uranium from seawater calls for the development of adsorbents with both high capacity and selectivity. Defective Zr-based metal–organic frameworks (MOFs) are potential candidates for uranium sequestration due to their high surface area and tunable active sites. In this work, MOF-808 samples with adjustable missing linker defects were successfully prepared by manipulating the concentration of the carboxylic acid modulator. Impressively, MOF-808 with the highest defect density, namely M808-4, showed excellent selectivity towards uranium in comparison with coexisting competitive ions in seawater. Moreover, M808-4 exhibited remarkable uranium extraction performance in real seawater with an uptake capacity of 5.83 mg/g in 28 d, which is 10.41 times higher than that for vanadium. The results indicated that the abundant Zr unsaturated active sites formed by defect inducing strategy are the key to the efficient capture of uranyl ions. This study highlighted the advantages of defect engineering in MOF based materials for highly selective uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

• Development of hybrid model for ion separation from aqueous solution. • Implementation of the advanced model for liquid molecular separation. • Validation of the model using experimental dataset of nanoporous material. • Prediction of adsorption equilibrium data using the developed model. We proposed a methodology based on machine learning approach for estimation of ion separation via adsorption technique. The case study considered in this work is removal of two water pollutants including Hg or Ni from water using a metal organic framework (MOF) material, with the formula of UiO-66-(Zr)-(COOH) 2. A set of data was collected from literature and then used for training and validation of the model. The used data have two outputs for Qe and Ce which are the adsorption capacity and the equilibrium concentration, respectively. The modeling takes two inputs: ion type (Hg or Ni) and initial ion concentration (C 0). We analyzed and modeled the data employing three different regression models, including multilayer perceptron (MLP), linear support vector regression (LSVR), and Gaussian process regression (GPR), to make regression on this data. Implementation and testing of the final models followed the tuning of hyper-parameters using SMA algorithm. With R2 criterion, three models were shown the score of more than 0.92 for both Ce and Qe. Despite the fact that all models have acceptable performances, GPR has been shown to have the largest generality and accuracy for both outputs. As a result, it was selected as the main model in our study. For Ce and Qe , the RMSE metrics calculated using GPR are 4.22E + 00 and 4.98E-01, respectively, based on the GPR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixed MOF materials were prepared by different synthesized strategies. • Mixed MOF materials exhibited different pore structures, thermal stability, defects leading to different adsorption behaviors. • Mixed MOF materials had more defects and higher adsorption capacity compared to MOF materials with monometallic center. • Existence of NaCl improved adsorption capacity, making potential use of prepared MOF materials in practical effluents. • Hydrogen bonding, electrostatic attraction, π-π and sieving effect dominated the adsorption system. Two kinds of metal organic framework (MOF) materials with Fe family elements as bimetallic center were synthesized via two different methods of one pot flux and MOF-on-MOF, respectively. The thermal stability and pore structure of the prepared MOF materials were different from each other. The prepared MOF materials were utilized to remove Congo red from aqueous solution to test their potential use in the treatment of wastewater containing organic dyes. Parameters affecting adsorption properties like contact time, initial concentration, ionic strength and pH of Congo red solution were systematically investigated. The adsorption capacity of CoFe-MOF material can reach as high as 1935.68 mg/g for Congo red and those of MOF materials with monometallic Fe and Co were 775.19 and 628.93 mg/g, respectively, indicating CoFe-MOF exhibited more defects leading to higher adsorption efficiency. It was surprising and interesting to find that the adsorption behaviors of the CoFe-MOF materials prepared by two different methods were different from each other. The prepared MOF materials can be used as potential candidates to treat organic dyes pollution especially anionic dyes from wastewater. This study provided guiding significance in the preparation of mixed MOF materials with more defects to be used in the remediation of effluents including organic dyes. [ABSTRACT FROM AUTHOR]

• Metal exchange on MFU-4 l based adsorbents promotes the inner-sphere surface adsorption of As(III). • Electrostatic and charge-transfer driving forces determine the adsorption mechanism. • As(III) adsorption is a spontaneous and exothermic process for pristine, Cu(II) and Fe(II)-based MOFs. • Aqueous environments have a weak influence on the adsorption stability of the As(III)-M-MFU-4 l complexes. • The recovery of the adsorbents can be reached by treatment with phosphate-based eluents. Searching and developing efficient adsorbent materials for arsenic removal is critical in water treatment. Recently, Metal-Organic Frameworks (MOFs) have gained attention due to their chemical stability and ability to capture water-soluble arsenic species. Here, we performed a computational chemistry study of the arsenic removal ability by the Zn-based MOF, MFU-4 l [Zn 4(Td) Zn (Oh) Cl 4 (BTDD) 3 ], and the effects of metal exchange [M-MFU-4 l , where M = Fe(II), Ni(II), Cu(II)]. Our results show that M-MFU-4 l based adsorbents promote the inner-sphere surface adsorption of arsenic in a wide range of pH. Metal exchange with Fe(II) species promotes a bidentate arsenic uptake, resulting in the highest adsorption ability compared to the reference system MFU-4 l. Energy decomposition analyses (ALMO-EDA) reveal that electrostatic and polarization driving forces dominate the adsorption mechanism, providing a partial orbital overlapping (coordinative bonding). In addition, thermochemical analyses reveal that arsenic adsorption is a spontaneous and exothermic process at room temperature for pristine, Cu(II) and Fe(II)-based MOFs, which are retained in a wide range of operating temperatures (298–1000 K). Finally, solvent effects have a weak influence on the adsorption stability because attractive electrostatic effects overcompensate the solvation destabilization, while the recovery of the adsorbent materials can be straightforwardly reached by treatment with phosphate-based eluents for repetitive cycles of use. Therefore, this study would provide new insights into MOFs application as technology remediation for arsenic removal from water. [ABSTRACT FROM AUTHOR]

[Display omitted] • The use of La/Ca-BDC-1 can reduce the cost of phosphorus removal by about 40%. • La/Ca-BDC-1 can efficiently remove phosphorus from natural water. • The phosphorus removal mechanism of La/Ca-BDC-1 was studied. In this study, low-cost and water-stable La/Ca bimetallic organic framework (La/Ca-BDC) are synthesized and used for the efficient removal of phosphorus in water. The study of adsorption isotherms shows that the high concentration of Ca in La/Ca-BDC-1 (prepared with Ca molar fraction in the precursor as high as 50%) has little interference to the phosphorous adsorption capacity (66.0 mg g−1) compared with that of the La-BDC (71.0 mg g−1), or only 7.0% drop, but it translates to significantly reduced cost of phosphorus removal by about 40.0%. The kinetic study of phosphorus removal process using the synthesized La/Ca-BDC-n conforms to the pseudo-second-order kinetic model. In addition, the synthesized La/Ca-BDC-1 is suitable for phosphorus removal in wide pH water (3.0–9.0). More importantly, the manufactured La/Ca-BDC-1 can efficiently remove the phosphorus in the actual water. In addition, even if there are interfering ions (Ca2+, Mg2+, CO 3 2–, HCO 3 –, SO 4 2- and Cl-) with concentration of five times of the phosphorus, the phosphorus removal efficiency of La/Ca-BDC-1is hardly affected. Interestingly, the removal efficiency of La/Ca-BDC-1 for phosphorus is still higher than 70% after five cycles. From the FT-IR and XPS analysis, it is shown that ligand exchange and complexation are the main phosphorus removal mechanisms of La/Ca-BDC-1. [ABSTRACT FROM AUTHOR]

In this study nanoporous metal organic framework (MOF-5) was synthesized as the copper ion (Cu 2 + ) adsorbent. The morphology and structure of the obtained adsorbent were characterized by XRD, SEM and nitrogen adsorption/desorption methods. The adsorption studies of copper ion by MOF-5 include both kinetic and equilibrium approaches and the obtained equilibrium and kinetic data were fitted with different models. The effect of temperature and solution pH on the removal efficiency was investigated as well. [ABSTRACT FROM AUTHOR]

• Separation of Cr(VI) via a hierarchical ordered composite material. • Artificial neural network simulation of Cr(VI) removal from water using adsorption. • Validation and training the ANN using measured data of Cr removal. We developed a novel methodology for simulation and computation of species adsorption on the surface of ordered nanoporous materials. The main aim was to develop an advanced and high-performance predictive model for prediction of adsorption behaviour of novel nanostructured materials which can be used for a variety of species. The simulations were conducted using artificial intelligence technique by considering the pH and adsorbent dosage as the inlet variables to the model for prediction of the output. The computations were carried out in order to predict the equilibrium amount of species in the solution. The study was performed on the adsorption of Cr (VI) ions using nanocomposite of layered double hydroxide-metal organic framework. Due to the ordered and high surface area of this composite material, it was considered for this computational study and removal of Cr (VI) ions. The collected data was used to train the artificial intelligence network, and the statistical analysis was performed for training and validation of the network in order to assess the accuracy of the trained model. The R2 value more than 0.999 was obtained for the fitting the Cr (VI) adsorption data by the model. A great agreement was obtained between the model's findings and the measured data for removal of Cr (VI) from water. Furthermore, the effect of adsorption parameters on the equilibrium concentration of Cr was studied using the validated model. It was revealed that the adsorption removal was increased by increasing the adsorbent dosage, while it decayed by enhancing the pH of solution. [ABSTRACT FROM AUTHOR]

• Molecular dynamic and quantum simulation of cationic dyes adsorption on MOF/(COOH) 2. • Fast removal of MG, MB, TB, and CV by acidic functionalized MOF for the first time. • The computational relative energies of different configurations were determined. • Highest adsorption capacity for CV dye and UiO-66-(COOH) 2 MOF surface. • Evaluation of σ , µ , ω, η and chemical reactivity of different configurations. Metal organic frameworks (MOFs) especially benzene-1,4-dicarboxylic acid-functionalized UiO-66 (UiO-66-(COOH) 2) with distinguished properties are great candidates for dyes removal from wastewater. In the current work organ-metal with anion groups, UiO-66-(COOH) 2 (MOF/(COOH) 2), was selected to adsorb four toxic cationic dyes from aqueous media. The quantum chemical calculations and molecular dynamic simulation were used to evaluate the adsorption mechanism of four toxic cationic dyes (malachite green (MG), methylene blue (MB), toluidine blue (TB) and crystal violet (CV)) on the MOF/(COOH) 2 in the presence of water molecules. The optimized geometry of all structures was obtained through Dmol3 module. According to the obtained results the highest adsorption energy was obtained for CV-water-MOF/(COOH) 2 configuration, while the MB-water-MOF/(COOH) 2 had the lowest adsorption energy. Also, the molecular electrostatic potential maps and frontier molecular orbitals (FMO) were achieved for all configurations. The HOMO and LUMO as well as energy gap (ΔE GAP) indicated that the highest adsorption affinity was belong to CV-water-MOF/(COOH) 2 configuration. Accordingly, the increasing of ΔE GAP was in the following order: CV-water-MOF/(COOH) 2 < MG-water-MOF/(COOH) 2 < TB-water-MOF/(COOH) 2 < MB-water-MOF/(COOH) 2. The quantum chemical descriptors such as chemical potential, electronegativity, nucleophilicity and electrophilicity index, chemical softness and hardness were obtained from HOMO and LUMO energy levels. Consequently, the results demonstrated that the chemical reactivity, softness, and polarizability of CV dye were higher compared to other studied dyes. The results of this theoretical revealed that UiO-66-(COOH) 2 as an acidic group functionalized MOF is highly recommended for removal of cationic dyes. Molecular dynamic simulations can be a very useful approach to make a brighter insight about the mechanism of cationic dyes adsorption on the MOF adsorbent and very effective from perspective of time and experimental costs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption of Cr (VI) on MOF-5 functionalized with amino groups. • Linear and nonlinear isotherms, kinetic models, and thermodynamic analysis. • Influence of coexisting ion species on the adsorption efficiency. • Thermodynamic studies revealed that adsorption nature is spontaneous and endothermic. • Maximum adsorption capacity of 78.6 mg/g was achieved. In the past decades, an extensive effort has been devoted to remove Hexavalent chromium H(Cr (VI)) from industrial effluents, owning to its great health concerns to humans and the environment. Recently, Metal organic framework (MOFs) adsorbents draws more attention of researchers to remove contaminants from aqueous environments in the recent years. In the present study, solvothermal method was employed to fabricate MOF-5 that was examined for Cr (VI) adsorption from water matrices. XRD, FESEM, EDS, FTIR and BET analyses were utilized to characterize MOF-5. The influence of some independent parameters on MOF-5 performance in Cr (VI) adsorption was explored in a batch mode system. It was found that the uptake rate of Cr (VI) is significantly affected by initial pH of solution; the maximum adsorption rate is favored by acidic pH. Also, the adsorption efficiency shows a direct relationship with contact time and adsorbent dose, and an indirect relation with initial Cr (VI) concentration. The adoption process was modeled and optimized successfully by two approach of response surface methodology and artificial neutral network approaches; both models indicated an accuracy of predictions by determining error distribution and statistical significance and a good fit to experimental data. The experimental data showed a superior agreement with linear and nonlinear Langmuir isotherm, as compared with the other isotherm models, and pseudo-second-order kinetic better described Cr (VI) adsorption data by MOF-5, compared to the other kinetic models. The maximum absorption capacity was 78.12 mg/g. Thermodynamic studies revealed that adsorption is spontaneous and endothermic process. The findings claimed the great reusability and high stability of MOF-5; adsorption efficiency decreased only by 92.4% after ten recycles. The interfering anions affected negatively on the adsorption efficiency in the order of phosphate > sulfate > chloride > nitrate. The present study provides valuable and good information for Cr (VI) adsorption on MOF-5 in water matrices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Understanding water adsorption on zirconium-based MOFs employing GCMC simulation. • Calculation of water adsorption isotherms and isosteric heat by GCMC and experiments. • Hydrophilic/hydrophobic characteristics are controlled by functionalization of MOFs. • Comparison study of GCMC simulation results and experimental data. • The design of new MOFs with hydrophilic/phobic behavior by GCMC simulation. This article focuses on Grand Canonical Monte Carlo (GCMC) simulation to tailor zirconium-based metal organic frameworks (MOFs) such as UiO-66 (Zr) and MOF-801(Zr). The hydrophilic functional group such as amine (–NH 2), hydroxyl (–OH) and pyridine (-C 5 H 5 N) and the hydrophobic functional group such as methyl (–CH 3) are studied by GCMC simulation. The water adsorption on these functionalized MOFs is calculated within a wide temperature range (25–80 °C) and pressures up to the saturated condition. Based on simulation, the functional MOFs are synthesized and characterized. Water adsorption isotherms are measured experimentally for a wide range of pressures and temperatures. The water adsorption phenomena captured by GCMC simulation are compared with experimental data within acceptable error ranges. The trends of isosteric heat of adsorption (Q st) are also evaluated by GCMC simulation techniques, and these results are compared with Q st calculated by isotherms data and Clausius-Clapeyron equation. The present findings show that the GCMC simulation can be applied to design and develop functionalized MOFs for characterizing and controlling both the hydrophobic/hydrophilic behaviors (especially at low pressure region) with water adsorption. Based on GCMC simulation, the suitable MOFs are designed and optimized for various heat transformation applications. [ABSTRACT FROM AUTHOR]

• Soft computing simulation of separation using a nanomaterial. • Machine learning computation of adsorption equilibrium concentrations. • Evaluation of the effect of adsorbent dosage and pH on removal using the model. Molecular separation using nanostructured materials have attracted much attention recently for various applications. Different classes of materials have been used among which metal organic framework (MOF) and layered double hydroxide (LDH) have been recently developed due to their superior structure in separation, specifically adsorption process. In this work, we have studied removal of dye from water using a nanocomposite of MOF/LDH. The method of investigation is development of an artificial intelligence-based model for prediction of the adsorption process. The adsorption data have been obtained for removal of a dye (orange II reactive dye) from water at different conditions. The model was proposed using artificial neural network for simulation of the adsorption output which was considered to be equilibrium concentration in the solution (C e). Indeed, the equilibrium concentration of solute was assumed as the main output in developing the model, while two inputs were postulated including the pH and adsorbent dosage. The model was built considering two hidden layers in the neural network. The validation and training steps were carried out and statistical analysis indicated excellent agreement between the simulated and measured data possessing high coefficient of determination (R2 greater than 0.999). The model revealed to be a high-performance model for simulation of dye removal using adsorption process with high accuracy. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption mechanisms of endotoxin on MOF functionalized with the amine groups. • Experimental and theoretical studies was studied. • Linear and nonlinear isotherms, kinetic models and thermodynamic studies. • Influence of interfering anions on the adsorption efficiency. Endotoxin is well-known as one of the emerging pollutants secreted from bacteria; cyanobacteria has drawn much attention over the years due to imposing health problems such as impairment of the immune system and toxic shock. A novel modified amino MOF (NH 2 -Cu(MOF)) was synthesized and its application for endotoxin (lipopolysaccharides) removal from aqueous solution was investigated. Physicochemical properties of NH 2 -Cu(MOF) structure were characterized by XRD, SEM, BET and FTIR analyses. In this study, the effects of different operational parameters: Initial pH, contact time, adsorbent dosage and endotoxin concentration on removal efficacy by MOF were surveyed by central composition design (CCD) approach under response surface methodology (RSM) and artificial neural network (ANN). The experimental data for pollutant removal were well fitted with quadratic polynomial model (based on RSM approach) and mathematical model (based on ANN approach) with a good prediction capability. Statistical ANOVA results indicated that the dosage of NH 2 -Cu-MOF and endotoxin concentration had high contribution on response prediction compared with other variables. Under optimum conditions, over 90% of endotoxin degradation was observed by the adsorbent. Adsorption kinetic was well designated by the pseudo second order kinetic model, especially its nonlinear form, while the adsorption isotherm was better fitted by Langmuir model in both linear and nonlinear forms with the maximum single-layer adsorption capacity of above 2500 Eu/mg. The possible mechanisms for endotoxin removal by NH 2 -Cu(MOF) were electrostatic interaction, hydrogen-bonding and π-π stacking. Recycling test showed a good reusability and stability result of NH 2 -Cu(MOF) during five subsequent recycles; the influence of interfering anions on the adsorption efficiency exhibited the following order: PO 4 3− > HCO 3 − > SO 4 2− > Cl− >NO 3 −. Our finding revealed that the NH 2 -Cu(MOF) structure could be suggested as a feasible and potential promising adsorbent for removal of toxic material from the aqueous solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption properties of ZIF-8. • Adsorption fit with pseudo second order kinetics and Langmuir isotherm model. • The AC and DC properties of ZIF-8 as semiconductor behavior. • The BET surface area was 21.824 m2/g and pore volume 0.026 cm3/g. The zeolitic imidazole framework-8 (ZIF-8) was prepared in this study, which is a form of metal organic framework (MOF). ZIF-8 was characterized using powder X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Brunauer-Emmett-Teller surface area (BET), scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX). The material was used to eliminate Remazol Black 5 (RB5) and Brilliant Green (BG) dyes from aqueous media via chemical adsorption process. Adsorption kinetics, isotherms, dosage effect, initial concentration effect and pH were all investigated. According to the findings of the previous studies, the pseudo-second-order kinetics model and the Langmuir isotherm match our experimental adsorption data. Thermodynamic adsorption characteristics such as enthalpy, entropy, and Gibb's free energy were calculated. The sorption process was taking place spontaneously and it was endothermic in nature with high disorder of solid–liquid interface. ZIF-8′s AC and DC properties were investigated, and it revealed typical semiconductor activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • An available and facile way for the magnetic MOF-NH 2 was reported. • The adsorption efficiency of the magnetic MOFs towards U(VI) was improved dramatically. • The interactional mechanism between the tuned amine groups and U(VI) was revealed. A magnetic metal organic framework was finely tuned by abundant amine groups (Mag MOF-NH 2) for the purpose of improving the U(VI) removal from solution. The Mag MOF-NH 2 displays outstanding removal capacity (80 mg⋅g−1) to U(VI) (10 ppm, 400 mL) within 15 min. To illuminate the adsorption mechanism of Mag MOF-NH 2 , the microstructure, the magnetic property, chemical composition of Mag MOF-NH 2 and the reaction system were characterized. The adsorption mechanism was systematically investigated. Equilibrium adsorption experiments verifies the improved adsorption capability from nearly 0 for MIL-101 to 82 mg⋅g−1 for Mag MOF-NH 2 , which could be explained mainly by the interaction between the amine groups and targeted ions. The effect of humic acid (HA) and coexisting ions on the U(VI) adsorption were also investigated. The Ca2+ and Mg2+ ions have passive impact on the adsorption and the high pH value can facilitate the process. Mag MOF-NH 2 holds great potential for the practical application owing to the outstanding U(VI) removal and satisfied regeneration in simulative wastewaters. [ABSTRACT FROM AUTHOR]

Soil, air, and water pollutions remain the major worldwide challenges for both human and eco-environment society. Decontamination of pollutants such as organic and inorganic compounds from an ecosystem remains a bottleneck over the years. Among several methods for removing pollutants, adsorption stands unique and usually simple and efficient. However, the versatility of the adsorption technique largely determines by the materials' sorption capacities which depend on the porous structures and surface property of the adsorbent. Metal-organic frameworks (MOFs) are a novel class of carbonaceous nanomaterials" having larger specific surface areas and their oxides have unique functional groups required for good adsorption processes. The applications of MOFs remain the focus of many kinds of researches in the last few years for effective removal of different contaminations from the soil, air, and water. This review presents some advancements in the usages of these novel MOFs for the adsorptive removal of different contaminants from the ecosystems. The study also highlighted some promising MOF adsorbents used for the effective removal of different pollutants including heavy metals, CO 2 , chlorinated volatile organic compounds (CVOCs), dyes, pesticides, food additives, veterinary, pharmaceutical and personal care products (PPCP), antibiotics, biological and chemical weapons, other industrial chemicals, etc. Still, the discovery of the actual feasibility and applicability of the MOFs usages as adsorbents on the commercial scales are highly needed. The reusability of these adsorbents is continuously desirable to reduce the cost and associated wastes produced from the pollutant removal processes. For more effective and practical applicability of MOFs, some frequent and unnoticed factors were also proposed as the challenges and prospects to foster the remarkable improvements in combating different pollutants. We further established that despite the existence of hitches and challenges associated with the use of MOFs, these materials are undeniably advantageous for decontaminating pollutants from wastewater, and upon sustaining efforts, their practical applications for water purification, separation, and other adsorption purposes will shortly be evident. [Display omitted] • The review highlights the effectiveness of novel MOFs for removal of different pollutants • It highlights various milestones of synthesis and application MOFs in water pollutant remediations • Recent advances in the applications of MOF for adsorption of different pollutants • Insight into stability of MOFs for better adsorption capacity • Briefly discussed challenges and prospects to foster better improvement pollutant removal [ABSTRACT FROM AUTHOR]

The increasing demand of superior adsorbents towards the elimination of anionic contaminants from the aqueous environment, in this work we have designed the iron-supported metal-organic framework (MOF) such as Fe-MIL-88B towards the remediation of nitrate and phosphate ions from the aqueous region. The effect of solution chemistry on the adsorption of above anions using Fe-MIL-88B was investigated. Chemical structure and morphology of the Fe-MIL-88B was effectively studied using various analytical techniques such as PXRD, FTIR, SEM with EDX, TGA-DTA, XPS and BET analysis. The experimental studies confirmed that Fe-MIL-88B was dominantly reducing the anionic concentration under optimized conditions. The competitive anions study showed that the as-synthesized adsorbent demonstrated significant adsorption efficiency and selectivity towards nitrate and phosphate ions, and the co-anions reveal negligible effects on nitrate and phosphate removal capacities and rate. The removal mechanism exhibited that both anionic ions were adsorbed mainly through complexation mechanism and electrostatic interaction. The anionic nature of both contaminants helps to enhance the adsorption by the synthesized MOF by effectively moving towards the adsorption spots available on Fe-MIL-88B. Additionally, the removal mechanism of nitrate and phosphate onto Fe-MIL-88B was examined using adsorption isotherm and kinetic parameters. Equilibrium analysis revealed that the maximum adsorption efficiency for nitrate and phosphate was 92.59 and 103.09 mg/g, respectively. Accordingly, spent adsorbent could be successfully regenerated using NaOH solution and showed constant adsorption-desorption performance. The results investigate in this present study highlight the feasibility of Fe-MIL-88B as a potential candidate for the elimination of both anions from wastewater. • Iron-based MOF was proposed as an effective adsorbent for nitrate and phosphate removal. • Fe-MIL-8B showed fast adsorption equilibrium within 60 min for both NO 3 − and PO 4 3−. • The pH significantly effects on nitrate and phosphate adsorption onto Fe-MIL-8B. • Electrostatic interaction and complexation are main mechanisms for nitrate and phosphate adsorption. • The exhausted Fe-MIL-8B can be recycled and reused for nitrate and phosphate adsorption. [ABSTRACT FROM AUTHOR]

In this work, flexible surface-supported metal-organic framework (MOF) membranes were successfully prepared on fabric by a simple method and used for cobalt adsorption for the first time. MIL-101-NH 2 crystals were deposited in-situ on the fabric by hydrothermal synthesis. SEM and XRD results demonstrated that the MOF membranes were robust, stable, and consistent. The influences of pH, temperature, and initial cobalt concentration on the cobalt adsorption capacity of the membranes were investigated. The maximum Co(II) adsorption capacity was found to be 116.3 mg g−1, and the MOF membranes retained excellent adsorption capacity even after ten cycles. The Co(II) adsorption process on the membranes was endothermic and spontaneous and followed pseudo-second-order chemisorption. The XPS analysis implied that the formation of Co2+ and -NH 2 complexes dominated the cobalt adsorption process. The application of MOF membranes in Co(II) adsorption simplified the MOF powder recycling process indicating that the easily-prepared and environment friendly flexible MOF membranes have a great potential for engineering applications in cobalt adsorption. Unlabelled Image • Surface-supported MOF membranes are used for cobalt adsorption for the first time • The use of the MOF membrane simplifies the traditional adsorption and separation process • The MOF membranes are easily prepared and environmental-friendly • The MOF membranes exhibit excellent adsorption capacity for Co(II) [ABSTRACT FROM AUTHOR]

In this research, imidazolium, quinolinum and benzothiazolium based ionic liquids (ILs) were immobilized on a metal organic framework (MOF) by solvent impregnation or capillary action. The synthesized IL@MOF composite materials were characterized by FTIR, XRD, SEM and TGA methods and then applied in removal of tetracyclines (TCs) from aqueous samples. The presence of ionic liquids significantly improved the adsorption efficiency of the metal organic framework, with 82% or higher removal percentage was obtained for the three target TCs while the pristine MOFs adsorption efficiency was below 50%. This could be attributed to the ability of ILs to make complex interaction with target drugs via multiple intermolecular forces. Experimental results revealed the effects of three significant factors including pH, temperature and solid-liquid ratio, and optimum adsorption efficiency could be achieved at pH 8 and 30 °C when solid-liquid ratio = 1:2 was adopted. The adsorption kinetics was properly fitted with pseudo-second order model and Redlich-Peterson model could be used to describe the adsorption isotherm for three antibiotics; moreover, the adsorption was an endothermic and spontaneous process in nature. Finally, the adsorbed TCs could be desorbed efficiently and the performance of the IL@MOF sorbent was further verified by actual water samples. • Typical antibiotics were adsorbed by various IL@MOF for the first time. • Good adsorption and desorption could be achieved by developed way. • Mechanisms were investigated comprehensively for adsorption behaviors. • The IL@MOF sorbent was effective for actual water samples from a lake. [ABSTRACT FROM AUTHOR]

In this work, a magnetic nitrogen-doped carbon nanotube/porous carbon hybrid was prepared by the facile carbonization of zeolitic imidazolate frameworks (ZIF-8) impregnated with iron salt. The as-obtained hybrid (denoted as Fe 3 O 4 @ Z -NCNT/PC), with a high surface area (1358 m2 g−1), large pore volume (1.61 cm3 g−1), and considerable functional groups, was used as a recyclable adsorbent for the selective removal of Pb(II) ions from water solution. The factors influencing the adsorption performance of Fe 3 O 4 @ Z -NCNT/PC toward Pb(II) ions were studied using batch experiments. The adsorbent exhibited very fast adsorption kinetics for Pb(II) ions and could efficiently remove more than 99% of Pb(II) in 20 min. The maximum adsorption capacity of the hybrid was found to be 789.87 mg g−1 which was much higher than most of the previously reported adsorbents. Moreover, the adsorbent exhibited high removal selectivity of Pb(II) ions in the presence of other ions and could maintain a high removal performance even after 10 cycles. The extraordinary adsorption performance of the adsorbent toward Pb(II) ions was attributed to the synergistic contributions of the unique hybrid structure providing abundant routs for easy mass transfer of Pb(II) ions to access active sites as well as nitrogen-functionalities introduced into the framework providing basic active sites for Pb2+ adsorption. This study provides a simple strategy for the construction of MOF-based adsorbents and also offers possible applications in water treatment due to their outstanding adsorption properties. Unlabelled Image • Magnetic N-doped CNT/PC hybrid was prepared by pyrolysis of Fe2+ loaded ZIF-8. • Z-MNCNT/PC showed high removal selectivity for Pb2+ in the presence of other ions. • Adsorbent provided advantages of magnetic NPs and N-doped CNT/porous carbon hybrid. • Sorbent had high removal efficiency, high adsorption capacity, and good reusability. • Fast adsorption kinetics with high adsorption capacity of 789.87 mg g−1 was obtained. [ABSTRACT FROM AUTHOR]

The UiO-66 NH 2 and ZIF-8 metal organic framework nanoparticles (NMOFs) were incorporated into the polyvinylidene fluoride (PVDF) nanofibrous membrane. Then, the chitosan nanofibers were coated on the PVDF nanofibers to produce the PVDF/chitosan nanofibers. The performance of synthesized PVDF/NMOFs single layer and PVDF/chitosan/NMOFs two layers nanofibrous membranes was investigated for BSA protein molecules and Cr(VI) ions separation via ultrafiltration membrane process. The potential of synthesized nanofibers was also examined for BSA and Cr(VI) adsorption in a batch system. The characteristics of synthesized nanofibrous membranes were determined using SEM, EDX, TGA, BET, porosity and water contact angle measurements. The PVDF/chitosan nanofibrous membrane containing 20 wt% UiO-66-NH 2 , exhibited the maximum water flux of 470 L.m−2 h−1, 98.1% BSA rejection and 95.6% Cr(VI) rejection. The nanofibers were sucessfully regenrated for five adsorption-desorption cycles. The maximum sorption capacities of BSA and Cr(VI) were found to be 574.5 and 602.3 mgg−1, respectively. The obtained results revelaed the high potential of PVDF/chitosan/UiO66-NH 2 nanofibers for membrane separation and adsorption of BSA molecules and Cr(VI) ions. The performance of MOF loaded ultrafiltration nanofibrous membrane for rejection of BSA and Cr(VI). Unlabelled Image • UiO-66 NH 2 and ZIF-8 MOFs were synthesized via microwave heating method. • MOFs were incorporated into the PVDF and PVDF/chitosan UF membranes. • The adsorption and separation of BSA protein and Cr(VI) ions were investigated. • The maximum water flux, BSA and Cr(VI) rejection were 470 Lm−2 h−1, 98.1 and 95.6%. • The maximum sorption capacities of BSA and Cr(VI) were 574.5 and 602.3 mgg−1. [ABSTRACT FROM AUTHOR]

A novel Zr-MOF adsorbent was synthesized by one-step method and was used to selectively adsorb Hg(II) and Pb(II) from wastewater. The adsorbent can reduce the concentration of mercury and lead to less than the national standard (Hg is 50 μg/L and Pb is 1 mg/L). The entire adsorption process conforms to the pseudo second-order kinetic and Hill isotherm models. At pH 4, the adsorbent removed more than 90% of mercury (to 22 μg/L) and lead (to 0.732 mg/L) in 10 min and 960 min, and the maximum adsorption capacity was 1080 mg/g and 510 mg/g, respectively. In addition, the practical application in wastewater proved that the adsorbent can selectively adsorb Hg(II) and Pb(II) from the mixed ion solution and it still meets national standards for wastewater discharge. The research of repeated experiments proves that the adsorbent can be used repeatedly. The adsorption mechanism was clarified by FTIR, XPS spectroscopy before and after adsorption, and density functional theory (DFT) calculation. In summary, the adsorbent is stable in aqueous solution and has great potential for the efficient removal of trace heavy metal ions (mercury and lead) in future treatment of wastewater. Unlabelled Image • The novel metal-organic frameworks adsorbent was synthesized using one-step method. • The adsorption capacity of Hg(II) and Pb(II) reached to 1080 mg/g and 510 mg/g at pH 4, respectively. • Both mercury and lead can be removed below international standards at low concentrations. • Adsorbent shows good reusability for Hg(II) and Pb(II). • Adsorption mechanism is chelation and the DFT calculation proved that the combination of heavy metals and sulfur is strong. [ABSTRACT FROM AUTHOR]

In the present study attempts have been made to improve the adsorption performance of Fe-Benzene dicarboxylic acid metal organic framework for the removal of methylene blue dye from waste waters through cobalt doping. The removal efficiency of Co doped Fe-BDC MOF improved from 8.56 to 23.92 mg/g. Batch and column methods have been used to evaluate removal efficiency of the Co doped Fe-BDC MOF for removal of methylene blue. Effect of various parameters such as pH, amount of adsorbent, dye concentration, temperature, and contact time on dye removal has been studied. It has been observed that extent of adsorption increases in acidic medium and dye removal decreases on increasing pH of dye solution. Langmuir adsorption isotherm has been found to best fit the adsorption process. Thermodynamic parameters, evaluated for the dye-adsorbent system, revealed that the adsorption process is endothermic in nature. Experimental data were modeled by using pseudo-first, pseudo-second and intraparticle diffusion models. Pseudo-second-order kinetics was found to describe the adsorption of methylene blue on MOF. Column operations were made to achieve bulk removal of the dye. Column adsorption capacity has been found to be greater than the batch adsorption capacity. The improved maximum adsorption capacity of the Co doped Fe BDC MOF in comparison to the previously developed Fe BDC MOF establishes the significance of the present investigation. • Synthesis of Co doped Fe BDC MOF for enhanced dye removal • Optimization of batch and column process for dye removal • Investigations of adsorption isotherms and kinetic model • Calculation of thermodynamic parameters [ABSTRACT FROM AUTHOR]

Nano zero-valent iron (nZVI) is a highly reactive particle but easily to be aggregated. Porous materials support can improve the stability of nZVI. Materials of Institute Lavoisier Frameworks (MILs), a type of metal-organic frameworks (MOFs), have enormous surface areas, ultrahigh porosity, and good water stability. The combination between MILs and nZVI can provide an intensively "capture & destroy" effect to micro-pollutants in water. In this study, a novel composite, nZVI modified MIL-101(Cr), was prepared, characterized, and applied for tetracycline (TC) adsorption and degradation. The surface morphology and micropore structure of nZVI/MIL-101(Cr) were characterized. The TC adsorption performance of the composite was investigated via various parameters, adsorption kinetics, isotherms, and thermodynamics. Results showed that the TC adsorption followed pseudo-second-order kinetic equation and the maximum adsorption quantity (q m) was 625.0 mg/g. The catalytic property of nZVI/MIL-101(Cr) was also investigated via heterogeneous Fenton-like process, and nZVI/MIL-101(Cr) showed 90% TC removal efficiency in a wide pH range. Moreover, nZVI/MIL-101(Cr) displayed good stability and reusability. The developed composite is a potential adsorbent and heterogeneous catalyst for antibiotics pollution control in water. Unlabelled Image • A novel composite was synthesized by impregnating nano zero-valent iron to MOF. • NZVI/MIL-101(Cr) was used as an adsorbent and heterogeneous catalyst to remove TC. • The maximum TC adsorption capacity was 625.0 mg/g for nZVI/MIL-101(Cr). • NZVI/MIL-101(Cr) exhibited higher catalytic activity for TC degradation. • NZVI/MIL-101(Cr) displayed high stability and reusability. [ABSTRACT FROM AUTHOR]

Dyes that are considered to be poisonous exist everywhere in our daily life. The most urgent task is to remove such dye molecules from effluents. In the present work, a cationic metal-organic framework, [Cd 2 (tib)(btb)(H 2 O) 2 ]∙NO 3 ∙2DMF (Cd-MOF), where charge neutrality is balanced by NO 3 −, was first synthesized to investigate its ability in the adsorption and separation of ionic dye molecules. It is found that anionic dye molecules can be efficiently adsorbed with a diverse adsorption rate, while neutral and cationic dye molecules cannot be adsorbed according to the color changes of Cd-MOF. Meanwhile, Cd-MOF serves as a column-chromatographic filler to adsorb and separate specific anionic dye molecules with visible effects. Furthermore, anionic dye molecules can be released gradually, and the release rate is faster in the presence of NaCl. It should be noted that Cd-MOF remains stable even after 6 cycles of adsorption and separation of ionic dye molecules, which implies that MOFs can be considered potential materials for dye adsorption and selective separation with the merits of convenience, rapidity and environmental friendliness. Unlabelled Image • Cd-MOF was adopted to investigate adsorption and separation for dyes firstly. • Anionic Dyes could be adsorbed efficiently with different rates. • Cd-MOF served as a column-chromatographic filler for separating anionic dyes. [ABSTRACT FROM AUTHOR]