COOH Sites Research Articles

Selective CO2 adsorption over a Zr-based metal–organic framework functionalized with tris(2-aminoethyl)amine

Selective capture of CO2 from off-gas or even the atmosphere is very important against global warming. In this work, a stable Zr-based MOF (MOF-808) was loaded with –COOH group and was further functionalized with tris(2-aminoethyl)amine (TREN), via a reaction between –NH2 of TREN and –COOH sites. The derived materials were analyzed with X-ray diffraction, scanning electron microscopy, FTIR, X-ray photoelectron spectroscopy, thermogravimetry analysis, elemental analysis, and nitrogen adsorption at 77 K; utilized in the adsorption of CO2 and N2 at relatively low pressure up to 100 kPa. One functionalized MOF-808 prepared in this work (named MOF808-EDTA-TREN(0.3)) showed remarkable performances in the selective capture of CO2 under low pressure. For example, the invented MOF exhibited the highest selectivity (based on ideal adsorbed solution theory) in CO2 capture from N2 and CO2 (SCO2/N2: 519 at 100 kPa) compared with any reported results, thus far, using MOF-808-based materials. Moreover, MOF808-EDTA-TREN(0.3) was recyclable up to the fifth run upon vacuum treatment. The noticeable performances of MOF808-EDTA-TREN(0.3) in CO2 adsorption could be explained by the loaded –NH2 sites of TREN (that are effective in carbamates formation) and bulky TREN that decreases the nitrogen adsorption because of the reduced porosity of the MOF. In brief, loading bulky amines with ample amino groups like TREN can be suggested as an attractive way to modify a MOF for selective CO2 capture from off-gas of various industries.

Effects of Sheep Bone Peptide-Chelated Calcium on Calcium Absorption and Bone Deposition in Rats Fed a Low-Calcium Diet

Sheep bones, as the main byproduct after sheep slaughter, are rich in proteins, but their utilization in deep processing is relatively low. Currently, calcium deficiency is a common health issue that can lead to metabolic bone diseases. Peptide calcium chelate is considered a superior substance, having a significant effect on improving the absorption and utilization efficiency of calcium in the human body. This study used sheep bone byproducts as the raw material to prepare sheep bone peptide-chelated calcium (SBP-Ca) and its structure was characterized and analyzed in depth. SBP-Ca was supplemented in a low-calcium diet to assess its effects on calcium absorption and bone formation in a rat model experiencing calcium deficiency. The results showed that under optimal preparation conditions for SBP-Ca (peptide-calcium ratio set at 1 : 1, pH maintained at 7, temperature set to 45°C, and duration of 60 min), calcium could chelate with sheep bone peptide (SBP) at the sites C=O, -NH2, and -COOH sites, forming a structurally dense SBP-Ca with a chelation rate of up to 89.24%. In rats fed a low-calcium diet, SBP-Ca significantly improved the rat femoral diameter, dry weight, trabecular bone structure, bone density, and bone volume fraction (P<0.05). A decline in serum alkaline phosphatase levels (P<0.05), elevation in bone calcium content, and a rise in serum osteocalcin levels (P<0.05) were observed. Furthermore, morphological studies on bone tissue suggest that SBP-Ca has the ability to restore trabecular bone structure. In conclusion, SBP-Ca has been successfully prepared as a novel calcium absorption promoter. By improving the bioavailability of calcium, bone formation was facilitated, demonstrating a significant application value in the prevention of calcium deficiency disorders.

Distinguishing between COOH, COO- , and hydrogen disordered COOH sites in solids with 13 C chemical shift anisotropy and T1 measurements.

Since 1993, it has been known that 13 C chemical shift tensor (i.e., δ11 , δ22 , and δ33 ) provides information sufficient to distinguish between COOH and COO- sites. Herein, four previously unreported metrics are proposed for differentiating COOH/COO- moieties. A new relationship is also introduced that correlates the asymmetry (i.e., δ11 -δ22 ) of COOH sites to the proximity of hydrogen bond donating partners within 2.6Å with high accuracy (±0.05Å). Conversely, a limitation to all proposed metrics is that they fail to distinguish between COO- and hydrogen disordered COOH sites. To reconcile this omission, a new approach is proposed based on T1 measurements of both 1 H and 13 C. The 13 C T1 values are particularly sensitive with the T1 for hydrogen disordered COOH moieties found to be nearly six times smaller than T1 's from COO- sites.

Binding of carbon dioxide and acetylene to free carboxylic acid sites in a metal-organic framework.

The functionalisation of organic linkers in metal-organic frameworks (MOFs) to improve gas uptake is well-documented. Although the positive role of free carboxylic acid sites in MOFs for binding gas molecules has been proposed in computational studies, relatively little experimental evidence has been reported in support of this. Primarily this is because of the inherent synthetic difficulty to prepare MOF materials bearing free, accessible -COOH moieties which would normally bind to metal ions within the framework structure. Here, we describe the direct binding of CO2 and C2H2 molecules to the free -COOH sites within the pores of MFM-303(Al). MFM-303(Al) exhibits highly selective adsorption of CO2 and C2H2 with a high selectivity for C2H2 over C2H4. In situ synchrotron X-ray diffraction and inelastic neutron scattering, coupled with modelling, highlight the cooperative interactions of adsorbed CO2 and C2H2 molecules with free -COOH and -OH sites within MFM-303(Al), thus rationalising the observed high selectivity for gas separation.

Designing Efficient Nitrate Reduction Electrocatalysts by Identifying and Optimizing Active Sites of Co-Based Spinels.

Cobalt-based spinel oxides (i.e., Co3O4) are emerging as low-cost and selective electrocatalysts for the electrochemical nitrate reduction reaction (NO3-RR) to ammonia (NH3), although their activity is still unsatisfactory and the genuine active site is unclear. Here, we discover that the NO3-RR activity of Co3O4 is highly dependent on the geometric location of the Co site, and the NO3-RR prefers to occur at octahedral Co (CoOh) rather than tetrahedral Co (CoTd) sites. Moreover, CoOhO6 is electrochemically transformed to CoOhO5 along with the formation of O vacancies (Ov) during the process of NO3-RR. Both experimental and theoretic results reveal that in situ generated CoOhO5-Ov configuration is the genuine active site for the NO3-RR. To further enhance the activity of CoOh sites, we replace inert CoTd with different contents of Cu2+ cations, and a volcano-shape correlation between NO3-RR activity and electronic structures of CoOh is observed. Impressively, in 1.0 M KOH, (Cu0.6Co0.4)Co2O4 with optimized CoOh sites achieves a maximum NH3 Faradaic efficiency of 96.5% with an ultrahigh NH3 rate of 1.09 mmol h-1 cm-2 at -0.45 V vs reversible hydrogen electrode, outperforming most of other reported nonprecious metal-based electrocatalysts. Clearly, this work paves new pathways for boosting the NO3-RR activity of Co-based spinels by tuning local electronic structures of CoOh sites.

Oxygen-doped carbon nanotubes with dual active cites to enhance •OH formation through three electron oxygen reduction

The electro-Fenton (EF) process generates H2O2 through the 2e- oxygen reduction reaction (ORR), which is subsequently activated to •OH by iron-based catalysts. To alleviate the potential risk of external Fe-based catalysts, along with metal dissolution in acidic or neutral environments, in this study we employed oxygen-doped carbon nanotubes (OCNT) as a bifunctional, metal-free cathode to establish a metal-free EF process for organic pollutant degradation. The results demonstrate that the metal-free electrode has excellent H2O2 accumulation (12 mg L−1 cm−1) and degrades sulfathiazole (STZ) with 97.05 % efficiency in 180 min with an explanation kinetic of 0.0189 min−1. For the first time, this enhancement came from the dual active site centers in OCNT: Ⅰ) -COOH and defects active sites were responsible for H2O2 production, Ⅱ) then -CO triggered H2O2 into •OH, avoiding the introduction of metal-based catalysts. These findings suggest that the EF system with in situ oxygen-doped cathodes have great potential for treating antibiotic wastewater.

A novel oil/brine surface complexation model: Capturing the dynamic nature of the interface using IFT

The electrical properties of the oil/brine interface play a principal role in wettability alteration during low salinity/water flooding. There are few existing surface complexation models (SCMs) for the oil/brine interface. Similar to the mineral surface, all models assume that the surface site density of oil/brine is always constant. Assessment of the existing models shows that they ignore the dynamic nature of the crude oil/brine interface and fail to capture experimentally measured ζ potentials appropriately. The current study proposes a novel diffuse layer SCM considering the interfacial concentration of surface carboxylic acid as a function of brine pH, salinity, and composition. The oil/brine interfacial tension (IFT) was utilized to describe the change in the interfacial concentration of > COOH sites vs. pH and ionic strength. The developed model matches the experimental data of the literature far better than previous models successfully. Based on the model, Na+, Cl-, and SO42- cannot be adsorbed on the oil/brine interface, however; the role of these ions in the electrical behavior of crude oil/brine is only to affect the interfacial concentration of > COOH. The novel model surpasses the previous model at high and low pH conditions. At a high pH range, due to the significant transport of acid groups to the interface, the oil surface becomes more negatively charged, which was accurately captured by the proposed model (while the previous models are malfunctioning at high pH conditions). Assuming maximum > COOH density at the whole pH range, previous models use a high > NH density to compensate for the extra negative surface charge due to > COOH dissociation. Therefore, these models overestimate the zeta potential significantly at low pH conditions, where > NH protonation is the dominant reaction. One of the main features of the developed model in this study is to predict a critical salinity for the extremum of zeta potential. All previous models state that salinity reduction must result in a decrease in the zeta potential. These models cannot capture the observed rise in zeta potential with further brine dilution after a specified salinity. However, the presented model of this study could predict the increase in the zeta potential at lower salinities.

Effect of morphology and structure of CuTCPP nanomaterials on the electrocatalytic CO2 reduction to methane and ethylene

The effect of Cu–N4, Cu–O4 and/or –COOH sites on the electrocatalytic CO2 reduction (ECR) activity and selectivity is rarely evaluated together and directly confirmed through the morphology and structure dependence of ECR performance. Here, the ECR performance of CuTCPP nanoparticles, nanorods, nanosheets and nanoflowers are systematically investigated. The experimental results show that their total ECR activity is nanoflowers > nanosheets > nanoparticles > nanorods. CuTCPP nanosheets with more Cu−N4 sites exposed showed the best ethylene selectivity of 40.6 % at –1.2 V vs. RHE. CuTCPP nanoflowers with more Cu−O4 sites were more stable than the nanosheets, showing 61.0 % methane selectivity at –1.3 V vs. RHE. A series of characterizations reveal that Cu−O4 is mainly responsible for methane production, while Cu–N4 is the main active site for ethylene production and its synergy with Cu–O4 or –COOH groups can improve the ethylene selectivity.

Robust microporous hydrogen−bonded organic framework for highly selective purification of methane from natural gas

Methane (CH4) purification using energy-efficient separation technology is important for the economic and safety of natural gas refining. Meanwhile, the common impurity acetylene (C2H2) was also served as raw material to produce various organic products, therefore the highly efficient purification of CH4 and C2H2 are very important and challenging. Herein, we demonstrate the separation ability of HOF-16 for C2H2/CH4 and CO2/CH4 mixtures in detail. HOF-16 has a potential affinity for C2H2 capture, resulting from the exposed free –COOH sites in the suitable pore channel. Gas sorption isotherms reveal that HOF-16a creates a high C2H2/CH4 uptake ratio of 7.9 at 298 K and 1 bar, resulting in a C2H2/CH4 separation selectivity of 107 (50/50, v/v) under ambient conditions, which is a record value among HOFs and even exceeds many MOFs. Theoretical calculations confirm that the free –COOH sites in the HOF-16a channel provide additional interactions for the C2H2 molecules. Dynamic breakthrough experiments indicate that C2H2 could be highly selective removed from C2H2/CH4 (1/99, v/v) mixture. Combined with the low isosteric heat of adsorption (Qst), HOF-16a can efficiently extract C2H2 from the adsorption bed and purify CH4 into high purity (>99.9%) with low energy consumption.

An enzyme-free and PCR-free biosensing platform for accurate monitoring of telomerase activity

We describe a PCR-free, enzyme-free, and simple biosensing platform for the electrochemical monitoring of telomerase activity based on Au nanorods (AuNRs) as an electrocatalytic redox mediator, which enhances the electrochemical signal by catalyzing acetaminophen (AP). In this process, acid-functionalized ordered mesoporous carbon (OMC) was modified on a glassy carbon electrode (GCE) surface to offer -COOH sites. Moreover, the amino-modified S1 was fixed on the modified electrode by conducting an amide reaction. TS is extended to (TTAGGG)n repeat units in the presence of telomerase extract and dNTPs. One end (5′) is hybridized with S1 on the electrode, and the remaining end (3′) is combined with AuNRs-S2 probe. Clearly, the telomerase activity is relevant to the amount of connected AuNRs, resulting in different response signals. Therefore, with the telomerase extension triggered hybridization reaction, a large amount of AuNRs catalyst was introduced onto the surface of GCE as the sensing platform, thus achieving a sensitive electrochemical telomerase activity assay in the range of 20–2.15 × 106 HeLa cells mL−1. This sensing platform shows that the limit of detection is 1.74 HeLa cells mL−1, thus providing a promising method for the determination of telomerase activity and a powerful biosensor for accurate cancer monitoring and diagnosis.

Active coordination sites of Co spinel oxides for NO reduction by CO

Cobalt spinel oxides, containing octahedral (Oh) and tetrahedral (Td) sites, exhibit high activity for NO reduction by CO. The active sites of cobalt spinel oxides for NO–CO reaction was identified using various cobalt spinel oxides having different CoOh/CoTd ratio. Comparing the CoOh/CoTd ratio determined by EXAFS fitting analysis and the rate of NO reduction, it was clarified that octahedral site is responsible for NO reduction by CO. Furthermore, synchrotron-based in-situ XAFS measurements unveiled the contribution of CoOh sites: The cobalt spinel oxides with high CoOh fraction were more easily reduced by CO to form oxygen vacancies than those with low CoOh fraction, and resulted in the higher activity for NO reduction by CO.

A remarkable adsorbent for denitrogenation of liquid fuel: Ethylenediaminetetraacetic acid-grafted metal–organic framework, MOF-808

• Porous MOF808 was functionalized with EDTA to load much –COOH sites. • MOF808/EDTA showed the highest adsorption for quinoline (625 mg/g). • The adsorption results were interpreted via acid-base and H-bonding interactions. • Reusable MOF808/EDTA showed effectiveness in adsorptive denitrogenation. Removal of nitrogen-containing compounds (NCCs) from the fuel is essential for clean energy. An efficient adsorbent with ample active sites was obtained via grafting ethylenediaminetetraacetic acid (EDTA) onto a metal–organic framework (MOF808). The obtained MOF808_EDTA was firstly applied in adsorptive removal of organics like NCCs from liquid; showed remarkable performances in NCCs removal. For example, MOF808_EDTA showed the maximum adsorption capacity ( Q 0 ) of 667 and 625 mg/g, respectively, in indole (IND) and quinoline (QUIN) removal from fuel. These Q 0 values for QUIN and IND adsorption are the highest and third position, respectively, compared with reported results. Additionally, the Q 0 values for IND and QUIN are > 10 times those of activated carbon. Importantly, the Q 0 value, in volume/weight (0.57 cm 3 / g), is very close to the total pore volume (0.59 cm 3 / g) of MOF808_EDTA, suggesting very effective utilization of pores of the MOF in the adsorption. The adsorption of IND and QUIN over MOF808_EDTA could be interpreted with H-bonding and acid-base interactions, respectively, based on properties of adsorbates and functional groups on MOF808_EDTA and MOF808_EDTA-Na (where hydrogen in EDTA was replaced with Na). The new adsorbent MOF808_EDTA, which is highly reusable, is being suggested as a prominent adsorbent to remove NCCs, especially basic QUIN, from fuel. This work will pave the way to modify MOFs to introduce ample functional groups that will be effective in adsorption.

A Microporous Hydrogen‐Bonded Organic Framework for the Efficient Capture and Purification of Propylene

AbstractAdsorptive separation of propylene/propane (C3H6/C3H8) mixture is desired for its potential energy saving on replacing currently deployed and energy‐intensive cryogenic distillation. Realizing efficient C3H6/C3H8separation in the emerging hydrogen‐bonded organic frameworks (HOFs) is very challenging owing to the lack of functional sites for preferential gas binding. By virtue of crystal engineering, we herein report a functionalized HOF (HOF‐16) with free ‐COOH sites for the efficient separation of C3H6/C3H8mixtures. Under ambient conditions,HOF‐16shows a significant C3H6/C3H8uptake difference (by 76 %) and selectivity (5.4) in contrast to other carboxylic acid‐based HOFs. Modeling studies indicate that free ‐COOH groups together with the suitable pore confinement facilitate the recognition and high‐density packing of gas molecules. The separation performance ofHOF‐16was validated by breakthrough experiments.HOF‐16is stable towards strong acidity and water.

A Microporous Hydrogen-Bonded Organic Framework for the Efficient Capture and Purification of Propylene.

Adsorptive separation of propylene/propane (C3 H6 /C3 H8 ) mixture is desired for its potential energy saving on replacing currently deployed and energy-intensive cryogenic distillation. Realizing efficient C3 H6 /C3 H8 separation in the emerging hydrogen-bonded organic frameworks (HOFs) is very challenging owing to the lack of functional sites for preferential gas binding. By virtue of crystal engineering, we herein report a functionalized HOF (HOF-16) with free -COOH sites for the efficient separation of C3 H6 /C3 H8 mixtures. Under ambient conditions, HOF-16 shows a significant C3 H6 /C3 H8 uptake difference (by 76 %) and selectivity (5.4) in contrast to other carboxylic acid-based HOFs. Modeling studies indicate that free -COOH groups together with the suitable pore confinement facilitate the recognition and high-density packing of gas molecules. The separation performance of HOF-16 was validated by breakthrough experiments. HOF-16 is stable towards strong acidity and water.

Electrochemical Cleavage of Carbon‐Chlorine Bonds in Multiply Bridge‐Chlorinated Bicyclo[1.1.1]pentane‐1,3‐dicarboxylic Acids

AbstractReduction of five derivatives of bicyclo[1.1.1]pentane‐1,3‐dicarboxylic acid containing one to four chlorine substituents on methylene bridges were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical cleavage of C−Cl bonds and the reduction of H+ provided by dissociation of COOH groups are two competing processes characterized by different time constants. A concerted mechanism of C−Cl bonds cleavage is operative. The location of LUMO orbitals changes with increasing number of chlorine substituents from COOH sites to bicyclo[1.1.1]pentane. Carboxylic groups participate in the protonation of intermediates formed by the C−Cl bond rupture. The esterification of two derivatives eliminates the self‐protonation. Esters are reduced only at very negative potentials near the end of an available potential window.

Pd nanoparticles-DNA layered nanoreticulation biosensor based on target-catalytic hairpin assembly for ultrasensitive and selective biosensing of microRNA-21

Herein, a Pd nanoparticles-DNA layered nanoreticulation (Pd NPs-DNA LNR) sensor was assembled to a graphene oxide (GO)-modified electrode by catalytic hairpin assembly (CHA) and a self-assembly process. In this process, GO was modified on the electrode surface to provide -COOH sites for DNA bonding. Moreover, with the CHA circular amplification strategy, many single DNA1 were exposed to be able to be bound with Pd-DNA2 for the formation of the Pd NPs-DNA LNR, which enabled the ultrasensitive detection of microRNA-21 (miR-21) with a low limit of detection 63.1 aM. This strategy combines the amplification technology of CHA and Pd NPs-DNA LNR with Pd NPs. Such a layered nanoreticulation material can support abundant Pd NPs to avoid aggregation and obtain enhanced electrochemical signals. Significantly, this method can be successfully applied in tumor cell lysates and provides a neoteric channel for early disease diagnosis.

Effects of functionalization and annealing in enhancing the interfacial bonding and mechanical properties of 3D printed fiber-reinforced composites

The properties of 3D printed polymer composites depend significantly on the fiber-matrix bonding, inter-bead bonding between each layer, and process-induced void contents. This study focuses to determine the effects of acid-based oxidation treatment of fibers on fiber-matrix interfacial bonding of fused filament fabrication (FFF) based 3D printed composites. The effects of nozzle geometry and post-manufacturing vacuum annealing on microstructure, inter-bead bonding, and mechanical properties of the composites are also studied. The surface treatment of fibers had a profound impact on the chemical compositions of the fibers. A significant increase in –COOH sites from 0.22 mmol/g to 0.98 mmol/g was observed with 30 min oxidation treatment. The energy dispersion spectroscopy (EDS) also showed the evidence of increased oxygen content on the fibers. Such treated fibers were found to improve both the tensile properties, short beam shear strength, and fracture toughness. The vacuum annealing almost doubled the degree of crystallinity of the composite and gave rise to a chain rearrangement in the polymer-crystalline phase, studied through Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The overall increase in tensile strength, tensile modulus, and short beam shear strength were about 20.58 %, 73 %, and 7 %, respectively in comparison to the baseline. The fracture toughness of the vacuum-annealed sample with functionalized fibers was 23 % higher than the un-annealed-untreated fiber-reinforced composite. Such increment in structural properties was further explained through the SEM analysis of the fracture surfaces. Evidence of crack deflection due to increased surface roughness, fiber alignment, pullouts, fiber-matrix debonding, and crystallinity of the matrix was observed from the analysis.

Gelation via cationic chelation/crosslinking of acrylic‐acid‐based polymers

AbstractThe gelation characteristics of acrylic‐acid‐based polymers in the presence of a range of cationic species, namely Ca2+, Mg2+ and Al3+, were investigated using in situ rheological measurements during photo‐polymerisation. Fourier transform mechanical spectroscopy was used to identify the gel point, using the Winter–Chambon criteria which allow the gel point to be pinpointed by establishing the sample spanning network and quantitatively determining stiffness, relaxation exponent, gel stiffness and fractal dimensions. The results showed that the gelation processes were greatly influenced by the type of cationic species that was used in the syntheses. At the gel point, more open network clusters were formed when Al3+ cations were used instead of Ca2+ cations or Mg2+ cations, all relating to chloride salts. Although the concentrations of the chelating/crosslinking aluminium species affected the kinetics of the gelation, the critical gel characteristics were hardly affected. Also the solubility of the chosen aluminium salt was shown to dictate the crosslinking rates and the properties of the critical gels. The extents of the reactions and the types of network formed at the gel point and beyond indicated that reactions between the Al3+ ions and COOH sites, from growing poly(acrylic acid) molecular chains, differ from those exhibited by Mg2+ and Ca2+ ions. All of the chelation/crosslinking reactions met the criteria of low mutation number (Nmu), such that in all cases Nmu ≪ 1. © 2019 Society of Chemical Industry

Thermally conductive adhesives from covalent-bonding of reduced graphene oxide to acrylic copolymer

ABSTRACTThis work reports about the enhancement of the thermal conductivity of an acrylic pressure-sensitive adhesive (PSA) with the incorporation of functionalized and reduced graphene oxide (frGO) sheet in the composition. Bifunctional isocyanatoethylmetharcylate (IEMA) was intercalated (so-called ‘functionalization’) to the GO surface mainly at its –COOH sites. The remaining oxygenated groups on the GO surface were reduced by dimethyl hydrazine. The frGO was successfully incorporated into PSA matrix through in-situ polymerization of acrylic monomers and subsequently crosslinked under UV radiation. The conductivity and the peel strength of the PSA were studied as a function of filler content, filler modification (functionalization and/or reduction), UV-radiation dosage and mode of filler insertion (through in-situ polymerization or mechanical mixing). frGO/PSA showed much better properties than the PSA system with bare or IEMA-functionalized unreduced GO. In-situ polymerization was found to be more effective method for frGO insertion. Within the range of filler content (0.0–1.0) wt% and UV-radiation dosages of (400–3000) mJcm−2, the thermal conductivity and peel strength of the acrylic PSA-system under investigation varied in the range of 0.17–1.03 Wm−1K−1 and 2831–299 gf/25 mm. This is the first report on ‘reduced GO covalently bonded to polymer chain in an adhesive-composition’ providing novel idea to make PSA-system with balanced thermal conductivity and peel strength with perspective for application in miniature electronic industries.

Zeolitic Imidazolate Framework-67: A promising candidate for recovery of uranium (VI) from seawater

With the development of the nuclear industry and nuclear technology application, it is important to develop adsorbents with high selectivity and adsorption capacity for removal of uranium from nuclear waste and for trace uranium capture from seawater. In this report, we investigated for the first time Zeolitic Imidazolate Framework-67 (ZIF-67) for the removal of uranium from aqueous solutions and trace uranium from simulated seawater. The influence of pH, contact time and initial uranium concentration were studied. Results showed that ZIF-67 possessed an ultrahigh adsorption capacity (Qm = 1683.8 mg g−1) and high removal rate at both ppb and ppm levels (>99%) for uranium. The adsorption process fits well with the Langmuir isotherm model and pseudo-second-order rate equation. In addition to the general characterization of ZIF-67 by XRD, SEM, TEM, and FT-IR, the uranium-adsorbed ZIF-67 was investigated by X-ray photoelectron spectroscopy (XPS), which revealed a possible mechanism that involved the existence of large amounts of CoOH and active sites produced after the dispersion of ZIF-67 in water; CoOH was the key factor that ZIF-67 possessed to realise a high adsorption capacity and affinity for uranium (VI).