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• Structure evolution features of LDHs precursors with pH was investigated. • Role of pH on activating the performance of LDHs type adsorbents was concluded. • Precipitative formation mechanism of LDHs adsorbents was firstly proposed. Aluminum-based adsorbents, simply prepared by eluting the lithium-aluminum layered double hydroxide precursors with deionized water, is the only industrialized adsorbents for selectively separating Li+ from saline brines. Taking the roles of lattice and surface Li+ active sites on its performances into consideration, influence of ending pH modulating on prominently improving the adsorbing capacity and stability of aluminum-based adsorbents prepared by precipitation method is initially investigated. As experimentally evidenced that, the maximum desorption amount of Li+ at the eluting stage should be controlled to around 20 mg/g Li+ rather than thoroughly removed to effectively avoid the topotactic solid-phase transformation from adsorbent to α-Al(OH) 3. As-prepared adsorbents not only has high adsorption capacity up to 8.4 mg/g in 400 ppm LiCl solution, but also owns unique self-healing ability, thus promising the excellent cycling stability. It is firstly proposed that the formation of the layer-structured precursor by precipitation method is well in accordance with the three-step formation mechanism and pH modulating mainly contributes to the anions exchange between solution Cl- and interlayer OH–. This study experimentally proves the importance of pH adjusting for preparing high performance lithium adsorbents by precipitation method, which is very significant and important for effectively extracting lithium resources from the complicated multi-component liquid minerals. [ABSTRACT FROM AUTHOR]

• K 2 FeO 4 is first utilized for the solid-phase oxidation of pitch by a high-energy ball mill. • The solid-phase reaction mechanism involving in oxidation and condensation was revealed. • Advanced pitch-based porous carbon (H-CBPF) was prepared by a solid–liquid synergistic strategy. • The synergistic effect improves both the porous geometric configuration and O content of H-CBPF. • H-CBPF delivers an excellent salt adsorption capacity and a superior charge efficiency. To address limited desalination capacity and insufficient charge efficiency for carbon materials in capacitive deionization (CDI), a solid–liquid synergistic oxidation strategy of potassium pertechnetate (VI) for pitch was proposed to construct porous carbon with a reasonable pore structure and high reactive surface. On the one hand, K 2 FeO 4 is first utilized for the solid-phase oxidation (SPO) of pitch by a high-energy ball mill, introducing rich oxygen-containing groups such as ether bonds. Meanwhile, dehydro-condensation reactions occurred during SPO, resulting in the formation of the oxidized pitch with a high degree of condensation. Importantly, the pyrolysis yield of the oxidized pitch is as high as 46.9 % at 800 °C, almost twice that of the pristine pitch, meaning that the oxidized pitch with high polymer degree and rich C-O bridge bonds facilitates the carbon fixation and emission reduction during carbonization. On the other hand, the self-oxidation of K 2 FeO 4 in aqueous solution forms bifunctional activators (KOH and Fe(OH) 3) for the preparation of pitch-based porous carbon. Benefiting from the crosslinking structure of oxidized pitch and the multi-effective activation, the prepared porous carbon (H-CBPF) exhibits a robust layered stacking topology with a high surface area and oxygen content. Thereby, it can deliver an excellent salt adsorption capacity (SAC) of 22.1 mg g−1 with an average desalination rate of 1.89 mg g−1 min−1 and a high charge efficiency of 85 % at 1.2 V in 500 mg L-1 NaCl solution. This work opens up a green and economical route for the preparation of pitch-derived porous carbon for high-performance CDI. [ABSTRACT FROM AUTHOR]

[Display omitted] • A comprehensive review to highlight the application of 3D faradic materials in CDI field is presented. • The desalination performances of non-3D faradic electrodes and 3D faradic electrodes are systematically compared. • The perspective of 3D faradic materials is discussed to provide guidelines for future CDI development. To address the water scarcity issue, capacitive deionization (CDI) as a burgeoning desalination technology for removing different ions from sea and wastewater have been intensively explored. However, the low salt adsorption capacity and poor cycling stability of widely used carbon materials are difficult to fulfill the demand of practical CDI application, while the non-three-dimensional (non-3D) faradic electrode materials manifest the drawbacks of low specific capacitance and dissolution loss of metal ions, which severely limit their CDI application. Notably, three-dimensional (3D) faradic materials usually possess higher desalination capacity and better cycling stability than carbon materials and non-3D faradic materials, due to their wide ion diffusion channels and versatile structure, which are highly promising for achieving practical CDI application. However, few review papers have specifically focused on the limitations and advantages of 3D faradic materials in CDI field. In this review, a comprehensive insight into 3D faradic materials in terms of the solutions of limitations and corresponding desalination performance (via comparing with the desalination performance of non-3D faradic materials) is provided and the development prospect of 3D faradic materials is also expounded. [ABSTRACT FROM AUTHOR]

Energy shortage severely impedes the advancement of human society and economy. The vigorous development of nuclear energy is a viable solution to address this issue. The escalating depletion of uranium resources necessitates prioritizing the selective extraction of uranyl from seawater and wastewater to ensure the prosperity of nuclear power. A bismuth-based MOF, CAU-17, was synthesized by the one-step solvothermal method for targeted selection of uranyl in the first time. The uranium adsorption tests demonstrated that CAU-17 exhibited a high adsorption capacity of 421.9 mg g−1 (T = 25 °C, pH = 7), exceptional selectivity, outstanding salt tolerance, and favorable stability with 83.6 % of the initial capacity retained after 5 cycles. Through the utilization of XPS and theoretical calculations, it was elucidated that the carboxyl oxygen that connects the Bi played a pivotal role in the binding process between CAU-17 and uranium ions, with bismuth acting as an electron regulator through its bridging effect with carboxyl oxygen. This work not only presents an exceptional uranium adsorption material but also elucidates the role of core metal atoms in MOFs during the binding to uranium process, thereby offering a novel perspective for future advancements in MOFs-based adsorbents. [Display omitted] • A bismuth-based MOF, CAU-17, was synthesized by the one-step solvothermal method for targeted selection of uranyl. • CAU-17 exhibited a high adsorption capacity (421.9 mg g-1), outstanding salt tolerance, and favorable stability with 83.6% of the initial capacity retained after 5 cycles • CAU-17 formed a complex coordination with uranium through carboxyl oxygen atoms while bismuth played a role in charge regulation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrode material with efficient and selective phosphate adsorption was developed. • ZnFe-PANI/CNT electrode exhibited remarkable capacitive behavior and charge storage capacity. • ZnFe-PANI/CNT had excellent phosphate adsorption capacity over a wide parameters range. • The high phosphate removal rate was maintained after 10th regeneration processes. Capacitive deionization technology possesses puissant competitiveness in the field of water treatment due to its low cost and high efficiency. In this study, polyaniline (PANI) doped and carboxyl intercalated metal hydroxide composite (ZnFe-PANI/CNT) was developed by a simple co-precipitation method, and used as anode electrode for phosphate removal in sewage. The results show that ZnFe-PANI/CNT electrode can efficiently remove phosphate at concentration of 2–10 mg/L at a wide range of pH (3–10) by electric double layer capacitive adsorption and pseudocapacitive adsorption. The concentration of phosphate in the effluent was as low as 0.095 mg/L, and the coexisting anions (Cl−, NO 3 −, SO 4 2− and HCO 3 −) hardly inhibited the phosphate adsorption by ZnFe-PANI/CNT composite electrode. In addition, under the optimal phosphate adsorption conditions (pH = 7 and applied voltage of 1.2 V), the energy consumption of CDI system was calculated as low as 0.00274 kWh/g P and 0.017 kWh/m3 water, realizing the expectation of low cost and high efficiency operation. [ABSTRACT FROM AUTHOR]

It is widely recognized that greenhouse gas emissions (e.g., CO 2 , SF 6 , and CH 4) play a significant role in global warming. Adsorption at point sources, using a suitable adsorbent, is an important method to reduce their release. Zn(mIm) 2 , where mIm = 2-methylimidazolate (referred to as SOD-ZIF-8), is a typical Zeolitic Imidazolate Framework (ZIF) that has shown outstanding performance in the adsorption of greenhouse gases. However, its conventional synthesis is time-consuming and requires the addition of large amounts of organic solvents. Herein, we report a solid-state synthesis of ultramicroporous n-ZIF-8 nanocrystals at room temperature within 5 min. The comprehensive characterization of n-ZIF-8 involved FTIR, XRD, SEM, TGA analyses, and N 2 adsorption. The obtained results indicate that n-ZIF-8 has potential as an adsorbent for greenhouse gas adsorption. The physisorption process of CO 2 , SF 6 , and CH 4 is corroborated by the isosteric heat of adsorption (Q ads) data. To further support the experimental data, quantum computational DFT-GD3 calculations were performed. Validation by the quantum theory of molecules (QTAIM) confirms that the selected gases are well adsorbed through major electrostatic interactions. Additional support from the 3D-ELF/2D-LOL analyses, agreeing with QTAIM claims, highlights that ZIF-8 highly adsorbs CO 2 and CH 4 through van der Waals interactions. In conclusion, ZIF-8 exhibits remarkable adsorption capabilities, efficiently adsorbing CO 2 in the cavity and N 2 on the surface, making it a potential candidate for greenhouse gas removal. [Display omitted] • A new n-ZIF-8 was synthesized and characterized. • The n-ZIF-8 has shown a high CO 2 adsorption capacity vs SF 6 , CH 4 , and N 2. • The CO 2 and SF 6 adsorption capacities were constant in multiple adsorption cycles. • CO 2 gas is adsorbed in the center of the cavity through electrostatic interactions. • The n-ZIF-8 nanoparticle is powerful for new generations of adsorbent systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • The roles of specific N-containing groups on HCHO removal were comprehensively studied. • The ACN-600 exhibited the superior HCHO adsorption capacity (16.37 mg/g). • DFT calculation results indicated that pyrrolic-N exhibited the highest HCHO adsorption energy (−32.83 kJ/mol). • Pyridinic-N could trigger the Cannizzaro-type disproportionation reaction. Inserting nitrogen (N) heteroatoms into the carbonaceous adsorbents has been confirmed to be one of efficient strategies for enhancing HCHO removal. However, the essential promotion mechanisms of specific N-containing groups (such as pyridinic-N, pyrrolic-N, and quaternary-N) remain blurred. Herein, a series of N-doped activated carbons were prepared by annealing the melamine impregnated activated carbons at 600–900 °C and used for HCHO elimination. It manifested that the HCHO elimination performance of samples was remarkably improved after N-doping and their HCHO adsorption capacities were in the order of ACN-600 (16.37 mg/g) > ACN-750 (9.87 mg/g) > ACN-900 (7.28 mg/g) > AC (5.09 mg/g). DFT calculation results revealed that there existed stronger attractive noncovalent interactions between pyrrolic-N doped carbon and HCHO due to the formation of stronger H-bonds. Therefore, the HCHO physisorption energy on pyrrolic-N doped carbon was the highest (−32.83 kJ/mol). Compared with the single physisorption mechanism of previous studies, the in-situ DRIFTS results manifested that the pyridinic-N atom (as a typical strong Lewis base) could trigger the Cannizzaro-type disproportionation reaction, which would transform toxic HCHO into relatively less toxic methanol and formic acid. Benefiting from the dual enhanced mechanisms of attractive noncovalent interactions and Cannizzaro-type disproportionation reaction, the ACN-600 manifested excellent HCHO removal performance. This study not only intrinsically discloses the promotion mechanism of specific N-containing groups on HCHO removal at molecular level but also provides guidelines for rational design and development of carbonaceous materials for effective HCHO elimination. [ABSTRACT FROM AUTHOR]

• A novel capacitive deionization with a three-phase architecture (T-CDI) was proposed. • Cathodic oxygen reduction was enhanced in T-CDI without affecting desalination. • SAC value and H 2 O 2 generation were 14.91 mg/g and 25.55 mg/L, respectively. • Simultaneous desalination and organics control was achieved by T-CDI/UV. • Applicability of T-CDI in long-term operation was investigated. Cathodic oxygen reduction, as a Faradaic side reaction, has been proven to be thermodynamically favorable for H 2 O 2 generation in capacitive deionization (CDI), which may provide a greener manner for organics control alongside desalination. However, the low levels of dissolved oxygen (DO) in saline water and its potential Faradaic degradation of carbon-based electrodes limit the H 2 O 2 generation in the conventional CDI (C-CDI). Herein, a novel three-phase CDI architecture (T-CDI) was proposed to simultaneously achieve stable desalination and supplementary H 2 O 2 generation. Unlike C-CDI architecture, T-CDI was open-ended at the cathode side, where porous nickel foam was used as current collector and air diffusion layer. Accordingly, a stable gas–liquid-solid three-phase interface was created inside the cathode, thus enhancing the diffusion and utilization of atmospheric air and preventing the damaging effects of excessive DO on the electrode. A stable electrosorption and electrocatalysis performance for T-CDI was obtained by regulating electrode hydrophilic-hydrophobic properties, comparing with other CDI configurations, and altering operating conditions. The salt adsorption capacity and H 2 O 2 accumulative concentration were 14.91 mg/g and 25.55 mg/L, respectively. Furthermore, the simultaneous desalination and organics control in T-CDI were investigated with the assistance of UV irradiation (T-CDI/UV). When treating NaCl and sulfamethazine (SMR) mixture solution, T-CDI/UV significantly reduced the irreversible electrode organic fouling and improved the desalination stability. Additionally, the potentially hazardous SMR was effectively removed alongside desalination. Finally, the long-term operation of T-CDI demonstrated that the generated H 2 O 2 cannot induce an additional substantial deterioration in desalination stability. The techno-economic assessment showed T-CDI was economically competitive compared with C-CDI. This study provides insights into the synergy of non-Faradaic and Faradaic processes and further diversifies the application of CDI in water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual cation titanosilicate(DTS) was utilized in CDI to capture Cs+ and Sr2+. • By applying −1.2 V, the DTS electrode exhibits a high adsorption capacity. • DTS electrode showed rapid kinetics over 95 % of adsorption capacity within 30 min. • It provides a high selectivity of 5x103 mL/g in 10000-fold Na concentrated solution. • It was regenerated by applying + 2.0 V and its structural integrity remains intact. The utilization of ion intercalate capacitive deionization technology is garnering attention as an electrified water treatment method. This study proposes a capacitive deionization technology incorporating Dual-cation TitanoSilicate (DTS) to enable efficient electro-sorption/desorption of radioactive ions Cs and Sr. The synthesized DTS possesses a robust structure, high selectivity for Cs and Sr, and substantial adsorption capacity, incorporating redox-active titanium. Employing DTS as an active material in the electrode demonstrated a high adsorption capacity (186 mg Cs/g, 177 mg Sr/g) and rapid adsorption kinetics, reaching maximum capacity within 30 min, even in environments with a tenfold excess of competing ions. Furthermore, our system exhibited stable performance over 5 cycles of adsorption/desorption, and post-desorption analyses confirmed the durable structure stability without significant alterations. This study highlights the feasibility of CDI technology utilizing DTS for cesium and strontium removal. [ABSTRACT FROM AUTHOR]

The open-cell bio-based biodegradable polymer foams show good application prospect in dealing with the serious environmental issue caused by oil spill and organic solvents spills, while the cell structures and hydrophobic properties of the foams limit their performance. In this work, the poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) was selected to help prepare bio-based biodegradable poly(lactic acid) (PLA) foams. Based on a two-step foaming method, the crystallization ability of different samples was regulated by the "original crystals" together with PHBV in the foaming process, where skeleton structures were provided to facilitate the open-cell structures and promote their mechanical property. As illustrated, PHBV facilitated the formation of open-cell PLA foams, where the foams displayed superior oil-water separation capacity. The maximum volume expansion ratio of the foams was 80.08, the contact angle of deionized water reached to 134.5°, the adsorption capacity for oil or organic solvents was 10.8 g/g-51.8 g/g, and the adsorption capacity for CCl 4 can still maintained 83.5 % of the initial value after 10 adsorption-desorption cycles. This work not only clarified the foaming mechanism of open-cell foams, but also provided a green and simple method for preparing bio-based biodegradable foams possessing excellent oil-water separation performance. [ABSTRACT FROM AUTHOR]

Efficient recovery of rare scattered metal Re(VII) from various resources is a prerequisite due to its important application. Herein, a type of novel nanofibrous membrane, 0.4P(Ph-3MVIm-Br)-3PVP/2TPU, is successfully prepared by electrospinning, where poly(ionic liquid) P(Ph-3MVIm-Br) is incorporated and could supply more adsorption sites. Meanwhile, PVP (polyvinyl pyrrolidone) and TPU (thermoplastic polyurethane) ensured the water flux and the structural stability of the membrane. The nanofibrous membrane exhibited a high adsorption capacity for ReO 4 −, which can reach 128 mg g−1 at pH 5. Its water flux is as high as 433 L m−2 h−1 at 0.4 g of poly(ionic liquid) addition, membrane thickness of 20 μm, and pressure of 1 bar. Furthermore, 0.4P(Ph-3MVIm-Br)-3PVP/2TPU nanofibrous membrane can remove 91.7% of ReO 4 − within 30 min. After 9 times recycling, the adsorption efficiency of the membrane can still maintain more than 90%. Dynamic ReO 4 − removal with 0.4P(Ph-3MVIm-Br)-3PVP/2TPU after one cycle was accomplished with a breakthrough volume of 24 mL ReO 4 − solution (feed 10 mg L−1, 100 mg membrane). The exchange of ReO 4 − and Br− of poly(ionic liquid) mostly promote the adsorption of ReO 4 −. Moreover, the structure of the membrane has excellent selectivity, mechanical performance, strong acid and alkali resistance stability, which endow the membrane easy to operate in practical applications. [Display omitted] • Nanofibrous membrane can remove 91.7 % of ReO 4 − within 30 min. • It has a great adsorption capacity of 128 mg g−1 for ReO 4 − at pH 5. • It has a good selectivity for ReO 4 − in the presence of SO 4 2− or NO 3 −. • It unfolds prominent regeneration ability after nine consecutive cycles. • It can achieve a water flux of 433 L m−2 h−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amidoxime-modified g-C 3 N 4 electrode was hydrothermally synthesized. • Th(IV) electrosorption was studied by varying voltage, time, and concentration. • Maximum adsorption capacity was 275.74 mg.g−1 at – 1.0 V within 30 min. • Chemisorption and double-layer charging occurred with AX/g-C 3 N 4 in electrosorption. • The electrosorption occurs via the abundant of N and O redox sites of AX/g-C 3 N 4. Electrosorption is a technique that combines electrical and adsorption processes and has been established to displace Th(IV) from aqueous solutions. The present study successfully synthesised a novel electrode, where graphitic carbon nitride was modified with amidoxime amidoxime groups (g-C 3 N 4 /AX) via the hydrothermal method. The batch experiments conducted in this study revealed that the g-C 3 N 4 /AX electrode possessed a favourable thorium adsorption capacity of 275.74 mg.g−1 and a swift elimination equilibrium of within 30 min. Furthermore, the removal efficiency at − 1.0 V (84.46 %) of the electrode was almost threefold greater than the removal efficiency at open circuit potential (24.09 %). The results were due to the free electrical charges on the g-C 3 N 4 /AX electrode, which induced the electrical driving force and facilitated the adsorption of Th(IV) ions onto the g-C 3 N 4 /AX surface. The shifted bands from the Fourier transform-infrared (FT-IR) spectrum post-electrosorption demonstrated a substantial complexation of Th(IV) with the amine groups of amidoxime and g-C 3 N 4. A significant transference in energy band peaks was also observed during the XPS assessment, indicating that the electrosorption process included oxygen (O), carbon (C), and nitrogen (N) species. In the practical real wastewater involving rare earth residue, which contains Ce, La, Nd and Pr ions, g-C 3 N 4 /AX exhibited good capabilities in selectively adsorbing Th(IV). The electrode synthesised in this study also exhibited the ability to regenerate with a reasonable ∼ 80 % removal ratio after five runs. The results indicated that the amidoxime-modified graphitic carbon nitride electrode demonstrated a good potential in removing thorium from aqueous solutions via electrosorption applications. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) holds great promise for phosphorus adsorption and recovery from wastewater, while current electrodes exhibit poor salt adsorption capacity (SAC) and selectivity due to co-ion effect and interference of co-existed ions with high concentration. Herein, to overcome these issues, a facile route was proposed to prepare a covalent organic framework-membrane coating electrode (COF-MCE) by depositing polyvinyl alcohol/polyethyleneimine membrane onto activated carbon fiber (ACF) followed by the in-situ growth of COF-LZU1. Compared to ACF and MCE, COF-MCE, with abundant functional groups and specific sites, facilitated electrical double layer (EDL)-based adsorption and induced hydrogen-bond interaction with phosphorus, contributing to a higher SAC of phosphorus (10.5 mg/g) in treating 1 mM NaH 2 PO 4. When treating different mixtures of NaH 2 PO 4 /NaCl, NaH 2 PO 4 /NaNO 3 , and NaH 2 PO 4 /Na 2 SO 4 with molar ratio of 1:5, COF-MCE exhibited the high phosphorus selectivity of 3.62, 5.98 and 7.01, respectively, which was attributed to the synergistic effects of EDL-based adsorption, hydrogen-bond and pseudocapacitance. Desorption experiments revealed that high reversal voltage and alkaline condition can weaken the hydrogen-bond interaction and strengthen the electrostatic repulsion between COF-MCE and phosphorus, thus improving the desorption and recovery of phosphorus. These findings confirmed the high potential of COF-MCE in the effective electrosorption and recovery of phosphorus from wastewater. • COF-MCE was prepared by casting followed by in-situ growth of COF powders. • Inhibited co-ion effect and enhanced EDL formation led to superb P adsorption. • Hydrogen-bond and redox-reaction interaction contributed to high selectivity for P. • A reversal voltage and high pH weakened the interaction and favored P recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Defective MoS 2 electrode exhibited highly efficient and selective lead(II) adsorption. • Removal efficiency at initial concentration from 1 to 100 mg/L can reach ∼ 100 % • Adsorption capacity and removal efficiency were enhanced almost 8 folds after applying voltage. • Introduction of defects strengthened chemicalsorption and electrosorption. • A complete lead(II) desorption and reusability of electrodes can be achieved. Developing method for efficient lead(II) removal from aqueous solutions over a wide concentration range is urgent but challenging. In this work, defective molybdenum disulfide (MoS 2) was served as electrode coating to capture lead(II) over a wide range from aqueous solution via chemisorption and electrosorption coupling (CEC) process. The distinct adsorption behaviors of lead(II) on defective MoS 2 electrode were theoretically and experimentally investigated. In a wide concentration range (1 ∼ 100 mg/L), the removal efficiency of lead(II) from aqueous solutions can be close to ∼ 100 %. Adsorption capacities for lead(II) removal at initial concentration of 8.37 and 18.71 mg/L were 64.99 and 159.98 mg/g, respectively. After applying voltage, adsorption capacity and removal efficiency were enhanced almost 8 folds due to strengthened migration of ions, electrostatic interaction and electric double layer. Besides, lead(II) was completely desorbed from defective MoS 2 electrode within 60 min, and defective MoS 2 electrode by CEC process maintained excellent regeneration ability even after 10 cycles. Defective MoS 2 electrode has shown superior properties for lead(II) removal, such as (i) great specific capacitance and (ii) low charge transfer resistance toward the enhanced adsorption capacity and diffusion for lead(II) in the electrical double layer, compared with MoS 2. Extensive computations and characterizations of defective MoS 2 -lead(II) interaction demonstrated that the active unsaturated S sites were indispensable for lead(II) adsorption, which was beneficial for chemisorption. Based on the strong interaction with lead(II), defective MoS 2 electrode showed high-selectivity lead(II) adsorption with co-existence metal ions. Overall, defective MoS 2 as electrode coating by CEC has a great potential for the practical application in removing heavy metal ions from aquatic environment. [ABSTRACT FROM AUTHOR]

Based on the electro-negativity and structural characteristics of CR, a novel copper-organic framework (Cu-MOF) was synthesized with unique cage topology and cation network. The Cu-MOF exhibited efficient and targeted adsorption, separation and recovery characteristics for CR. The DFT calculation and two-dimensional correlation spectroscopy analysis further revealed that the energy distribution in CR adsorption was dominated by electrostatic interactions, followed by π-π stacking and van der Waals interactions. [Display omitted] • A novel Cu-MOF with caged topology and cation framework was synthesized for Congo Red (CR) specific-adsorption. • The Cu-MOF exhibited the efficient performance with the maximal adsorption capacity of 119.76 mg/g. • The Cu-MOF realized the separation, purification and recovery of the CR from mixed dyes. • Mechanism revealed the adsorption was spontaneous and exothermic with monolayer diffusion. • DFT and 2D-COS analysis clarified the adsorption was generated through electronic interaction and π-π stacking. Metal-organic frameworks (MOFs) with a three-dimensional (3D) caged structure and charged networks are promising adsorbents for separation and purification applications. However, it is a challenge to synthesize the MOFs in crystalline structures with a targeted ability of efficiently removing and reutilizing the individual diazo dye from sewage. Here, we report the synthesis of a novel copper-organic framework (Cu-MOF) with a 3D caged stucture and cationic networks using CuCl 2 and a triazole ligand (methyl-1H-1,2,4-triazole-3-carboxylate MTC). The novel Cu-MOF exhibited highly efficient and targeted adsorption, separation and recovery characteristics for Congo Red (CR). Specifically, the maximal adsorption capacity was 119.76 mg·g−1, and the adsorbed CR can be efficiently released in NaCl-DMF solution with a recovery rate of almost 100%. After suffered from three adsorption–desorption cycles, the Cu-MOF could still reach a adsorption rate of >85% and maintain an intact skeleton structure. The batch-equilibrium experiment combined with density functional theory calculation further revealed that the adsorption process was spontaneous and exothermic, following the pseudo-second-order kinetic equation with monolayer diffusion. The specific adsorption of Cu-MOF for CR was precisely generated through electronic interaction with the –NH 2 and -SO 3 groups, exhibiting the adsorption energies of −2.16 eV and −2.04 eV, respectively. The two-dimensional correlation spectroscopy analysis comfirmed that the energy distribution in CR adsorption was dominated by electrostatic interactions, followed by π-π stacking and van der Waals interactions. In summary, our work not only presents a promising strategy for the targeted separation and purification of CR from wastewater, but also contributes to the design of highly efficient MOF-adsorbents for other organic pollutants. [ABSTRACT FROM AUTHOR]

As an eco-friendly technique with the superior adsorption performance, electroadsorption has shown great potential for application in uranium (U(VI)) recovery in recent years. However, the electrodes used in the electrosorption generally suffer the adsorbent to be loaded on the conductors, which greatly limited the adsorption performance of the electrodes for uranyl ions. In present study, a flexible self-supporting Na 3 MnTi(PO 4) 3 @C fibers (NMTP@C fibers) electrode material was rationally designed and prepared by electrostatic spinning method and annealing technique, and its ability to capture U(VI) efficiently was preliminarily demonstrated by batch adsorption and electro sorption. The plentiful phosphate groups provide sufficient active sites for adsorption, while the axially continuous electron conduction and radially short-range ion transport give NMTP@C fibers fast charge/ion transport capability. The NMTP@C fiber can remove 99% of 5 ppm U(VI) in seawater by electro absorption within 1 h. After several cycles of adsorption under seawater conditions, the adsorbent can still maintain a stable adsorption capacity. The adsorption mechanism of NMTP@C nanofibers for U(VI) was investigated by XPS, FT-IR, Raman, SEM-EDS, and XRD, which was electrostatic interactions and surface complexation. These results suggest that NMTP@C fibers are promising high-capacity adsorbents for efficient and selective capture of U(VI) from seawater. [Display omitted] • Na 3 MnTi(PO 4) 3 @C was rationally designed as flexible self-supporting electrode. • Na 3 MnTi(PO 4) 3 @C is ecofriendly, low cost and low energy consumption. • Na 3 MnTi(PO 4) 3 @C exhibit high selectivity and uptake capacity for U(VI) with remarkable reusability. • U(VI) adsorption mechanism involves electrostatic interactions and surface complexation. [ABSTRACT FROM AUTHOR]