Excellent Adsorption Ability Research Articles

Preparation of Loess‐Clay Based Eco‐Friendly Geopolymer for Efficient Removal of Pollutants in Water

AbstractHeavy metals and dyes cause serious harm for water environment, geopolymer materials with the large pores and specific surface area, and easy modification of pore surface have received extensive attention in wastewater treatment. Herein, using loess‐clay (LC) as natural mineral materials, we developed an eco‐friendly geopolymer of loess‐clay (GpLC) with excellent adsorption properties and promotion plant growth was prepared by alkali excitement. Its morphology and structure were exhibited by scanning electron microscopy, Fourier transform infrared spectroscopy, XRD, and Brunauer–Emmett–Teller. Moreover, its adsorption property for removing metal ions and different dyes was measured, and the adsorption kinetics and thermodynamics were investigated. GpLC presented excellent adsorption ability for Pb2+, which the removal rate got to 98.7 %. It had the universality of removing organic pollutants, and the removal rate reached to 98.0 %. It was dominated chemisorption and single‐layer adsorption, which GpLC conformed to quasi‐second‐order adsorption kinetics, and being more consistent with Langmuir isothermal model. Furthermore, it was found that GpLC could promote growth of crops as it contain P and K element with essential element of plants. In summary, it provides insights and strategy for developing a kind of eco‐friendly functional materials with strong adsorption capacity and promoting plant growth, and it is an effective method for reusing loess resources.

In-situ Assembly of Polyoxometalate-Based Metal-Organic Framework for High-Efficiency Recovery of Uranium

Extracting uranium from water is crucial for environmental protection and the sustainable nuclear power industry. However, high-efficiency extraction and mild desorption condition still poses significant challenges. Herein, a polyoxometalate-based metal-organic framework (POMOF) for high-performance uranium extraction is prepared by in situ confined encapsulating H3[PW12O40] (PW12) into MIL-101(Cr). The highly dispersed PW12 enables adsorption sites to be sufficiently exposed, supports the pore structure of MIL-101(Cr), while being protected by spatial confinement. Furthermore, its abundant oxygen groups form high-affinity coordination with uranium and provide the pH-dependent conformation switch to achieve selective adsorption and instantaneous structural transformation. The assembly of structure and function makes POMOF exhibit substantial synergistic stability and adsorption capacity. Consequently, the constructed MIL-101(Cr)@PW12 exhibits excellent uranium adsorption ability of 461.88mg/g, as well as superior selectivity towards a wide variety of metal ions. Remarkably, instantaneous desorption can be achieved in 2s under mild desorption conditions of 0.005mol/L HCl, and the adsorption capacity remained at 94.30% after 8 adsorption cycles. POMOF demonstrates the vast potential for uranium capture from water and offers new insight into designing structure and functional synergistic materials for the selective adsorption and instantaneous desorption of uranium.

Biomass-based perovskite/graphene oxide composite for the removal of organic pollutants from wastewater

Water pollution is a critical issue that affects both human health and the environment. Biomass-based LaFeO3 is prepared by the microwave-assisted method using rice straw as a cellulose source. Then LaFeO3/graphene oxide (GO) composite is prepared by ultrasonication to facilitate the perovskite-GO binding. Raman and FTIR spectra of the prepared composite identify the presence of the perovskite, biochar, cellulose and GO oxide phases and proves the surface functional groups interactions. Transmission electron microscope image shows that the GO sheets are homogeneous covered with the perovskite nanoparticles. The adsorption performance of the LaFeO3/GO composite for the removal of methylene blue (MB) and congo red (CR) dyes from aqueous solution is optimized. Adsorption follows pseudo 2nd order kinetic model and Freundlich isotherm, with maximum adsorption capacities of 319.5 and 416.7 mg/g for MB and CR, respectively. These values are higher than those reported for magnetic GO composites, indicating the excellent adsorption ability of the proposed perovskite/GO composite. A thermodynamic study shows that the adsorption of MB is exothermic, while it is endothermic for CR and combines physisorption and chemisorption characteristics for both dyes. The proposed adsorbent shows a good performance in the presence of NaCl interferent, with the possibility of regeneration and efficient successive reuse.

A novel strategy for sequential separation of Th(IV) from highly acidic wastewater based on solid phase extraction

The potential applications and advantages of thorium(Th) in the development of the nuclear industry make the effective separation of Th(IV) crucial for depleted fuel management and environmental safety. However, selectively capturing of Th(IV) from high-concentration nitric acid remains a challenging task. In this work, a novel solid-phase extraction resin (TOPO/XAD-7) was successfully synthesized by vacuum impregnation of trioctylphosphine oxide (TOPO) into an acrylic-based polymer (XAD-7 resin). It exhibited excellent adsorption abilities for Th(IV), including wide highly concentration acid tolerance (0.01–6 mol L−1 HNO3), high adsorption capacity of 59.79 mg g−1, fast adsorption kinetic (< 60 min) and super elevated selectivity. The adsorption mechanism of the resin involves neutral chelation extraction, with the PO group being the main adsorption binding site. Additionally, the resin was demonstrated good reusability and stability under extreme conditions (high acidity, high temperature and high radiation). Furthermore, dynamic column experiments conducted using an automated separation system validated the practical application of TOPO/XAD-7 resin for the separation of Th(IV) and U(VI)/Th(IV) in wastewater, achieving high element recovery (> 99.5%) and a high U(VI) decontamination factor (3.5 × 105). This work confirms the excellent potential of TOPO/XAD-7 resin for the separation and enrichment of Th(IV) in nuclear wastewater.

Self-assembled fluorescent Zn-MOF with high specific surface area based on the coordination interaction for sensitive detection and selective removal of tetracycline antibiotic in water

As one of most common used antibiotics, tetracyclines (TCs) have been widespread used in many fields. However, the abuse of antibiotics resulted in serious environmental pollutants. Therefore, it is of great significance to develop new materials for rapid detection and effective removal of tetracyclines. In this study, a step-by-step synthesis strategy was adopted to prepare a fluorescent LMOF material Znq2@ZIF-8, and it was well characterized. Znq2@ZIF-8 showed strong green emission and has large specific surface area, with excellent stability and good recyclability. The fluorescence of Znq2@ZIF-8 can be quenched with the addition of tetracycline (TC) in the aqueous environment, demonstrating good selectivity and strong interference resistance, with a limit of detection (LOD) of 0.13 μmol∙L−1. In addition, Znq2@ZIF-8 exhibits excellent adsorption and removal abilities for TC. As a result, Znq2@ZIF-8 enables the simultaneous detection and removal of TC in aqueous environments, providing a solution for future TC pollution in water.

Synthesis of bulk foam-like palygorskite based adsorbent for efficient and convenient recyclable removal of radioactive iodine and iodide

Radioactive iodine is the inevitable product of nuclear fission, and the types and valence states of iodine are relatively rich and easy to convert to each other. Therefore, the synthesis of a material that can be easily recovered and efficiently remove polyvalent radioactive iodine has great strategic significance for the safe use of nuclear power. Bulk foam-like palygorskite based adsorbents (PDMA-PAL) with the macroscopic pore size of 40 to 150 μm were synthesized by the emulsion template method using dimethylaminoethyl methacrylate (DMAEMA) as the functional monomer and cheap palygorskite (PAL) as the matrix material. The excessive addition of DMAEMA and PAL will lead to the collapse of the porous structure. Optimized PDMA2-PAL shows excellent adsorption capacity (2.14 g/g) for iodine in cyclohexane solution with the equilibrium time of 5 h. PDMA2-PAL also exhibits an excellent adsorption capacity for gaseous iodine (308 wt%), and the I2 adsorption mechanism is the strong affinity and charge transfer of electron-rich N heteroatoms for electron-deficient iodine. PDMA2-PAL also achieves an outstanding iodide adsorption capacity (2.1mmol/g) within 5 min, and the I− adsorption mechanism is the electrostatic interaction between I− and the derivatization of tertiary amine under acidic conditions. Moreover, the deprotonation in alkaline solution can desorb iodide efficiently, which makes PDMA-PAL exhibit excellent recyclability. Importantly, PDMA-PAL also shows excellent simultaneous adsorption ability of iodide and iodine, and also exhibits stable adsorption activity in actual water. This study provides promising results for the removal of polyvalent radioactive iodine by bulk foam-like palygorskite based adsorbent in environmental remediation.

Removal of Acid Orange 7 dye using Makgeolli lees with ultrasonic assistance

AbstractThis study investigated the efficient removal of Acid Orange 7 (AO7) dye in water by using Makgeolli lees, a popular by‐product obtained during the production of traditional Makgeolli beverages in Korea. By incorporating ultrasound, the effects of contact time, Makgeolli lees dosage, initial AO7 dye concentration, and initial pH of the dye solution were investigated and comprehensively compared with the same experiment using the stirring method. The results consistently showed ultrasound not only enhances the excellent adsorption ability of Makgeolli lees but also accelerates the process compared to the stirring method. The Langmuir isotherm model best described the adsorption process for both methods, suggesting monolayer adsorption on the surface of Makgeolli lees, with maximum capacities of 25.13 mg/g for ultrasound at 40 kHz and 20.41 mg/g for stirring methods. Furthermore, the study showed that optimal dye removal efficiency can be achieved with ultrasound conditions at 28 kHz frequency, 125 W/L power density, and 100% ultrasound intensity. This research promises that the integration of low‐cost biomass coupled with ultrasound could provide a potential solution for dye wastewater treatment.

Metal-Organic Framework with Dual Excitation Pathways as Efficient Bifunctional Catalyst for Photo-assisted Li-O2 Batteries.

Li-O2 batteries (LOBs) have sparked significant interest due to their fascinating high theoretical energy density. However, the large overpotential for the formation and oxidation of Li2O2 during charge and discharge process seriously hinders the further development and application of LOBs. In this work, metal-organic frameworks (MOFs) with different metal clusters (Fe, Ti, Zr) are successfully synthesized, and they are employed as the photoelectrodes for the photo-assisted LOBs. The special dual excitation pathways of Fe-MOF under illumination and the superior separation efficiency of photocarriers, which significantly enhance the activation of O2/Li2O2, improving the catalytic activity of oxygen reduction reaction and oxygen evolution reaction. Moreover, compared to traditional inorganic semiconductor crystals, Fe-MOF exhibits large specific surface area and excellent O2 adsorption ability. Therefore, the LOB with Fe-MOF as the cathode exhibits large specific capacity, ultralow charge/discharge overpotential of 0.22V at 0.05mA cm-2 and excellent stability of 195 cycles under illumination. This study provides an environmentally friendly and highly efficient photocatalyst for LOBs, and a new strategy for designing photoelectrodes.

Controllable preparation of carbon coating Ge nanospheres with a cubic hollow structure for high-performance lithium ion batteries

Germanium based nanomaterials are very promising as the anodes for the lithium ion batteries since their large specific capacity, excellent lithium diffusivity and high conductivity. However, their controllable preparation is still very difficult to achieve. Herein, we facilely prepare a unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) via a hydrothermal synthesis and subsequent pyrolysis using low-cost GeO2 as precursors. The hollow Ge@C nanostructure not only provides abundant interior space to alleviate the huge volumetric expansion of Ge upon lithiation, but also facilitates the transmission of lithium ions and electrons. Moreover, experiment analyses and density functional theory (DFT) calculations unveil the excellent lithium adsorption ability, high exchange current density, low activation energy for lithium diffusion of the hollow Ge@C electrode, thus exhibiting significant lithium storage advantages with a large charge capacity (1483 mAh/g under 200 mA g−1), distinguished rate ability (710 mAh/g under 8000 mA g−1) as well as long-term cycling stability (1130 mAh/g after 900 cycles under 1000 mA g−1). Therefore, this work offers new paths for controllable synthesis and fabrication of high-performance Ge based lithium storage nanomaterials.

Enhancement of dye treatment efficiency of TiO2/C3N4 photocatalysts synthesized by hydrothermal method

Abstract Using sunlight to generate energy is a trend to establish a sustainable economy while protecting the environment. Photocatalytic breakdown of organic molecules on the surfaces of semiconductors is an important topic of current research. In this study, competent TiO2/g-C3N4 photocatalysts produced by the hydrothermal technique demonstrated outstanding photoactivity. To determine the best-performing photocatalyst, TiO2/g-C3N4 materials were analyzed by using Scanning Electron Microscopy (SEM), X-ray diffraction analysis (XRD), Energy Dispersive X- ray (EDX), Brunauer-Emmett-Teller (BET) analysis, and Differential Reflectance Spectroscopy (DRS). XRD results indicate that the addition of C3N4 increases the ratio of TiO2 Anatase. Optical studies unveiled a significant reduction in the forbidden band. The experiments using photocatalysis revealed that the action of TiO2/g-C3N4 on methylene blue (MB) dyes exhibited not only momentous photocatalytic performance but also excellent adsorption ability. The result of this study is anticipated to offer a solid basis for the creation and synthesis of cutting-edge materials for applications including the treatment of textile effluent.

Conversion of rice husks into carbonaceous materials with porous structures via hydrothermal process

Carbonaceous materials hydrothermally produced using waste biomass have small specific surface areas (SSA) and poor porosity properties. In this study, we prepare a novel carbonaceous material with excellent porosity properties by suppressing the formation of a secondary char phase (spheres) and promoting biomass hydrolysis by controlling the hydrothermal conditions. Rice husk powders, as the starting material, are hydrothermally treated using acidic solvents of different types and concentrations at 180 °C. The surfaces of the samples hydrothermally prepared using the acidic solvents have no spheres. In the case of 0.1–0.2 mol L−1 hydrochloric acid (HA), the amorphous carbonaceous materials contain numerous mesopores and exhibit a larger SSA (approximately 100 m2 g−1) than those prepared using acetic acid and distilled water. An increase in the hydrothermal temperature reduces the porosity properties of the materials. Finally, the high-porosity amorphous carbonaceous material showed excellent trimethylamine adsorption ability.

Dual-template magnetic molecularly imprinted polymers for selective extraction and sensitive detection of aflatoxin B1 and benzo(α)pyrene in environmental water and edible oil

The coexistence of multiple contaminates in the environment and food is of growing concern due to their extremely hazard as a well-known class I carcinogen, like aflatoxin B1 (AFB1) and benzo(α)pyrene (BaP). AFB1 and BaP are susceptible to coexistence in environmental water and edible oil, posing a significant potential risk to environmental monitoring and food safety. The remaining challenges in detecting multiple contaminates include unsatisfied sensitivity, insufficient targets selectivity, and interferences in complex matrices. Here, we developed dual-template magnetic molecularly imprinted polymers (DMMIPs) for selective extraction of dual targets in complex matrices from the environment and food. The DMMIPs were fabricated by surface imprinting with vinyl-functionalized Fe3O4 as carrier, 5,7-dimethoxycoumarin and pyrene as dummy templates, and methacrylamide as functional monomer. The DMMIPs showed excellent adsorption ability (12.73–15.80 mg/g), imprinting factors (2.01–2.58), and reusability of three adsorption-desorption cycles for AFB1 and BaP. The adsorption mechanism including hydrogen bond, electrostatic interaction and van der Waals force was confirmed by physical characterization and DFT calculation. Applying DMMIPs in magnetic solid phase extraction (MSPE) followed by high-performance liquid chromatography (HPLC) analysis enabled detection limits of 0.134 μg/L for AFB1 and 0.107 μg/L for BaP. Recovery rates for water and edible oil samples were recorded as 86.2%–110.3% with RSDs of 4.1%–11.9%. This approach demonstrates potential for simultaneous identification and extraction of multiple contaminants in environmental and food.

Efficient U(VI) removal by Ti3C2Tx nanosheets modified with sulfidated nano zero-valent iron: Batch experiments, mechanism, and biotoxicity assessment

The MXenes, a new class of two-dimensional layered materials, have found extensive applications in water treatment for its excellent thermal stability, electrical conductivity, and excellent adsorption ability. Sulfidized nano zero-valent iron (S-nZVI) is a good reducing agent, however, the practical application of S-nZVI is currently restricted due to the tendency of nano materials to agglomerate. Herein, MXenes use as a support and in situ loading S-nZVI on it to prepare a new material (S-nZVI/Ti3C2Tx), and applied it to U(VI) removal in water treatment. The microscopic characterization proves that S-nZVI on Ti3C2Tx has good dispersion and effectively alleviates agglomeration. Batch experiments shown that S-nZVI/Ti3C2Tx has a very good effect on U(VI) removal, and the maximum adsorption capacity reaches 674.4 mg/g under the aerobic condition at pH=6.0. The pseudo-second-order kinetic model and the Langmuir isotherm model were found to be more appropriate for describing the adsorption behavior. This indicates that the removal process is a single molecular layer chemisorption. Moreover, the S-nZVI/Ti3C2Tx maintained a removal efficiency of over 85 % for U(VI) even after being reused five times, demonstrating its excellent reusability. It is worth noting that the material can remove 79.8% of 50 mg/L of U(VI) in simulated seawater, indicating that S-nZVI/Ti3C2Tx possessed an excellent uranium extraction performance from seawater. Experimental results and XPS analysis showed that U(VI) was removed by adsorption, reduction and co-precipitation. Moreover, S-nZVI/Ti3C2Tx was a low toxicity material to hyriopsis cumingii. Therefore, S-nZVI/Ti3C2Tx was expected to be a candidate as adsorbent with great potential in removal of uranium from wastewater and seawater.

Engineered K-doped ZnO/borneol based hydrogel composite material for led-based photocatalytic degradation of methylene blue and evaluation of antimicrobial activity

The significant improvement of decolorization and disinfection technologies has been a hotspot in wastewater reutilization. In this study, we realized a novel construction of K-doped nano-ZnO and borneol based hydrogel composite material (K-ZnO/B-hydrogel) by low-temperature in situ sol–gel growth. The techniques such as fourier transform infrared (FTIR), X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS) were applied to recognize the synthesized hydrogel. The results revealed that K-doped ZnO nanoparticles had been uniformly decorated onto the B-hydrogel. Ultraviolet-visible (UV–vis) absorption spectra showed that impurity doping of potassium element into ZnO could reduce the band gap, improving the visible light absorption efficiency. Under LED illumination, the photodegrading rate of K-ZnO/B-hydrogel was approximately 2.3 times greater than that of K-ZnO/B-hydrogel on methylene blue (MB) removal. Remarkably, aside from CO2 and H2O, no by-products were generated during the photodegradation process. In addition, the antimicrobial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of K-ZnO/B-hydrogel achieved up to 99.9%, which were at least 1.5 times higher than K-ZnO/B-hydrogel. This composite will push ahead with a closed-loop wastewater treatment system for dye and pathogenic microorganism disposal, which combines the excellent adsorption ability of hydrogel and the outstanding photocatalytic ability of ZnO nanoparticles with easy sample handling and separation, and help to eliminate secondary pollution.

Potential-dependent photo-electro-catalysis coupling mechanism for methanol oxidation: A case study over Pt/Cu-Nb2O5 nanorod arrays

The sluggish methanol oxidation kinetics has seriously hindered the development of direct methanol fuel cells. Photo-electro-catalysis is expected to accelerate reaction rates, yet suffers from lack of efficient photoelectrocatalysts and more importantly, less understanding on photo-electro-catalysis mechanism. Herein, a unique Cu-Nb2O5 nanorod array with excellent light adsorption and charge transfer ability, on which supports Pt nanoparticles, is constructed for photo-electrocatalytic methanol oxidation reaction (MOR). Systematical investigation discovers a potential-dependent photo-electro-catalysis coupling mechanism, i.e., at lower potential bias where the Fermi level of semiconductor (Ef,s) is beyond the Fermi level of Pt (Ef,Pt), electrons transferring from Pt to semiconductor is switched off, so semiconductor Cu-Nb2O5 alone takes a dominant role for both methanol and water activation; at higher potential bias where Ef,s is below Ef, Pt, electrons flowing from Pt to semiconductor is switched on, so methanol dehydrogenation on Pt surface is allowed energetically. Further investigation on the MOR processes prompts us to propose a MOR pathway that methanol dehydrogenates on Pt surface, with the aid of *OH from the photo-activated water on Cu-Nb2O5 to proceed via formaldehyde, formic acid to carbon dioxide, resulting to a low apparent activation energy and fast kinetics of MOR as compared to its counterpart Pt/Nb2O5. This work not only provides an efficient photoelectrocatalyst for methanol oxidation, but also sheds lights on the underlying photo-electro-catalysis coupling mechanism over semiconductor–metal catalysts.

Adsorption and catalytic degradation of tetracycline hydrochloride by HCNTs /MnFe2O4

Developing efficient, stable and selective materials is essential for removing antibiotics from aquatic systems. In this study, one composite is prepared via loading of magnetic MnFe2O4 onto hydroxylated multi-walled carbon nanotubes (HCNTs) through co-precipitation, named as HCNTs/MnFe2O4. The characterization of materials was performed using various methods, such as Vibrating Sample Magnetometer (VSM), Electron Paramagnetic Resonance (EPR), etc. There are larger surface and good magnetic property, which are useful to bind adsorbate and easy separation from mixtures. The as-synthesized composite exhibited excellent adsorption capacity and ability to activate potassium persulfate (KPS) for the efficient removal of Tetracycline hydrochloride (TC) from solution. The results showed that the adsorption capacity of HCNTs/MnFe2O4 towards TC was 341 mg·g–1 at 303 K. The kinetic process can be elucidated using pseudo-second-order kinetic model while the adsorption equilibrium can be fitted by Freundlich model. The mechanism of adsorption may include electrostatic attraction, complexation, π-π stacking, etc. To initiate Fenton-like heterogeneous catalytic degradation, KPS was added to the adsorption system to degrade and remove TC from solution. The experimental results showed that HCNTs/MnFe2O4 as a catalyst could achieve up to 89 % degradation of TC in the range of pH=3–8 due to its ability to generate active species such as ‧OH, SO4‧-, ‧O2- and 1O2 as confirmed from radical capturing experiments and EPR analysis. The removal efficiency after three adsorption regeneration or degradation cycles could reach up to 56 %, confirming its good reusability properties. There are good prospects of HCNTs/MnFe2O4 for the practical removal of antibiotics from aqueous solutions.

High-performance lithium batteries achieved by electrospun MXene-Enhanced cation-selective membranes

Conventional separators applied in lithium batteries face limitations like low porosity, poor electrolyte wettability, lower cation selectivity, and thermal instability, which impact battery performance and safety characteristics. Besides the challenge in separator design, transition metal ion migration from positive electrodes during cycling greatly accelerates capacity fading because of unrestricted diffusion of transition metal cation across the separator. This study explores an innovative strategy for the separator design by incorporating MXene (spraying MXene solution on both sides of the separator), a two-dimensional material, into electrospun Polyacrylonitrile/Polyetherimide membranes with the function of cation selection. Li+ can be accelerated, and its transference number increases along with the anion limitation in the MXene layer. Ni, Co, and Mn ion dissolution from the positive electrode is inhibited due to the cation selectivity of the MXene layer. Leveraging electrospinning advantages, the resultant membranes exhibit high porosity, excellent liquid absorption, mechanical strength, and superior thermal properties. Benefiting from MXene's layered structure and excellent adsorption ability, the membrane significantly inhibits the dissolution of transition metal ions while enabling smooth lithium deposition due to its cation selectivity. Eventually, the Li||NMC811 batteries deliver outstanding cyclic performance (91.3 % capacity retention after 200 cycles) and robust lithium dendrite suppression (800 h of stable cycling). Moreover, the MXene-modified membrane demonstrates exceptional electrolyte wettability, significantly improving ionic transference number (0.67) and conductivity (1.6 mS/cm). Modification of membrane surfaces with MXene offers insights into addressing transition metal ion migration from the positive electrode material perspective, providing a promising avenue for high-performance LIBs.

Effective Removal of Nile Blue Dye from Wastewater using Silver-Decorated Reduced Graphene Oxide.

Nile blue (NB) dye is a highly toxic substance that when discharged into sewage presents a significant risk to the environment and human health. Carbon-based nanomaterials, such as graphene oxide (GO), reduced graphene oxide (rGO), and their nanocomposites, offer considerable potential for eliminating hazardous pollutants from aqueous systems. In this study, we have successfully fabricated bare GO and rGO, and then, the rGO was decorated with silver (Ag) nanoparticles to develop the Ag-rGO composite. The as-prepared materials were characterized by various techniques, such as UV-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies, X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and scanning electron microscopy (SEM) to elucidate their structure, morphology, and chemical composition. The pollutant removal performance of the as-prepared materials was evaluated through a batch approach under the effect of various experimental variables for removal of NB dye from wastewater. As obvious, the Ag-rGO composite revealed exceptional performance for NB dye removal from wastewater, with a maximum removal percentage of 94% within 60 min, which is remarkably higher than those of the rGO (i.e., 59%) and GO (i.e., 22%), under the same experimental conditions. The adsorption data was analyzed with thermodynamics, isotherms, and kinetics models to better understand the physicochemical mechanisms driving the effective removal of the NB dye. The results reveal that Ag-rGO nanocomposite exhibit excellent adsorption ability as well as favorable thermodynamic and kinetic parameters for NB dye removal. It was also found that the presence of light enhanced the adsorptive removal of NB while using Ag-rGO as an adsorbent. The present study noted significant reusability of the Ag-rGO nanocomposite, likely due to minimal Ag leaching and/or the robust stability of the Ag-rGO. It is suggested that Ag-rGO-based hybrid materials could serve as promising candidates for efficiently adsorbing and catalytically removing various toxic pollutants from wastewater.

Empowering powdered activated carbon (PAC) with 3D printing: Achieving highly efficient and reusable cationic dye removal

Powdered activated carbon (PAC) has been extensively used as an effective adsorbent. Despite its excellent adsorption ability, PAC has drawbacks, including difficulty in filtration and reactivation after use, limitations of mass transfer in deeper areas because of its aggregated powder form, and limited applicability in high-flow systems. To overcome these limitations, we used a three-dimensional (3D) printing system to fabricate PAC into a 3D structure. Spectral and microscopic analyses indicated that PAC was embedded into 3D monolith and exhibited high porosity suitable for facile mass transfer. The designed 3D PAC filter effectively removed 200 ppm-methylene blue (MB) within 8 h and showed an adsorption efficiency of 93.4 ± 0.9%. The adsorption of MB onto the 3D PAC filter was described by the pseudo-first-order kinetic and Freundlich isotherm models. The negatively charged 3D PAC filter might attract the positively charged MB, thus favoring the physical adsorption of MB onto the 3D PAC filter. The adsorption performance of the 3D PAC filter was tested at various pH levels of 4–10 and against MB spiked in seawaters and freshwaters to evaluate its feasibility for use in real environments. Finally, the reproducibility and reusability of the 3D PAC filter were demonstrated through repeated adsorption and desorption processes against MB.

Structural and coordination microenvironment regulated MOF with phosphorylurea group to boost uranium adsorption

With the rapid industrial development and growing environmental awareness, the efficient extraction of uranium from seawater and wastewater has emerged as a research hotspot in nuclear energy development. Although metal–organic frameworks (MOFs) materials are widely used for uranium extraction, their low stability and poor selectivity hinder further development. Herein, a novel phosphorylurea functionalized metal–organic frameworks (MOFs) with optimized pore structure and hydrophilicity is fabricated (DUT-5-POR) by in situ induced etching strategy, which synergistically achieves the regulation of structural and coordination microenvironment. The presence of mesoporous pores can accelerate ion transport and expose abundant adsorption sites to enhance the adsorption capacity of uranium. Meanwhile, the introduction of phosphorylurea groups optimizes the hydrophilicity microenvironment and surface group density of DUT-5-POR to improve selectivity and kinetics. Consequently, DUT-5-POR shows an excellent adsorption ability (Qm = 263.4 mg⋅g−1) at pH = 6 and high selectivity for various competing metal ions, particularly in the separation of uranium and vanadium. Moreover, this work provides a feasible strategy for adjusting the structure and the coordination microenvironment of MOFs and a comprehensive perspective on the adsorption of uranium by MOF-based materials.