Multiple Ion Research Articles

Machine learning assists the sensor array constructed by the tri-emission carbon dots to detect multiple metal ions

Metal ions are related to the health of daily life, which urges to be detected and identified by efficient sensors. We first synthesize tri-emission carbon dots for the functional determination of six metal ions and obtain the multi-dimension data to construct the fluorescent sensor array in the work. Inspired by the data-driven method, machine learning is employed in a sensor array to detect and analyze the six metal ions. The ion classification and concentration models are constructed to identify metal ion types and corresponding concentrations. The classification model could correctly discriminate six metal ions, reaching 99.5 % accuracy and the concentration model exhibits an excellent performance range from 30 to 330 μM, with a mean concentration difference value of 0.12 μM and R2 value of 0.9845 for the unknown sample. Furthermore, six metal ions in tap water also can be distinguished with 96 % accuracy and the recovery rate is between 101.89 % and 106.37 %. This work shows that the machine learning combined sensor array has significant advantages in detecting multiple metal ions and provides a novel thought for analyzing sensing data, accelerating the development of data-driven strategies in the sensing field. © 2001 Elsevier Science. All rights reserved.

Fluorescent multichannel sensor array based on three carbon dots derived from Tibetan medicine waste for the quantification and discrimination of multiple heavy metal ions in water.

Afluorescent multichannel sensor array has been establishedbased on three carbon dots derived from Tibetan medicine waste for rapid quantification and discrimination of six heavy metal ions. Due to the chelation between metal ions and carbon dots (CDs), this fluorescence "turn off" mode sensing array can quantify six metal ions as low as "μM" level. Moreover, the six heavy metal ions display varying quenching effects on these three CDs owing to diverse chelating abilities between each other, producing differential fluorescent signals for three sensing channels, which can be plotted as specific fingerprints and converted into intuitive identification profiles via principal component analysis (PCA) and hierarchical cluster analysis (HCA) technologies to accurately distinguish Cu2+, Fe3+, Mn2+, Ag+, Ce4+, and Ni2+ with the minimum differentiated concentration of 5μM. Valuably, this sensing array unveils good sensitivity, exceptional selectivity, ideal stability, and excellent anti-interference ability for both mixed standards and actual samples. Our contribution provides a novel approach for simultaneous determination of multiple heavy metal ions in environmental samples, and it will inspire the development of other advanced optical sensing array for simultaneous quantification and discrimination of multiple targets.

Synergistic Stabilization of Zn Metal Anodes by 3D Carbon Frameworks with Multiple Ion Channels Loaded with Zincophilic BaTiO3 Nanoparticles

Aqueous zinc‐ion batteries (AZIBs) suffer from rampant Zn dendrites growth, corrosion and sluggish transport kinetics, all of which have a serious impact on their performance and practical applications. Therefore, porous carbon nanofibers (BTO@PCNFs) loaded with BaTiO3 nanoparticles (BTO NPs) are constructed as a multifunctional interlayer for stabilizing the Zn anodes. Owing to the synergistic effect of BTO NPs and 3D porous carbon framework, this interlayer can achieve uniform electric field distribution, accelerate Zn2+ migration, and promote ion flux homogenization, thus leading to uniform Zn deposition. Meanwhile, the BTO@PCNFs interlayer demonstrates excellent anti‐corrosion effect, which can effectively prevent the side reactions. Benefiting from the synergistic effect of interlayers, the BTO@PCNFs multifunctional interlayers achieve a comprehensive optimization of the Zn anodes. The BTO@PCNFs‐Zn electrode exhibits lower nucleation overpotential (33.5 mV) at 0.5 mA cm−2. The Zn//Zn symmetrical cell with BTO@PCNFs interlayer exhibits ultra‐low overpotential (14 mV) and ultra‐long cycle life (5250 h at 0.5 mA cm−2). Even at high current density (30 mA cm−2), the BTO@PCNFs‐Zn electrode can be stably cycled for more than 830 h, achieving an ultra‐high cumulative capacity of 12 450 mAh cm−2. The multifunctional interlayers can provide a reference for the design of high‐performance Zn anodes.

Balancing Group I Monatomic Ion-Polar Compound Interactions for Condensed Phase Simulation in the Polarizable Drude Force Field.

Molecular dynamics (MD) simulations are a commonly used method for investigating molecular behavior at the atomic level. Achieving reliable MD simulation results necessitates the use of an accurate force field. In the present work, we present a protocol to enhance the quality of group 1 monatomic ions (specifically Li+, Na+, K+, Rb+, and Cs+) with respect to their interactions with common polar model compounds in biomolecules in condensed phases in the context of the Drude polarizable force field. Instead of adjusting preexisting individual parameters for ions, model compounds, and water, we employ atom-pair specific Lennard-Jones (LJ) (known as NBFIX in CHARMM) and through-space Thole dipole screening (NBTHOLE) terms to fine-tune the balance of ion-model compound, ion-water, and model compound-water interactions. This involved establishing a protocol for the optimization of NBFIX and NBTHOLE parameters targeting the difference between molecular mechanical (MM) and quantum mechanical (QM) potential energy scans (PES). It is shown that targeting PES involving complexes that include multiple model compounds and/or ions as trimers and tetramers yields parameters that produce condensed phase properties in agreement with experimental data. Validation of this protocol involved the reproduction of experimental thermodynamic benchmarks, including solvation free energies of ions in methanol and N-methylacetamide, osmotic pressures, ionic conductivities, and diffusion coefficients within the condensed phase. These results show the importance of including more complex ion-model compound complexes beyond dimers in the QM target data to account for many-body effects during parameter fitting. The presented parameters represent a significant refinement of the Drude polarizable force field, which will lead to improved accuracy for modeling ion-biomolecular interactions.

Association and mediation analyses among multiple metal exposure, mineralocorticoid levels, and serum ion balance in residents of northwest China

Toxic metals are vital risk factors affecting serum ion balance; however, the effect of their co-exposure on serum ions and the underlying mechanism remain unclear. We assessed the correlations of single metal and mixed metals with serum ion levels, and the mediating effects of mineralocorticoids by investigating toxic metal concentrations in the blood, as well as the levels of representative mineralocorticoids, such as deoxycorticosterone (DOC), and serum ions in 471 participants from the Dongdagou–Xinglong cohort. In the single-exposure model, sodium and chloride levels were positively correlated with arsenic, selenium, cadmium, and lead levels and negatively correlated with zinc levels, whereas potassium and iron levels and the anion gap were positively correlated with zinc levels and negatively correlated with selenium, cadmium and lead levels (all P < 0.05). Similar results were obtained in the mixed exposure models considering all metals, and the major contributions of cadmium, lead, arsenic, and selenium were highlighted. Significant dose–response relationships were detected between levels of serum DOC and toxic metals and serum ions. Mediation analysis showed that serum DOC partially mediated the relationship of metals (especially mixed metals) with serum iron and anion gap by 8.3% and 8.6%, respectively. These findings suggest that single and mixed metal exposure interferes with the homeostasis of serum mineralocorticoids, which is also related to altered serum ion levels. Furthermore, serum DOC may remarkably affect toxic metal-related serum ion disturbances, providing clues for further study of health risks associated with these toxic metals.

A Novel Ionospheric Inversion Model: PINN‐SAMI3 (Physics Informed Neural Network Based on SAMI3)

AbstractPurely data‐driven ionospheric modeling fails to adequately obey fundamental physical laws. To overcome this shortcoming, we propose a novel ionospheric inversion model, Physics‐Informed Neural Network based on fully physical models SAMI3 (PINN‐SAMI3). The model incorporates the governing equations of the ionospheric physical model SAMI3 into the neural network to reconstruct the temporal‐spatial distribution of ionospheric plasma parameters. The objective of this study is to investigate the feasibility of integrating physical models with machine learning for ionospheric modeling. The PINN‐SAMI3 framework enforces physical laws through the multiple ion species of continuity, momentum, temperature equations in the magnetic dipole coordinate system. The simulation results show that if sparse ion densities are used as training data, it is possible to retrieve ionospheric electron densities, ion velocities and ion temperatures, respectively. The optimal physical constraints have been also investigated for different inversion quantities. Furthermore, the impact of incorporating E × B velocity terms on inversion results during the periods of ionospheric calm and geomagnetic storm is analyzed. The PINN‐SAMI3 achieves good inversion results even using sparse data in comparison to the traditional artificial neural networks (ANN). The framework will contribute to advance the future space weather prediction capability with artificial intelligence (AI).

Polyethyleneimine-derived fluorescent conjugate for trace-level detection of multiple ions via signal amplification

Fluorescent conjugates, based on polyethyleneimine were prepared by incorporating salicylaldehyde and 2-hydroxynaphthaldehdye respectively in the aqueous medium. The polymer derived from salicylaldehyde showed a dual-mode response with Cu2+ and Zn2+ ions. The addition of Zn2+ could change the cyan fluorescence into a blue-colored one, while the Cu2+ ion could result in a turn-off response. On the contrary, the polymer functionalized with 2-hydroxynaphthaldehdye showed fluorescence response only with Cu2+ ions. The fluorescent polymers prepared at different polyethyleneimine and salicylaldehyde ratios not only showed the formation of nanoparticles of different sizes but also, interacted with Cu2+ ions to different extents. The mechanistic investigation suggested that the enhanced sensitivity of such fluorescent nanoparticles was due to the signal amplification attributed to the polymeric backbone. Further, the in-situ synthesized Cu and Zn complex of polymers showed interaction with pyrophosphate in the aqueous medium. However, the mode of interaction as well as fluorescence response depended on the nature of the metal ions involved.

Metal coordination combining with electrodialysis for one-step separation of valuable metals from spent lithium-ion batteries

Efficient recycling of valuable metals from spent lithium-ion batteries (LIBs) is essential for the circular economy and ecological environment. However, the simultaneous separation and recovery of multiple metal ions face a huge challenge due to their similar physicochemical properties. Herein, we propose metal coordination combing with electrodialysis to achieve one-step separation of lithium, cobalt, and nickel. By regulating the ligands and ligand concentration, the Co2+ selectively coordinates with ligand to form anionic complex, which passes through the home-made anionic polymer inclusion membrane under electric field. Li+ passes through the monovalent cationic exchange membrane, whereas the Ni2+ is retained in the feed solution, thereby achieving the one-step separation of metal ions. When using NH4SCN as ligand, the transport flux of Li+ and Co(SCN)42- reaches around 25.0 µmol m−2 s−1 and 12.7 µmol m−2 s−1, respectively. Meanwhile, the separation efficiency of lithium and cobalt is 80 % and 95 %, respectively at the NH4SCN concentration of 0.1 M and current density of 10 mA/cm2. Additionally, sustainable solar energy is successfully applied to drive the electrodialysis system, and the purity of lithium, cobalt, and nickel is as high as 94.3 %, ∼100 %, and 99.2 %, respectively, demonstrating great potential in decreasing energy consumption. This work which applies metal coordination combining with electrodialysis for one-step separation of lithium, cobalt, and nickel, provides a promising candidate for the recycling of valuable metals from spent LIBs.

Multifunctional Sr, Mg, Ag-substituted octacalcium phosphate/carboxymethyl chitosan scaffolds: Antibacterial activity and osteogenic differentiation of human mesenchymal stem cells

Numerous studies indicate that octacalcium phosphate (OCP) possesses promising bone regenerative properties. To further improve the regenerative properties of OCP, several ionic substitutions have been proposed. However, knowledge regarding the synergic effect of multiple ions substituted in OCP crystals and fabricated scaffolds is lacking. In this work, plate-like OCP crystals substituted with 1 and 2.5 mol.% of Mg2+, Sr2+ and Ag+ were prepared by the wet precipitation method. Rietveld refinement analysis indicated a successful substitution of Ca2+ by Mg2+, Sr2+and Ag+ ions. The prepared substituted OCP powders showed a high antibacterial effect towards Gram-negative and Gram-positive bacteria. Further, composite scaffolds based on substituted OCP and carboxymethyl chitosan were prepared by the freeze-crosslinking method. The scaffolds had a highly porous structure, with interconnected pores and homogeneously dispersed OCP within the polymer matrix, and high stability in simulated physiological conditions during 28 days. Good viability and proliferation of human bone marrow-derived mesenchymal stem/stromal cells were confirmed by Live/Dead and CyQUANT assays. Additionally, successful osteogenic differentiation was confirmed by quantification of alkaline phosphatase activity and immunocytochemical staining for type I collagen. Results indicate that ionic substitutions with 1.0 mol.% have the most beneficial effect on stem cell differentiation towards osteoblast phenotype.

Trapping Ion Coulomb Crystals in an Optical Lattice.

We report the optical trapping of multiple ions localized at individual lattice sites of a one-dimensional optical lattice. We observe a fivefold increased range of axial dc-electric field strength for which ions can be optically trapped with high probability and an increase of the axial eigenfrequency by 2 orders of magnitude compared to an optical dipole trap without interference but of similar intensity. Our findings motivate an alternative pathway to extend arrays of trapped ions in size and dimension, enabling quantum simulations with particles interacting at long range.

Self-adhesive, freeze-tolerant, and strong hydrogel electrolyte containing xanthan gum enables the high-performance of zinc-ion hybrid supercapacitors

Hydrogel electrolyte is an ideal candidate material for flexible energy storage devices due to its excellent softness and conductivity properties. However, challenges such as the inherent mechanical weakness, the susceptibility to be frozen in low-temperature environments, and the insufficiency of hydrogel-electrode contact persist. Herein, a “Multi in One” strategy is employed to effectively conquer these difficulties by endowing hydrogels with high strength, freeze-resistance, and self-adhesive ability. Multiple hydrogen bond networks and ion crosslinking networks are constructed within the hydrogel electrolyte (PVA/PAAc/XG) containing polyvinyl alcohol (PVA), acrylic acid (AAc), and xanthan gum (XG), promoting the enhanced mechanical property, and the adhesion to electrode materials is also improved through abundant active groups. The introduction of zinc ions provides the material with superior frost resistance while also promoting electrical conductivity. Leveraging its multifunction of superior mechanical strength, anti-freeze property, and self-adhesive characteristic, the PVA/PAAc/XG hydrogel electrolyte is employed to fabricate zinc ion hybrid supercapacitors (ZHS). Remarkably, ZHS exhibits outstanding electrochemical performance and cycle stability. A remarkable capacity retention rate of 83.86 % after 10,000 charge-discharge cycles can be achieved at high current densities, even when the operational temperature decreases to −60 °C, showing great potential in the field of flexible energy storage devices.

Anomalous Emission from Li- and Na-like Ions in the Corona Heated via Alfvén Waves

The solar ultraviolet intensities of spectral lines originating from Li- and Na-like ions have been observed to surpass the expectations derived from plasmas with coronal approximation. The violation of the coronal approximation can be partially attributed to nonequilibrium ionization (NEI) due to dynamic processes occurring in the vicinity of the transition region. To investigate the impact of these dynamics in the Alfvén wave-heated coronal loop, a set of equations governing NEI for multiple ion species was solved numerically in conjunction with 1.5-dimensional magnetohydrodynamic equations. Following the injection of Alfvén waves from the photosphere, the system undergoes a time evolution characterized by phases of evaporation, condensation, and quasi-steady states. During the evaporation phase, the ionization fractions of Li- and Na-like ions were observed to increase when compared to the fractions in ionization equilibrium, which led to an enhancement in the intensity of up to 1.6. This over-fractionation of Li- and Na-like ions was found to be induced by the evaporation process. While collisions between shocks and the transition region temporarily led to deviations from ionization equilibrium, on average over time, these deviations were negligible. Conversely, under-fractions of the ionization fraction led to a reduction in intensity down to 0.9 during the condensation phase and the quasi-steady state. Given the dependency of the over/under-fractionation on mass circulations between the chromosphere and the corona, these observations will serve as valuable benchmarks to validate not only Alfvén wave models but also other existing mechanisms on coronal heating.

Formation of multiple ion types during MALDI imaging mass spectrometry analysis of Mitragyna speciosa alkaloids in dosed rat brain tissue

Mitragyna speciosa, more commonly known as kratom, has emerged as an alternative to treat chronic pain and addiction. However, the alkaloid components of kratom, which are the major contributors to kratom's pharmaceutical properties, have not yet been fully investigated. In this study, matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry was used to map the biodistribution of three alkaloids (corynantheidine, mitragynine, and speciogynine) in rat brain tissues. The alkaloids produced three main ion types during MALDI analysis: [M + H]+, [M − H]+, and [M − 3H]+. Contrary to previous reports suggesting that the [M − H]+ and [M − 3H]+ ion types form during laser ablation, these ion types can also be produced during the MALDI matrix application process. Several strategies are proposed to accurately map the biodistribution of the alkaloids. Due to differences in the relative abundances of the ions in different biological regions of the tissue, differences in ionization efficiencies of the ions, and potential overlap of the [M − H]+ and [M − 3H]+ ion types with endogenous metabolites of the same empirical formula, a matrix that mainly produces the [M + H]+ ion type is optimal for accurate mapping of the alkaloids. Alternatively, the most abundant ion type can be mapped or the intensities of all ion types can be summed together to generate a composite image. The accuracy of each of these approaches is explored and validated.

A novel electrode for simultaneous detection of multiple heavy metal ions without pre-enrichment in food samples

Integrating a pre-enrichment step into electrochemical detection methodologies has traditionally been employed to enhance the performance of heavy metal detection. However, this augmentation also introduces a degree of intricacy into the sensing process and increases energy consumption. In this work, Mo-doped WO3 is grown in situ on carbon cloth by one-step electrodeposition. The electrode detect multiple heavy metal ions simultaneously in the range of 0.1–100.0 μM with LODs ranging from 11.2 to 17.1 nM. The electrode successfully detected heavy metal ions in diverse food samples. This pioneering detection strategy realized the direct and simultaneous detection of multiple heavy metal ions by utilizing the valence property of WO3 and oxygen vacancies generated by molybdenum doping. The Mo-WO3/CC pre-enrichment-free detection electrode boasts straightforward preparation, a streamlined detection procedure, swift response kinetics, and superior performance relative to previously reported electrodes, which makes it possible to develop a portable heavy metal ion detection device.

Determination of trace anions in battery-grade lithium carbonate by double-inhibition on-line matrix-removal ion chromatography

A method was developed for the determination of trace anions in battery-grade lithium carbonate. In this method, lithium carbonate was dissolved in ultrapure water with ultrasound assistance, and its matrix was removed using an on-line matrix-removal method. In the matrix-removal process, the sample was first passed through an ADRS600(4 mm) suppressor (suppressor current, 150 mA; external water flow rate, 2 mL/min). Hydrogen and lithium ions were then completely exchanged via the ion-exchange membrane in the suppressor, converting the lithium carbonate into carbonic acid. The carbonic acid entered the waste-liquid channel in the form of carbon dioxide through a CRD 200(4 mm) carbonate removal device to remove the lithium carbonate matrix. Finally, the target anions were automatically enriched on an IonPac UTAC-LP2 concentration column (35 mm×3 mm) and automatically transferred to a chromatographic system using valve-switching technology. The chromatographic system featured an IonPac AG18 column (50 mm×2 mm) as the protection column and an IonPac AS18 column (250 mm×2 mm) as the analytical column. The column temperature was 30 ℃, gradient elution was performed using KOH solution as the eluent, and the pump flow rate was 0.30 mL/min. An ADRS600(2 mm) suppressor, suppressor current of 25 mA, injection volume of 250 μL, and conductance detector were also used. The results showed good linear relationships (r≥ 0.999) for F-, Cl-, [Formula: see text] in their respective concentration ranges. The limits of detection (LODs) and quantification (LOQs) were 0.05-0.88 and 0.15-2.92 μg/L, respectively. Lithium carbonate samples were tested six consecutive times, and the relative standard deviations (RSDs) of the peak areas of each ion were less than 0.73%. The same lithium carbonate samples were injected after 0, 2, 4, 8, 12, 18, and 24 h, and the RSD of the peak areas of each ion was less than 0.96%. The average recoveries ranged from 93.3% to 99.3%, and the RSDs (n=6) of samples spiked at three levels were in the range of 0.97%-3.45%. The proposed method has a low method limit of quantification of only 0.5 mg/kg for each ion analyzed and is capable of the simultaneous analysis of multiple ions. Thus, it is suitable for the detection of trace anions in battery-grade lithium carbonate.

Seasonal charge distributions of submicron atmospheric particles in Yokohama, Japan

Charge distribution measurements are required to understand the spatiotemporal distribution of the number concentrations of submicron atmospheric particles that affect radiative forcing and particle deposition in human airways. The number concentrations of non-charged and charged particles within the 0.3–0.5 μm diameter (D) range were measured at Keio University in Yokohama, Japan, from June 2022 to January 2023 by combining a parallel-pate particle separator and optical particle counters to investigate critical parameters controlling the charging state of submicron atmospheric particles. The measurement uncertainties in the average charge number per particle (pave) and the standard deviation (1σ), derived from the charge distribution of the submicron particles, were within 15%. The monthly median values of 1σ increased in summer and decreased in winter and correlated with the water vapor amount and wind speed. The 1σ values in summer and winter, derived from the seasonally averaged charge distributions of particles, were close to those from the theoretically calculated charge distribution of particles within 0.387–0.5 μm D range and with D = 0.3 μm, respectively, suggesting that the observed particle charge distributions approached the stationary charge distribution for the effective D. In summer, the frequent transport of water molecules and ions from the Pacific Ocean causes efficient collisions between multiple ions and submicron particles with a larger effective D, which may expand the charge distribution of particles. The polarity ratio, the concentration of positively charged particles relative to that of negatively charged particles, was almost unity, indicating the well-balanced charge polarity of the submicron atmospheric particles. The polarity ratio and pave changed significantly during lightning events, indicating that the atmospheric particle charge balance broke. Our findings show that the charge distribution of submicron atmospheric particles can be partly controlled by meteorological parameters (e.g., absolute humidity) and the microphysical properties of the particles.

Membrane behavior of clay under mixed solution conditions

Compacted clay is employed as the buffer material for landfills, and multiple ions are dissolved in the leachate restricted by the compacted clay layer. The membrane efficiency is an important indicator to assess the barrier properties of the compacted clay layer and is measured through membrane tests. However, most membrane tests are currently conducted with a single solute solution, which does not reflect the mixed solution characteristics of leachates. To assess the membrane efficiency of compacted clay under mixed solution conditions, 13 membrane tests were conducted on a bentonite-amended soil using KCl–NaCl mixed solutions, KCl–CaCl2 mixed solutions, and KCl–AlCl3 mixed solutions with different mixing ratios at a total concentration of 20 mM. Nuclear magnetic resonance (NMR) tests were conducted on the soil specimen after the membrane tests to investigate the micromechanism of the membrane behavior under mixed solution conditions. Results indicate that the membrane efficiency increased with the mixing ratio of Na+ but decreased with the mixing ratio of Ca2+ or Al3+. In the 13 membrane tests, the lowest membrane efficiency was achieved when the specimen was tested with pure AlCl3 solution. The relationship between the membrane efficiency and mixing ratio was also investigated at the microscopic scale. As the ion valence increases, the diffuse double layer thickness is smaller and the proportion of macropores is larger, as verified by NMR tests.

Rapid identification of Radix Astragali origin by using fluorescence probe combined with chemometrics

Fluorescent probes for metal ion recognition can be divided into selective probes, weakly selective probes, and non-selective probes roughly. Weakly selective probes are not often used for quantitative analysis of metal ions due to their overlapping spectra resulting from simultaneous interactions with multiple metal ions. Conversely, the different metal ions contained in herbal medicine extracts from different geographical origins will produce corresponding fluorescence fingerprint profiles after interaction with weakly selective fluorescence probes. The performance can be used in the study of origin tracing of food or Chinese herbal medicine. Weakly selective fluorescent probes of benzimidazole derivatives have been synthesized and attempted to be used in the origin tracing of Radix Astragali in this work. Radix Astragali from different origins will produce different fluorescence fingerprint spectra due to the difference of metal ions and content in combination with the probe. Excitation-emission matrix (EEM) fluorescence spectroscopy in conjunction with N-way partial least squares discriminant analysis (N-PLS-DA), and unfolded partial least squares discriminant analysis (U-PLS-DA) were used to identify the origin of 150 Radix Astragali samples from five geographical origins. The prediction results showed that the correct recognition rates of the U-PLS-DA model and N-PLS-DA model are 95.92% and 93.88%, respectively. In comparison, the results of U-PLS-DA are slightly better than those of N-PLS-DA. These findings indicate that EEM fluorescence spectroscopy based on weakly selective fluorescent probes combined with multi-way chemometrics provides a good idea for the origin tracing of traditional Chinese medicine.

Remediation of multifarious metal ions and molecular docking assessment for pathogenic microbe disinfection in aqueous solution by waste-derived Ca-MOF.

The present study demonstrates an eco-friendly and cost-effective synthesis of calcium terephthalate metal-organic frameworks (Ca-MOF). The Ca-MOF were composed of metal ions (Ca2+) and organic ligands (terephthalic acid; TPA); the former was obtained from egg shells, and the latter was obtained from processing waste plastic bottles. Detailed characterization using standard techniques confirmed the synthesis of Ca-MOF with an average particle size of 461.9 ± 15nm. The synthesized Ca-MOF was screened for its ability to remove multiple metal ions from an aqueous solution. Based on the maximum sorption capacity, Pb2+, Cd2+, and Cu2+ ions were selected for individual parametric batch studies. The obtained results were interpreted using standard isotherms and kinetic models. The maximum sorption capacity (qm) obtained from the Langmuir model was found to be 644.07 ± 47, 391.4 ± 26, and 260.5 ± 14mgg-1 for Pb2+, Cd2+, and Cu2+, respectively. Moreover, Ca-MOF also showed an excellent ability to remove all three metal ions simultaneously from a mixed solution. The metal nodes and bonded TPA from Ca-MOF were dissociated by the acid dissolution method, which protonated and isolated TPA for reuse. Further, the crystal structure of Ca-MOF was prepared and docked with protein targets of selected pathogenic water-borne microbes, which showed its disinfection potential. Overall, multiple metal sorption capability, regeneration studies, and broad-spectrum antimicrobial activity confirmed the versatility of synthesized Ca-MOF for industrial wastewater treatment.

Ultra-strong adsorption of organic dyes and antibiotic onto the alk-MXene/ZIF adsorbents with a specific intercalation structure

By in-situ growing tiny ZIF (ZIF-67/ZIF-8) particles on the interlayer and surface of alkalized MXene (alk-MXene), alk-MXene/ZIF adsorbents with specific intercalation structure and ultra-strong adsorption capacity for antibiotics and dyes are designed. The introduction of ZIF particles offers a larger specific surface area and more adsorption functional groups in alk-MXene/ZIF composites. Changing the additive amount of alk-MXene (1, 0.5 and 0.25 g) can effectively tune the adsorption properties and morphology of the composites. Herein, when the additive amount of alk-MXene is 0.5 g (sample S2) exhibits optimal adsorption performance with maximum adsorption capacities qm of 539.7, 1053.3 and 7111.3 mg g−1 for Congo Red (CR), Tetracycline (TC) and Malachite Green (MG). That is, too much (sample S1) or too little (sample S3) addition of the alk-MXene into the composites will suffer the performance degradation. Impressively, the composites show fast adsorption kinetics, strong recycling ability and powerful anti-interference capacity to multiple ions in contaminants. Benefiting from the intercalation structure, ZIF particles protect alk-MXene from being oxidized in air, making the composites exhibit excellent chemical stability. Typically, Sample S2 retains its stable microstructure and outstanding adsorption properties in air for 45 days. Also, the actual application of sample S2 is analyzed by filtering the adsorbates multiple times. Furthermore, it is demonstrated that the synergistic effects of electrostatic interaction, hydrogen bonding and π-π stacking lead to the excellent adsorption capacity of alk-MXene/ZIF composites. This study suggests that alk-MXene/ZIF can be regarded as a high-efficiency and promising adsorbent to remove organic dyes and antibiotics.