Target Ion Research Articles

In Situ Laser-Induced Breakdown Spectroscopy for Chromium Speciation Analysis Based on the Interactions of Oxygen-Containing Groups with Functionalized Co3O4-rGO: Evidence from Advanced Optical Techniques and Density Functional Theoretical Calculations under Electric Field.

Achieving accurate detection of different speciations of heavy metal ions (HMIs) in an aqueous solution is an urgent problem due to the different bioavailabilities and physiological toxicity. Herein, we nominated a novel strategy to detect HCrO4- and Cr(OH)2+ at a trace level via the electrochemical sensitive surface constructed by Co3O4-rGO modified with amino and carboxyl groups, which revealed that the interactions between distinct functional groups and different oxygen-containing groups of target ions are conducive to the susceptible and anti-interference detection. The detection sensitivities of 19.46 counts μg-1 L for HCrO4- and 13.44 counts μg-1 L for Cr(OH)2+ were obtained under optimal conditions, while the limits of detection were 0.10 and 0.12 μg L-1, respectively. Satisfactory anti-interference and actual water sample analysis results were obtained. A series of advanced optical techniques like X-ray photoelectron spectroscopy, X-ray absorption near-edge structure technology, and density functional theory calculations under an electric field demonstrated that chemical interactions between groups contribute more to the fixation of target ions than electrical attraction alone. The presence of oxygen-containing groups distinct from simple ionic forms was a critical factor in the selectivity and anti-interference detection. Furthermore, the valence cycle of Co(II)/(III) synergistically boosted the detection performance. This research provides a promising tactic from the microscopic perspective of groups' interactions to accomplish the precise speciation analysis of HMIs in the water environment.

Development and Testing of a High-Frequency Driver for a Charge-Exchange Source of Negative Hydrogen Ions

A source of negative hydrogen ions based on the recharging of a beam of positive ions in a gas target is being developed at the Institute of Nuclear Physics. G.I. Budker SB RAS. The charge exchange source can be used to inject into the tandem accelerator a neutron source intended for boron neutron capture therapy. One of the important elements of the source is the plasma emitter, which creates positive ions for primary acceleration. As an emitter, a high-frequency driver based on an induction discharge and designed for a multi-second operating mode was chosen. In this work, we measured the emission characteristics of a high-frequency driver using a moving grid probe. As a result, the parameters necessary for the use of the driver in a rechargeable source of negative ions have been achieved. The analysis of experimentally measured thermal loads in the multisecond mode is carried out.

Molecular Probe Embedded Porous Polymer Scaffold as Solid‐State Visual Sensor for Selective and Sequential Sensing of Ultra‐Trace Toxic Heavy Metal Ions in Environmental/Commercial Samples

AbstractThe article reports on the tailor‐made solid‐state optical sensor through controlled imbuement of an amphiphilic probe onto a dual interwoven macro‐/meso‐porous polymer monolithic scaffold for the selective ocular sensing of ultra‐trace toxic heavy metal ions. The structural/surface morphology of the poly(LMC‐co‐TMP) monolith is customized through the stochiometric inclusion of lauryl methacrylate (LMC), trimethyl propanetrimethacrylate (TMP) and porogenic solvents. The riveting sensing performance of the poly(LMC‐co‐TMP) scaffolds for the target ions arises from the built‐in twofold intermingled porous architects that render voluminous surface area and porosity for the embedding of 2‐((1H‐benzoimidazol‐2‐yl)‐4‐butan‐2‐yl)phenol (HBBP), a chromoionophoric probe. The sensor's unique structural and surface properties endure stable ion‐complexation through color transitions from yellow (blank) to a leafy green, peanut brown, and dark blue for Pb2+, Hg2+, and Cd2+, respectively. The sensor imposes high binding affinity for the target ions, with a linear response range of 0–200 ppb for Pb2+/Hg2+ and 0–300 ppb for Cd2+. The detection limit values are 0.46, 0.52, and 0.41 ppb for Pb2+, Hg2+, and Cd2+, respectively. The sensor's hassle‐free on‐field testing in environmental and synthetic samples reveals excellent data reproducibility (Relative Standard Deviation (RSD) ≤1.97%), with pH‐assisted reliable color transitions for eight regenerative trials, with a response time of 45 s.

Systematical targeted multicomponent characterization and comparison of Arnebiae Radix and its three confusing species by offline two-dimensional liquid chromatography/LTQ-Orbitrap mass spectrometry.

Arnebiae Radix, commonly known as "Zicao," can be easily confused with other compounding species, posing challenges for its clinical use. Here, we developed a comprehensive strategy to systematically characterize the diverse components across Arnebiae Radix and its three confusing species. First, an offline two-dimensional liquid chromatography (2D-LC) system integrating hydrophilic interaction chromatography (HILIC) and reverse phase (RP) separations was established, enabling effective separation and detection of more trace constituents. Second, a polygonal mass defect filtering (MDF) workflow was implemented to screen target ions and generate a precursor ion list (PIL) to guide multistage mass (MSn) data acquisition. Third, a three-step characterization strategy utilizing diagnostic ions and neutral losses was developed for rapid determination of molecular formulas, structure classes, and compound identification. This approach enabled systematic characterization of Arnebiae Radix and its three confusing species, with 437 components characterized including 112 shikonins, 22 shikonfurans, 144 phenolic acids, 131 glycosides, 18 flavonoids, and 10 other compounds. Additionally, 361, 230, 340, and 328 components were identified from RZC, YZC, DZC, and ZZC, respectively, with 142 common components and 30 characteristic components that may serve as potential markers for distinguishing the four species. In summary, this is the first comprehensive characterization and comparison of the phytochemical profiles of Arnebiae Radix and its three confusing species, advancing our understanding of this herbal medicine for quality control.

Synthesis of ion-imprinted polymers for speciation analysis of chromium(III)

A new sorbent based on ion-imprinted polymers has been successfully synthesized to examine chromium(III) in environmental water samples. In this study, Cr(III)−IIPs was synthesized using Cr(III)−DPCO complex as a templating molecule, and ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA), and benzoyl peroxide (BPO) as crosslinking agent, functional monomer, and radical initiator, respectively. The fabricated Cr(III)−IIPs polymer was characterized using Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscope (SEM). The FTIR results confirm that Cr(III)−IIPs has been successfully synthesized. A peak at 495 cm-1 indicated the stretching vibrations of Cr−N. The firm peaks at 1732 cm-1 and 1163 cm-1 are assigned to C=O and C−O stretching vibrations of methacrylic acid. The broad and strong peak at 3483 cm-1 corresponded to hydroxyl bonds between the templating molecule and functional monomer. The SEM images revealed that the morphology of the polymer was irregular and large. The Imprinting factor (IF) values of Cr(III)−IIPs/NIPs−DPCO and Cr(III)−IIPs/NIPs were 3.12 and 1.53, respectively. The sorbent developed by this technique can be selective to the target ions.

Fabrication of an anionic layered metal-organic framework for the efficient removal of Sr2+

Efficient removal of radioactive 90Sr from solutions is of vital importance due to its radioactive nature and high mobility. Herein, a 2D anionic metal-organic framework (MOF) [Me2NH2][KZn(pydc)2(H2O)2]∙H2O (K-Zn-MOF; pydc = 2,6-pyridinedicarboxylic acid) was synthesized and characterized. The prepared K-Zn-MOF was in turn applied for the removal of Sr2+ ions and various experimental conditions including contact time, initial concentration, and temperatures were optimized. Experimental findings revealed that the adsorption of Sr2+ on K-Zn-MOF reached equilibrium within 60 min at room temperature with Re = 95.39%. K-Zn-MOF exhibited ultra-high adsorption capacity (878.3 mg g−1), remarkable affinity (Kd = 5.8 × 105 mL g−1) in solutions and super-high selectivity in the presence of interfering coexisting ions (Na+, K+, Mg2+, and Ca2+). Mechanistic investigation suggested that free exchangeable [Me2NH2]+ ions and strong interactions between uncoordinated oxygens from COO− groups with target ions significantly contributed to the rapid adsorption of Sr2+ ions.

The application of barcode readable assay and linear regression RGB analysis using a customized smartphone app in on-chip electromembrane extraction for simultaneous determination of heavy metal ions

This paper presents an on-chip electromembrane extraction (OC-EME) followed by RGB analysis with a barcode-readable customized app for the determination of three heavy metal ions; Cr(VI), Ni(ΙΙ), and Cu(ΙΙ) in water samples. First, the OC-EME procedure was performed on a single transparent platform including three divided channels for extraction of analytes and subsequently complex formation with chromogenic reagents. The RGB values of colorful complexes were then analyzed by Photoshop software and green value intensities of all three colors showed the best concentration dependence signal. Effective parameters such as the composition of supported liquid membrane (SLM), the voltage of extraction, the composition of donor and acceptor solutions, sample volume, and flow rate were investigated and optimized. Also, a smartphone app was developed for RGB analysis on a barcode-readable program to detect and quantify the extracted heavy metal(s). A fast, easy, and accurate quantification analysis was offered using principal component analysis (PCA) and a trained linear regression model. Under optimized conditions, good calibration fittings were observed within the ranges of 0.05–1.5 mg l−1 for Cr(VI), 1.0–70.0 mg l−1 for Ni(II), and 0.5–30.0 mg l−1 for Cu(II) via the customized app. Intra- and inter-day RSDs% of the method were obtained less than 6.9 % and 7.8 %, respectively. Finally, the proposed procedure was successfully applied for the analysis of target ions in water samples with relative recoveries between 85.0 % and 116.4 %.

Bipolar ionization rapidly inactivates real-world, airborne concentrations of infective respiratory viruses.

The SARS-CoV-2 (COVID-19) pandemic has highlighted the urgent need for strategies that rapidly inactivate airborne respiratory viruses and break the transmission cycle of indoor spaces. Air ions can reduce viable bacteria, mold, and virus counts, however, most studies use small test enclosures with target microbes and ion sources in close vicinity. To evaluate ion performance in real-world spaces, experiments were conducted in a large, room-size BSL-3 Chamber. Negative and positive ions were delivered simultaneously using a commercially available bipolar air ion device. The device housed Needle Point Bipolar ionization (NPBI) technology. Large chamber studies often use unrealistically high virus concentrations to ensure measurable virus is present at the trial end. However, excessively high viral concentrations bias air cleaning devices towards underperformance. Hence, devices that provide a substantial impact for protecting occupants in real-world spaces with real-world virus concentrations are often dismissed as poor performers. Herein, both real-world and excessive virus concentrations were studied using Influenza A and B, Human Respiratory Syncytial Virus (RSV), and the SARS-CoV-2 Alpha and Delta strains. The average ion concentrations ranged from 4,100 to 24,000 per polarity over 60-minute and 30-minute time trials. The reduction rate was considerably greater for trials that used real-world virus concentrations, reducing infectivity for Influenza A and B, RSV, and SARS-CoV-2 Delta by 88.3-99.98% in 30 minutes, whereas trials using in-excess concentrations showed 49.5-61.2% in 30 minutes. These findings strongly support the addition of NPBI ion technology to building management strategies aimed to protect occupants from contracting and spreading infective respiratory viruses indoors.

Development and evaluation of thiosalicylic-modified/ion-imprinted chitosan for selective removal of cerium (III) ion

Chitosan was used in this study as the bio-based product for the development of microparticles for the specifically targeted removal of cerium ions (Ce3+) by ion-imprinting technology. A thiosalicylic hydrazide-modified chitosan (TSCS) is produced via cyanoacetylation of chitosan, followed by hydrazidine derivatization to finally introduce the thiosalicylate chelating units. Ion-imprinted Ce-TSCS sorbent microparticles were prepared by combining the synthesized TSCS with Ce3+, crosslinking the polymeric Ce3+/TSCS complex with glutaraldehyde, and releasing the chelated Ce3+ using an eluent solution containing a mixture of EDTA and HNO3. Ce-TSCS had a capacity of 164 ± 1 mg/g and better removal selectivity for Ce3+ because it was smart enough to figure out which target ions would fit into the holes made by Ce3+ during the imprinting process. The kinetic data were well suited to a pseudo-second-order model, and the isotherms were well described by the Langmuir model, both of which pointed to chemisorption and adsorption through Ce3+ chelation. XPS and FTIR analyses demonstrate that the predominant adsorption mechanism is the coordination of Ce3+ with the -NH-, -NH2, and -SH chelating units of the thiosalicylic hydrazidine. These findings provide fresh direction for the development of sorbent materials that can effectively and selectively remove Ce3+ from aqueous effluents.

A Critical Analysis of Target Ionization and Projectile Electron Loss in Neutral– and Ion–Atom Collisions

Electron removal (target ionization and/or projectile electron loss) in neutral–atom collisions is theoretically studied for the impact of H0, He0 and He+ beams on noble gases (He, Ne and Ar). These reactions are investigated theoretically within the Continuum Distorted Wave-Eikonal Initial State model. New features have been included in the theoretical model: (i) a scaled projectile charge depending on its velocity and charge, (ii) a dynamic projectile-effective-charge depending on the momentum transfer, and (iii) a dynamic target-effective-charge depending on the kinematics of the emitted electron. The energy and angular spectra of emitted electrons from the target and from the projectile are calculated and compared with the available experimental data. Also, the influence of each one of the corrections on the resulting spectra will be studied.

Thermo-Electro-Responsive Redox-Copolymers for Amplified Solvation, Morphological Control, and Tunable Ion Interactions.

Electro-responsive metallopolymers can possess highly specific and tunable ion interactions, and have been explored extensively as electrode materials for ion-selective separations. However, there remains a limited understanding of the role of solvation and polymer-solvent interactions in ion binding and selectivity. The elucidation of ion-solvent-polymer interactions, in combination with the rational design of tailored copolymers, can lead to new pathways for modulating ion selectivity and morphology. Here, we present thermo-electrochemical-responsive copolymer electrodes of N-isopropylacrylamide (NIPAM) and ferrocenylpropyl methacrylamide (FPMAm) with tunable polymer-solvent interactions through copolymer ratio, temperature, and electrochemical potential. As compared to the homopolymer PFPMAm, the P(NIPAM0.9-co-FPMAm0.1) copolymer ingressed 2 orders of magnitude more water molecules per doping ion when electrochemically oxidized, as measured by electrochemical quartz crystal microbalance. P(NIPAM0.9-co-FPMAm0.1) exhibited a unique thermo-electrochemically reversible response and swelled up to 83% after electrochemical oxidation, then deswelled below its original size upon raising the temperature from 20 to 40 °C, as measured through spectroscopic ellipsometry. Reduced P(NIPAM0.9-co-FPMAm0.1) had an inhomogeneous depth profile, with layers of low solvation. In contrast, oxidized P(NIPAM0.9-co-FPMAm0.1) displayed a more uniform and highly solvated depth profile, as measured through neutron reflectometry. P(NIPAM0.9-co-FPMAm0.1) and PFPMAm showed almost a fivefold difference in selectivity for target ions, evidence that polymer hydrophilicity plays a key role in determining ion partitioning between solvent and the polymer interface. Our work points to new macromolecular engineering strategies for tuning ion selectivity in stimuli-responsive materials.

Ionophore-Based Polymeric Sensors for Potentiometric Assay of the Anticancer Drug Gemcitabine in Pharmaceutical Formulation: A Comparative Study.

Gemcitabine is a chemotherapeutic agent used to treat various malignancies, including breast and bladder cancer. In the current study, three innovative selective gemcitabine hydrochloride sensors are developed using 4-tert-butylcalix-[8]-arene (sensor 1), β-cyclodextrin (sensor 2), and γ-cyclodextrin (sensor 3) as ionophores. The three sensors were prepared by incorporating the ionophores with o-nitrophenyl octyl ether as plasticizer and potassium tetrakis(4-chlorophenyl) borate as ionic additive into a polyvinyl chloride polymer matrix. These sensors are considered environmentally friendly systems in the analytical research. The linear responses of gemcitabine hydrochloride were in the concentration range of 6.0 × 10-6 to 1.0 × 10-2 mol L-1 and 9.0 × 10-6 to 1.0 × 10-2 mol L-1 and 8.0 × 10-6 to 1.0 × 10-2 mol L-1 for sensors 1, 2, and 3, respectively. Over the pH range of 6-9, fast-Nernst slopes of 52 ± 0.6, 56 ± 0.3, and 55 ± 0.8 mV/decade were found in the same order with correlation regressions of 0.998, 0.999, and 0.998, respectively. The lower limits of detection for the prepared sensors were 2.5 × 10-6, 2.2 × 10-6, and 2.7 × 10-6 mol L-1. The sensors showed high selectivity and sensitivity for gemcitabine. Validation of the sensors was carried out in accordance with the requirements established by the IUPAC, while being inexpensive and easy to use in drug formulation. A statistical analysis of the methods in comparison with the official method showed that there was no significant difference in accuracy or precision between them. It was shown that the new sensors could selectively and accurately find gemcitabine hydrochloride in bulk powder, pharmaceutical formulations, and quality control tests. The ionophore-based sensor shows several advantages over conventional PVC membrane sensor sensors regrading the lower limit of detection, and higher selectivity towards the target ion.

Enhancing ion mobility spectrometry performance through a programmable ion swarm shaping method based on Bradbury-Nielsen gates

The ion gate is a critical element in drift tube ion mobility spectrometry (IMS) as it directly influences the resolving power and sensitivity of the system. However, the conventional Bradbury-Nielsen gate (BNG) often leads to deformation of the ion swarm shape, resulting in reduced resolving power and significant discrimination effects. To address these limitations, we propose a novel method that incorporates a cutting phase following the gate opening. This approach effectively reduces trailing edge deformation, resulting in a maximum resolving power of over 100 and increased signal intensity. Additionally, this method maintains high resolving power even during longer gate opening times. Remarkably, this method not only significantly reduces the mobility discrimination effect but also enables the achievement of reverse discrimination by adjusting the duration of the cutting phase. Consequently, it demonstrates the potential to selectively amplify the peak height of target ions. Our method offers straightforward implementation across all IMS systems utilizing the BNG, thereby significantly improving system performance.

Study on the production of hydrogen atomic beams by stripping negative hydrogen ions in a gas target

The neutralization process and beam quality of a hydrogen beam prepared by emitting 1–––10 MeV negative hydrogen ions to a hydrogen target were studied. The simulation of the neutralization of negative hydrogen ions followed the construction of the neutralization theoretical model and beam transport model. Finally, calculations and analyses were performed to determine the effects of various variableson the neutralization of negative hydrogen ions, such as the transport distance, energy, and target gas density. According to the findings, since negative hydrogen ions in the target gas are transmitted farther, neutralization efficiency first rises and then falls. To achieve the highest neutralization efficiency, the gas vessel must be thicker depending on the incoming negative hydrogen ions are more energetic. Conversely, the denser the target gas, the thinner the gas vessel must be. The maximal neutralization efficiency, however, is unaffected by the density of the target gas or the negative hydrogen ion energy.

Electrically Redox-Active Membrane with Switchable Selectivity to Contaminants for Water Purification.

Membrane technology provides an attractive approach for water purification but faces significant challenges in separating small molecules due to its lack of satisfactory permselectivity. In this study, a polypyrrole-based active membrane with a switchable multi-affinity that simultaneously separates small ionic and organic contaminants from water was created. Unlike conventional passive membranes, the designed membrane exhibits a good single-pass filtration efficiency (>99%, taking 1-naphthylamine and Pb2+ as examples) and high permeability (227 L/m2/h). Applying a reversible potential can release the captured substances from the membrane, thus enabling membrane regeneration and self-cleaning without the need for additives. Advanced characterizations reveal that potential switching alters the orientation of the doped amphipathic molecules with the self-alignment of the hydrophobic alkyl chains or the disordered sulfonate anions to capture the target organic molecules or ions via hydrophobic or electrostatic interactions, respectively. The designed smart membrane holds great promise for controllable molecular separation and water purification.

SRIM Simulation of Ion Beam Irradiation Effects on Oxide Thin Films

In recent studies, multifunctional oxide thin films have been given attention because of their special properties, such as ferroelectricity, gas sensitivity, and magnetism. Ion beam irradiation arose as a well-developed technique for tuning such properties. This study investigates the ion beam irradiation effects of He, Ni, and Kr ions on BiFeO3, SnO2, and ZnO thin films, respectively. The study utilized the 2013 version of Stopping and Range of Ions in Matter (SRIM) software to identify ion trajectory distribution and oxygen target vacancy differences on the Transport of Ions in Matter (TRIM) calculation types at various ion energies. A greater distribution of ion trajectories and higher peaks of oxygen target vacancies in oxide thin films were generated from monolayer TRIM than full cascade TRIM for all ion–thin-film pairs. The monolayer TRIM is preferable for ion beam irradiation of oxide thin films with its greater oxygen target vacancies and ion trajectory distribution for better analysis of ferroelectric coercive fields, adsorbed oxygen ions interaction with gas molecules, and the emergence of green emission for photoluminescence. The use of SRIM allows an alternative yet more flexible way of analyzing beam irradiation effects on oxide films considered in this work without resorting to costly or sophisticated experimental setups, which are a usual approach considered in most of the work under this topic. As such, the results presented here provide an initial or complementary basis should irradiation effect experiments require analysis of ion trajectories and oxygen vacancies.

Convenient high resolution mass spectrometry characterization of aromatic sulfur-containing petroleum components following by preliminary S-alkylation with aliphatic alcohols

This paper describes rather suitable and variable preliminary derivatization strategy that may precede the molecular level characterization of sulfur-containing compounds of a particularly aromatic nature by high-resolution MALDI and ESI mass spectrometry. We demonstrated for the first time that free aliphatic alcohols (primary 1-alkanols C3–C20) in the presence of triflic acid provide easy S-alkylation of not only saturated sulfides but also most typical aromatic sulfur-containing compounds (benzothiophene, dibenzothiophene and their homologues) widely distributed and frequently analyzed in oil. The reaction proceeds quantitatively at rather mild conditions and gives rise to corresponding S-alkyl sulfonium salts the cation moieties of which can be detected using MALDI and ESI mass spectrometry with excellent signal/noise (S/N) ratios; the response ratios for target ions being quite close for both methods. Collision-induced dissociation (CID) of S-alkylsulfonium cations proceeds only by the elimination of entire S-alkyl group yielding protonated molecule of the analyte. This process can be useful for a reliable determination of target aromatic heterocyclic compounds in complex mixtures. The applicability of the method is illustrated by the analysis of deasphalted medium petroleum sample. The proposed derivatization principle is considered to be highly applicable as an alternative approach to routine characterization and sensitive determination of most typical sulfur-containing compounds and particularly of aromatic S-heterocycles in crude oils by soft-ionization mass spectrometry methods.

An Overview of Current Biomarkers, the Therapeutic Implications, and the Emerging Role of hERG1 Expression in Gastric Cancer: A Literature Review.

Gastric cancer remains one of the most commonly diagnosed cancers in the world. It carries a high mortality rate, with cases being more prevalent in the developing world, and has been linked to diet and Helicobacter pylori infection. It is a highly heterogeneous disease, with most cases being of a sporadic nature. Most patients present at an advanced stage due to the asymptomatic nature of the early stages of the disease. A multidisciplinary approach is often best implemented to help decide how to best manage individual cases. However, the overall clinical outcome and survival of patients with advanced gastric cancer remain poor. Recent therapeutic advancements focus on the identification of molecular biomarkers associated with gastric cancer that have predictive, diagnostic, and prognostic implications. This enables the development of specific targeted therapies that have shown efficacy in numerous trials, either as monotherapy or in combination with standard chemotherapy. Despite this, tumour heterogeneity and treatment resistance are still issues leading to poor survival outcomes. An emerging approach is focusing efforts on the bidirectional crosstalk between tumour cells and the microenvironment through targeting ion channels. A key player in this is human ether-á-go-go-related gene 1 (hERG1). This voltage-gated potassium ion channel has been shown to have predictive, diagnostic, and prognostic significance, enabling the stratification of high-risk individuals. In addition, targeting hERG1 in combination with chemotherapy has been shown to potentiate tumour regression. This comprehensive literature review will aim to consolidate our understanding of current biomarkers in gastric cancer. The relevance of hERG1 in gastric cancer as a useful novel biomarker and the potential therapeutic implications as targeted therapy will be explored. This offers a new and personalised approach to helping to manage patients with gastric cancer.

Synthesis of 1,5-diphenylcarbazone-functionalized epoxy-activated agarose and its application as a highly efficient adsorbent for Hg2+, Cd2+, and Pb2+ ions

The real applicability of an adsorbent for the removal of heavy metal ions from large volumes of polluted waters critically depends on its cost, capacity, selectivity, and level of environmentally friendly nature of it. In this regard, an epichlorohydrin-activated agarose adsorbent was synthesized and functionalized by 1,5-diphenylcarbazone for the selective removal of Hg2+, Cd2+, and Pb2+ ions from aqueous solutions. The physicochemical properties of the adsorbent were characterized using FT-IR, FE-SEM, EDS, and BET analysis. The total pore volume and the specific surface area of the synthesized adsorbent were measured to be 0.023 m3.g−1 and 39 m2.g−1, respectively. The experimental maximum absorption capacities for Hg2+, Cd2+, and Pb2+ were obtained to be 307, 311, and 305 mg.g−1, respectively. In addition, the color of the adsorbent is changed during the adsorption of ions, thus this adsorbent can act as dual-function material for both the detection and adsorption of heavy metal ions. The adsorption isotherm and kinetics were well-fitted with the linear Freundlich and the linear pseudo-second-order models, respectively. The synthesized adsorbent was able to selectively adsorb target ions in the presence of possible interfering ions such as Fe3+, Fe2+, Al3+, Ca2+, K+ and Na+.

Nanochannel characteristics contributing to ion/ion selectivity in two-dimensional graphene oxide membranes

Selective ion/ion transport is of great importance in environmental and energy applications. Nanofiltration membranes possessing sub-nanometer pore sizes and charge characteristics have garnered significant attention in effectively separating target ions. Nevertheless, the contributions of pore size, charge, and their combined impact on ion/ion separation have remained relatively unexplored. In this study, a well-defined example is presented using multilayered graphene oxide membranes with ordered interlayer nanochannels. These membranes were utilized to prepare diverse nanochannel types, each possessing distinct channel sizes and charge properties. A systematic investigation was conducted to discern their separation selectivity for mono-/di-valent ion pairs. The dominant factor governing mono-/di-valent ion selectivity was not found to be the channel pore size within the sub-nanometer scale. This could be because nanochannels are flexible and cannot strictly sieve ions based on their specific size. Instead, the difference in electrostatic effects between mono- and di-valent ions plays a more significant role in enhancing ion/ion selectivity within the subnanometer channel. This study offers certain insights into selective ion transport in two-dimensional membrane nanochannels, potentially assisting in the design of nanochannels with single-ion selectivity.