Adsorption Of Ions Research Articles

Activated carbon fibers derived from waste textiles for the removal of lead ions from water

Activated carbon fibers (ACFs) demonstrate exceptional performance across a range of applications, including environmental remediation and energy storage. However, significant challenges, such as high production costs and low yield, hinder their widespread adoption. In light of the substantial global generation and inefficient recycling of textile waste, this study aimed to enhance resource valorization and promote environmental sustainability through the conversion of waste textiles into activated carbon fibers (W-ACFs). The research successfully synthesized W-ACFs, which exhibit physical and chemical properties comparable to those of commercial activated carbon fibers (C-ACFs). When applied to the adsorption removal of lead ions in water, W-ACFs showed similar lead ion adsorption efficiency to C-ACFs at low concentrations. Although the adsorption capacity of W-ACFs reached approximately 70% (adsorption capacity of nearly 62 mg g−1) of that of C-ACFs at high initial concentrations, it nonetheless exhibited significant application potential. The production efficiency and adsorption performance of W-ACFs were further enhanced by optimizing key preparation parameters, including pre-oxidation temperature, carbonization activation temperature, and the dosage of chemical activating agents. This research not only provides an effective adsorbent material for water treatment but also introduces a novel approach to waste recycling and environmental remediation, thereby achieving the dual objectives of economic efficiency and environmental protection.

Harnessing C@Zn@TiO2 nanocomposites for cadmium adsorption in aquatic media

ABSTRACT In this work, the elimination of Cd+2 ions in aqueous solution using carbon/Zn/TiO2 nanoparticles, synthesised by sol – gel based Pechini method at intermediate temperature, was studied. The synthesised C@Zn@TiO2 was characterised by SEM, TEM, EDX, XRD, BET, and XPS techniques to verify the formation of semi-spherical nanoparticles with dominant anatase TiO2 phase and elemental composition of the expected elements. Concurrently, the impact of the solution pH, pHpzc, contact time, adsorbent dose, and initial ions concentration were discussed. The findings revealed that at pH 7.0, a maximum of 174 mg. g−1 of Cd+2 ions were adsorbed at 120 minutes of equilibrium time. The Langmuir and pseudo-second-order models appropriately fitted the isotherm and kinetics data. The intraparticle model analysis indicated that film diffusion controls the adsorption of metal ions adsorption at the initial stage and, the intraparticle diffusion at the second stage. The FTIR and XPS analysis further proved Cd+2 ions being adsorbed onto the surface via an electrostatic mechanism. The fabricated nanostructure could be recycled and reused four times with a high competence above 71.5%. The facile synthesis, low cost, harmlessness, and remarkable removal efficiency make the C@Zn@TiO2 a promising material for treating heavy metal-contaminated water.

Single-atom lead ion adsorption behavior on Ti2CO2 MXene under different electrode potentials.

First-principles calculations, particularly density functional theory (DFT) combined with D3 dispersion correction (DFT+D3), have proven to be valuable tools in simulating the adsorption of lead ions on Ti2CO2 surfaces. However, conventional theoretical models assume electrically neutral systems under vacuum conditions, neglecting the solvent environment and electrode potential's crucial effects. This study employed an implicit solvent model, treating the solvent as a continuous and homogeneous medium to capture the influence of different solvents by varying their dielectric constants. Additionally, the role of electrode potential on the adsorption behavior of lead ions on Ti2CO2 surfaces was explored. The findings demonstrated that electrode potential significantly affected lead ion adsorption with adsorption strength increasing as the electrode potential decreases. This observation was supported by electronic structure analyses, such as the density of states, band structure and ICOHP. This study provides important insights into the influence of electrode potential on metal ion adsorption on MXene materials, offering a theoretical foundation for the design and optimization of MXene-based adsorbents for environmental applications.

Progress on layered double hydroxides as green materials in sustainable agricultural production.

As the global population continues to grow, there is increasing demand for high-quality and high-yield food. However, traditional agrochemicals such as fertilizers and pesticides suffer from low utilization rates and can be hazardous to non-target organisms and the soil environment. Two-dimensional layered double hydroxides (LDHs) have attracted considerable attention in the agricultural sector owing to their excellent properties. To alleviate the general concern about the use of LDH materials in combination with agrochemicals, this paper presents a comprehensive overview of the structure, properties, preparation methods, and cytotoxicity of LDHs, with a focus on the advantages and disadvantages of different synthesis methods. In addition, the current research status of the application of LDHs as green materials in modern agricultural production is presented, and the applications of nano fertilizers for promoting crop growth, nano pesticides for efficient herbicide and insecticide, efficient adsorption of pollutants and soil heavy metal ions to maintain soil stability, and applications in genetic modification and enhancement of plant photosynthesis are discussed in detail. Finally, future research directions for LDH are envisioned. We hope that this study will promote the use of LDH materials in agricultural practices.

Boosting Capacitive Deionization in MoS2 via Interfacial Coordination Bonding and Intercalation-Induced Spacing Confinement.

Capacitive deionization (CDI) is a green and promising technology for seawater desalination, with its capacity and industrial application being severely hindered by efficient electrode materials. Layered molybdenum disulfide (MoS2) has garnered significant attention for CDI applications, while its performance is hampered by weak surface hydrophilicity, high interfacial resistance, and sluggish electron transport. Herein, we introduce an interfacial and intercalation dual-engineering strategy by covalently functionalizing the hydrophilic pyridine groups within the 1T-MoS2 layer (Py-MoS2); an electron-rich interface with an expanded interlayer spacing has been achieved synergistically. A state-of-the-art high desalination capacity of 43.92 mg g-1 and exceptional cycling stability have been achieved, surpassing all of the reported existing MoS2-based CDI electrodes. Comprehensive characterization and theoretical modeling reveal that covalently engineered pyridine groups enhance ion affinity via interfacial coordination, accelerate charge transfer, and expand ion-accessible sites within the MoS2 interlayer spacing through intercalation-induced structural modulation. These synergistic effects dramatically boost the ion adsorption kinetics, mass transfer efficiency, and salt ion uptake capacity within Py-MoS2 for CDI application. Our work presents an interfacial and intercalation dual-engineering strategy to promote the seawater desalination of 2D materials, paving new insights for next-generation high-performance CDI electrode development.

Isotherms, Kinetics and Thermodynamics of Removal of Pb (II), Cd (II) and Cr (III) Ions in Wastewater onto Green Silver Nanoparticle Adsorbent

Moringa oleifera leaf extract mediated silver nanoparticles (MOR-AgNPs) were synthesized from a water-soluble leaf using a green technique. The plant's secondary metabolites served as capping and reducing agent. The spectroscopic characterization of the material was carried out by means of Scanning Electron Microscope (SEM), Ultraviolet-Visible Spectroscopy (Uv-vis), X-ray Diffraction Spectroscopy (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Transition Electron Microscope (TEM), Energy Dispersion Spectroscopy (EDS), and Dynamic Light Scattering (DLS). The UV–Vis spectrum showed absorption peak between 400 – 500 nm, while TEM revealed spherical images of sizes in the nano region. The MOR-AgNPs adsorbent uptake of the metal ions was optimized by varying concentration, shaking time, adsorbent mass, pH, and temperature conditions. The isotherm models studies revealed that the type-1 Langmuir fitted well to the adsorption showing monolayer/homogeneous adsorption. The second order kinetics fitted well to the adsorption study, while positive values of ΔH° and ΔS° indicated endothermic and increased randomness at the MOR-AgNPs-aqueous interface. The ΔG° showed that the sorption of the metal ions onto the adsorbent was spontaneous, making the adsorption process feasible. The Ea values for the metal ion adsorption onto the adsorbent used in this study suggest a physical adsorption process. The adsorption capacity of 294.15 mg/g (40 °C, and pH of 6) of Cd(II), 123.63 mg/g (40 °C, and pH 10) of Pb(II), and 122.93 mg/g (40 °C, and pH 6) of Cr (III) ions on MOR-AgNPs adsorbent were obtained.

Drug-loaded Fe3O4/lignin nanoparticles to treat bacterial infections.

Lignin is a biopolymer employed for various biomedical applications. Nevertheless, the drug loading and release mechanism of Fe3O4 nanoparticles with surface functionalization by lignin has yet to be described. Hence, this study functionalizes Fe3O4 nanoparticles surface with lignin (Fe3O4/Lig) for ciprofloxacin delivery and examines its adsorption-release mechanisms. The presence of lignin and ciprofloxacin on Fe3O4 nanoparticles were verified using FT-IR that shows distinct peaks for each functional group of lignin and ciprofloxacin. The study has proved selective adsorption of ciprofloxacin ions via electrostatic interactions. The optimal adsorption efficiency in the examined region was 65%, with a capacity of 9.55mg/g. Drug release efficiency was evaluated in buffer at pH7.4 and pH1.2-6.8, yielding ∼66% and ∼100%, respectively. The release profile fits Peppas's model, which uses a diffusion and disintegration mechanism. Furthermore, the HET-CAM model study presented that the substance does not irritate the cell membranes of the egg, indicating that it is safe for mucosa and tissues. The IC50 value for antibacterial activity against Gram-negative Salmonella enterica and Escherichia coli was 10.00±0.76μg/mL and 1.87±0.06μg/mL, respectively. In summary, the study effectively prepared Fe3O4/Lig-CIP nanoparticles, as well as remained antibacterial properties against both Gram (+) and Gram (-) microorganisms.

Nanocellulose-based aerogels for the adsorption and removal of heavy-metal ions from wastewater: A review

Nanocellulose-based aerogels for the adsorption and removal of heavy-metal ions from wastewater: A review

Study on the preparation of polyurethane foam and adsorption of gallium ions in gangue acid leach solution

Study on the preparation of polyurethane foam and adsorption of gallium ions in gangue acid leach solution

Surface-functionalized polydimethylsiloxane sponges for facile and selective recovery of molybdenum from aqueous/acidic solutions.

The present study fabricated two types of surface-functionalized polydimethylsiloxane sponges (amine-functionalized and extractant-impregnated), and investigated their applicability as a novel separation-recovery method for molybdenum ion (Mo(VI)) in aqueous and HNO3 solutions. An amine-functionalized polydimethylsiloxane (PDMS) sponge was prepared using glycine hydrochloride as a functional ligand, called the Glycine-PDMS sponge, and bis(2-ethylhexyl) phosphate (HDEHP) and 2,2'-(Methylimino)bis(N,N-di-n-octylacetamide) (MIDOA) were used as extractants for the extractant-impregnated sponges, called the HDEHP-PDMS and MIDOA-PDMS sponges, respectively. The adsorption and desorption of Mo(VI) were demonstrated by facile soaking and squeezing of the sponges, which is unavailable in conventional adsorbents. Each PDMS sponge enabled selective Mo adsorption in aqueous and acidic solutions, and had different ligand and HNO3 concentration dependence of the Mo(VI) adsorption capacities. The pseudo-second-order kinetic model was found to be applicable for the Mo(VI) adsorption process on the sponge surfaces. A regression analysis of the isothermal adsorption curves for Mo ions clarified that the adsorption of Mo ions onto all PDMS sponges occurs spontaneously, and that Mo(VI) adsorption mechanism is different depending on sponges; chemisorption for extractant-impregnated sponges and physisorption for an amine-functionalized, respectively. Furthermore, the squeezing of the Mo ion adsorbed PDMS sponges allowed the rapid desorption and recovery of Mo ions into eluent solutions such as deferoxamine B (DFOB) and H2O2 within a few minutes. These results prove that the novel PDMS sponge approach, enabling facile chemical-mechanical adsorption and desorption control of target elements, has great potential in various fields involving the environment, medicine, energy, and so on.

Theoretical investigation of adsorptive nitrate ion removal by pure graphene, Mo-decorated graphene and reduced graphene oxide based adsorbents: a DFT study

Density functional theory (DFT) calculations were used to investigate the efficacy of pure graphene (G), Mo-decorated graphene and Mo-decorated reduced graphene oxide (rGO) in removing nitrate anion (NO3 −) pollutants. Initially, the adsorption mechanism was analyzed to identify the most probable position of nitrate adsorption through optimized geometries, adsorption energy, bond length and electronic structures. Subsequently, a comprehensive analysis was executed to examine the adsorption properties of the NO3 − anion. Analyses of the adsorption energy, charge density difference and density of states indicated that defect sites, functional groups and Mo-atom decorations in graphene could significantly enhance the nitrate adsorption energy. The results indicated that the adsorption mechanisms of the NO3 − anion on pure G, Mo-decorated G and Mo-decorated rGO were different. NO3–Mo-decorated rGO demonstrated the highest adsorption energy. Conversely, NO3–pure G exhibited the lowest adsorption energy, while the NO3–Mo-decorated G showed the highest Fermi energy. Bader and projected density of states analyses suggest that the orbitals in the NO3–Mo-decorated G structure occupy the largest share in the valence band compared with the NO3–Mo-decorated rGO structure, which led to high electron accumulation. Consequently, the NO3–Mo-decorated rGO structure allows the complete absorption of nitrate, resulting in the breaking of chemical bonds. These results indicate that the NO3–Mo-decorated rGO structure has the highest nitrate absorption energy among the studied structures.

Effects of the Ion Exchange and Adsorption Behavior of Clinoptilolite on Chloride Solidification in Cement Paste

Effects of the Ion Exchange and Adsorption Behavior of Clinoptilolite on Chloride Solidification in Cement Paste

Removal of fluoride from wastewater with the Mg/Al impregnated adsorbent prepared from Chinar leaves: Adsorption isotherm, kinetic and thermodynamic studies.

The present study focuses on creating a novel functionalized adsorbent AC-Al-Mg-La for the extraction of fluoride ions from wastewater. The characterizations of the adsorbent were analyzed before and after modification by employing the techniques such as FTIR, XRD, SEMand zeta potential. The suggested adsorbent materials were evaluated for their effectiveness in treating fluoridated water. The impacts of the adsorbent dosage, initial pollutant level, water pH, and regeneration efficiency were assessed. Fluoride ion adsorption was highest at the optimal conditions of pH 4.0 ± 0.1; 30 minutes contact time, and a 0.15 g/L adsorbent dose. However, adsorption efficiency decreased at higher pH levels.At pH 4.0 ± 0.1, the peak adsorption efficiencies observed after 30 minutes of contact time with 0.15 g/L of the adsorbent dose were 72% for AC-La, 81% for AC-Al, 89% for AC-Mg, and 96% for AC-Al-Mg-La. The analysis of the AC-Al-Mg-La material's regeneration capabilities showed that, even after five consecutive cycles of adsorption and regeneration, it maintained decontamination potential of 71% after first cycle and reduced to 41% after fifth regeneration, representing a 30% reduction in effectiveness. This paper intends to encourage novel ideas and advancements in the creation of the next generation of eco-friendly adsorbent for defluorination.

Probabilistic prediction of phosphate ion adsorption onto biochar materials using a large dataset and online deployment.

Phosphate (PO4(III)) contamination in water bodies poses significant environmental challenges, necessitating efficient and accurate methods to predict and optimize its removal. The current study addresses this issue by predicting the adsorption capacity of PO4(III) ions onto biochar-based materials using five probabilistic machine learning models: eXtreme Gradient Boosting LSS (XGBoostLSS), Natural Gradient Boosting, Bayesian Neural Networks (NN), Probabilistic NN, and Monte-Carlo Dropout NN. Utilizing a dataset of 2952 data points with 16 inputs, XGBoostLSS demonstrated the highest R2 (0.95) on new adsorbents. SHapely Additive exPlanations analysis showed that adsorption experimental conditions had the most significant impact (43%), followed by synthesis conditions (29%) and adsorbent characteristics (28%). Optimized conditions included an initial PO4(III) concentration of 125mg/L, carbon content of 11.5%, oxygen content of 23%, a contact time of 1440min, a heating rate of 5°C/min, 200rpm, and a surface area of 410m2/g, using Ra-LDO adsorbent synthesized from rape cabbage feedstock. This study developed and presented a practical online framework for predicting PO4(III) removal onto biochar using a web-based graphical user interface.

Zn2+ adsorption in ferric-silicates microstructures in sulfidic tailings mediated through mineral weathering by Acidithiobacillus species.

Heavy metals released from metallic sulfidic tailings pose significant environmental threats by contaminating surface and groundwater in mining areas. Sustainable rehabilitation methods are essential to remove or stabilize these metals, improving the quality of acid mine drainage and minimizing pollution. This study examines the adsorption capacity of zinc ions (Zn2+) by different iron-silicate mineral groups under natural weathering and bacteria-regulated weathered conditions. Batch experiments revealed that all tested mineral groups exhibit limited adsorption Zn2+ on iron-silicate surfaces, with adsorption behavior aligning with Langmuir and Freundlich isotherm models. Among the mineral groups, pristine iron-muscovite (2.58mg/g) and iron-chlorite (4.52mg/g) demonstrated the highest Zn2+adsorption capacity, primarily due to favorable ion exchange properties and surface characteristics. Acidic conditions induced by pyrite oxidation and the experimental growth medium slightly reduced Zn2+ adsorption in samples without microbial inoculation. In contrast, the addition of Acidithiobacillus species modestly enhanced Zn2+ adsorption, likely through microbial alteration of silicate surface properties and the formation of secondary iron-silicate aggregates with high adsorption potential. The dominant adsorption mechanisms included electrostatic attractions, surface complexation and coprecipitation. It is recommended to elevate pH levels and thus enhance metal ion adsorption through the incorporation of alkaline additives such as zeolites or bauxite residue to optimize Zn2+ immobilization in sulfidic tailings. This study highlights the importance of both microbial and clay mineral selection in designing effective strategies for stabilizing Zn2+ in metallic sulfidic tailings.

Modelling of a new form of nitrogen doped activated carbon for adsorption of various dyes and hexavalent chromium ions

This study reports a new form of nitrogen-doped activated carbon (AC5-600) produced from a blend of sawdust (SD) and fish waste (FW) treated with urea and ZnCl2 for the adsorption of toxic metals and dyes. The adsorbent was also explored in the treatment of acid brown 14 (AB14) and acid orange 7 (AO7) dye molecules and hexavalent chromium (Cr6+) ions. The pH controls the sorption of individual contaminants, with an observed superlative % of individual contaminants removed at pH 1.5. Removal at pH was credited to the electrostatic interaction (EI) between the anion dyes and Cr6+ species at this pH and the protonated sites accessible on the AC5-600 adsorbent surface. Based on the error values obtained from the non-linear modelling (NLM) of the kinetic and isotherm models, the Elovich (ELM-AB14 and Cr6+), pseudo-first- (PFOM-AB14) and second-order models (PSOM-AB14, AO7 and Cr6+) and the Freundlich (FRHM) model were found to ideally define the sorption of the various contaminants. The determined maximum sorption capacity (Qm) based on the NLM was 1114, 1929 and 318 mg.g-1 for AB14 dye, AO7 dye and Cr6+ ions, respectively. Based on the computational adsorption calculations, the sorption energies for the AO7 and AB14 dyes were -4.492 and -8.090 eV and 2.563, 1.789, 1.226 and 1.928 eV for Cr2, CrO3, CrO4, and CrO4H species. AB14 and AO7 dyes and Cr6+ ions adsorption to synthesised AC5-600 was predicted employing the response surface methodology (RSM) and artificial neural network (ANN) models. The ANN model was more effective in predicting AB14 and AO7 dyes and Cr6+ ions adsorption than the RSM, and it was highly applicable in the sorption process.

Ultrafast Li-Rich Transport in Composite Solid-State Electrolytes.

Solid-state lithium (Li) metal batteries (SSLMBs) have garnered considerable attention due to their potential for high energy density and intrinsic safety. However, their widespread development has been hindered by the low ionic conductivity of solid-state electrolytes. In this contribution, a novel Li-rich transport mechanism is proposed to achieve ultrafast Li-ion conduction in composite solid-state electrolytes. By incorporating cation-deficient dielectric nanofillers into polymer matrices, it is found that negatively charged cation defects effectively intensify the adsorption of Li ions, resulting in a high Li-ion concentration enrichment on the surface of fillers. More importantly, these formed Li-rich layers are interconnected to establish continuous ultrafast Li-ion transport networks. The composite electrolyte exhibited a remarkably low ion transport activation energy (0.17eV) and achieved an unprecedented ionic conductivity of approaching 1×10⁻3Scm⁻1 at room temperature. The Li||LiNi0.8Co0.1Mo0.1O2 full cells demonstrated an extended cycling life of over 200 cycles with a capacity retention of 70.7%. This work provides a fresh insight into improving Li-ion transport by constructing interconnected Li-rich transport networks, paving the way for the development of high-performance SSLMBs.

Inhibition of manganese ion migration and dissolution by selective ions sieving effect of MOF-based solid electrolytes.

Lithium manganese oxide (LiMn2O4) is a promising cathode material for Li-ion batteries due to its abundant reserves and high discharge voltage. However, the dissolution and migration of transition metal Mn ions during the cycling process will cause a significant deterioration of capacity. In this study, a MOF-based quasi-solid electrolyte (UiO-QSE) is proposed to tackle this issue. The large specific surface area and open metal sites of UiO-QSE facilitate the adsorption of Mn ions, thereby inhibiting their migration. Furthermore, the disproportionation of Mn3+ on LiMn2O4 is suppressed by maintaining a highly concentrated Mn2+ layer around the cathode surface, thereby providing cathode protection in accordance with Le Chatelier's principle. The excellent inhibitory effect of UiO-QSE on the dissolution and migration of Mn ions is reflected in the fact that the prepared LiMn2O4|UiO-QSE|Li battery exhibits high discharge capacity (100.2mAh·g-1 after 100 cycles), which is much higher than LiMn2O4|LE|Li (78.1mAh·g-1), and a high capacity retention of 97.91% after 50 cycles at a high-temperature of 45°C. The Li|Li symmetrical cell exhibits an ultralong cycle life of more than 1300h even at a high current density of 1mA cm-2 due to the uniform Li-ion transport channel and high Young's modulus in the UiO-QSE. This study is the first to employ the MOF-QSE strategy to inhibit the dissolution and migration of manganese during cycling, providing a new perspective on the development and enhancement of lithium-manganese-based batteries.

Combination of lime stone and fly ash in the adsorption of iron (Fe) metal from coal acid mine drainage

Coal mining activities often produce acid mine drainage characterized by low pH values below 5 and high concentrations of heavy metals including iron (Fe). If the water is not managed properly, it can impact the environment due to the influence of acidity and high concentrations of dissolved metals. This research aims to utilize the combination of activated limestone and fly ash by heating at 110°C for 3 hours for acid mine drainage treatment, namely neutralizing pH and adsorbing heavy metal Fe. The selection of adsorbent materials was based on economic considerations, abundant availability, and utilization of fly ash waste. The method used was batch adsorption experiments with contact times of 30 and 60 minutes. Acid mine drainage from coal mine with initial pH 4.55 and Fe metal concentration 7.58 mg/L. The adsorbent combination of limestone and fly ash in the ratio of 1:1, 1:2, and 2:1. From the experimental results, it was obtained that the adsorbent combination was able to neutralize pH up to 6 and remove Fe up to 1.35 mg/L was the ratio of 1:2 with a stirring time of 30 minutes. So it can be concluded that adding fly ash dose 2 times compared to the dose of limestone is more effective to raise the pH value and remove Fe heavy metal, because the higher the dose given, the more ion adsorption sites will be available

Nanostructured Quasiplanar Heterointerface for a Highly Stable and Ultrafast Switching Flexible Inorganic Electrochromic Smart Window.

Electrochromic (EC) technology can adjust optical properties under electrical stimulation with broad applications in smart windows, displays, and camouflage. However, significant challenges remain in developing inorganic EC films with high durability, rapid response, and mechanical flexibility due to intrinsic brittleness and dense microstructure. Herein, a nanostructured quasiplanar heterointerface (Q-PHI) is first introduced into the electrode/EC interlayer to realize a robust, ultrafast switching tungsten trioxide (WO3) EC film. The 200 nm-thick Q-PHI WO3 film exhibits remarkable EC performance, including large optical contrast (81.8% and 83.4% at 700 and 1500 nm), ultrafast switching of 2.4 and 1.8 s, and excellent stability (10,000 cycles with 21.3% optical-contrast loss). A large-area (20 × 15 cm2) flexible EC smart window is also successfully achieved. The mechanism lies in the intense built-in electric field and strong interfacial bonding induced by the Q-PHI with unique longitudinal gradient distribution, greatly enhancing the electron/ion transport kinetics, surface ion adsorption, and durability.