Diffusion Of Metal Ions Research Articles

Modeling the Process of Sorption for the Purification of Waste Water from Petroleum Products and Heavy Metals

Fixed-bed adsorption is widely applied for the purification of liquid mixtures, including industrial waste water. The adsorption purification of waste water from petroleum products and heavy metals with the use of peat is modeled. A process model taking the longitudinal stirring of the liquid-phase flow, the outer- and inner-diffusion resistance of flow in sorbent grains, and the phenomena of adsorption on the peat surface into account is constructed. The results of experimental studies are presented. The effect of the abnormal diffusion of heavy metal ions in peat has been revealed and explained. Based on these studies, the isotherm of petroleum product adsorption from waste water and the change in the mass transfer coefficient depending on the adsorption value were plotted. The effect of chemical kinetics on the ion-exchange rate has been experimentally determined. The experimental curves of the adsorption of heavy metal ions are processed using the equations of diffusion and chemical kinetics. Based on these results some conclusions have been made.

Chitosan-Glycerol Gel as Barrier Formulation for Metal Allergy.

Metal-induced allergic contact dermatitis, particularly nickel, affects over 10% of the general population. Herein, chitosan–glycerol gel as protective barrier formulation was synthesized by neutralization reaction with an aim to reduce metal-ion diffusion into the skin to prevent allergy. Active functional groups in chitosan–glycerol gel were able to capture allergenic metal ions present in artificial sweat solution. The efficacy of the barrier formulation against nickel-ion penetration was evaluated ex vivo using pig skin. We found that the percutaneous absorption of nickel ion reduced by ∼98% when chitosan–glycerol gel was used as a barrier formulation.

Interplay between grain boundary diffusion and annealing temperature on the conductivity of NiO coated Samarium doped ceria

Elemental diffusion in ceramics can modulate the conductivity as well as fuel cell performance. Here, we report the effect of diffusion on NiO coated samarium doped ceria (SDC) with temperature and correlated with conductivity. NiO thin film was deposited using electron beam physical vapor deposition over the pre-sintered SDC substrate and subsequently treated at 800 °C, 1000 °C, and 1200 °C. Depth profiling analysis across NiO-SDC hetero-interface using FESEM-EDAX revealed that the width of the diffusion zone increased with temperature. All the constituent ions like Ni, Sm and Ce diffuse mutually without forming any impurity phases at the NiO-SDC interface. The estimated diffusivity values demonstrated that the nickel predominantly diffuses through the grain boundary of SDC. The constituent cations were found to diffuse several hundred nanometers through grain boundaries at a temperature of 1200 °C. An increase in the electrical conductivity was observed in proportion to the width of the diffusion layer. The diffusion of nickel predominantly along the grain boundary reduced the grain boundary resistance by altering the space charge potential at the NiO-SDC interface. Our study demonstrates that the modification of grain boundary through the controlled diffusion of metal ions reduce the resistance for oxygen ion transport in NiO-SDC electrolyte.

Molten alkali carbonates pyrolysis of digestate for phenolic productions

Molten alkali carbonates (MC) pyrolysis technology is proposed to dispose digestate waste and convert it into high value-added phenolics in this work. The results showed that temperature strongly affected phenolic production by promoting the depolymerization of lignin, while particle size had less influence on phenolic productions owing to the catalysis and dynamic diffusion of alkali metal ions. Meanwhile, the effect of mass ratio between sample and molten carbonates was investigated by a series of differentiated proportions from 5 to 25%. The optimum reaction conditions were 10% of mass ratio in a particle size from 0.6 to 0.85 mm at 450 °C, with the maximum phenolics yield of 67.08% in organic. In sum, 5.6 g of phenolics and 0.96 g of guaiacols were generated from 100 g of digestate. Compared with conventional pyrolysis method, the methoxyl group in liquid product could be efficiently removed at atmosphere in molten carbonates. Additionally, thermogravimetric analysis further demonstrated that alkali metal ions (Li+, Na+ and K+) promoted the primary degradation of lignin and secondary monomolecular dissociation reactions of methoxyphenol.

Hybrid dynamic windows using reversible metal electrodeposition and ion insertion

Dynamic windows with electronically controlled transmission reduce glare without obstructing views while increasing the energy efficiency of buildings and automobiles via lighting, heating and cooling savings. Electrochromic materials, which change colour with voltage, are widely explored for use in dynamic windows, but they have not been extensively commercialized due to problems associated with colour, cost, switching speed and durability. Here, we develop a class of dynamic windows that combines reversible metal electrodeposition with ion insertion chemistry. These devices function through the reversible electroplating of Bi and Cu at the working electrode and Li+ insertion in a nickel oxide counter electrode. In one minute, 100 cm2 windows uniformly switch between a clear state with 75% transmission and a colour-neutral black state possessing 10% transmission, which represents a significant improvement over previous metal-based architectures. We demonstrate that these hybrid windows cycle at least 4,000 times without degradation and are compatible with flexible substrates. Lastly, we discuss how this approach can be used to design practical large-scale windows. Metal-based smart windows allow for light and heat transmission control but suffer from poor metal ion diffusion over large areas. Here, the authors demonstrate a 100 cm2 window that is uniformly switchable from clear to black in 60 s by combining reversible metal electrodeposition with ion insertion.

Steam Oxidation of Austenitic Heat-Resistant Steels TP347H and TP347HFG at 650⁻800 °C.

Steam oxidation of austenitic heat-resistant steels TP347H and TP347HFG at 650–800 °C was investigated. Comprehensive micro-characterization technologies containing Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) were employed to observe and analyze the oxidation products. Results show that breakaway oxidation behaviors were observed on TP347H at 700 °C and 800 °C. The oxidation kinetics of TP347HFG at 650–800 °C followed a parabolic law. The oxide scales formed on TP347HFG were composed of MnCr2O4 and Cr2O3. A thin and protective Cr-rich oxide scale was replaced by Fe2O3 nodules due to the insufficient outward migration of metallic ions, including Cr and Mn at the subsurface of coarse-grain TP347H. Smaller grain of TP347HFG promoted the formation of the compact Cr-rich oxide scales. At higher temperatures, the incubation period for breakaway oxidation of the Cr-rich oxide scale was much shorter because of quick evaporation of the Cr2O3 oxide scale and the slower outward diffusion of metallic ions via the grain boundaries.

New Insights into the Electrochemistry Superiority of Liquid Na-K Alloy in Metal Batteries.

The significant issues with alkali metal batteries arise from their poor electrochemical properties and safety problems, limiting their applications. Herein, TiO2 nanoparticles embedded into N-doped porous carbon truncated ocatahedra (TiO2 ⊂NPCTO) are engineered as a cathode material with different metal anodes, including solid Na or K and liquid Na-K alloy. Electrochemical performance and kinetics are systematically analyzed, with the aim to determine detailed electrochemistry. By using a galvanostatic intermittent titration technique, TiO2 ⊂NPCTO/NaK shows faster diffusion of metal ions in insertion and extraction processes than that of Na-ions and K-ions in solid Na and K. The lower reaction resistance of liquid Na-K alloy electrode is also examined. The higher b-value of TiO2 ⊂NPCTO/NaK confirms that the reaction kinetics are promoted by the surface-induced capacitive behavior, favorable for high rate performance. This superiority highly pertains to the distinct liquid-liquid junction between the electrolyte and electrode, and the prohibition of metal dendrite growth, substantiated by symmetric cell testing, which provides a robust and homogeneous interface more stable than the traditional solid-liquid one. Hence, the liquid Na-K alloy-based battery exhibits to better cyclablity with higher capacity, rate capability, and initial coulombic efficiency than solid Na and K batteries.

On‐Site Surface Coordination Complexation via Mechanochemistry for Versatile Metal–Phenolic Networks Films

AbstractThe development of functional metal–phenolic networks (MPNs) films by a simple and green strategy on metallic plane substrates for surface modification is a big challenge. Herein, tribochemistry, as an effective and robust method to prepare MPNs films with versatile applications and controllable thickness (≈1.5 nm to 2.2 µm) by surface coordination complexation derived from tannic acid (TA) and metal oxides or ions (M) on plane substrates, is reported. The mechanism of the formation of TA‐M films is investigated in detail, showing that films are constructed by two‐layer structures. At the bottom of films, the chelation of TA active moieties and M is triggered by friction, facilitating the coating growth and reducing the friction coefficient. There is a downward trend in the concentration of M with the thickness of films increasing, which is attributed to the diffusion of metal ions. As a result, the dominant structure of films changes into the hydrogen bonding or π–π stacking interaction among oligomers derived from coupling of the TA active moieties. Such facile surface modification strategy can broaden in situ mechanochemical synthesis of functional layers and open a promising route for the design of patterning, antifouling, and controlled release coatings.

Boron-graphdiyne as an anode material for Li, Na, and K ion batteries with high capacities and low diffusion barriers

Inspired by the recent experimental synthesis of boron-graphdiyne [Wang et al., Angew. Chem. Int. Ed. 57(15), 3968–3973 (2018)], we have carried out systematic density functional studies on the adsorption and diffusion of alkali metal ions (Li, Na, and K) on boron-graphdiyne monolayer and bilayers, where multiple adsorption sites with strong adsorption energies are identified for all the studied alkali metal ions. Bader charge analysis indicates that significant charge transfer occurs upon absorption, leading to ionic bonding with the substrate and exhibiting a high storage capacity of 1294, 1617, and 1617 mAh g−1 for Li, Na, and K, respectively. Moreover, the migration energy barriers are found in the range of 0.36–0.47 eV for Li, 0.28–0.39 eV for Na, and 0.12–0.32 eV for K. These findings suggest that boron-graphdiyne based materials are promising for ion battery applications.

Size control over metal-organic framework porous nanocrystals.

Porous nanocrystals of metal-organic frameworks (MOFs) offer greater bioavailability, higher surface-to-volume ratios, superior control over MOF membrane fabrication, and enhanced guest-sorption kinetics compared to analogous bulk phases, but reliable synthesis of uniformly sized particles remains an outstanding challenge. Here, we identify the smallest and most probable sizes of known MOF nanocrystals and present an exhaustive comparative summary of nano- versus bulk-MOF syntheses. Based on critical analysis of reported size data and experimental conditions, an alternate to the LaMer model is proposed that describes nanocrystal formation as a kinetic competition between acid-base and metal-ligand reactivity. Particle growth terminates when ligands outcompete metal-ion diffusion, thereby arresting polymerization to produce kinetically trapped particle sizes. This model reconciles disparate trends in the literature and postulates that minimum particle sizes can be achieved by minimizing the relative ratios of metal-to-linker local concentrations. By identifying conditions that disfavor small nanocrystal sizes, this model also provides routes towards macroscopic MOF single crystals. A universal "seesaw" relationship between nanocrystal sizes and the concentrations of acidic surface-capping ligands provides a roadmap for achieving precise synthetic control. Best practices in synthesis, characterization, and data presentation are recommended for future investigations so that MOF nanocrystals may achieve their full potential as advanced nanomaterials.

Biochemodynamic Features of Metal Ions Bound by Micro- and Nano-Plastics in Aquatic Media.

A simple model, based on spherical geometry, is applied to the description of release kinetics of metal species from nano- and micro-plastic particles. Compiled literature data show that the effective diffusion coefficients, Deff, for metal species within plastic polymer bodies are many orders of magnitude lower than those applicable for metal ions in bulk aqueous media. Consequently, diffusion of metal ions in the aqueous medium is much faster than that within the body of the plastic particle. So long as the rate of dissociation of any inner-sphere metal complexes is greater than the rate of diffusion within the particle body, the latter process is the limiting step in the overall release kinetics of metal species that are sorbed within the body of the plastic particle. Metal ions that are sorbed at the very particle/medium interface and/or associated with surface-sorbed ligands do not need to traverse the particle body and thus in the diffusion-limiting case, their rate of release will correspond to the rate of diffusion in the aqueous medium. Irrespective of the intraparticulate metal speciation, for a given diffusion coefficient, the proportion of metal species released from plastic particles within a given time frame increases dramatically as the size of the particle decreases. The ensuing consequences for the chemodynamics and bioavailability of metal species associated with plastic micro- and nano-particles in aquatic systems are discussed and illustrated with practical examples.

Mechanistic insights into metal ions transit through threefold ferritin channel

BackgroundThe mechanism of how the hydrophilic threefold channel (C3) of ferritin nanocages facilitates diffusion of diverse metal ions into the internal cavity remains poorly explored. MethodsComputational modeling and free energy estimations were carried out on R. catesbeiana H´ ferritin. Transit features and associated energetics for Fe2+, Mg2+, Zn2+ ions through the C3 channel have been examined. ResultsWe highlight that iron conduction requires the involvement of two Fe2+ ions in the channel. In such doubly occupied configuration, as observed in X-ray structures, Fe2+ is displaced from the internal site (stabilized by D127) at lower energetic cost. Moreover, comparison of Fe2+, Mg2+ and Zn2+ transit features shows that E130 geometric constriction provides not only an electrostatic anchor to the incoming ions but also differentially influence their diffusion kinetics. ConclusionsOverall, the study provides insights into Fe2+ entry mechanism and characteristic features of metal-protein interactions that influence the metal ions passage. The dynamics data suggest that E130 may act as a metal selectivity gate. This implicates an ion-specific entry mechanism through the channel with the distinct diffusion kinetics being the discriminating factor. General SignificanceFerritin nanocages not only act as biological iron reservoirs but also have gained importance in material science as template scaffolds for synthesizing metal nanoparticles. This study provides mechanistic understanding on the conduction of different metal ions through the channel.

Preparation of guanidinylated carboxymethyl chitosan and its application in the diffusive gradients in thin films (DGT) technique for measuring labile trace metals in water

ABSTRACTGuanidinylated carboxymethyl chitosan (GCMCS) was prepared via the guanidinylation of carboxymethyl chitosan (CMCS). A device employing the diffusive gradients for thin films (DGT) technique was made using a GCMCS aqueous solution as the binding agent and a cellulose acetate dialysis membrane (CADM) as the diffusion phase to measure labile Cu2+, Pb2+ and Cd2+ in water. The percentage uptake (U%) values of labile Cu2+, Pb2+ and Cd2+ in a synthetic water sample were almost consistent with the theoretical values at 101.6 ± 2.8%, 104.6 ± 6.1% and 95.9 ± 4.4%, respectively. The optimum pH ranges for the measurement of labile Cu2+, Pb2+ and Cd2+ were 3.0–7.0, 3.0–7.0 and 4.0–8.0, respectively. The ionic strength mainly affected the diffusion of metal ions in the CADM. The diffusion rates decreased with increasing concentrations of NaNO3 solutions. The application of GCMCS-DGT in natural water and industrial wastewater showed that dissolved organic carbon (DOC) only affects metal species, and the accurate determination of labile Cu2+, Pb2+ and Cd2+ can be achieved when the diffusion coefficients of these metal ions in the diffusion phase have been determined. GCMCS is suitable for DGT application as a chelating agent for metal ions.

Cover Image, Volume 101, Issue 12

Cover Photograph: Top‐left: SEM‐EDS analysis in line‐scan mode across the cross section at BZCY‐containing anode|GDC electrolyte interface. Top‐middle: Schematic diagram of the metal ion diffusion mechanism at BZCY‐containing anode|GDC electrolyte interface. Top‐right: OCV values of some typical DCO‐based SOFCs with or without electron‐blocking layers. Bottom‐left: TEM image of the grain from NiO‐BZCY|GDC foam|NiO‐BZCY. Bottom‐middle: EDS results in line‐scan mode of the grain from NiO‐BZCY|GDC foam|NiO‐BZCY. Bottom‐right: HRTEM image of the grain obtained from NiO‐BZCY|GDC foam|NiO‐BZCY. image

Boundary conditions of implicit affective influences on effort-related cardiovascular response

A large percentage of oil paintings in museum collections suffers from chemo-mechanical degradation phenomena that are primarily due to metal soap formation. Metal soaps result from the chemical reaction between metal ions present in the pigments and saturated fatty acids released by the oil paint. They appear as large protrusions that disfigure the surface texture, possibly triggering mechanical damage and flaking of the painting. Despite that these phenomena have been widely observed in situ, the interaction between chemical and mechanical degradation processes is far from being understood. This paper proposes a chemo-mechanical model to predict metal soap formation and the resulting chemo-mechanical damage in historical oil paintings. The chemical process is described by means of a diffusion-reaction model, whereby the spatial growth of the metal soap crystal takes place in a small reaction zone at the boundary of the crystal. Metal soap crystallization and growth, driven by the diffusion of saturated fatty acids and metal ions, result in a chemically-induced volumetric growth strain. This introduces stresses in the paint, ultimately promoting crack nucleation and propagation. The fracture process is simulated with a cohesive zone approach, using interface elements equipped with a traction-separation law. The mass flux-concentration relation at the interfaces is consistently specified as a function of the mechanical damage. A set of numerical simulations illustrates the capability of the model to predict metal soap crystallization and growth and the fracture induced in the paint. The study finally illustrates the influence of various chemical and mechanical parameters (i.e., the size of the metal soap nucleus, the mismatch in elastic stiffness parameters between the metal soap and paint materials, the fracture length scale of the paint material, the chemical growth strain and the reaction rate) on the chemo-mechanical degradation of the paint layer.

Excellent Supercapacitor Performance of Robust Nickel–Organic Framework Materials Achieved by Tunable Porosity, Inner-Cluster Redox, and in Situ Fabrication with Graphene Oxide

Metal–organic frameworks have shown promising applications as electrode materials for supercapacitors because of the high porosity and tunable structures, but their poor water stability and conductivity limit their capacitance and efficiency. To demonstrate how to overcome these drawbacks, three isostructural Ni–organic frameworks with [NiII2NiIII(μ3-OH)(COO)6] trinuclear building blocks are selected. Taking advantage of high-connected architectures, absence of open metal sites, and effective inner-cluster redox process, three Ni–organic frameworks all are stable in KOH electrolyte and exhibit a pseudo-capacitor behavior with high specific capacitances up to 394, 426, and 465 F g–1. The increasing porosity facilitates the diffusion of metal ions and electrons and thus increases their electrochemical performance. Furthermore, we demonstrate that the in situ fabrication of metal–organic frameworks with graphene oxide can effectively promote their supercapacitor performance. With a given 3% graphene oxide do...

Efficient removal of heavy metals from melting effluent using multifunctional hydrogel adsorbents.

It is hard to balance high water permeability and good mechanical strength of hydrogel adsorbents. In this study, an enhanced double network hydrogel adsorbent of poly (vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PVA/PAMPS) was prepared via simple free-radical polymerization. Hydrophilic PAMPS guaranteed high swellability of the adsorbent, which made the sufficient diffusion of metal ions towards adsorbent inside. Meanwhile, the cross-linkage between PVA and PAMPS chains ensured good mechanical strength of the adsorbent. Significantly, the introduction of multifunctional groups (-NHR, -SO3H and -OH) endowed the adsorbent with both chelation and ion exchange function for enhancing heavy metal adsorption. The maximum adsorption capacities of Pb2+ and Cd2+ reached 340 and 155.1 mg/g, respectively. The adsorbent could efficiently remove heavy metals in melting effluent, especially Pb2+ and Cd2+. The removal efficiencies reached 88.1% for Pb2+, 91.4% for Cd2+, 70.4% for Zn2+, 77.4% for Cu2+, 42.5% for Mn2+, 45.1% for Ni2+ and 95.4% for Fe3+ using 2 g/L adsorbent in 2 h. Moreover, the adsorbent showed a good reusability, and the removal efficiencies maintained 94% for Pb2+ and 93% for Cd2+ in the fifth cycle (m/V = 1 g dry gel/L). This work developed a highly practical hydrogel adsorbent for heavy metal removal from wastewater.

Efficient and Stable Nonfullerene‐Graded Heterojunction Inverted Perovskite Solar Cells with Inorganic Ga2O3 Tunneling Protective Nanolayer

AbstractInverted planar perovskite solar cells (PSCs) exhibit advantages in terms of simple device fabrication, good reproducibility, and less hysteresis. However, there still remain challenges to passivate the trap states within the perovskite film and reduce interface instability arising from penetration of moisture and the diffusion of metal electrode. In this work, perovskite passivation is reported using gradiently distributed nonfullerene electron‐rich Lewis bases small molecule IDIC (a π‐conjugated Lewis base: indacenodithiophene end‐capped with 1.1‐dicyanomethylene‐3‐indanone), which is realized through an antisolvent dropping process. Additionally, an inorganic wide band gap Ga2O3 is introduced as a tunneling nanolayer into interface between the metal electrode and electron transport layer that effectively passivate interface and mitigate moisture and metal ion diffusion. These treatments enable the fabrication of CH3NH3PbI3‐based inverted PSCs with excellent power conversion efficiencies up to 19.86% as well as enhanced ambient stability. This work provides new strategies to improve the performance and stability for the inverted PSCs.

Correlation between soil electrical resistivity, polarisation resistance and corrosion of steel

ABSTRACTSoil electrical resistivity, polarisation resistance and similar techniques sometimes are used for predicting both the short and the long-term corrosion of metals such as steels in soils. Herein new field data for pipes after 63 years exposure are presented that show poor correlations to electrical resistivity. One of the reasons is that electrical current flow and hence resistivity cannot be a surrogate for the electrolytic ionic diffusion of metal ions in the corrosion process. Also, corrosion in soils largely is governed by differential aeration, facilitated by air-voids at the soil/metal interface. This phenomenon is not considered in conventional electrochemical experiments. The practical implications are discussed.

Reconfiguring graphene for high-performance metal-ion battery anodes

Reconfiguring structures in materials is one of the most important building approaches in new material design. The atomically precise control of reconfiguration of two-dimensional (2D) carbon-based materials reshapes their properties for engineering applications. Herein, by employing density functional theory and tight-binding modeling, we reconfigured atomically precise structure in graphene and proposed a new 2D carbon allotrope Θ-graphene. The reconfiguring procedure adopted was realized in experiments using an electron beam. It exhibits semiconductor features with a bandgap of 0.58 eV, and is extendable to semimetal or metal. Mechanically-induced directional-dependent topological node line states are formed and their origin is the breaking of the geometrical symmetry. The reconfiguring procedure reshapes the adsorption and diffusion properties of Θ-graphene, promoting its storage capacities for metal ions (876.65/1275.12/956.34 mA h/g for Li/Na/K- ion batteries) and lowing its metal ion-diffusion energy barriers (≤ 0.48 eV) and lowing its average open circuit voltages (≤ 0.60 V). The transition from semiconductor to metal with metal ions introduced improves its high electronic conductivity, which could be beneficial to the fast charge/discharge rates. Our results show that the reconfigured structure in graphene reshapes its properties, bringing it numerous promising engineering applications such as in metal-ion batteries and in nanoelectronic devices and in energy storage. This work provides a new channel for materials design and innovation by combining the reconfiguring strategy and the structure-property-application relationship, and opens up a new strategy to extend the applications of low-dimensional materials such as graphene and to promote their application performance.