Initial Zn Research Articles

An electron-losing regulation strategy for stripping modulation towards a highly reversible Zn anode.

The practical application of aqueous zinc-ion batteries (AZIBs) is hindered by their low coulombic efficiency (CE) and unstable cycle life. Numerous electrolyte-additive-related studies have been performed, but most of the focus has been on the Zn plating process. In fact, practical AZIBs undergo stripping in practice rather than plating in the initial cycle, because the commonly used cathodes in the charged state do not have zinc ions, so a uniform stripping process is crucial for the cell performance of AZIBs. Here, we propose an electron-losing regulation strategy for stripping modulation by adding additives. Oxolane (OL) was chosen as the model additive to verify this assumption. It is found that OL adsorbs onto the uneven initial Zn surface and accelerates the dissolution of the Zn tips, thus providing a uniform Zn anode during the stripping process. The oxygen atoms in OL reduce the surface energy of Zn and promote the exposure of the Zn (002) surface during plating. Consequently, cells with the OL electrolyte additive maintained a long lifespan and showed superior reversibility with a high average CE. The findings of this work lead to a deep understanding of the underlying mechanism of Zn anode stripping and provide new guidance for designing electrolyte additives.

Adsorption−desorption of Zn2+ ions using hydroxyapatite and recovery of zinc by electrochemical precipitation method into deep eutectic solvent

Hydroxyapatite has a nanostructure, the chemical formula of Ca10(PO4)6(OH)2 and a specific surface area of 91.42 m2/g. In this paper, hydroxyapatite is used to adsorb Zn2+ ions as effective adsorbent. The influence of some factors on Zn2+ adsorption capacity and efficiency has been studied. Under the suitable adsorption conditions were hydroxyapatite mass of 0.15 g in 50 mL solution, 50 mg L−1 initial Zn2+ concentration, pH 5.0, exposure time of 60 min at room temperature (25 °C), Zn2+ adsorption efficiency and capacity reached 94.79 % and 15.80 mg g−1, respectively. The process of desorption of Zn2+ from the loaded adsorbent and recovery of metallic Zn was also investigated. Zinc recovery efficiency reached 93.26 % under appropriate conditions such as applied current intensity of 7.5 mA, electrolysis time of 10 h, loaded hydroxyapatite mass of 0.1 g, temperature 60 °C. After desorption process, the adsorbent was regenerated for further studies. The adsorption isotherm was studied based on three Langmuir, Freundlich and Redlich-Peterson models. The adsorption thermodynamics were investigated and calculating the parameters. The adsorption kinetics were examined using two pseudo-first-order and pseudo-second-order kinetic models. The negative value of Gibb’s free energy change showed that the adsorption process was feasible and spontaneous in nature. The positive value of enthalpy change indicated that the process was endothermic. The positive value of entropy change showed increased randomness at the solid and solution interface.

Solvation Barrier Remodeling‐Dictated Fast‐Kinetics Top–Down Zn Stripping/Plating in Water‐Lean Organic Electrolytes

AbstractDifferent from “bottom–up” Zn plating/stripping, “top–down” Zn stripping/plating provides a new perspective to reinvent current aqueous Zn batteries (AZBs), yet related studies remain absent. Herein, a chelation‐induced solvation barrier remodeling strategy is initiated toward fast‐kinetics “top–down” Zn stripping/plating in original Zn2+‐free water‐lean organic electrolytes (WLOE) for durable Zn batteries. It is found that in WLOE, the initial Zn stripping kinetics of the Zn anode remarkably limits the “top–down” Zn stripping/plating. The intervention of multidentate chelant (2‐methoxyethylamine, MEA) in WLOE greatly lowers the solvation reorganization energy of in situ stripped Zn2+ from the Zn anode, enabling the fast‐kinetics “top–down” Zn stripping/plating. Spectral characterization and fitted overpotential‐reorganization energy correlation strongly confirm the underlying mechanism. As such, the Zn stripping/plating in the MEA‐mediated WLOE shows a 90‐fold‐enhanced current response, triple‐lowered overpotential, and 170‐fold‐prolonged cyclability (over 1700 h at 0.5 mA cm−2) of those in MEA‐free counterpart. The assembled Zn||LiFePO4 hybrid full cell in MEA‐regulated WLOE exhibits a distinct and high voltage plateau of 1.50 V and a low polarization voltage of 0.14 V, far surpassing those in conventional WLOE. This work opens a new avenue to break the kinetics bottleneck of Zn stripping/plating in WLOE for durable Zn batteries.

Viability and life cycle assessment of Fuller's Earth as a low-cost adsorbent for zinc removal from aqueous solutions: Operating parameters, removal mechanisms and environmental impacts

Zinc is a heavy metal that has several health risks and must be removed from wastewater effluents before discharge to water bodies or reuse. Fuller's earth is a sedimentary clay and characterized by its low cost and availability. In this research, Fuller's earth (FE) was investigated as an adsorbent for the Zinc (Zn) removal from aqueous solutions to understand its performance, the mechanism of removal, and the potential environmental impacts. Life cycle assessment (LCA) was conducted using ReCiPe 2016 midpoint method. Zn adsorption studies on FE were conducted at various pH (2.5–9), temperatures (10°C, 25°C, and 40°C), initial concentrations of Zn (25, - 150 mg/L) and adsorbent doses of (0.25–4 g/ 50 ml). The Zn removal efficiency reached 99% at pH = 9 at an initial Zn concentration = 100 mg/L and the adsorbent dose = 0.25 g/ 50 ml. The experimental data fit into the Temkin isotherm, while kinetics were best expressed by pseudo-second order. The controlling step of the adsorption process was the film diffusion according to Boyd model. Thermodynamic experiments showed that adsorption is endothermic with an accompanying rise in randomness in the system. The adsorption capacity was 3.56 mg/g. Images by SEM confirmed the occurrence of adsorption. The desorption was successful at different concentrations of HCl. LCA results showed that the maximum negative and positive environmental impacts were associated with mineral resource scarcity (7.5*10–5 kg Cu eq) and human non-carcinogenic toxicity (−0.821 kg 1,4-DCB), respectively.

203 The relationship between potentiated zinc oxide and monovalent copper in a dietary administration for weanling piglets

Abstract The aim of this study was to evaluate different dietary level of Zinc (Zn) and Copper (Cu) supplementation according to European and non-European levels on the health and performance of pigs 14 d after weaning. A total of 120 piglets [initial body weight = 7.14 ± 0.92 kg] were divided into 4 experimental treatments: positive control (PC, 2,500 ppm of Zn, ZnO) and 3 treatments in which Zn and Cu were added through potentiated ZnO and Cu2O according to different European and non-European levels of inclusion: EU (120 ppm of Zn; 140 ppm of Cu), non-EU+ (300 ppm of Zn; 200 ppm of Cu) and non-EU- (300 ppm of Zn; 140 ppm of Cu). Growth performance, serum Zn and Cu concentrations, fecal score, blood biomarkers of intestinal integrity, and fecal microbial composition were examined and analyzed using GLM and MIXED procedures of SAS. Fecal samples at 14 d were collected and the V3–V4 hypervariable regions of the bacterial 16S gene were sequenced in one Illumina MiSeq run. Body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR) and (feed efficiency (FE) were not affected by the experimental treatments. The fecal score suggests that during the first 14d, the consistency of the feces tended (P < 0.10) to be less in the three treatment groups while in PC, the greatest concentration of Zn favored a better fecal consistency. The initial serum Zn and Cu concentrations were similar for all dietary treatment groups. After 14 d, serum Zn concentration was significantly greater in PC (15.71 ± 6.25 µg/L, P < 0.05). No differences were highlighted in serum Zn concentration among the other 3 treatment groups. Serum Cu concentrations revealed statistically significant results (P < 0.05) on 14 d after weaning in EU, non-EU+ and non-EU- groups, showing greater concentrations of Cu (17.65 ± 5.49 µmol/L, 17.73± 3.46 µmol/L 18.33 ± 4.13 µmol/L, respectively) compared with PC (11.87 ± 3.60 µmol/L). These results suggested that the EU level of inclusion of both potentiated Zn and monovalent Cu is enough to reach the same Cu and Zn plasma concentrations of non-EU treatments. Plasma DAO was negatively (P < 0.05) affected in non-EU-. Firmicutes and Bacteroidetes were the most abundant phyla in fecal microbiome. Non-EU- contributed to a significant decrease in biodiversity in fecal microbiota as depicted with Shannon for diversity and Simpson for evenness indexes (P < 0.05). In fecal samples, the presence of genera linked to a greater disruption of the gut barrier (Escherichia-Shigella) was depicted in non-EU- group, indicating significant modifications of the microbial community. These results suggest the need for a balanced supplementation of Cu and Zn through more bioavailable sources. The use of potentiated ZnO and Cu2O according to European levels could represent a valid strategy to enhance weanling piglets gut health and to reduce the environmental impact.

Effects of humic acid and mineral Zn fertilizer on Zn uptake and maize yield in soils formed on limestone and marl parent materials

In this study, the effects of zinc (Zn) and humic acid (HA) applications on soils (12 Aridisol soil samples) formed on limestone and marl parent materials, which are very common in Türkiye, were tested by incubation, adsorption, and greenhouse experiments. Adsorption experiments were carried out using the batch sorption technique, and the Langmuir and Freundlich isotherm parameters were calculated. In the incubation, soils were incubated with control, HA, Zn, and HA+Zn, and the DTPA-Zn was tested in five different periods (1, 7, 15, 30, and 90th days). Maize was grown for eight weeks in pots in the greenhouse. The maximum Zn adsorption for all soils ranged between 3333 and 6250 mg kg-1 in marl soils and 1042 and 5263 mg kg-1 in limestone soils, which decreased to ranges between 2631 and 5555 mg kg-1 in marl soils and 1052 and 5000 mg kg-1 in limestone soils with HA appli-cation, respectively. The desorption rate (%) of adsorbed Zn increased as the initial Zn concentration increased in all soil series formed on marl (smectite clay mineral) and lime-stone (kaolinite clay mineral) parent materials. The effects of humic acid and Zn applica-tion on the fresh and dry weights of maize were found to be statistically significant at the 5% level for marl and limestone parent material. Humic acid application increased the fresh weight of maize compared with that of the control. The highest available Zn was determined in Başkuyu series (0.79 mg kg-1) formed on marl parent material, while the lowest available Zn was obtained in Saraççeşme series (0.60 mg kg-1) formed on limestone parent material. In the greenhouse, HA increased the fresh weight of maize in soils formed on both parent materials by 0.4 and 19.6%, respectively, compared to the control. Zn fertili-zation with HA further increased the fresh and dry yields, with 12 mg kg-1 performing bet-ter. Smax (maximum Zn adsorption of the soil) parameters of soils were negatively corre-lated with EC, Pav, Kav, organic matter, silt, clay, total N, and cation exchange capacity (CEC) of the samples. Although HA alone increases the availability of Zn in plants, HA + Zn appli-cations should be applied together to obtain higher yields.

A Cofacial Porphyrin Dimer Generated by Cooperative Zinc Ion Binding

Noncovalent cofacial porphyrin dimers have attracted interest due to their potential use as host materials or catalysts. In this study, we introduce a novel coordination‐directed cofacial porphyrin dimer from a meso‐tetraphenylporphyrin derivative modified with 2,2'bipyridine moieties at the meta positions of the phenyl groups. Spectroscopic investigation has shed light on the binding processes and the structure of the dimer in solution in detail. Initial Zn2+ ion binding to the porphyrin hinders the subsequent Zn2+ binding and the binding of the second porphyrin. However, once the dimer is formed, additional Zn2+ binding is notably enhanced, resulting in a pronounced S‐shaped binding curve. The detailed structure of the dimer in solution was established based on UV‐vis spectroscopy, various 1H NMR spectroscopy techniques and mass spectrometry. Simulations of ringcurrent‐induced chemical shift changes provided evidence for the face‐to‐face porphyrin structure with tetrahedral coordination of the bipyridine ligands. The X‐ray single crystal structure provided conclusive evidence for the structure of the face‐to‐face dimer, which remarkably resembles the model structure from the 1H NMR simulation. The stability of the dimer structure makes it promising for further exploration of this motif in developing new supramolecular structures and for their potential applications as host compounds and catalysts.

Extraction and separation of potassium, zinc and manganese issued from spent alkaline batteries by a three‐unit hydrometallurgical process

AbstractBackgroundBatteries play a vital role in meeting global energy needs. When their life cycle concludes, improperly discarded spent batteries can pose environmental risks primarily due to their metal content. In this sense, the recycling of metals contained in spent batteries could mean a huge advantage if they are extracted and purified using environmentally friendly processes.ResultsIn this study, the recovery of potassium (K), zinc (Zn) and manganese (Mn) from alkaline batteries was performed using a hydrometallurgical process consisting of neutral, acid and acid reductive leaching steps at room temperature and atmospheric pressure to extract K, Zn and Mn. In the neutral leaching step, 76.8 ± 3.4 (wt. %) of the K present in the spent batteries was extracted. Thus, in the acid leaching step, 90.9 ± 0.1 (wt. %) of the initial Zn and 36.7 ± 0.4 (wt. %) of the initial Mn was extracted using sulfuric acid (H2SO4) 2 M. In a subsequent acid reductive leaching step using H2SO4 2 M and oxygen peroxide (H2O2) 0.8 M as reducing agent, 8.7 ± 0.1 (wt. %) of the initial Zn and up to 49.4 ± 0.2 (wt. %) of the initial Mn were extracted.ConclusionThe three‐unit process led to an overall extraction of 99.6 ± 0.3 (wt. %) of Zn and 86.1 ± 0.1 (wt. %) of Mn. Regarding the latter step, the extraction was not 100% because Mn complexes which are nearly insoluble were generated. This shows that extraction of valuable minerals from industrial residues is possible by hydrometallurgical processes.This article is protected by copyright. All rights reserved.

Sustainable and integrated approaches for carbon capture and rapid remediation of Cr- and Zn-contaminated soils

Soil contamination is a growing concern for sustainable development worldwide. Conventional remediation approaches, such as using ordinary Portland cement (OPC) or lime are limited due to high CO2 emissions, energy consumption, and natural resource consumption. This paper proposes a sustainable method using CO2 and a waste from steel production (ladle slag, LS) for rapid remediation of Cr and Zn-contaminated soils. Contaminated soils spiked by Cr and Zn with various initial concentrations were treated with 10% LS and subjected to conventional and CO2 curing for different periods. The results demonstrated that LS with conventional curing could reduce leaching concentrations of Cr and Zn in contaminated soils. However, it necessitated 28 days to meet the criteria of inert waste and drinking water standards. In contrast, LS with CO2 curing required significantly less time (32 h for Cr and 8 h for Zn) to achieve lower leaching concentrations of Cr and Zn than those with 28-day conventional curing. After CO2 curing for 152 h for Cr- and 80–120 h for Zn-contaminated soils, leaching concentrations of Cr and Zn were 1.5–4 times and 6–72 times lower than those with 28-day conventional curing, respectively. Simultaneously, carbon capture was increased from 10.6% to 17.5% and 19.9%, respectively, with the initial Cr and Zn concentrations increased from 0 to 8000 mg/kg. The strength of Cr- and Zn-contaminated soils with CO2 curing also effectively enhanced up to around 3.3–3.6 times and 1.3–3.3 times higher than those with 28-day conventional curing, respectively.

Establishing Pinhole Deposition Mode of Zn via Scalable Monolayer Graphene Film.

The uneven texture evolution of Zn during electrodeposition would adversely impact upon the lifespan of aqueous Zn metal batteries. To address this issue, tremendous endeavors are made to induce Zn(002) orientational deposition employing graphene and its derivatives. Nevertheless, the effect of prototype graphene film over Zn deposition behavior has garnered less attention. Here, it is attempted to solve such a puzzle via utilizing transferred high-quality graphene film with controllable layer numbers in a scalable manner on a Zn foil. The multilayer graphene fails to facilitate a Zn epitaxial deposition, whereas the monolayer film with slight breakages steers a unique pinhole deposition mode. In-depth electrochemical measurements and theoretical simulations discover that the transferred graphene film not only acts as an armor to inhibit side reactions but also serves as a buffer layer to homogenize initial Zn nucleation and decrease Zn migration barrier, accordingly enabling a smooth deposition layer with closely stacked polycrystalline domains. As a result, both assembled symmetric and full cells manage to deliver satisfactory electrochemical performances. This study proposes a concept of "pinhole deposition" to dictate Zn electrodeposition and broadens the horizons of graphene-modified Zn anodes.

Adsorption performance of bentonite and clay for Zn(II) in landfill leachate

BackgroundThe increasing prevalence of the Galvanized and dry battery industries has led to a rise in zinc proportions in landfills, posing environmental risks. This study explores the potential of bentonite, renowned for its metal adsorption capability, as a landfill barrier material.MethodsAdsorption characteristics of Zn(II) in natural bentonite and Shanghai clay were investigated. Various factors affecting Zn(II) adsorption, including pH, Na ion strength, contact time, initial Zn(II) concentration, and adsorption temperature, were analyzed through batch-type adsorption tests.ResultsThe change in pH and Na strength demonstrates no significant impact on the adsorption of Zn(II) onto bentonite, highlighting the strong selectivity of bentonite for Zn(II). Conversely, the equilibrium adsorption capacity of Zn(II) onto clay increases with rising pH or decreasing ion strength. The Zn(II) adsorption onto bentonite is well-described by the pseudo-second-order, intra-particle diffusion, and Elovih models, each achieving an R2 value exceeding 0.9. While both physical and chemical adsorption coexist in Zn(II) adsorption onto bentonite or clay, the primary determinant of the adsorption rate is chemical adsorption. The adsorption onto bentonite is spontaneous, whereas onto clay it is not. The mechanism involves van der Waals forces, ion exchange, and chemical actions such as inner-sphere complexation for Zn(II) adsorption onto both bentonite and clay.

Coordination Engineering of N, O Co‐Doped Cu Single Atom on Porous Carbon for High Performance Zinc Metal Anodes

AbstractTraditional challenges of poor cycling stability and low Coulombic efficiency in Zinc (Zn) metal anodes have limited their practical application. To overcome these issues, this work introduces a single metal‐atom design featuring atomically dispersed single copper (Cu) atoms on 3D nitrogen (N) and oxygen (O) co‐doped porous carbon (CuNOC) as a highly reversible Zn host. The CuNOC structure provides highly active sites for initial Zn nucleation and further promotes uniform Zn deposition. The 3D porous architecture further mitigates the volume changes during the cycle with homogeneous Zn2+ flux. Consequently, CuNOC demonstrates exceptional reversibility in Zn plating/stripping processes over 1000 cycles at 2 and 5 mA cm−2 with a fixed capacity of 1 mAh cm−2, while achieving stable operation and low voltage hysteresis over 700 h at 5 mA cm−2 and 5 mAh cm−2. Furthermore, density functional theory calculations show that co‐doping N and O on porous carbon with atomically dispersed single Cu atoms creates an efficient zincophilic site for stable Zn nucleation. A full cell with the CuNOC host anode and high loading V2O5 cathode exhibits outstanding rate‐capability up to 5 A g−1 and a stable cycle life over 400 cycles at 0.5 A g−1.

Adsorption thermodynamics and kinetics of hydrochloric-acid-modified bentonite for Zn(II) in wastewater

In order to study the Zn(II) adsorption characteristics of hydrochloric-acid-modified bentonite in wastewater, physical characterization of hydrochloric-acid-modified bentonite was carried out, the effects of the initial concentration, reaction time, and temperature on the Zn(II) adsorption were investigated, and the adsorption kinetics and thermodynamic mechanism of the hydrochloric-acid- modified bentonite adsorption of Zn(II) were examined. The results showed that hydrochloric acid modification increased the interlayer spacing of the bentonite, and the structure of the binding between slices became looser. Hydrochloric acid modification altered the hydroxyl groups on the bentonite surface, and the hydrophilicity was enhanced. The Zn(II) adsorption capacities of bentonite and hydrochloric-acid-modified bentonite increased with the increase in the initial Zn(II) concentration, and the adsorption followed the Langmuir and Freundlich equations. The thermodynamic parameters suggested that the adsorption of Zn(II) was an endothermic, spontaneous, and entropy-increasing process. The adsorption basically reached equilibrium within 120 min, and the adsorption followed the quasi-second-order adsorption kinetic equation. The adsorption process was mainly chemical adsorption, and the intra-particle diffusion process was not the only step controlling the adsorption rate. This study provides a theoretical basis for the remediation of toxic metal wastewater and contaminated soil.

Biopolymer-Based Protective Layer for Stable and Highly Reversible Zinc Metal Anodes

Zinc (Zn) metal has attracted considerable attention because of its natural abundance and stability in aqueous environments compared with lithium/sodium metal anodes. Moreover, Zn metal as anode showed a high theoretical capacity (820 mAh g−1), high energy per volume (5855 mA cm−3), and low operational potential (–0.78 V vs SHE) in electrochemical systems. However, Zn metal suffers from dendrite growth and poor plating/stripping reversibility, resulting from inhomogeneous Zn ion flux and contamination by generally used glass fiber membranes (GFs) as separators. Although studies to inhibit dendritic Zn growth have been conducted, dendritic Zn remains still a major problem during long-term cycling under practical rate and capacity conditions. In this context, it is essential to investigate Zn deposition behavior from initial nucleation to Zn growth morphologies after long-term cycling.Among the problematic factors pointed out by researchers, the irregular pore distribution of GFs causes uneven Zn ion flux. Moreover, the detached fibers after cycling contaminate the Zn anode surface, resulting in nonuniform Zn deposition and trapping of Zn metal in the separator. To stabilize Zn metal anodes, introducing a protective layer can be an effective strategy to construct ion channels with abundant functional groups for high affinity with Zn metaland protect from direct contact with GFs. Organic polymers are suitable candidates for construction of protective layer which tolerates the volume changes of Zn metal and exhibit good chemical compatibility with Zn metal.Polysaccharides are favorable for use as gel polymers, separators, and binders owing to their cost-effectiveness and good electrochemical properties. Besides, they contain various oxygen-containing groups, resulting in relatively high ionic conductivity. However, it is not sufficient to fabricate membranes for the stabilization of Zn metal using polysaccharide alone because of insufficient ion conductive properties. This problem can be solved by blending polymers with high ionic conductivities such as poly(ethylene oxide) (PEO), poly(vinylidene difluoride), and poly(vinyl chloride). Notably, PEO has mainly been used in gel polymer electrolytes. The hydroxyl groups of PEO can facilitate the transport of metal ions and ether linkages can enhance the affinity with cations, resulting high ionic conductivity.In this study, we designed a functional protective layer by blending polysaccharide and PEO and investigated Zn deposition behavior from the formation of initial nucleation to Zn growth process after long-term cycling. The protective layer, fabricated by a one-pot method, featured highly dispersed blending polymers by phase separation and contained uniformly distributed oxygen-containing functional groups. Moreover, we demonstrated that the protective layer induced the formation of regular Zn nucleation sites and smooth Zn deposition after long-term cycling under the realistic conditions required for high-energy metal battery systems. Using the Zn||Cu and Zn||Zn cells stabilized by the protective layer under low capacity (0.1 mAh cm−2), we confirmed that homogeneous initial Zn deposition patterns were induced by ex situ SEM images of Cu and Zn electrodes. Subsequently, smooth and dense Zn growth was confirmed under fast Zn plating/stripping conditions, indicating that protective layer can induce basal plane (002) dominant deposition to mitigate dendrite formation and protect physically and chemically from GFs.Based on the morphological Zn deposition behavior, we successfully fabricated a functional protective layer and significantly enhanced the electrochemical performance of Zn metal battery systems. The Zn||Cu cells with a functional protective layer showed significantly increased long-term cycling above 3850 cycles (more than 160 days) at high rate and capacity condition (2 mA cm−2 and 1 mAh cm−2). In addition, the durability of protective layer was confirmed by a high-rate test (at 10 mA cm−2). These results are consistent with those of the Zn||Zn symmetric cell tests under harsh conditions of 5 mA cm−2 and 5 mAh cm−2. Furthermore, full cell with the protective layer using vanadium disulfides as the cathode exhibited enhanced cyclability over 1000 cycles with 87 % capacity retention compared to the bare full cell that short-circuited at the 340th cycle.Our work demonstrated that there are two important factors affecting the durability of Zn anodes: (i) Zn metal surface should be protected by a smooth and dense layer with high affinity to Zn metal and ions and (ii) physical and chemical contamination from GFs. Figure 1

Gold-Nanolayer-Derived Zincophilicity Suppressing Metallic Zinc Dendrites and Its Efficacy in Improving Electrochemical Stability of Aqueous Zinc-Ion Batteries.

Herein, an Au-coating layer adjusted on the surface of a Zn metal electrode that effectively suppresses the dendrite growth as well as the mechanisms underlying the dendrite suppression as a result of the zincophilic character of Au is introduced. For the Au-coated Zn metal symmetric cell, uniform deposition of Zn-derived compoundswas revealed by operando synchrotron tomography. Microscopic studies demonstrate that the Au-coating layer is induced to form a new Zn-Au alloy during the initial Zn deposition, resulting in stabilized long-term stripping/plating of Zn via the 'embracing effect' that intimately accommodates Zn deposition for further cycles. This property supports the successful operation of symmetrical cells up to 50 mA cm-2 . According to Zn electrodeposition simulation, it is verified that the suppression of dendrite growth is responsible for the electro-conducting Au nanolayer that uniformly distributes the electric field and protects the Zn electrode from corrosion, ultimately promoting uniform Zn growth. The compatibility of the Au-coating layer for full cell configuration is verified using NaV3 O8 as a cathode material over 1000 cycles. This finding provides a new pathway for the enhancement of the electrochemical performance of ZIBs by suppressing the dendritic growth of Zn by means of a zincophilic Au nanolayer.

Entrapment of green seaweed Caulerpa Scalpelliformis for extracting Pb(II), Ni(II) and Zn(II) metal ions from aqueous solutions

<p>From this study, green seaweed Caulerpa Scalpelliformis is utilized as a sorbent for the removal of three metals such as lead (Pb), nickel (Ni) and zinc (Zn). Adsorption tests showed that maximum removal efficiency of 75.02% for Pb, 80% for Ni and 91.11% for Zn was obtained at an optimal equilibrium pH of 7 for Pb and 6 for Ni, Zn, 2g/L sorbent at an ionic strength of 100 mg/L of 30°C. Four isotherm models, such as Langmuir, Freundlich, Toth, and Sips used in this study to determine the correct fit model from test results. The toth model (R2=0.999) was well fit compared to other isotherms models based on correlation coefficients. Kinetic model results obtained at initial Pb, Ni and Zn concentrations revealed a high biosorption rate. In contrast, the results have been modelled effectively with the pseudo-first and second orders. As a result, tests with elutants found that 0.1M HCl is the perfect desorption elutant for three metal ions.</p>

Revealing the missing puzzle piece of concentration in regulating Zn electrodeposition.

Despite achievements in suppressing dendrites and regulating Zn crystal growth, secondary aqueous Zn batteries are still rare in the market. Existing strategies mainly focus on electrode modification and electrolyte optimization, while the essential role of ion concentration in liquid-to-solid electrodeposition is neglected for a long time. Herein, the mechanism of concentration regulation in Zn electrodeposition is investigated in depth by combining electrochemical tests, post hoc characterization, and multiscale simulations. First, initial Zn electrodeposition is thermodynamically controlled epitaxial growth, whereas with the rapid depletion of ions, the concentration overpotential transcends the thermodynamic influence to kinetic control. Then, the evolution of the morphology from 2D sheets to 1D whiskers due to the concentration change is insightfully revealed by the morphological characterization and phase-field modeling. Furthermore, the depth of discharge (DOD) results in large concentration differences at the electrode-electrolyte interface, with a mild concentration distribution at lower DOD generating (002) crystal plane 2D sheets and a heavily varied concentration distribution at higher DOD yielding arbitrarily oriented 3D blocks. As a proof of concept, relaxation is introduced into two systems to homogenize the concentration distribution, revalidating the essential role of concentration in regulating electrodeposition, and two vital factors affecting the relaxation time, i.e., current density and electrode distance, are deeply investigated, demonstrating that the relaxation time is positively related to both and is more sensitive to the electrode distance. This work contributes to reacquainting aqueous batteries undergoing phase transitions and reveals a missing piece of the puzzle in regulating Zn electrodeposition.

Investigation of performance and mechanism of zinc removal from polluted water by concrete fines derived from aggregate recycling: From problematic byproducts to effective adsorbent

Concrete fines are byproducts produced from aggregate recycling. Because of their properties, they cannot be directly recycled for use in concrete manufacturing, which is problematic to move the cement and concrete industry toward sustainable development goals and reduce its environmental impact. Taking advantage of concrete fines unique properties was regarded as a possible research direction. The hydrated cement fraction was expected to provide alkalinity to neutralize the acidic solutions, while calcium related compounds were expected to provide the function of heavy metals removal. In this research, concrete fines were used to remove Zn from acid mine drainage as an active treatment. The removal performance was comprehensively investigated. The maximum capacity of Zn-adsorption is 111.9 mg/g, and almost 100% Zn can be removed for an initial Zn concentration of 20 mg/L. The dominant reaction mechanism of Zn adsorption to concrete fines was determined to be ion-exchange reaction with surface complexation and precipitation. The Zn2+ ions in solution can exchange with the Ca2+ ions in calcium silicates and calcium silicate hydrates in concrete fines and replace the protons released by ionization of the silanol group for complexation, and thus Zn removal is not limited to an alkaline environment or high initial Zn concentration. The acidity was alkalized by hydration reaction, mainly consuming calcium hydroxide. Based on these mechanisms, concrete fines are effective adsorbent to remove Zn without the need for the synergistic reactions of other metals and for making the aqueous solution strongly alkaline, even in the strongly acidic environments and in effluents with high Zn concentration. Through evaluation and comparison of Zn adsorption capacity with other materials, concrete fines were regarded as promising alternative adsorbent for Zn removal.

Ion Tunnel Matrix Initiated Oriented Attachment for Highly Utilized Zn Anodes.

Metallic zinc is an ideal anode for aqueous energy storage, however, Zn anodes suffer from nonhomogeneous deposition, low reversibility and dendrite formation; these lead to an over-provision of zinc metal in full cells. Herein, we report oriented-attachment-regulated Zn stacking initiated through a trapping-then-planting process with a high zinc utilization rate (ZUR). Due to the isometric topology features of cubic-type Prussian blue analogue (PBA), the initial Zn plating occurs at specific sites with equal spacing of ∼5 Å in the direction perpendicular to the substrate; the trace amount of zinc ions trapped in tunnel matrix provides nuclei for the oriented attachment of Zn (002) deposits. As results, the PBA-decorated substrate delivers high reversibility of dendrite-free zinc plating/stripping for more than 6600 cycles (1320h) and achieves an average Coulombic efficiency (CE) of 99.5% at 5mA cm-2 with 100% ZUR. Moreover, the anode-limited full cell with a low negative-positive electrode ratio (N/P) of 1.2 can be operated stably for 360 cycles, displaying an energy density of 214Wh kg-1 ; this greatly exceeds commercial aqueous batteries. This work provides a proof-of-concept design of metal anodes with high utilization ratio and a practical method for developing high energy density batteries. This article is protected by copyright. All rights reserved.

Immobilized sulfate reducing bacteria (SRB) enhanced passivation performance of biochar for Zn

The low survival rate in harsh environments has been hindering the transformation of microbial remediation technology for heavy metal-contaminated soil from laboratory to field application. Therefore, biochar was selected as the carrier in this study to immobilize the heavy metal tolerant sulfate-reducing bacteria of SRB14-2-3 for the passivation of Zn-contaminated soil. The results showed that the immobilized bacteria of IBWS14-2-3 exhibited the highest passivation performance, as the total content of bioavailable Zn fractions (exchangeable + carbonates) in soil with initial Zn concentration of 350, 750 and 1500 mg·kg−1 decreased by almost 34.2 %, 30.0 % and 22.2 % compared to the control group, respectively. In addition, the introducing of SRB14-2-3 into biochar has successfully alleviated the possible adverse effects on soil caused by the application of large amounts of biochar, while the protection of biochar against immobilized bacteria significantly improved the reproduction of SRB14-2-3, since the number of SRB14-2-3 increased by 82,278, 42 and 5 times in three different level contaminated soil. Furthermore, the new passivation mechanism for heavy metals brought by SRB14-2-3 is expected to make up for the deficiency of biochar in long-term application. And more attention should be paid on the performance of immobilized bacteria under field practical application in the future research.