Zinc Salt Concentration Research Articles

From waste to added-value product: A case of efficient separation and recovery of zinc and iron from spent galvanizing acid

Spent galvanizing acid solution contains high concentrations of zinc salts, ferrous salts, and residual acids, exhibiting extremely high value-added recovery potential. However, achieving the efficient extraction and separation of Zn over Fe becomes particularly challenging under elevated Zn ion concentration. Here, the key extraction parameters, such as modifier ratio, Cyanex 923 concentration and ratio of organic phase to aqueous phase (O/A), are investigated. The stripping and regeneration of extractant, extraction mechanism, as well as high-value recovery of Zn and Fe resources are also comprehensively expounded. After the two-stage extraction, the extraction efficiency of Zn and Fe is 98.92 ​% and 2.09 ​%, respectively. Moreover, the stripping efficiency of Zn reaches 92.3 ​% with O/A ratio of 1 : 2, using oxalic acid as stripping agent. The predominant extracted species is confirmed to be ZnCl3−, resulting in the formation of HZnCl3∙R3PO complex. More importantly, the regenerated extractant can be recycled back into the extraction process, and the reproduced HCl, high-value recovered ZnO and Fe2O3 can be used for different industrial fields. These findings lay a solid foundation for the efficient separation and comprehensive recovery of high-concentration spent galvanizing acid solution.

Field emission properties of LIG/ZnO heterojunction prepared by ultrafast laser direct writing

The facile in situ synthesis of graphene-coated metal-oxide nanoparticles and their potential applications in optoelectronic devices are highly anticipated. In this study, we prepared three-dimensional graphene flakes decorated with ZnO nanoparticles (LIG/ZnO) using femtosecond laser-induced zinc salt-containing cork. The LIG/ZnO heterojunction was formed by carbonizing the cork and decomposing the zinc salt in situ to coat LIG during laser irradiation. The correlation between the zinc salt concentration and the morphology, structure, and field-emission characteristics of LIG/ZnO was systematically investigated. The optimized LIG/ZnO-5 emitters demonstrate a decreased threshold electric field (Eth) of 1.07 V/μm, an enhanced field enhancement factor (β) value of 20,559, and a maximum current density of 18.07 mA/cm2 at 1.96 V/μm, representing the most superior performance reported to date. The enhanced field-emission performance of LIG/ZnO can be attributed to the larger number of effective emission sites from ZnO nanoparticles and LIG edges, as well as to the energy band variation induced by the heterostructures. Density functional theory (DFT) calculations show the migration of electrons from the LIG to the ZnO after the formation of the heterojunction, which elevates the Fermi level of emitters. In addition, the accumulation of electrons on the surface of ZnO nanoparticles in the presence of a strong electric field results in a downward shift of the energy band, thereby enhancing the likelihood of electron-vacuum tunneling.

Hybrid Co‐Solvent‐Induced High‐Entropy Electrolyte: Regulating of Hydrated Zn2+ Solvation Structures for Excellent Reversibility and Wide Temperature Adaptability

AbstractAs a new generation of lithium‐ion battery alternative, aqueous zinc (Zn) ion batteries (ZIBs) garner tremendous interests for future energy storage application owing to their inherent incombustible, nontoxic, and low‐cost features. However, their practical utilization is hampered by the electrolyte freezing at subzero conditions. In this study, a novel high‐entropy (HE) electrolyte fabricated is presented with hybrid solvents to mitigate electrolyte freezing at low temperatures, restrain calendar corrosion, and boost Zn‐ion transfer kinetics. Specifically, the isovolumetric combined ethyl acetate, ethylene glycol, and dimethyl sulfoxide as solvent components not only induce a reconfiguration of hydrogen bonding, but also alter the solvation sheath of Zn ions within the HE electrolyte environment. This synergistic coupling of hybrid co‐solvents effectively harnesses the features of individual solvent additive and facilitates the remarkable advantages on cycling reversibility, especially in the low‐temperature conditions. Benefiting from the anti‐freezing and solvation structure regulation features, Zn symmetrical batteries equipped with HE electrolytes can work over 2500 h in low zinc salt concentration (1 m) at various temperatures. This work provides a facile modulation strategy to achieve the HE electrolyte, promoting the practical application and commercialization of advanced ZIBs with wide‐temperature adaptability.

Influence of Zinc Salt Concentration on Structured ZnO Composition and Morphology

AbstractIn the present work, Zinc oxide nanorods (ZnO NRs) and Simonkolleite (Zn5(OH)8Cl22H2O) nanodisks were successfully prepared hydrothermally using zinc chloride as a zinc source salt. The molarity of the zinc salt was varied to investigate its effect on the structure of the synthesized nanostructures. X‐ray diffraction (XRD), scanning electron microscopy (SEM), UV‐visible optical transmittance, and photoluminescence were used to characterize the synthesized nanostructures. These results suggest that the morphology of the synthesized nanostructures was significantly influenced by the molarity of zinc chloride. We inferred that increasing zinc salt molarity above 0.01 M leads to a pure simonkolleite nanodisks. In contrast, ZnO NRs were formed at low concentrations.

Phyto-Mediated Controllable Synthesis of ZnO Clusters with Bactericidal Activity.

The rapid development of antibiotic resistance has been considered a major threat to public health. Nanomaterials have risen to be an effective weapon to tackle this problem through multiple antibacterial mechanisms. The improved and tailored physiochemical properties of fine-tuned secondary nanoarchitectures contribute to the superior bactericidal actions of metal oxide structures. However, it is still challenging to construct secondary structures through mild green manufacturing methods. Here, we report the preferred antibacterial ZnO nanocrystal clusters formed by a green structure-tuning synthesis process, in which the primary ZnO nanoparticles with sizes <10 nm were assembled into different forms of clusters depending on the zinc salt concentration and temperature. ZnO clusters with a stable loose-assembly structure and a rougher surface exhibited better bactericidal ability with minimal inhibitory concentrations of 0.5 and 0.1 mg/mL against Escherichia coli and Staphylococcus aureus, respectively. The underlying mechanism is related to enhancing contact with bacteria, releasing small ZnO nanoparticles, and generating additional reactive oxygen species, which could aggravate the damage to bacterial cell membrane and eventually lead to bacterial death. Furthermore, attachment of phenolic compounds from olive leaf extract would promote membrane penetration by ZnO nanoparticles, resulting in the improvement of antibacterial activities, which profit from the green route mediated by Olea europaea leaf extract that could structure-tune ZnO nanocrystal clusters in one simple step that retains the active ingredients on the nanoparticles. This work proposes a feasible and clean strategy to improve the structure-bioactivity relationship of ZnO by controlling its growth into a preferable structure, and the developed ZnO clusters have a good prospect in antibacterial applications because of their excellent performance and green fabrication method.

Study of zinc salt concentration effect on the growth of zno nanostructured oxides obtained by direct electrodeposition

"Effect of zinc salt concentration on the growth of electrodeposited zinc oxide phases was investigated. ZnO thin films were elaborated via chronoamperometry on fluorine doped tin oxide (FTO) substrates from aqueous mixed bath of zinc nitrate and chlorate at 70°C. X ray diffraction patterns showed nanocrystalline films of hexagonal wurtzite phase with (101) preferential orientation for ZnO as grown in low concentration of Zn2+ salt. High concentration of Zn2+ favor the formation of Zn5(OH)8Cl2H2O simonkolleite phase. After heat treatment at 400 °C for 1h this later decomposes to ZnO oxide which presents no preferential orientation. The route mean square RMS roughness of surfaces estimated from AFM technique shows that ZnO generated from heat treated Zn5(OH)8Cl2H2O present more increasing roughness than ZnO deposits obtained at lower salt concentration. The photoelectrochemical answer indicated important generated photocurrents for both films which present n-type electrical conductivity"

Study of the Effect of Selective Media with High Doses of Zinc on Regeneration Ability and Rutin Accumulation in Common Buckwheat In Vitro

Biotechnological methods are widely used in modern common buckwheat (Fagopyrum esculentum Moench) studies, constitute an effective tool to create the best agronomic traits of the crop, and can also be used to breed forms, resistant to heavy metal ion toxicity, which is important in the environment of constantly growing anthropogenic pressure on ecosystems. The studied high concentrations of zinc salts (808–1313 mg L−1) in the nutrient medium in vitro had an inhibitory effect on buckwheat, which was manifested by a decrease in values of its morphological indicators. Ion stress had an adverse effect on 7–9% of plants from their total number, indicating high plasticity and resistance of F. esculentum to highly toxic doses of zinc. The stress state of F. esculentum significantly increases the production of flavonoid compounds, including rutin, in plant cells, which is used in biotechnology to assess and obtain buckwheat forms of high flavonoid induction capacity. The processes of rutin biosynthesis were most intense in test-tube plants of the Izumrud × Inzerskaya hybrid obtained after exposure to high doses of zinc 1010–1212 mg L−1. F. esculentum genotypes obtained using selective backgrounds with high zinc concentrations are promising biosystems for synthesis of rutin, valuable for pharmacology and medicine.

Electrodialysis enhanced with disodium EDTA as an innovative method for separating Cu(II) ions from zinc salts in wastewater

In recent years, interest in developing methods for hazardous metal recovery from wastewater has grown steadily within the scientific community. This report describes a method based on electrodialysis enhanced with metal-complex formation to separate cupric ions from zinc sulfate present in a model zinc plating bath. The investigated method can be applied for resource (zinc sulfate) recovery, or to reduce the amount of hazardous galvanic wastes. In this work, the disodium salt of ethylenediaminetetraacetic acid (Na2EDTA) is employed as a complexing agent. The effects of the membrane and current density on the separation efficiency are evaluated and discussed. Finally, the optimal conditions for selective removal of Cu(II) ions from a zinc salt bath are identified, and the effectiveness of the examined method is demonstrated in a batch test. It was determined that, by using thick heterogeneous AM(H)-CM(H) ion-exchange membranes an approximately 13-fold reduction in Cu(II) content, relative to Zn(II), can be achieved at high Zn(II) recovery (94.6%) and current density (220 A/m2). The possibility of applying the described method for concentration of zinc salts in the plating bath was also evaluated. It was shown that Zn(II) content can be increased of up to 1.5 times.

Zinc-Ion Conducting Nonaqueous Polymer Electrolyte for Zinc-Metal Batteries through UV-Light Induced Cross-Linking Polymerization

Recently, rechargeable zinc-metal batteries (ZMBs) employing a metallic zinc (Zn) anode (negative electrode) coupled with a suitable cathode (positive electrode), and a zinc-ion conducting electrolyte are receiving tremendous attention as a post-lithium battery technology among the electrochemists.(1) Mostly, the electrolyte of choice in ZMBs are aqueous liquid electrolytes with few available reports on aqueous gel polymer electrolytes. The use of aqueous electrolytes often restricts the operation of the cell to potentials below 2V vs. Zn|Zn2+.(2) To improve the operating voltage of the ZMB cells, nonaqueous electrolytes can be employed. Despite few available reports suggesting acetonitrile and carbonate solvent-based nonaqueous liquid electrolytes for ZMBs, nonaqueous zinc-ion conducting polymer electrolytes (ZIPs) are rarely explored in ZMB full-cells.(3) During the evolution of nonaqueous ZMB technology, a transition from nonaqueous liquid electrolytes to solid/semi-solid-state ZIPs is highly desirable, which can leverage the prospects of futuristic safe and flexible ZMBs.In this context, we are reporting a simple and scalable process for the preparation of cross-linked ZIPs by ultraviolet (UV)-light induced cross-linking polymerization. The reactive mixture consisting of mono- and di-functional acrylate monomers, propylene carbonate solvent as the active plasticizer, zinc trifluoromethanesulfonate (Zn(OTf)2) as the conducting salt, and a photo-initiator, on UV curing produces mechanically stable ZIP films.(4) Depending on the concentration of zinc-salt in the ZIP, the physicochemical properties were found to be varied. For instance, the glass transition temperature, as well as the compressibility of the ZIPs, increased with an increase in zinc-salt content. The optimized ZIP with ≈ 20 wt.% Zn-salt displayed the highest ionic conductivity value in the order of 10-3 S/cm at room temperature. The same ZIP exhibited an oxidation stability beyond 2.4 V vs. Zn/Zn2+, which was higher than ZIPs with low zinc-salt content. Besides, the same ZIP exhibited a stable plating/stripping profile for approximately 8 days in Zn|ZIP|Zn symmetric cell indicating excellent interfacial compatibility against Zn metal. For fabricating ZMB full-cell using the optimized ZIP, vanadyl phosphate (VOPO4. 2H2O) was used as the cathode. The VOPO4. 2H2O|ZIP|Zn cell was fabricated by the direct generation of ZIP over the cathode electrode (the in situ polymerizationprocess)(5). The in situ process helps in achieving an improved electrode|electrolyte interface compared to the ZIP film-based ZMB cell. On cycling, the in situ fabricated ZMB cell exhibited a specific capacity of ≈ 80 mAh g-1 at a current density of 0.50 A/g. At 0.20 A/g, the ZMB cell retained 63% of the initial capacity over 50 continuous galvanostatic charge-discharge cycles. Considering the rarely explored nonaqueous zinc electrochemistry in polymer electrolytes, this report is important, improving the prospects of zinc-based post-lithium battery technology. References G. Fang, J. Zhou, A. Pan and S. Liang, ACS Energy Letters, 3, 2480 (2018).M. Ghosh, V. Vijayakumar and S. Kurungot, Energy Technology, 7, 1900442 (2019).Y. Zhang, Z. Chen, H. Qiu, W. Yang, Z. Zhao, J. Zhao and G. Cui, NPG Asia Materials, 12, 1 (2020).V. Vijayakumar, D. Diddens, A. Heuer, S. Kurungot, M. Winter and J. R. Nair, ACS Applied Materials & Interfaces, 12, 567 (2020).V. Vijayakumar, B. Anothumakkool, S. B. Nair, M. V. Badiger and S. Kurungot, Journal of Materials Chemistry A, 5, 8461 (2017). Figure 1

Effect of the zinc salt concentration on the ZnO thin films properties grown by MWCBD

Nanostructured ZnO thin films with different surface morphologies have been synthesized by the microwave assisted chemical bath deposition technique (MWCBD), adjusting the pH of the reaction solution between 9 and 11.14. Newest results are presented in this work supported by previous investigations. Morphology, structure and optical properties of the films have been studied by scanning electron microscopy (SEM), x-ray diffraction (XRD) and room temperature photoluminescence (PL) techniques. It has been observed that the zinc salt concentration and the pH of the reaction solution determines the reaction kinetics, affecting strongly the morphology of the final product. However, the rapid heating in microwave irradiation process facilitates the crystallization of the formed nano-/microstructures. Effects of composition and morphology of the grown nano-/microstructures on their photoluminescence (PL) behaviors have been discussed.

Low-temperature hydrothermal synthesis of ZnO nanorods: Effects of zinc salt concentration, various solvents and alkaline mineralizers

ZnO has been produced using various methods in the solid, gaseous, and liquid states, and the hydrothermal synthesis at low temperatures has been shown to be an environmentally-friendly one. The current work utilizes a low reaction temperature (60°C) for the simple hydrothermal synthesis of ZnO nanorod morphologies. Furthermore, the effects of zinc salt concentration, solvent type and alkaline mineralizer type on ZnO nanorods synthesis at a low reaction temperature by hydrothermal processing was studied. Obtained samples were analyzed using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Increasing the concentration of the starting zinc salt from 0.02 to 0.2M changed ZnO nucleation system from the homogeneous to the heterogeneous state. The XRD results confirmed the production hexagonal ZnO nanostructures of with a crystallite size of 40.4nm. Varying the experimental parameters (mineralizer and solvent) yielded ZnO nanorods with diameters ranging from 90–250nm and lengths of 1–2μm.

Miniemulsion-Based Process for Controlling the Size and Shape of Zinc Oxide Nanoparticles

A miniemulsion-based approach to produce crystalline ZnO nanoparticles with narrowly distributed sizes and well-defined faces and shapes is presented. The synthesis reaction in the aqueous droplets of the water-in-oil miniemulsion is induced by mass transfer of the base triethylamine (TEA) across the liquid/liquid interface. In a preliminary study, the dosage of TEA was determined to ensure the required pH range in the aqueous phase. Miniemulsions with a mean droplet size of about 200 nm were produced with a rotor–stator device. The aqueous zinc salt concentration was varied as the parameter in the experimental study. At low zinc salt concentrations, platelike nanoparticles were obtained. An increase in the zinc ion concentration resulted in a decrease in the mean particle size. The shape of the ZnO crystals changed from platelike to rodlike. On the basis of the resulting particle size, it can be deduced that interdroplet exchange is an essential part of the presented miniemulsion-based process.

Zinc uptake by lactic Acid bacteria.

The study aims to investigate zinc biosorption by strains of lactobacilli and bifidobacteria with a view to exploit them as organic matrixes for zinc dietary supplementation. Sixteen human strains of Lactobacillus and Bifidobacterium were assayed for zinc uptake. The minimum inhibitory concentration of zinc salts differed among the strains, but was never below 15 mmol L−1. When cultured in MRS broth containing 10 mmol L−1 ZnSO4, all the strains were capable of accumulating zinc in the range between 11 and 135 μmol g−1. The highest amount of cell-bound zinc was obtained in L. acidophilus WC 0203. pH-controlled batch cultures of this strain revealed that zinc uptake started in the growth phase, but occurred mostly during the stationary phase. Pasteurized and viable cultures accumulated similar amount of zinc, suggesting that a nonmetabolically mediated mechanism is involved in zinc uptake. These results provide new perspectives on the specific use of probiotics, since L. acidophilus WC 0203 could function as an organic matrix for zinc incorporation. The bioavailability of Lactobacillus-bound zinc deserves to be investigated to provide a future basis for optimization of zinc supplementation or fortification.

Understanding the Factors That Control the Formation and Morphology of Zn5(OH)8(NO3)2·2H2O through Hydrothermal Route

The influence of the choice of ethanol‐water volume ratio, concentration of zinc salt, and ZnO buffer layer on the formation and morphology of grown from the hydrothermal route was systematically discussed. Experimental results suggested that rectangle sheets and upright‐standing plates were obtained by limiting ethanol‐water volume ratio. The concentration of zinc salt was crucial for getting phase‐pure . The presence of ZnO buffer layer could lead to the that chemical composition of product grown on the substrate was totally different from the product grown in the solution. Possible formation mechanism of was also studied. Raman spectrum of displays a complex behavior with four modes, which can be assigned to the vibrational modes of Zn–H–O, Zn–O, H2O‐nitrate, and nitrate. Porously ZnO rectangle sheets were obtained by thermal treatment of rectangle sheets.

Synthesis of ZnO Nanostructures Using Domestic Microwave Oven Based Remote Plasma Deposition System

ZnO nanostructures were deposited on various substrates like glass, Si wafer and Al2O3/Si substrates using microwave oven based plasma deposition system at oxygen and atmospheric plasma conditions. Various morphologies were exhibited by the ZnO nanostructures grown on different substrates depending on Zinc salt concentration, plasma source and substrate material.

Synthesis and gas-sensing properties of ZnO particles from an ionic liquid precursor

The synthesis and gas-sensing properties of ZnO particles from an ionic liquid precursor benzyltrimethylammonium hydroxide (BTMAH) is studied. The BTMAH, acting as reactant precursor and solvent, is demonstrated to be effective for synthesis of ZnO particles with controlled morphologies. The effect of the water and zinc salt concentration on the morphology of the synthesized particles is investigated. The gas-sensing tests shows that the sensors based on the synthesized ZnO nanoplates exhibit excellent ethanol-sensing properties.

Growth and UV Emission of Preferred Oriented ZnO Nanowires Using Hydrothermal Process

1-D ZnO nanowires have been attractive for their peculiar properties and easy growth at relatively low temperature. The length, diameter, and density of ZnO nanowires were determined by the several synthetic parameters, such as PEI concentration, growth time, temperature, and zinc salt concentration. The ZnO nanowires were grown on the <001> oriented seed layer using the hydrothermal process with zinc nitrate and HMTA (hexamethylenetetramine) and their structure and optical properties were characterized. The morphology, length and diameter of the nanowires were strongly affected by the relative and/or absolute concentration of <TEX>$Zn^{2+}$</TEX> and <TEX>$OH^{-1}$</TEX> and the hydrothermal temperature. When the concentrations of the zinc nitrate HMTA were the same as 0.015 M, the length and diameter of the nanowires were <TEX>$1.97{\mu}m$</TEX> and <TEX>$0.07{\mu}m$</TEX>, respectively, and the aspect ratio was 28.1 with the preferred orientation along the <001> direction. XRD and TEM results showed a high crystallinity of the ZnO nanowires. Optical measurement revealed that ZnO nanowires emitted intensive stimulated UV at 376 nm without showing visible emission related to oxygen defects.

Protein Spherulites for Sustained Release of Interferon: Preparation, Characterization and in vivo Evaluation

This study develops protein spherulite, a new form of protein aggregation, for sustained-release applications of recombinant human interferon α-2b (rhIFN). rhIFN spherulites were prepared with different pH solutions with different kinds and concentrations of zinc salts at various incubation temperatures. rhIFN spherulites produced under different systems were of different morphology properties and in vitro release characters. Size-exclusion high-performance liquid chromatography analysis has shown that no protein aggregates were generated during spherulite formation, and cytopathic inhibition assay has demonstrated that the spherulitic rhIFN well maintained its structure and antiviral activity. In vivo studies showed that rhIFN spherulites provided a significantly prolonged pharmacokinetics profile profile as compared with the soluble rhIFN formulation, and the relative bioavailability based on serum rhIFN levels was about 170%. The work described here demonstrates the possibility of protein spherulites as a long-acting formulation for rhIFN.

Solution-derived 40 µm vertically aligned ZnO nanowire arrays as photoelectrodes in dye-sensitized solarcells

Well-aligned ZnO nanowire arrays with a long length of more than 40 µm were prepared successfully by using the polyethylenimine (PEI)-assisted preheatinghydrothermal method (PAPHT). Several important synthetic parameters such as PEIcontent, growth time, preheating time and zinc salt concentration were found to determinethe growth of ultralong ZnO nanowire arrays, including length, diameter, density andalignment degree. The photoluminescence (PL) spectrum of as-grown ultralong ZnOnanowire arrays revealed a UV emission and a yellow emission, which was attributed to theabsorbed hydroxyl group based on the peak shift after annealing in various atmospheres.The performance of dye-sensitized solar cells (DSSCs) increased with increasing length ofZnO nanowire arrays, which was mainly ascribed to the aggrandized photocurrent andreduced recombination loss according to electrochemical impedance spectroscopy(EIS). A maximum efficiency of 1.3% for a cell with a short-circuit current density(Jsc) = 4.26 mA cm2, open-circuit voltage(Voc) = 0.69 V and (fill factor)FF = 0.42 was achieved witha length of 40 µm.

Single crystalline zinc structures synthesized spontaneously in solution

We report a method for the synthesis of Zn structures with a variety of morphologies through a spontaneous solution phase reaction without application of an electropotential under ambient conditions. We also describe, in detail, the influence of several experimental conditions on the morphology and microstructure of the Zn structures. The morphology of the Zn structures transitioned from hexagonal disks to dendritic forms as the reaction temperature was increased due to an increase in the driving force for Zn structure formation (over a temperature range from room temperature, 22 °C, to 95 °C). The size of the Zn structures was controlled by adjusting the concentration of zinc acetate dihydrate added to the reaction solution. When the concentration of zinc salt was reduced, smaller Zn structures were synthesized. Control experiments revealed that the aluminium layer, ammonia additions, and ammonia concentration were key factors for the formation of Zn metal structures. A zinc ion complex, Zn(NH3)42+, played a critical role in the formation of the Zn structures. Zn nanowires were synthesized in the presence of a 1.5 μm thick Al layer substrate. Based on these observations, we propose possible formation mechanisms for the spontaneous assembly of the various Zn structures.