Aqueous Solutions Of ZnCl2 Research Articles

Hydrogen production from ZnCl2 salt: Application of chlor-alkali method

This experimental study investigates the efficiency of hydrogen production from an aqueous ZnCl2 solution using an electrochemical method within a chlor-alkali reactor. A laboratory-scale reactor with separate anode and cathode compartments was constructed for this purpose. The compartments are separated by a Nafion 212 membrane, which prevents the mixing of the anolyte and catholyte solutions while allowing the passage of positive ions (Zn+). Each compartment is equipped with five carbon rod electrodes. The anode chamber is fed with an aqueous ZnCl2 solution, while the cathode chamber is supplied with pure water. The experiments were conducted with a constant electrolyte transfer rate of 0.3g/s into the reactor, at three different cell voltages (5.0, 7.5, and 10.0V) and two different cell temperatures (20 °C and 45 °C). Due to the small reactor dimensions and the dilution effect caused by adding pure water to the cathode compartment which decreases electrolyte density and adversely affects the current a noticeable reduction in hydrogen gas production was observed. Furthermore, the ZnCl2 electrolyte mass flow rate did not significantly impact the current or the generation of hydrogen and chlorine gases. Consequently, no changes were made to the mass flow rate of pure water or the electrolyte. The presence of active chlorine gas was found to cause the erosion of the carbon rod electrodes in the anode chamber. As a result, the amount of chlorine gas produced in the anode chamber is significantly lower than the hydrogen gas produced in the cathode chamber. At a cell temperature of 20 °C, a mass flow rate of 0.3 g/s, and a cell voltage of 5 V with ZnCl2 aqueous solution, the minimum hydrogen production rate is 0.625 mL/min. In contrast, at a cell temperature of 45 °C, a mass flow rate of 0.3 g/s, and a cell voltage of 10 V, the maximum hydrogen production rate is 4.97 mL/min.

The Thermal Stability and Photoluminescence of ZnSeO3 Nanocrystals Chemically Synthesized into SiO2/Si Track Templates

We report the effect of high-temperature treatment on the structure and photoluminescence of zinc selenite nanocrystals (ZnSeO3) deposited into SiO2/Si track templates. The templates were formed via irradiation with Xe ions (200 MeV, 108 ions/cm2) followed by etching in HF solution. ZnSeO3 nanocrystals were obtained via chemical deposition from the aqueous solution of ZnCl2 and SeO2 as Zn-, Se- and O-precursors. To estimate the thermal stability of the deposited precipitates, heat treatment was carried out at 800 and 1000 °C for 60 min in a vacuum environment. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), photoluminescence (PL) spectroscopy, and electrical measurements were used for the characterization of ZnSeO3/SiO2nanoporous/Si nanocomposites. Thermal treatment of the synthesized nanocomposites resulted in structural transformations with the formation of ZnSe and ZnO phases while the content of the ZnSeO3 phase decreased. For the as-deposited and annealed precipitates, an emission in the range of (400 to 600) nm was observed. PL spectra were approximated by four Gaussian curves with maxima at ~550 nm (2.2 eV), 488 nm (2.54 eV), ~440 nm (2.82 eV), and 410 nm (3.03 eV). Annealing resulted in a decrease in PL intensity that was possibly due to the weight loss of the deposited substance during high-temperature treatment. The redistribution of maxima intensities after annealing was also observed with an increase in blue and violet emissions. The origin of the observed PL is discussed. The I–V curve analysis revealed an electronic type of conductivity for the ZnSeO3(NCs)/SiO2nanoporous/Si structure. The values of the specific conductivity were calculated within the percolation model. The sample annealed at 800 °C showed the highest specific conductivity of 8.5 × 10−6 Ohm−1·cm−1.

Aqueous Electrolyte With Weak Hydrogen Bonds for Four-Electron Zinc-Iodine Battery Operates in a Wide Temperature Range.

In the pursuit of high-performance energy storage systems, four-electron zinc-iodine aqueous batteries (4eZIBs) with successive I-/I2/I+ redox couples are appealing for their potential to deliver high energy density and resource abundance. However, susceptibility of positive valence I+ to hydrolysis and instability of Zn plating/stripping in conventional aqueous electrolyte pose significant challenges. In response, polyethylene glycol (PEG 200) is introduced as co-solvent in 2 m ZnCl2 aqueous solution to design a wide temperature electrolyte. Through a comprehensive investigation combining spectroscopic characterizations and theoretical simulations, it is elucidated that PEG disrupts the intrinsic strong H-bonds of water by global weak PEG-H2O interaction, which strengthens the O─H covalent bond of water and intensifies the coordination with Zn2+. This synergistic effect substantially reduces water activity to restrain the I+ hydrolysis, facilitating I-/I2/I+ redox kinetics, mitigating I3 - formation and smoothening Zn deposition. The 4eZIBs in the optimized hybrid electrolyte not only deliver superior cyclability with a low fading rate of 0.0009% per cycle over 20000 cycles and a close-to-unit coulombic efficiency but also exhibit stable performance in a wide temperature range from 40°C to -40°C. This study offers valuable insights into the rational design of electrolytes for 4eZIBs.

Biodegradable, UV-blocking, and antioxidant films from alkali-digested lignocellulosic residue fibers of switchgrass

The development of bio-friendly materials to replace single-use plastics is urgently needed. In this regard, cellulosic material from plants is a promising alternative. However, due to the risk of forest depletion, agricultural biomass stands out as a favorable choice. Toward this end, switchgrass, an underutilized grass, presents itself as a viable source of lignocellulose that can be turned into a bio-friendly material. Herein, lignocellulosic residue from switchgrass has been extracted using two different concentrations of NaOH (20% and 50% w/v), solubilized in aqueous ZnCl2 solution, and crosslinked with CaCl2 (200, 300, 400, and 500 mM) to prepare biodegradable films. The color, thickness and moisture, water solubility, water absorption, water vapor permeability, tensile strength and elongation, biodegradation, UV transmittance, and antioxidant activity of films have been studied. The films possess a high tensile strength of 14.7 MPa and elongation of 4.7%. They block UVB-radiation and hold antioxidant properties. They display good water vapor permeability of 1.410–1.6 × 10−11 gm−1s−1Pa−1 and lose over 80% of their weight at 30% soil moisture within 40 days. An increase in the CaCl2 amount decreased the water vapor permeability, elongation, UV transmittance, and biodegradation but increased the transparency, tensile strength and antioxidant property. Overall, films of alkali-digested lignocellulosic residue of switchgrass showed excellent potential to be used against lightweight plastics and support the circular economy.

Zinc ion storage abilities of Mo3WOx nano-ceramic under extreme-cold environments

It is imperative to develop new electrode materials for aqueous multivalent metal ion batteries with electrochemistry abilities at extreme-low temperatures due to the possible extreme-cold operating conditions of batteries in the present or the future. Herein, as a proof-of-concept experiment, a new orthorhombic molybdenum-tungsten oxide (Mo3WOx) is synthesized by a wet-chemical method and tested as anode material for aqueous zinc ion batteries at extreme-cold temperatures (−40, −60 and −75 °C) for the first time. Two anti-freezing electrolytes are selected to examine the related half-cell performances, and 7.5 m ZnCl2 aqueous solution is more suitable for Mo3WOx half-cells than 2 m Zn(BF4)2 aqueous solution. At −40 °C, Mo3WOx exhibits reversible charge capacity of 104.1 mAh g−1 at 100 mA g−1 and the charge capacity can still maintain 82.3 mAh g−1 after 100 cycles; and under further test at 5000 mA g−1, Mo3WOx shows a high initial charge capacity of 42.5 mAh g−1 together with a capacity retention ratio of 81.6 % after 10,000 cycles. It is worth highlighting that the high capacities of Mo3WOx delivered at −40 °C are even comparable with the capacities of some “new-type” anode materials for aqueous zinc ion batteries exhibited at ambient temperature. At colder temperatures of −60 and −75 °C, the as-prepared compound still owns certain zinc ion storage abilities, especially high discharge/charge capacities of 48.9/48.7 mAh g−1 can be still achieved in the 100th cycle at −75 °C (100 mA g−1). Furthermore, a full-cell with operational capability at −40 °C is also built here, and it can exhibit discharge capacity of 66.1 mAh g−1 (coulombic efficiency of 99.7 %) in the 3rd cycle and discharge capacity of 48.2 mAh g−1 (coulombic efficiency of 99.7 %) in the 50th cycle.

Preparation of natural antibacterial regenerated cellulose fiber from seed-type hemp

Seed-type hemp fiber is hard to spinning and weaving because of its high lignin and hemicellulose content. In this work, the impurities in seed-type hemp fiber were removed by alkali degumming method, ammonium oxalate-complex enzyme method, ethylenediamainetetraacetic acid disodium -complex enzyme method, ammonium oxalate-complex enzyme-chemical method and ethylenediamainetetraacetic acid disodium -complex enzyme-chemical method, and the results were compared. The fibers were characterized by scanning electron microscopy (SEM) and fourier-transform infrared spectroscopy (FTIR). The fiber after impurity removal is prepared into pulp, and the structure of pulp was characterized by fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The hemp pulp was dissolved into ZnCl2 aqueous solution at a specific temperature to prepare a spinning solution and spun to produce antimicrobial seed-type hemp regenerated cellulose fibers by using a self-made spinning machine. The surface morphology, strength, moisture regain, and antibacterial properties were evaluated, the regenerated fibers had a superior performance.

New Eco-Friendly and Low-Energy Synthesis to Produce ZnO Nanoparticles for Real-World Scale Applications.

This paper presents an original and sustainable method for producing ZnO nanoparticles (NPs) in response to global challenges (low energy requirements, low environmental impact, short production times, and high production yield). The method is based on an ion exchange process between an anionic resin and an aqueous ZnCl2 solution; it operates in one step at room temperature/ambient pressure without the need for complex apparatus or purification steps. From the kinetics, we observed the formation of pure simonkolleite, a zinc-layered hydroxide salt (Zn5(OH)8Cl2·H2O), after only 5 min of reaction. This compound, used elsewhere as a ZnO precursor after calcination at high temperatures, here decomposes at room temperature into ZnO, allowing extraordinary savings of time and energy. Finally, in only 90 min, pure and crystalline ZnO NPs are obtained, with a production yield > 99%. Several types of aggregates resulting from the self-assembly of small hexagonal platelets (solid or hollow in shape) were observed. Using our revolutionary method, we produced almost 10 kg of ZnO NPs per week without any toxic waste, significantly reducing energy consumption; this method allows transferring the use of these unique NPs from the laboratory environment to the real world.

Effect of Different Zinc Species on Mn-Ce/CuX Catalyst for Low-Temperature NH3-SCR Reaction: Comparison of ZnCl2, Zn(NO3)2, ZnSO4 and ZnCO3

The effects of four distinct zinc species (ZnCl2, Zn(NO3)2, ZnSO4, and ZnCO3) on a Mn-Ce co-doped CuX (MCCX)catalyst were investigated and contrasted in the low-temperature NH3-SCR process. Aqueous solutions of ZnCl2, Zn(NO3)2, ZnSO4, and ZnCO3 were used to poison the catalysts. The catalytic activity of all catalysts was assessed, and their physicochemical properties were studied. There was a notable drop trend in catalytic activity in the low temperature range (200 °C) after zinc species poisoning on MCCX catalyst. Interestingly, ZnSO4 and ZnCO3 on MCCX catalyst had more serious effect on catalytic activity than Zn(NO3)2 and ZnCl2 from 150 °C to 225 °C, in which NO conversion of the MCCX-Zn-S and MCCX-Zn-C catalysts dropped about 20–30% below 200 °C compared with the fresh MCCX catalyst. The zeolite X structure was impacted by Zn species doping on the MCCX catalyst, and the Zn-poisoned catalysts had less acidic and lower redox ability than fresh Mn-Ce/CuX catalysts. Through the results of in situ DRIFTS spectroscopy experiments, all catalysts were governed by both Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanisms, and the possible mechanism for poisoning the Mn-Ce/CuX catalyst using various zinc species was revealed.

A study of the local atomic structure the environment of zinc ions of different concentrations during their interaction with the arachidic acid Langmuir monolayer

Vital cellular processes depend on the controlled transport of metal ions across biological membranes. A biological membrane is a complex system consisting of lipids and proteins, that is why simplified systems, in particular monomolecular layers, are used to model it. This work presents the results of a study of the interaction of zinc ions from the aqueous subphase with the Langmuir monolayer of arachidic acid. The study was carried out for the first time and used total external reflection X-ray absorption spectroscopy. It considers the influence of the concentration of a ZnCl2 aqueous subphase solution on the local environment of zinc ions when interacting with the lipid monolayer immediately after its formation. The theoretical analysis of experimental XANES spectra showed that one of the interaction ways of arachidic acid molecules with zinc ions immediately after the monolayer formation is an intramolecular interaction with the formation of spodium bonds between the zinc cation and the OH carboxyl group of arachidic acid

Development of rechargeable high-energy hybrid zinc-iodine aqueous batteries exploiting reversible chlorine-based redox reaction

The chlorine-based redox reaction (ClRR) could be exploited to produce secondary high-energy aqueous batteries. However, efficient and reversible ClRR is challenging, and it is affected by parasitic reactions such as Cl2 gas evolution and electrolyte decomposition. Here, to circumvent these issues, we use iodine as positive electrode active material in a battery system comprising a Zn metal negative electrode and a concentrated (e.g., 30 molal) ZnCl2 aqueous electrolyte solution. During cell discharge, the iodine at the positive electrode interacts with the chloride ions from the electrolyte to enable interhalogen coordinating chemistry and forming ICl3-. In this way, the redox-active halogen atoms allow a reversible three-electrons transfer reaction which, at the lab-scale cell level, translates into an initial specific discharge capacity of 612.5 mAh gI2−1 at 0.5 A gI2−1 and 25 °C (corresponding to a calculated specific energy of 905 Wh kgI2−1). We also report the assembly and testing of a Zn | |Cl-I pouch cell prototype demonstrating a discharge capacity retention of about 74% after 300 cycles at 200 mA and 25 °C (final discharge capacity of about 92 mAh).

In-situ synthesis of floating ZnIn2S4/cellulose foam for facile photocatalysis

The delicate design of photocatalyst monoliths is of great significance for the practical applications of artificial photocatalysis. An in-situ synthesis to prepare ZnIn2S4/cellulose foam was developed. Cellulose is dispersed in a highly concentrated ZnCl2 aqueous solution to prepare Zn2+/cellulose foam. Zn2+ ions are pre-anchored by hydrogen bonds on cellulose and become in-situ sites for synthesizing ultra-thin ZnIn2S4 nanosheets. This synthesis method makes ZnIn2S4 nanosheets and cellulose tightly bound and prevents ZnIn2S4 nanosheets from stacking in multiple layers. As a proof of concept, the prepared ZnIn2S4/cellulose foam exhibits a favorable performance for photocatalytic reduction of Cr(VI) under visible light. By adjusting the concentration of zinc ions, the optimal ZnIn2S4/cellulose foam is capable to completely reduce Cr(VI) in 2 h and the photocatalytic activities show no decrease after 4 cycles. This work could inspire people to build floating cellulose-based photocatalysts via in-situ synthesis.

LOCAL ATOMIC ENVIRONMENT OF Zn<sup>2+</sup> IONS IN A LOW-CONCENTRATION ZnCl<sub>2</sub> AQUEOUS SOLUTION: XANES STUDY

The diverse local environment of zinc ions in a ZnCl2 solution, depending on the symmetry, ligand type, and solution concentration, has been analyzed using the data in the literature. Experimental zinc K-edge XANES spectra in a ZnCl2 aqueous solution with a critically low concentration (10–3 М) have been theoretically analyzed. It is shown that Zn(H2O) complexes with Zn2+ ions in the octahedral coordination environment of water molecules are dominant in this solution.

Selective Solvolysis of Bio-Based PU-Coated Fabric.

Polyurethane (PU) coatings are widely applied on high performing textiles due to their excellent durability and mechanical properties. PUs based on renewable resources were developed to improve the environmental impact of coatings by decreasing the carbon footprint. However, at the end-of-life, PU-coated textiles still end up as landfill or are incinerated since PUs are not biodegradable and are not being recycled at this moment. Therefore, the recycling of PU-coated substrates needs to be examined. This study reports the selective solvolysis of a polyester (PET) fabric coated with a bio-based PU using a 70% ZnCl2 aqueous solution. This method allowed the easy separation of the coating from the fabric. The thermal, chemical and mechanical characteristics of the virgin PET and recycled PET were examined via tensile strength tests, IR, TGA, DSC and GPC. Analysis of the fractions after solvolysis revealed that the PU was converted into the original polyol and an amine, corresponding to the isocyanate used for PU synthesis.

The Synthesis of ZnMn2O4 by Glycine Nitrate Combustion and an Examination of Its Electrochemical Properties in Aqueous Solutions of ZnCl2 and NaNO3

The Synthesis of ZnMn2O4 by Glycine Nitrate Combustion and an Examination of Its Electrochemical Properties in Aqueous Solutions of ZnCl2 and NaNO3

Interaction of Zinc Ions with Hydrated Calcium Silicate Surfaces

Cement materials with calcium silicate hydrate (CSH) gel as the main hydration product have good ability to immobilize heavy metal contaminants. In order to fundamentally understand the curing mechanism of cement materials, the atomic intensity distribution, kinetic properties of Zn2+ ions near the interface of CSH gels were investigated by molecular dynamics method by building a realistic CSH gel nanopore model and aqueous Zncl2 solution. The simulation results show that the interaction between zinc ions and hydrated calcium silicate surface is mainly through the desorption of calcium ions, which leads to the negative charge of the whole hydrated calcium silicate matrix, and thus the adsorption of Zn2+ by coulombic force, and thus the immobilization effect of Zn2+.

A comparison of the inhibition effect of Zn2+or Fe2+ in the oxidation of [formula omitted]-thiophenol groups in coal

To improve the formulation of high-sulfur coal inhibitor, the inhibition mechanism of Zn2+ and Fe2+ on the α-thiophenol groups in coal was analyzed. The results of natural bond orbital analysis show both Zn2+ and Fe2+ formed coordination bonds with –SH, but the Zn2+ complex was more stable. The activation energy required for the chemical adsorption of O2 on α-thiophenol groups increased by 47.62 kJ/mol due to the influence of Zn2+, which is 12.02 kJ/mol higher than that of the Fe2+ complex. In addition, thermal analysis experiments show 20% ZnCl2 aqueous solution increased the ignition point of Hulusu coal by 27 °C, and the oxidation reaction temperature of various active functional groups increased by 17.3 °C–45.9 °C; FeCl2 only inhibited the functional groups containing O/N/S; and catalyzed the combustion of aliphatic carbon and aromatic carbon skeletons. Therefore, the inhibition effect of Zn2+ was stronger than that of Fe2+.

A flexible zinc-ion battery based on the optimized concentrated hydrogel electrolyte for enhanced performance at subzero temperature

The emerging aqueous zinc-ion rechargeable batteries have attracted much attention, owing to their intrinsic safety and low cost. However, it is not practical to use zinc-ion batteries in frigid environments due to their liquid water-based electrolytes. To alleviate this issue, we have developed a flexible zinc-ion battery consisting of an optimized concentrated hydrogel electrolyte sandwiched between an ultrathin zinc anode and a NH4V3O8•1•9H2O cathode for enhanced performance at subzero temperature. The hydrogel electrolytes, synthesized by simply mixing xanthan gum and aqueous ZnCl2 solution, are examined via various characterizations, such as thermogravimetric analysis, tensile tests, adhesion tests, and impedance measurements, for understanding their fundamental properties. The contents of the xanthan gum and the zinc salt can be facilely tuned and optimized for maximized battery performance. It is found that when a concentrated hydrogel electrolyte is prepared using 1.2 g xanthan gum mixed in 4 m ZnCl2 solution, the resulted flexible battery delivers the best performance, exhibiting a very high capacity of 201 mAh g − 1 and 83 mAh g − 1 under 0.2 A g − 1 at -20 °C and -40 °C, respectively. The battery also exhibits remarkable cyclability over 1500 cycles at -20 °C. Additionally, the battery shows capacity retention of 92% capacity over 100 cycles while being bent by 90° then 180° at -20 °C. As such, this battery demonstrates excellent electrochemical performance and mechanical durability/flexibility as well as anti-freezing property, showing high potential to be used to power wearable electronics in cold environments or where safety is most crucial.

A Zn-S aqueous primary battery with high energy and flat discharge plateau.

We demonstrate a disposable aqueous primary battery chemistry that comprises environmentally benign materials of the sulfur cathode and Zn anode in a 1 M ZnCl2 aqueous electrolyte. The Zn-S battery shows a high energy density of 1083.3 Wh kg-1 for sulphur with a flat discharge voltage plateau around 0.7 V. When operating at a high mass loading of 8.3 mg cm-2 for sulfur in the cathode, the battery exhibits a very high areal capacity of 11.4 mA h cm-2 and areal energy of 7.7 mW h cm-2.

Synthesis, physicochemical properties and antibacterial activity of hybrid nanocomposite of ZnS nanoparticles- decorated GO@CS

In this study, green-ZnS nanoparticles (g-ZnS NPs) were synthesized via chemical precipitation using aqueous solutions of ZnCl2 and Na2S at the presence of green tea solution. The ternary hybrid nanocomposite of green-ZnS@ Graphen oxide@Chitosan (g-ZnS@GO@CS) was also prepared through in situ chemical deposition of g-ZnS nanoparticles on GO@CS composite. The obtained nanostructures were characterized by FTIR, SEM, XRD, EDX, X-map, photoluminescence (PL), TGA, and UV-DRS analyses. Based on the results, the g-ZnS@GO@CS composite possessed cauliflower morphology in which ZnS NPs were homogeneously distributed on the composite matrix. Crystallographic investigations revealed the fcc phase of ZnS NPs. Moreover, the crystallite sizes of ZnS, g-ZnS, and g-ZnS@GO@CS samples were estimated as 28.8, 17.9, and 14.8 nm, respectively. Using UV–vis spectroscopy, the bandgap energy of g-ZnS@GO@CS composite, pure ZnS, and g-ZnS were determined 3.02, 3.37, and 4.42 eV, respectively; suggesting a significant reduction in the bandgap of the composite sample due to the synergic effect of GO@CS. Among various g-ZnS@GO@CS composites with different GO@CS contents (4, 8, and 12 wt%) the sample containing 4 wt% GO@CS exhibited the highest photoluminescence intensity. The g-ZnS@GO@CS nanocomposite displayed higher antibacterial activity (growth inhibition zone of 27.6 mm) on Gram-positive Staphylococcus aureus bacteria compared to g-ZnS NPs (growth inhibition zone of 23.5 mm). No significant bioactivity was, however, observed against Gram-negative bacteria (Escherichia coli). According to the results, g-ZnS@GO@CS composite with reduced bandgap, enhanced PL intensity, and smaller ZnS NPs can offer better antibacterial activity as compared to pristine g-ZnS NPs.

Nitrogen-Doped Porous Carbon Nanospheres Activated under Low ZnCl2 Aqueous System: An Electrode for Supercapacitor Applications.

We reported a controlled synthesis method to obtained carbon spheres with tunable geometry under low ZnCl2 aqueous solution conditions using polytriazine as a precursor. The polytriazine precursor was polymerized by mixing/reaction of 2,6-diaminopyridine and formaldehyde in the presence of a diluted ZnCl2 aqueous system. The obtained nanospheres were then decomposed to adulterate nitrogen porous carbon nanospheres (N-PCNSs) by the decomposition and blistering process at high temperature by degrees. ZnCl2 worked as a solid-template and played the role of a stabilizing and foaming agent in the reaction. The as-prepared N-PCNSs with controllable spherical geometry, large micro-/mesoporous volume and high nitrogen content (∼8.5 wt %) were employed in electric double-layer capacitors that have a good specific capacitance (636 F/g at 1 A/g) and are long lasting. Besides, the N-PCNS delivered a high energy density of 22.1 Wh/Kg at a power density of 500 W/kg.