Zinc Chloride Hydroxide Research Articles

Zinc hydroxide salts as new supports for the immobilization of Pseudomonas cepacia lipase

Layered double hydroxides (LDHs) are brucite-like nanomaterials that have been used to immobilize several enzymes. However, layered hydroxide salts (LHSs), another group of brucite-like nanomaterials, have not yet been used for enzyme immobilization. In this work, we prepared two types of layered hydroxide salts, zinc hydroxide nitrate (ZHN: Zn5(OH)8(NO3)2 .2H2O) and zinc hydroxide chloride (ZHC: Zn5(OH)8Cl2 .H2O) and used them to immobilize Pseudomonas cepacia lipase (LipPS). The best protein loading for both ZHN and ZHC was 162.5 mg g−1 of LHS, which gave high values of triolein-hydrolyzing activity in organic medium (103 U g−1 for LipPS-ZHN and 105 U g−1 for LipPS-ZHC), immobilization efficiencies above 90% and activity retentions above 170%. In the kinetic resolution of (R,S)-1-phenylethanol, LipPS-ZHN gave better results, with 50% conversion being obtained in 2 h and an ee s of 99%. With LipPS-ZHC, the conversion at 2 h was 40% and the ee s, was lower, only 73%. For both immobilized materials, the eep was higher than 99% and E was higher than 200. The immobilized materials were stable after 5 cycles of reuse in successive 2-h kinetic resolutions. These results demonstrate that the layered hydroxide salts ZHN and ZHC have good potential as supports for the immobilization of lipases.

Electrochemical behavior of Sn-9Zn-xCu solder alloy in 3.5 wt% NaCl solution at room temperature

The effect of Cu addition on potentiodynamic and static immersion corrosion behavior of Sn-9Zn-xCu (x=0,1,2,3 wt%) was evaluated for their application in the electronic industry. Samples of solder alloy were prepared through vacuum induction furnace melting. Techniques such as SEM, XRD, and XPS were applied to evaluate the morphology and corrosion products on the surface. Microstructural characterization and phase analysis before the corrosion test show the presence of Cu 5 Zn 8 and Cu 6 Sn 5 intermetallics in the matrix. The primary corrosion products were found to be zinc hydroxide chloride Zn 5 (OH) 8 Cl 2 .H 2 O, tin oxide chloride hydroxide (Sn 3 O(OH) 2 Cl 2 ), SnO, and ZnO. The possible reasons for the generation of zinc corrosion products were critically discussed, and the most precise mechanism was proposed. Adding 1 to 3 wt.% copper to the Sn-9Zn solder alloy increased its corrosion resistance, owing to coarser and more evenly distributed corrosion-vulnerable Zn-rich precipitates. Static corrosion tests show that the weight loss decreases with increased copper content, indicating an increase in corrosion resistance. Sn-9Zn-3Cu alloys recorded the maximum corrosion resistance among all the alloys in the above corrosion tests.

Zinc chloride hydroxide - A recyclable diffusion source for fabrication of zinc rich coatings on magnesium alloys

To reduce greenhouse gas emissions and fuel consumption, it is important to utilize lighter materials in vehicles. Magnesium is the lightest structural metal, but the corrosion resistance of magnesium and magnesium alloys is limited. The powder thermal diffusion alloying method can enhance the surface of magnesium alloys by fabricating a metallic coating. The huge consumption of powders and potential environmental pollution problems should be controlled for the sustainable development of related industries. Here, based on the investigation of the evolution of a diffusion source in powder thermal diffusion alloying processes, we propose a recyclable diffusion source that can be utilized in a series of diffusion alloying processes without reloading a new diffusion source or the addition of other powders. This diffusion source is mainly based on reversible chemical reactions related to zinc hydroxide chloride. With such a recyclable diffusion source, diffusion alloying processes can be carried out more fluently, and the powders can be saved effectively. Meanwhile, both the environment and the health of workers can be protected. It is our hope that this idea could inspire traditional pack cementation industries to find similar resource-conserving and environmentally friendly approaches. Meanwhile, widespread application of both magnesium alloys and zinc hydroxide chlorides can be promoted.

Application of a hybrid material formed by layered zinc hydroxide chloride modified with spiropyran in the adsorption of Ca2+ from water

The excess of metal ions in water is associated with drawbacks in industrial processes due to the precipitation of insoluble compounds in pipes and cooling systems. Therefore, investigating alternatives for the removal of ions is especially important and can be achieved with the use of adsorbing materials. In this paper, a novel hybrid material formed by zinc hydroxy chloride (ZHC) functionalized with molecules of the spiropyran class is presented as an alternative for the removal of calcium ions from water. Characterization techniques, including XRD, FTIR, and EDS allowed to identify the spiropyran molecules covering the surface of ZHC in the merocyanine form, forming active sites for calcium chemisorption. The material, described as ZHC/MC24, showed good adsorption capacities that reached 19 mg g−1 at pH 8.0. ZHC/MC24 presented a negatively charged surface, according to zeta potential analyses. Shifting the pH to alkaline values increased the negative potential, which reflected in greater calcium adsorptions. The isotherm investigation showed that the adsorption occurs in a monolayer process, and a first-order adsorption model was found to describe the process. Control tests performed with the ZHC without spiropyran showed low adsorption capacities, inferior to 2 mg g−1, evidencing the importance of the functionalization with spiropyran to the proposed application.

Synthesis and characterisation of ammonia intercalated zinc hydroxide chloride hydrate: a potential photocatalyst for methyl orange degradation under sunlight

ABSTRACT In this work, ammonia intercalated zinc hydroxide chloride hydrate (ZHC-NH3), Zn5(OH)8Cl2.4[(H2O)x(NH3)1-x)] was synthesised using precursor, [ZnCl2.2{HONC(CH3)2}] by sol-gel method in presence of ammonia and characterised by FT-IR, SEM-EDX, and XRD analysis. On sintering at 500°C, ZHC-NH3 transformed to ZnO nanoparticles (ZnO NPs) as confirmed by the XRD patterns. ZHC-NH3 has nanoplates-like morphology with a positive surface charge (+28.8 mV) while synthesised ZnO nanoparticles (ZnO-NPs) have spherical morphologies with negative surface charge (−8.28 mV). Band gap of 2.7 eV was observed in ZHC-NH3 while in ZnO NPs it was obtained as 3.3 eV. A comparison has been done on the photocatalytic activities of ZHC-NH3 and ZnO NPs towards the degradation of methylene blue (cationic dye) and methyl orange (anionic dye) under sunlight and it was found that photo-degradation of anionic dye, methyl orange is superior (96.28%) in presence of ZHC-NH3 photocatalyst as compared to ZnO photocatalyst (55.42%). The adsorption capacities of ZHC-NH3 towards Pb2+, Cd2+, and Cr3+ heavy metal ions were found 47.00 mg. g−1, 20.40 mg. g−1, and 48.85 mg. g−1 whereas ZnO-NPs have adsorptions capacities of 46.97 mg. g−1, 43.07 mg. g−1, 29.21 mg. g−1, for Pb2+, Cd2+, and Cr3+ heavy metal ions, respectively.

A Sight of Zinc Corrosion in Various Alkaline Media

This review concentrates on corrosion properties that expose to zinc by various alkaline media. The assumption has been advanced that zinc corrodes electrochemically in the first stage of exposition, but the chemical corrosion prevails after a longer time. Different types of electrolyte had been tested on zinc such as sodium chloride, sodium hydroxide and potassium hydroxide. Each of alkaline media can produced corrosion product such as zinc hydroxide chloride, zinc hydroxide carbonate, zinc oxide, and zinc hydroxide. The production of corrosion products is depending on the carbon dioxide content that introduced to the air. Potassium hydroxide is the highest and active alkaline where it contains the highest ionic conductivity potassium ions, K+ after hydronium, H3O+ among the cations and hydroxide, OH ? has the highest ionic conductivity among the anions.

A multi-analytical exploration of the chemical composition, microstructural properties and corrosion inhibiting treatment for an archaeological brass censer from Umm Zuwaytinah, Amman

This study discusses a multi-analytical exploration of the chemical composition, microstructural properties and corrosion inhibiting treatment for a decorated Byzantine brass censer from Umm Zuwaytinah, Amman. X-ray diffraction (XRD) analysis showed cuprite, brochantite, malachite, atacamite, zincite, and zinc chloride hydroxide as the corrosion products for the censer. Scanning electron microscopy/ energy dispersive X-ray spectroscopy (SEM/EDX) analysis showed α-brass as the alloy of the body and a quaternary Cu, Zn, Sn, Pb as the alloy of the chains of the censer. Optical microscopy examination showed partially recrystallized grains with some annealing twins, strain lines and intergranular corrosion in the body and chain alloys. Microhardness testing results for the censer’s body were consistent with a cast α-brass alloy that was not sufficiently annealed in the manufacturing process, and a drawn quaternary Cu, Zn, Sn, Pb alloy for the chains. SEM examination showed that a treatment bya salicylaldoxime-Paraloid B72 containing solutionwas effective in forming a protective corrosion inhibiting film on the censer's surface.

Characterization and crystal structure determination of zinc hydroxide chloride tetrahydrate [formula omitted

A zinc hydroxide chloride compound precipitated from the ammonia stripping step of a zinc ammonia ammonium chloride complex solution was found to have an unidentified crystal structure. Ab initio structure determination was performed based on Synchrotron X-ray powder diffraction data. The derived space group and unit cell values are consistent with the Selective Area Electron Diffraction analysis in Transmission Electron Microscopy. The new structure is similar to an established crystal structure of zinc hydroxide chloride monohydrate (Zn5(OH)8Cl2⋅H2O), but with a wider interlayer to accommodate water and ammonia molecules. It is proposed that the new compound has a monoclinic space group of P121/c1, No. 14, with unit cell of a ​= ​6.30407(16) Å, b ​= ​21.36561(16) Å, c ​= ​6.26238(15) Å, β ​= ​119.795(3)∘, with a formula of Zn5(OH)8Cl2⋅4[(H2O)x(NH3)1−x]. Complimentary techniques including Scanning Electron Microscopy & Energy Dispersive Spectroscopy analysis, Thermogravimetry & Differential Scanning Calorimetry and Fourier-transform infrared spectroscopy provide additional characteristics for the new compound. The newly solved structure of this phase will provide XRD reference for previously unsolved structure reported from mineral processing, solid-state chemistry and zinc-air battery researches.

Electrodeposition and corrosion behavior of Zn−Ni−Mn alloy coatings deposited from alkaline solution

Abstract The potentiostatic electrodeposition of Zn−Ni−Mn was carried out in an alkaline solution with the addition of Mn salt. The effects of electrolyte Mn2+ concentration and deposition potential on the surface morphology, phase structure and corrosion behavior of coatings were studied. The results of corrosion polarization showed that the presence of higher Mn content in Zn−Ni−Mn coatings could lead to the formation of a good passive layer with a 7-fold increase in Rp of coating and a significant decrease in the corrosion current density compared to those of Zn−Ni coating. The XRD and the XPS analyses from the surface of Zn−Ni−Mn after corrosion test showed that the passive layer was composed of zinc hydroxide chloride, zinc oxide, zinc hydroxide carbonate, and manganese oxides.

Effect of Deposition Potential and Bath Temperature on One-Step Electrochemical Synthesis of One and Two Dimensional Nanostructured ZnO Thin Films on Fluorine Doped Tin Oxide Substrates

Different zinc oxide (ZnO) morphologies such as platelets, nanowalls and nanorods were electrochemically synthesized on fluorine doped tin oxide (FTO) substrates by varying the deposition potentials and bath temperatures, respectively. Cyclic voltammetry (CV) curves reveal that ZnO deposition potentials are decreased as the bath temperatures are increased. X-ray diffraction (XRD) patterns and transmission electron microscope (TEM) images confirm that the synthesized ZnO nanostructures are hexagonal wurtzite structure. The XRD results reveal that the crystallinity of the films is increased when ZnO deposition potentials and temperatures are increased. Field emission scanning electron microscope (FE-SEM) images display platelets, nanowalls and nanorods structures for films synthesized -1.1 V, -1.2 V and -1.3 V respectively. The increase in deposition potential not only increases the growth rate of ZnO with metallic zinc deposition, but also decreases zinc hydroxide chloride hydrate. Fourier transform infrared microscope (FTIR) spectra confirm that the formation of zinc hydroxide (Zn(OH)₂) is decreased as the bath temperatures are increased from 30 to 70 °C. Photoluminescence (PL) spectra depict that the crystal quality of the ZnO films are notably improved as the bath temperatures are increased. The film thickness is increased as the deposition potentials and bath temperatures are increased. The dye absorbance is increased with respect to the film thickness. The efficiencies of dye sensitized solar cells (DSSCs) fabricated with diverse morphologies such as platelets, nanowalls and nanorods are found to be 0.10, 0.49 and 0.47%, respectively. Electrochemical impedance spectroscopy (EIS) spectra reveal that the charge transfer recombination resistance (Rrec) is continuously decreased as metal zinc deposition is increased in ZnO films with increase in deposition potentials.

Comparison between catalytic activities of two zinc layered hydroxide salts in brilliant green organic dye bleaching

This paper reports the use of two layered hydroxide salts (LHS) (zinc hydroxide nitrate – ZHN – Zn5(OH)8(NO3)2·2H2O, and zinc hydroxide chloride – ZHC – Zn5(OH)8Cl2·H2O) as catalysts for brilliant green (BG) organic dye bleaching, using hydrogen peroxide as oxidant. The LHS were prepared by precipitation reaction between an aqueous solution of zinc salts and an aqueous ammonia solution. The solids were characterized by powder X-ray diffraction (XRD), electron paramagnetic resonance (EPR), ultraviolet-visible electronic spectroscopy (UV–Vis) and Fourier-transform infrared spectroscopy (FTIR). The catalytic activity of the solids was investigated at temperatures of 25, 35 and 45 °C, using different molar ratios of oxidant:dye:Zn2+ ions (present in the catalyst), in the absence and presence of ambient light. The kinetic aspect of the reaction was investigated considering that the reaction showed pseudo-first order behavior in relation to BG dye concentration. We propose a mechanism where superoxide radicals account for most of the bleaching taking place. The catalytic results obtained, along with the low cost and low toxicity of zinc compounds, establish ZHN and ZHC as novel catalysts for dye wastewater treatment, an area with constant demand for new methods and materials given its relationship with environmental equilibrium and human health.

Initial formation of corrosion products on pure zinc in saline solution

Corrosion product formed on zinc sample during 2 weeks immersion in saline solution has been investigated. The corrosion layer morphology as well as its chemical composition, was analyzed using scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Electrochemical measurement was used to analyze the corrosion behavior. Zinc oxide, zinc hydroxide and zinc hydroxide chloride were formed on zinc surface in saline solution. The thickness of corrosion layer increased with the time increased. The pure Zn has an estimated corrosion rate of 0.063 mm y−1 after immersion for 336 h. Probable mechanisms of zinc corrosion products formation are presented.

Effect of hexamethylenetetramine on the properties of electrodeposited ZnO thin films for dye sensitized solar cell applications

Zinc oxide (ZnO) thin films were obtained on fluorine doped tin oxide substrates by pyrolyzing the electrodeposited zinc hydroxide chloride thin films. The effect of hexamethylenetetramine (HMTA) concentrations on the structural, morphological, vibrational and optical properties was investigated. The ZnO growth orientation is changed from (101) to (002) plane as the HMTA concentrations get increased from 0 to 9 mM. The well-defined hexagonal nanorods and nanowires structures are observed for ZnO thin films deposited in the absence and presence of HMTA. The increase in intensity of E2 (high) vibrational mode, near band edge emission and UV absorbance confirms the ZnO nanowires synthesized in the solution containing 9 mM HMTA having better crystallinity, lesser atomic defects and higher dye loading, respectively. The efficiency of dye sensitized solar cells (DSSCs) based on nanorods and nanowires synthesized in the solutions containing 0 and 9 mM HMTA is 0.36 and 1.02%, respectively. The DSSC based on nanowires photoanode has a higher Rrec, τn, σn and Ln than another DSSC.

Hydrometallurgical treatment of zinc ash from hot-dip galvanizing process

The oxide fraction of industrial zinc ash was characterized in terms of chemical and phase composition, leaching behavior in sulfuric acid solutions, and leaching thermal effect. The waste product contained about 68 percent zinc (Zn), 7 percent chlorine (Cl), 2 percent aluminum (Al) and less than 1 percent other metals, such as iron (Fe), manganese (Mn), calcium (Ca) and silicon (Si). It consisted mainly of zinc oxide contaminated with metallic zinc and zinc hydroxide chloride. The dissolution of metals from the zinc ash was determined for solid-to-liquid ratios ranging from 100 to 500 kg/m3, acid concentrations of 10 and 20 percent, and temperatures of 20 and 40 °C. The best result — 130 g/dm3 Zn(II) at 95 percent zinc recovery — was obtained at a solid-to-liquid ratio of 200 kg/m3, sulfuric acid concentration of 20 percent and initial temperature of 40 °C. The final solutions were contaminated mainly by Mn(II) and Fe(III) ions, but the presence of cadmium (Cd(II)) and lead (Pb(II)) ions enabled electrowinning of zinc of about 99 percent purity at high current efficiency of 85 to 99 percent. Leaching of the material was an exothermic process with reaction heat of about 520 kJ/kg.

Effects of zinc precursor, basicity and temperature on the aqueous synthesis of ZnO nanocrystals

The effects of the zinc salt precursors, the reaction temperature and the alkaline ratio b (b = [OH-]/[Zn 2+ ]) on the aqueous synthesis of ZnO nanocrystals were investigated. Depending on the type of the zinc precursor, Zn 5 (OH) 8 Cl 2 ·H 2 O or Zn 5 (OH) 8 (NO 3 ) 2 .2H 2 O lamellar phases were obtained at room temperature (20°C) when the alkaline ratio is lower (0.5 ≤ b ≤ 1, 6 ≤ pH ≤ 6.4). When the reaction temperature increased to 95 °C, zinc hydroxide chloride monohydrate was obtained in one case whereas zinc oxide was formed in the other, and no lamellar phase of Zn 5 (OH) 8 (NO 3 ) 2 .2H 2 O was obtained. Thermal decomposition of the two lamellar phases was carried out and mainly showed that Zn 5 (OH) 8 (NO 3 ) 2 .2H 2 O was completely decomposed to ZnO when the annealed temperature reached ~250 °C while Zn 5 (OH) 8 Cl 2 ·H 2 O was totally transformed to ZnO at about 400 °C, a higher comparative temperature that confirms the better thermal stability of the zinc hydroxide chloride monohydrate. Keywords: Oxides, ZnO, chemical synthesis, X-ray diffraction, crystal structure, luminescence

Comparative studies on acid leaching of zinc waste materials

Three industrial waste materials were characterized in terms of their elemental and phase compositions, leaching behaviour in 10% sulfuric acid solution as well as leaching thermal effects. Slag from melting of mixed metallic scrap contained about 50% Zn and 10% Pb. It consisted mainly of various oxides and oxy-chlorides of metals. Zinc spray metallizing dust contained about 77% Zn in form of zinc and/or zinc-iron oxides, zinc metal and Zn-Fe intermetallic. Zinc ash from hot dip galvanizing was a mixture of zinc oxide, metallic zinc and zinc hydroxide chloride and contained about 80% Zn. Dissolution efficiency of zinc from the first material was 80% (independently on the solid to liquid ratio, 50–150 kg/m3), while decrease of the efficacy from 80% to 60% with increased solid to liquid ratio for the two remaining materials was observed. Both increase in the temperature (20 °C to 35 °C) and agitation rate (300 rpm to 900 rpm) did not improve seriously the leaching results. In all cases, transfer of zinc ions to the leachate was accompanied by different levels of solution contamination, depending on the type of the waste. Leaching of the materials was exothermic with the similar reaction heats for two high oxide-type products (slag, zinc ash) and higher values for the spray metallizing dust.

Corrosion Behavior of Cu40Zn in Sulfide-Polluted 3.5% NaCl Solution

The corrosion behavior of a duplex-phase brass Cu40Zn in clean and sulfide-polluted 3.5% NaCl solutions was investigated by conducting electrochemical and gravimetric measurements. The corrosion product films were analyzed by scanning electron microscopy, energy-dispersive spectroscopy and x-ray diffraction. The presence of sulfide shifted the corrosion potential of Cu40Zn toward a more negative value by 100 mV and increased the mass loss rate by a factor of 1.257 compared with the result in the clean solution. The corrosion product film in the clean solution was thin and compact; it mainly consisted of oxides, such as ZnO and Cu2O. By contrast, the film in the sulfide-polluted solution was thick and porous. It mainly contained sulfides and zinc hydroxide chloride (i.e., Zn5(OH)8Cl2·H2O). The presence of sulfide ions accelerated the corrosion damage of Cu40Zn by hindering the formation of protective oxides and promoting the formation of a defective film which consisted of sulfides and hydroxide chlorides.

Preparation, characterization and application of synthesized nano Zn(OH)8Cl2H2O in removing of dye pollutants: Modeling of removal process by response surface methodology

Zinc hydroxide chloride nanostructure was successfully synthesized through a simple method at low temperature by sonochemical process. The morphology and crystalline of the products were examined by X-ray diffraction (XRD) analysis, Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Response surface methodology was used to optimize the Reactive Yellow 145 dyes dye adsorption onto zinc hydroxide chloride nanostructure. The effect of independent variables including contact time, solution pH, adsorbent dosage and the concentration of dye on removal performance was investigated based on Central Composite Designs. ANOVA was applied to analyze the responses. Maximum removal was achieved about 52.11% at following conditions: dye concentration=40mg/l; pH=4; dosage=0.02g/50ml; time=80min. Investigating the isotherm and kinetic models showed that the experimental data were correlated with Temkin adsorption isotherm and pseudo-second order kinetic models.

Comparative study of photocatalytic activities of Zn5(OH)8Cl2·H2O and ZnO nanostructures in ciprofloxacin degradation: Response surface methodology and kinetic studies

Zinc hydroxide chloride monohydrate (Zn5(OH)8Cl2·H2O) and zinc oxide (ZnO) nanostructures were synthesized by simple precipitation and pyrolysis methods, respectively and characterized by means of various instrumental methods. Their photocatalytic efficiencies as two potential photocatalysts for photodegradation of a clinical wastewater, ciprofloxacin (CIP), were probed and compared. The results indicated that in comparison with Zn5(OH)8Cl2·H2O nanoplates, the photodegradation was 1.4 times faster when using ZnO nanoparticles as well as higher removal percentage. The optimum pH obtained was 8 that it is typically found for hospital wastewater. Analysis of variance (ANOVA) exhibited high R2 values, high F-values, very low P-values, and non-significant lack of fit values demonstrating good correlation between experimental and predicted values of the response for both catalysts. Kinetic studies identified first order model as a suitable model for description of photodegradation processes for both nanosized Zn5(OH)8Cl2·H2O and ZnO. The chemical oxygen demand (COD) removal of 43.30 and 56.30% were obtained after 24h for Zn5(OH)8Cl2·H2O nanoplates and ZnO nanoparticles, respectively. Ultra-performance liquid chromatography method coupled with tandem mass spectrometry (UPLC-MS/MS) for the determination of CIP degradation products has been used. Taken together, ZnO nanoparticles were more efficient in CIP removal due to some properties as in higher surface area and lower band gap.

Thermal transformation of layered zinc hydroxide chloride

Zinc hydroxide chloride, Zn5(OH)8Cl2·H2O, belongs to a special group of layered materials which are used in a wide variety of commercial applications. During the heating, Zn5(OH)8Cl2·H2O undergoes a complex transformation which involves several overlapping stages and highly depends on the experimental conditions. Although it is well established that the thermal transformation of Zn5(OH)8Cl2·H2O leads to the formation of ZnO as final product, there is still no generally accepted mechanism explaining the intermediate stages of this process. This review provides a summary of the studies devoted to this topic complemented by critical data assessment and generalisation of the established information. We hope that the review conveys to the reader state of the art of this problem and provides baseline knowledge required for complete understanding of thermal behaviour of this material.