Zn Dust Research Articles

Zinc‐mediated efficient and environmentally benign synthesis of salicylate esters

AbstractConsiderable synthetic effort has been devoted to acid‐ or base‐catalysed transesterification of alkyl salicylate with alcohol in order to synthesize salicylate esters efficiently. In this study, the transesterification of methyl salicylate with 12 different alcohols was carried out by the use of Zn dust as a catalyst. Depending on the alcohol used in the transesterification reaction, the completion of the reaction was within a range of 8–15 h at a temperature between 100 and 170°C. The use of Zn dust provided reusability and almost complete recovery with moderate to excellent yields (42%–97%). The structural elucidation of the products was performed using IR, 1H NMR, 13C NMR and GC–MS data obtained from the Wiley GC/MS Library and the in‐house “Parkim Fragrance House GC/MS Library.”

Evaluation of recycled galvanised steel as a resource for Zn production

The high reduction potential of zinc has enabled its extensive use in the steel industry as a protective galvanising coating. Galvanising, which consumes approximately 50-60% of the global production of zinc, significantly increases the life span of steel products and contributes towards addressing the costly global problem of corrosion. While there does not appear to be a readily available and agreed-upon annual quantity of galvanised steel produced, it has been estimated by the authors to be 320-390 Mt/a (equating to 15-20% of the annual steel production). Due to the various methods employed to galvanise steel and different steel shapes which are coated, there is no clarity on the average percentage of zinc which galvanised steel is comprised of. However, a zinc content of between 1.5-2.5% appears to correlate with the estimated annual galvanised steel production.The reprocessing of secondary zinc streams is becoming increasingly important due to legislation changes and increased consumer demand for recycled and low carbon metals. Within the steel industry this will include the recycling of galvanised scrap steel, using primary process routes, as well as the re-processing of waste streams, such as steel dusts, using additional technologies such as the Waelz kiln. Zinc associated with galvanised scrap steel would exclusively report to these dusts, and thus represents a key resource for recycled zinc.Although there are two main steel process routes preceding the galvanising process, the focus here is on the Electric Arc Furnace (EAF) process route due to its ability to incorporate high levels of secondary (zinc containing) steel feeds, and the dust produced typically contains economically recoverable levels of zinc. EAF dust production is estimated between 5-10 Mt/a at a zinc content of 10-36%. Failure to recover this zinc would represent a loss of 0.5-3.6 Mt Zn/a to waste. The Waelz kiln is the most prominent technology utilised to recover Zn from EAF dust. However, this process requires additional energy, and thus the associated carbon footprint needs to be included in the evaluation of the potential of Waelz oxide as a secondary Zn resource. To this end, model analysis of a simplified Waelz kiln using the HSC simulation software shows that the carbon footprint associated with the processing of EAF dust ranges from 4-12 kg CO2/kg Zn dust at 10 wt.% Zn in the dust to 1-4 kg CO2/kg Zn at 35 wt.% Zn in the dust.

Nickel-Catalyzed Reductive Arylation of Redox Active Esters for the Synthesis of α-Aryl Nitriles: Investigation of a Chlorosilane Additive.

A nickel-catalyzed reductive cross-coupling of redox active N-hydroxyphthalimide (NHP) esters and iodoarenes for the synthesis of α-aryl nitriles is described. The NHP ester substrate is derived from cyanoacetic acid, which allows for a modular synthesis of substituted α-aryl nitriles, an important scaffold in the pharmaceutical sciences. The reaction exhibits a broad scope, and many functional groups are compatible under the reaction conditions, including complex highly functionalized medicinal agents. Mechanistic studies reveal that reduction and decarboxylation of the NHP ester to the reactive radical intermediate are accomplished by a combination of a chlorosilane additive and Zn dust. We demonstrate that stoichiometric chlorosilane is essential for product formation and that chlorosilane plays a role beyond activation of the metal reductant.

Green synthesis of nitroaryl thioureas: Towards an improved preparation of guanidinium DNA binders

We present a general efficient green method for the preparation of nitro N,N′-diaryl thioureas via a one-pot method using cyrene as a solvent with almost quantitative yields. This confirmed the viability of cyrene as a green alternative to THF in the synthesis of thiourea derivatives. After screening different reducing conditions, the nitro N,N′-diaryl thioureas were selectively reduced using Zn dust in the presence of water and acid to the corresponding amino N,N′-diaryl thioureas. These were then used to test the installation of the Boc-protected guanidine group with N,N′-bis-Boc protected pyrazole-1-carboxamidine as a guanidylating reagent not requiring mercury(II) activation. Finally, the TFA salts obtained after Boc-deprotection of two sample compounds were tested for their affinity towards DNA showing no binding.

Bifunctionality of Zn dust in Ullmann C–C cross-coupling by Ni/Pd dual catalysis: theoretical insight

Zinc powder presents bifunctionality for heterogeneous single-electron reduction and homogeneous transmelation in Ullmann C–C bond cross-coupling by Ni/Pd dual catalysis.

Sources, pathways and concentrations of potentially toxic trace metals in home environments

Despite ongoing concerns about trace metal and metalloid (trace metals) exposure risks from indoor dust, there has been limited research examining their sources and relationship to outdoor soils. Here we determine the concentrations and sources for potentially toxic trace metals arsenic (As), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) and their pathways into homes in Sydney, Australia, using home-matched indoor dust (n = 166), garden soil (n = 166), and road dust samples (n = 51). All trace metals were more elevated indoors versus their matched garden soil counterparts. Indoor Cu and Zn dust concentrations were significantly more enriched than outdoor dusts and soils, indicating indoor sources were more relevant for these elements. By contrast, even though Pb was elevated in indoor dust, garden soil concentrations were correspondingly high, indicating that it remains an important source and pathway for indoor contamination. Elevated concentrations of As, Pb and Zn in garden soil and indoor dust were associated with home age (>50 years), construction materials, recent renovations and deteriorating interior paint. Significant correlations (p < 0.05) between road dust and garden soil Cu concentrations, and those of As and Zn in soil and indoor dust, and Pb across all three media suggest common sources. Scanning electron microscopy (SEM) analysis of indoor dust samples (n = 6) showed that 57% of particles were derived from outdoor sources. Lead isotopic compositions of soil (n = 21) and indoor dust (n = 21) were moderately correlated, confirming the relevance of outdoor contaminants to indoor environments. This study illustrates the source, relationship and fate of trace metals between outdoor and indoor environments. The findings provide insight into understanding and responding to potentially toxic trace metal exposures in the home environment.

Investigation and recovery of copper from waste silicon solar module

Photovoltaic (PV) technology has seen exponential growth in the last few decades with the total global installation reaching 849 GW by year 2021. With the estimated solar waste of nearly 78 million tonnes by year 2050, its high time to emphasise on the development of the recycling processes for valuable materials contained in end-of-life (EoL) solar panels. Crystalline silicon (c-Si) technology, owing to the largest market share, is forecasted to generate the majority of solar waste flux. A c-Si panel contains metals like Ag, Cu, Al, Pb and Sn. Most of the metallic fraction (Cu, Pb and Sn) by weight is contained in the connecting wires of the panel. In the present study, a process is developed for recovery of metallic Cu along with Pb and Sn without their exposure to the environment. Initially, connecting wires were separate out from panel using toluene solution. These wires were then thermally treated at 800 °C for 7 h in a sealed quartz tube to get impure Cu strips and Pb-Sn powder. A set of chemical reactions was carried out next to first recover CuO powder followed by subsequent treatment with H2SO4 and Zn dust to recover 97.27% pure reddish brown Cu powder. As high purity copper powder with a good recovery rate of around 90% is obtained as the end product, the present study demonstrates a very simple process to recycle connecting wires in an ecological way with trapping toxic Pb and Sn.

Assignment of the Crystal Structure to the Aza-Pinacol Coupling Product by X-ray Diffraction and Density Functional Theory Modeling.

Aza-pinacol coupling of N-benzyl-1-phenylmethanimine using Zn dust affords a mixture of R,S- or R,R-diastereomers in a 1:1 ratio. The R,S-diastereomer is solid with an m.p. of 135 °C, while the R,R-diastereomer is liquid at room temperature. The configuration of stereocenters was determined by combining X-ray powder diffraction and density functional theory (DFT) modeling.

Alternative Method for Treating Electric Arc Furnace Dust: Simulation and Life Cycle Assessment

The technical and environmental aspects of treating electric arc furnace dust (EAFD) using a novel process including alkaline roasting and organic acid leaching were evaluated and compared to the globally applied conventional Waelz process. The global warming potentials of the roasting–organic acid leaching process (with co-product credits) and the Waelz processes were 7.48 and 4.71 kg CO2-eq with 33% Zn dust as the feed material. However, with decreasing Zn content, the novel process become environmentally more competitive, and with 12% Zn, the corresponding GWP values were 6.31 and 9.26 kg CO2-eq. Co-product recovery decreased the net environmental impacts from the processing of the dust, which gave some benefits to the novel process. The Waelz process was observed to be energy intensive; however, the high consumption of leaching and roasting chemicals was the issue in the novel process. The excess caustic soda in the roasting step was observed to be a significant factor in the overconsumption of the organic acid in the leaching stage, and therefore, optimization of the roasting step is crucial. Other ways to decrease leaching chemical consumption include investigating the possibility to reuse the raffinate in leaching, or scrubbing the leach calcine from acid-consuming alkali. Evaluating the impacts of novel processes early enables iterative and agile process development and the directing the focus on the problem areas.Graphical

Efficient utilization of copper slag in an innovative sintering process for Fe–Ni–Cu alloy preparation and valuable elements recovery

In this study, copper slag and low-grade nickel laterite were synergistically utilized via an innovative sintering process with multi-force fields. Their sintering performance and the reduction and softening dripping characteristics of Fe–Ni–Cu product sinter were determined. The strengthening mechanism of the innovative sintering technology was revealed. The obtained Fe–Ni–Cu alloy and smelting slag from the melting dripping process were characterized. Carbon emissions reduction and other valuable elements treatment were also discussed. Due to the formation of the denser sinter microstructure and the reduction of high smelting components, sintering performances in the innovative sintering process are substantially improved. Compared with the base case, tumble index and productivity are improved by 24.87% and 19.59%, respectively. Solid fuel consumption is reduced by 27.14%. The reduction and softening dripping characteristics of Fe–Ni–Cu product sinter are excellent as well. The obtained Fe–Ni–Cu alloy with high purity can be used as the high-quality burden for copper-bearing stainless steel and high-strength alloy steel and its quality can be further improved by optimizing the smelting process parameters in the near future. In addition, the obvious carbon emissions reduction in sintering-blast furnace production can be achieved and other valuable elements such as S, Zn and Pb can be conveniently recycled in form of sulphuric acid and Pb–Zn dust, respectively.

Concepts of steel protection by coatings with a reduced content of zinc pigments

In zinc-rich primers Zn acts in the initial stage as sacrificial anode (cathodic protection). During lifetime Zn is transformed into its corrosion products, which seal the coating's pores (barrier protection). Such coatings are typically very highly pigmented which could cause the deterioration of cohesion and/or adhesion as well as mechanical properties. The formulations of different Zn pigments in epoxy matrices were developed with concentration of zinc particles reduced to about 50 wt% in the dry coatings. As Zn pigments were used: mixtures of zinc pigments with different particle size and particle shape (dust, flakes), zinc dust with organic surface treatment, zinc alloy pigments – ZnMg and ZnSn as well as Zn dust with an addition of graphene or carbon nanotubes.The mechanisms of protection by coatings with a reduced content of zinc pigments were studied in comparison with that of commercial zinc rich primers – epoxy and ethyl silicate – by the following methods: Scanning Kelvin Probe (SKP) detection of artificially inflicted samples after impact of salt spray test (SST), polarization experiments and EOC detections in combination with different corrosive impact, as well as by SST and the exposure to the natural marine environment (sea water splash zone).It was found that cathodic protection is shown by primer pigmented with Zn flakes, with zinc phosphate and barium sulphate addition as well as by primer containing Zn dust and graphene. They reach an open circuit potential (EOC) significantly below −0.86 V. Primers pigmented with ZnSn or Zn dust with an addition of carbon nanotubes (CNT) keep their EOC in the transition phase between −0.7 V and −0.86 V. Other primers with a reduced content of zinc pigments show only barrier protection.Coatings characterized by EOC in the range of cathodic protection or in the transition phase have very good protective properties in the corrosive environment. However, good anticorrosive properties were found also in the case of primers which do not show any cathodic protection, such as the primer pigmented with a mixture of Zn particles with different size and the primer containing Zn dust with chemical surface treatment. This shows that good anticorrosive properties can be obtained even if cathodic protection is not observed.

Synthesis of selenol esters via the reaction of acyl chlorides with diselenides in the presence of Zn dust catalyzed by CoCl2·6H2O

A practical and efficient approach for the synthesis of selenol and thiol esters is described via the reaction of acyl chlorides with diselenides or disulfides in the presence of Zn dust catalyzed by inexpensive CoCl2·6H2O This protocol tolerates a wide range of substrates, including aromatic and aliphatic acyl chlorides, with a variety of sensitive functional groups to afford the respective products in good yields. Furthermore, the method was also extended to use anhydrides as substrates. In addition, the obtained selenol esters could be readily transformed into vinyl selenide ketones by the selenocarbonylation of terminal alkynes catalyzed by a palladium/copper system.

The effect of zinc shape on its corrosion mitigation as an anode in aqueous Zn/MnO2 battery

• Developing of Zn powder and dust electrode for aqueous Zn/MnO 2 battery. • Zn powder with grain sizes >500 µm attenuate its corrosion and dissolution in NH 4 Cl solution. • Assembling of Zn powder or dust (anode) with electrolytic (EMD) or nanostructured (NMD) MnO 2 (cathode) in Zn/MnO 2 cell. • Zn powder (>500 µm)/NMD cell yields a highest output voltage of 1.646 V. • Specific energy (109.722 mWh/g) and the lowest voltage drop of 0.7% after 2 h of discharge. This work gives an insight into how zinc (Zn) anode in the Zn/MnO 2 batteries is corroded depending on its shape (in the form of powder or dust), and how such shape can play a role to attenuate the Zn corrosion and dissolution during an electrochemical process. Indeed, the corrosion of Zn anodes in powder and dust shape was investigated in ammonium chloride aqueous NH 4 Cl solution using open circuit potential (OCP) plot, linear polarization (LP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) methods. The electrodes were also observed by scanning electron microscopy (SEM) and analyzed using X-ray diffraction (XRD). The results show that the corrosion rate significantly depends on Zn grain size and surface area. In addition, the SEM observations showed clearly some corrosion features on the surface of Zn grains. Furthermore, the XRD analysis confirms the formation of a corrosion layer constituted of ZnO and adsorbed Zn(NH 3 ) 2 Cl 2 molecules. These electrodes, with two distinct shapes, were used as anodes in assembled Zn/MnO 2 batteries with two types of MnO 2 cathode namely nanostructured manganese dioxide (NMD) and electrolytic manganese dioxide (EMD). Discharge tests showed high performance for Zn/MnO 2 cell based on Zn powder (>500 µm) as anode and NMD as a cathode in NH 4 Cl electrolyte, with an output voltage of 1.65 V and specific energy of 109.72 mWh/g after 2 h under 1 mA. Moreover, this cell is the most stable with a voltage drop as low as 0.7% after 2 h of continuous discharge. Such results demonstrate that the assembled Zn/MnO 2 can be used for low cost and high-performance battery with a specific structure and shape of both anode and cathode materials.

Removal process and mechanism of lead in Zn-containing rotary hearth furnace dust

To deal with the removal of PbO2 during the purification process of the Zn-containing rotary hearth furnace (RHF) dust, this study adopts a choline chloride-urea (ChCl-urea) based deep eutectic solvent system and water-washed Zn-containing RHF dust as the main target of investigations, preparing ZnO nanoparticles using a Zn-induced PbO2 removal and thermal treatment of the precursor. The effects of the mass ratio of Zn particles and Zn dust (maked as Zn particles - Zn dust), reaction temperature, and reaction time on the removal of PbO2 were also investigated. The ZnO nanoparticles and the PbO2-removed products were characterized by X-ray diffractometry, X-ray fluorescence spectroscopy, scanning and transmission electron microscopy. The results showed that the optimal conditions for efficient removal of PbO2 included the reaction temperature of 80 °C, The Zn particles - Zn dust is 1.6, with a reaction time of 3 h. The final product had a ZnO content of 98.332% with a particle size distribution in the range of 10–100 nm with an average diameter of 39 nm, belonging to the Category-II ZnO nanoparticles. The PbO2 removal mechanism mainly involved the dissolving of PbO2 in ChCl-urea, forming [Pb(ClO·urea)2]2−, and the replacement reaction between Zn particles and [Pb(ClO·urea)2]2−, producing metallic Pb and [ZnClO·urea]−.

Electrochemical Reduction of CO2 at Coinage Metal Nanodendrites in Aqueous Ethanolamine.

Electrocatalytic reduction of CO2 into usable chemicals is a promising path to address climate change and energy challenges. Herein, we demonstrate the synthesis of unique coinage metal (Cu, Ag, and Au) nanodendrites (NDs) via a facile galvanic replacement reaction (GRR), which can be effective electrocatalysts for the reduction of CO2 in an ethanolamine (EA) solution. Each metal ND surface was directly grown on glassy-carbon (GC) substrates from a mixture of Zn dust and the respective precursor solution. The electrocatalytic activities of the synthesized ND surfaces were optimized for CO2 reduction in EA solution by varying their composition. It was determined that a 0.05 mol fraction of EA exhibited the highest catalytic activity for all metal NDs. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques showed that metal-ND electrodes possessed higher current densities, lower onset potentials and lower charge-transfer resistances for CO2 reduction than their smooth polycrystalline electrode counterparts, indicating improved CO2 reduction catalytic activity. It was determined, using FTIR and NMR spectroscopy, that formate was produced as a result of the CO2 reduction.

Radical Cyclic [3]Daisy Chains

Summary Mechanically interlocked molecules (MIMs) that undergo controllable internal motions of their component parts in more than one dimension are rare entities in the molecular world. Cyclic [2]daisy chains ([c2]DCs) are a class of MIMs that have been identified as prototypes for molecular muscles. It remains, however, a challenge to synthesize [cn]DCs with n > 2 selectively and efficiently. Herein, we report the design and synthesis of [c3]DCs employing radical and anionic templates. Two mechanically interlocked [c3]DCs with 18 positive charges were obtained in >90% yields. One [c3]DC displayed good air stability in its radical cationic form, while the other underwent reversible “co-conformational” switching between open macrocyclic and closed trisarm-shaped forms under electrochemical control. These findings provide not only two-dimensional MIMs with attractive electronic and switchable properties, but also a starting point for the design of extended molecular arrays, which could become the forerunners of adjustable molecular nets and breathable molecular membranes.

Iron-Catalyzed Conjugate Addition of Aryl Iodides onto Activated Alkenes under Air in Water

The combination of commercially available FeCl3·6H2O with a water-soluble cationic 2,2′-bipyridyl catalytic system was found to enable the direct conjugate addition of aryl iodides onto activated alkenes, such as an α,β-unsaturated ester and a ketone, in a weakly acidic aqueous solution. This operationally simple protocol was carried out at 80 °C under air atmosphere in a potassium acetate-buffered aqueous solution for 12 h in the presence of Zn dust as a reductant to provide the desired 1,4-adducts in good yields.

Synthesis and electrochemical study of coinage metal nanodendrites for hydrogen evolution reaction

Herein, we report a facile one-step synthesis route to fabricate the coinage metal nanodendrites (NDs) via a tailored galvanic replacement reaction (GRR). Cu, Ag and Au NDs are directly grown on glassy carbon plate (GCP) from the mixture of their precursor solutions and Zn dust. The formed NDs are uniformly distributed to the substrate and obtained the unique structures with sharp tips and tertiary branches. The electrocatalytic activity of the synthesized NDs towards the hydrogen evolution reaction (HER) is further investigated in 0.5 M H2SO4 using linear sweep voltammetry (LSV) and the Tafel slope. The results demonstrate that the nanodendrites formed through the GRR process exhibit greater catalytical activity towards HER in comparison to the polycrystalline Cu, Ag and Au. The prepared Au NDs exhibits the highest catalytic performance with a current density of −10.68 mA cm−2 at overpotential of 67 mV and a low Tafel slope of 65 mV dec−1. The simple and easy synthesis approach, the unique morphology and high electrocatalytic activity and excellent stability make the developed Cu, Ag and Au NDs highly efficient catalysts for green energy and electrochemical applications.

Zn-dust derived Zn/ZnO cermet fillers for thermally conductive High-k epoxy dielectrics

The fabrication of Zn/ZnO metal–semiconductor cermet architecture via simple heat treatment of raw Zn dust was investigated at different calcination temperature and time under air atmosphere. Raw Zn dust was calcined in the temperature range 450–600 °C for 1–3 h. The epoxy-cermet composites were fabricated by simple solution casting method. The effect of ceramic to metal ratio of cermet particle on the properties of epoxy composite was analyzed by incorporating cermet particle obtained at different calcination condition in the epoxy matrix. The enhancement in dielectric properties of epoxy-cermet composites is resulted from the duplex interfacial polarization induced by metal–semiconductor and semiconductor-insulator interfaces of cermet particle. Initially epoxy-cermet composite was fabricated by loading 30 wt% of cermet filler obtained at different calcination conditions. Further the effect of particle loading on properties of epoxy-cermet composite was investigated by varying the loading (10–30 wt%) of cermet particle obtained at 500 °C/3 h. With different filler loading the dielectric constant was varied in the range 16–102 while keeping dielectric loss and conductivity within an acceptable limit. The thermal conductivity of epoxy cermet composite has also enhanced to 1.152 W m−1 K−1 for epoxy loaded with 30 wt% cermet particle (Zn/ZnO @ 500 °C/3 h). The enhancement in the dielectric and thermal properties of epoxy composites were resulted from the interface design of epoxy-cermet composite by adjusting metal to semiconductor ratio of cermet particle. The obtained high-k epoxy-cermet composites can be used for the fabrication of embedded passive components and other related electronic devices.

Antimony-tin based intermetallics supported on reduced graphene oxide as anode and MnO2@rGO as cathode electrode for the study of microbial fuel cell performance

The development of clean sources of energy is important as the world is threatened by global warming and other serious consequences. The microbial fuel cell technology is considered as clean technology for the production of clean energy. The electrode materials used in the microbial fuel cell decides the major cost of MFCs. The use of novel antimony-tin based anode material and manganese dioxide as cathode material is demonstrated here. The present study discusses the synthesis and application of SnSb@rGO, Sb–SnSb@rGO and Sb–SnO2@rGO as anode electrode in three different microbial fuel cells for studying their performance, while using MnO2@rGO as cathode in all the setups. The synthesized materials were analysed for their structural characterisation by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, field mission scanning electron microscopy. Performance analysis of all MFCs are carried out to obtain polarization curves, maximum power density, current density, COD removal percentage and substrate degradation percentage. The results indicate that among the three MFCs, The MFC with Sb–SnSb@rGO prepared with Zn dust showed higher performance.