Volatilization Of Zn Research Articles

“One‐Stone, Two‐Birds”: Zinc‐Rich Metal–Organic Frameworks as Precursors for High‐Entropy Zn‐Air Battery Electrocatalysts with Hierarchical Pore Structures

AbstractThe active sites of inexpensive transition metal electrocatalysts are sparse and singular, thus high‐entropy alloys composed of non‐precious metals have attracted considerable attention due to their multi‐component synergistic effects. However, the facile synthesis of high‐entropy alloy composites remains a challenge. Herein, we report a “one‐stone, two‐birds” method utilizing zinc (Zn)‐rich metal–organic frameworks as precursors, by virtue of the low boiling point of Zn (907 °C) and its high volatility in alloys, high‐entropy alloy carbon nanocomposite with a layered pore structure was ultimately synthesized. The experimental results demonstrate that the volatilization of zinc can prevent metal agglomeration and contribute to the formation of uniformly dispersed high‐entropy alloy nanoparticles at slower pyrolysis and cooling rates. Simultaneously, the volatilization of Zn plays a crucial role in creating the hierarchically porous structure. Compared to the zinc‐free HEA/NC‐1, the HEA/NC‐5 derived from the precursor containing 0.8 Zn exhibit massive micropores and mesopores. The resulting nanocomposites represent a synergistic effect between highly dispersed metal catalytic centers and hierarchical adsorption sites, thus achieving excellent electrocatalytic oxygen reduction performance with low catalyst loading compared to commercial Pt/C. This convenient zinc‐rich precursor method can be extended to the production of more high‐entropy alloys and various application fields.

"One-Stone, Two-Birds": Zinc-Rich Metal-Organic Frameworks as Precursors for High-Entropy Zn-Air Battery Electrocatalysts with Hierarchical Pore Structures.

The active sites of inexpensive transition metal electrocatalysts are sparse and singular, thus high-entropy alloys composed of non-precious metals have attracted considerable attention due to their multi-component synergistic effects. However, the facile synthesis of high-entropy alloy composites remains a challenge. Herein, we report a "one-stone, two-birds" method utilizing zinc (Zn)-rich metal-organic frameworks as precursors, by virtue of the low boiling point of Zn (907 °C) and its high volatility in alloys, high-entropy alloy carbon nanocomposite with a layered pore structure was ultimately synthesized. The experimental results demonstrate that the volatilization of zinc can prevent metal agglomeration and contribute to the formation of uniformly dispersed high-entropy alloy nanoparticles at slower pyrolysis and cooling rates. Simultaneously, the volatilization of Zn plays a crucial role in creating the hierarchically porous structure. Compared to the zinc-free HEA/NC-1, the HEA/NC-5 derived from the precursor containing 0.8 Zn exhibit massive micropores and mesopores. The resulting nanocomposites represent a synergistic effect between highly dispersed metal catalytic centers and hierarchical adsorption sites, thus achieving excellent electrocatalytic oxygen reduction performance with low catalyst loading compared to commercial Pt/C. This convenient zinc-rich precursor method can be extended to the production of more high-entropy alloys and various application fields.

A biodegradable Zn–Se alloy with potent osteogenicity, antibacterial ability, and antitumor efficacy for bone-implant applications

Biodegradable zinc-selenium (Zn-Se) alloys are expected to become a competitive material for implantation into hard tissues due to the antitumor function of Se in cancer prevention and treatment. However, adding Se to Zn to create Zn-Se alloys is a challenging task due to the high volatilization of the monomeric Zn and Se elements, and the immiscibility of Se and Zn. In this study, we have successfully prepared biodegradable Zn-xSe (x = 0, 1, 3, and 5 at. %) alloys using ultrahigh pressure sintering, which effectively suppressed the volatilization of monomeric Zn and Se elements and increased the solid solubility of Se in Zn. The microstructure characteristics, mechanical properties, degradation rate, anticoagulant, osteogenic ability and antitumor properties of the ultrahigh pressure sintered (UPS) Zn-Se alloys were systematically evaluated. The microstructure of the UPS Zn-Se alloys consisted of Zn matrix phases, Zn(Se) solid solution, and ZnSe second phases formed around the elemental Se phase. The UPS Zn-1Se showed the highest compressive yield strength of ∼205.8 ± 2.3 MPa, a fracture strain of 16.4 %, a degradation rate of 44.6 ± 0.6 μm/y, effective antibacterial ability against S. aureus, effective antitumor activity against Cal-27 carcinoma cells, dramatic osteogenic ability and excellent biocompatibility toward pre-osteoblast MC3T3-E1 cells. Overall, the addition of 1 at. % Se to Zn does not affect the growth of normal cells, but effectively inhibits the growth and reproduction of tumor cells and the Zn-1Se alloy is promising for orthopedic applications due to its unique combination of mechanical and biological properties.

Sintering behavior, zinc volatilization, microstructure and microwave dielectric properties of ZnxSiO2+x ceramics

In this paper, the evolution of the microstructure for the zinc silicate ceramics with different Zn/Si ratios was revealed, and the factors influencing their dielectric properties were discussed. Our results demonstrate that Zn volatilization plays an important role on the defect structure of the samples. Low relative density, high conductivity loss caused by volatilization, and the presence of ZnO phase collectively result in low quality factor (Qf) of Zn2.0SiO4.0. By using the powder embedded sintering method, the loss could be reduced owing to the suppression of volatilization. As the Zn/Si ratio decreases, the ZnO disappears, while the Si-rich phase emerges and increases. The formation of a liquid phase results in a dense microstructure of the non-stoichiometric samples. Moreover, these samples exhibit a minor degree of Zn loss, probably because the presence of liquid phase constraints the volatilization during sintering. The samples with x = 1.8 display desirable properties, including a relative dielectric constant (εr) of 6.5, a Qf of 100,800 GHz, and a temperature coefficient of resonant frequency (τf) of −21.3 ppm/°C, due to their high degree of densification, slight zinc loss, and the elimination of the ZnO phase.

Triple Templates Directed Synthesis of Nitrogen-Doped Hierarchically Porous Carbons from Pyridine Rich Monomer as Efficient and Reversible SO2 Adsorbents.

Herein, a variety of 2,6-diaminopyridine (DAP) derived nitrogen-doped hierarchically porous carbon (DAP-NHPC-T) prepared from carbonization-induced structure transformation of DAP-Zn-SiO2-P123 nanocomposites are reported, which are facilely prepared from solvent-free co-assembly of block copolymer templates P123 with pyridine-rich monomer of DAP, Zn(NO3)2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO2 templates promote the formation of mesoporous and supermicroporous structures in the DAP-NHPC-T, while high-temperature volatilization of Zn contributed to generation of micropores. The DAP-NHPC-T possess large BET surface areas (≈956-1126 m2g-1), hierarchical porosity with micro-supermicro-mesoporous feature and high nitrogen contents (≈10.44-5.99 at%) with tunable density of pyridine-based nitrogen sites (≈5.99-3.32 at%), exhibiting good accessibility and reinforced interaction with SO2. Consequently, the DAP-NHPC-T show high SO2 capacity (14.7mmolg-1, 25°C and 1.0bar) and SO2/CO2/N2 IAST selectivities, extraordinary dynamic breakthrough separation efficiency and cycling stability, far beyond any other reported nitrogen-doped metal-free carbon. As verified by in situ spectroscopy and theoretical calculations, the pyridine-based nitrogen sites of the DAP-NHPC-T boost SO2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.

Effect of lattice defects on crystal structure and microwave properties of Ba(Ga1/2Ta1/2)O3 doped Ba(Zn1/3Nb2/3)O3 ceramics

Traditionally, B-site cation ordering structure in Ba(B′1/3B″2/3)O3 based ceramics with complex perovskite structure is considered to be the dominant factor in determining the dielectric loss. The crystal structure of BZN-BGT ceramics changes to the B-site disordering from B-site 1:2 ordering accompanying with remarkably reduced dielectric loss. Ba(Ga1/2Ta1/2)O3 doping also inhibits the formation of Nb-rich secondary phases induced by Zn volatilization on the surface of BZN-BGT ceramics as well. The conductive activation energy Ea, an energy required for electrons to escape from the traps, increases to 0.55 eV from 0.40 eV, indicating the decrease of lattice defects concentration. As Ba(Ga1/2Ta1/2)O3 doping concentration increases, the dielectric thermal relaxation process of BZN-BGT ceramics weakens and the electrical conductivity decreases. These results indicate that the dielectric loss of BZN-BGT ceramics containing volatile Zn could be controlled by the lattice defects and secondary phases rather than B-site 1:2 ordering structure.

Diatomite supported highly-dispersed ZnO/Zn-co-embedded ZIF-8 derived porous carbon composites for adsorption desulfurization

The metal organic framework (MOFs)-derived porous carbon materials with highly dispersed metal active sites were of the exclusive application foreground in many field, such as catalyst, electrochemistry, adsorption desulfurization and so on. However, the loss issue of metal active sites in MOFs frame was indispensable during the high temperature carbonization because of the lower boiling point of many metals, thus fundamentally affecting the atom-scale uniform distribution merit of MOFs-derived porous carbon materials. This work was to provide a novel strategy to address the loss issue of the active metal volatilization in the fabrication of MOFs-derived porous carbon materials. The ZnO nanosheets were pre-grown on the surface of diatomite by using in-situ microwave-assisted preparation, and thereafter the Zn-containing ZIF-8 particles covered the surface of ZnO nanosheets by virtue of the ZnO-induced growth. The results affirmed that the high content Zn-doped porous carbon materials were achieved and the Zn volatilization in MOFs was restrained on account of the occurrence of ZnO on diatomite (DE) surface during the carbonization. The adsorption desulfurization performance of the ZnO/Zn-embedded porous carbon materials/DE (ZnO/Zn/C@DE) was examined by the sulfur-containing compounds in simulated oil. The adsorption desulfurization performance investigation indicated that the ZnO/Zn/C@DE had the optimum adsorption capacities of 45.3 mg/g for benzothiophene and 37.4 mg/g for thiophene. Nonetheless, the competitive adsorption desulfurization finding of toluene in simulated oil showed that the adsorption capacities of ZnO/Zn/C@DE for TH and BT were dramatically descended, suggesting the presence of S-M interaction, wherein S stood for the S atom in a thiophene molecule and their analogs, and M for Zn atoms in porous carbon materials.

Minutes‐Fast Production of Vacancy‐Enriched MXenes as an Efficient Platform for Single‐Atom Electrocatalysts

AbstractAlthough MXenes have been synthesized by liquid phase and molten salt etching approaches, it still suffers from sluggish reaction kinetics of removing A species from MAX phases associated with an overlong production time (5–48 h). Here, a minute‐level production approach is developed to produce MXenes (Ti2CClx) by selectively etching MAX phases (Ti2AlC) under metal chloride (ZnCl2) vapor. In this synthetic protocol, metal chloride vapor possesses a very high chemical activity to the interlaminar A metal layers of MAX phases owing to negative Gibbs free energies, accompanied with the fast removal of gaseous A‐containing chlorides in the reaction system. Moreover, some M species can be controllably etched off from the lattice of MX slabs to generate metal vacancies, which have a high reducing ability to implant single‐atom Zn from ZnCl2 vapor. Finally, vacancy‐enriched MXenes are produced after the volatilization of Zn. In this manner, the etching time is less than one‐sixtieth those of liquid phase and molten salt etching approaches. The resultant MXenes can be employed as an efficient platform for implanting single‐atom Pt, showing a low overpotential of 41 mV at a current density of 10 mA cm−2 and a good long‐term stability up to 5000 cycles.

Volatilization Kinetics of Zinc from the Flotation Products of Low-Grade Lead–Zinc Oxide Ore during Carbothermic Reduction

Zinc extraction from oxide ore has been paid more and more attention to due to the exhaustion of zinc sulfide ore resources. In this work, the volatilization kinetics of Zn from the flotation products of low-grade lead–zinc oxide ore during carbothermal reduction in the temperature range of 900–1300 °C were investigated. The phase transformation in briquettes during the reduction process was investigated by XRD and EPMA. The results showed that the transformation of ZnS by CaO may begin within the temperature range of 900–1050 °C, with the main occurrence observed in the range of 1050–1250 °C. The kinetics behavior of Zn volatilization was associated with the phase transformation. The volatilization of Zn was controlled by the interfacial chemical reaction within 900–1150 °C. As the reaction proceeded, the generation of the product layers (CaS, FeS and new slag phase) impeded the internal diffusion of Zn, CO and CO2. At this time, internal diffusion served as the rate-controlling step for Zn volatilization in the range of 1150–1300 °C. Hence, a staged kinetics model of Zn volatilization during carbothermal reduction in the form of carbon-bearing briquettes was established, and the apparent rate constants (k(T)) and activation energies (Ea) were obtained. This work provides a scientific basis for the flotation products treatment by carbothermal reduction and is of great significance in improving the sustainability of resources in the zinc smelting industry.

Thermodynamic behavior and kinetic analysis of carbothermal reduction process of low-grade oxysulfur lead–zinc ore

During the exploitation of sphalerite resources, a considerable amount of low-grade oxysulfur Pb–Zn deposits is generated, which poses a significant threat to the environment and soil and water conservation in mining areas. Therefore, low-grade Pb–Zn resources urgently require source emission reduction and appropriate utilization. This study applied a mineral technology and conducted X-ray diffraction and scanning electron microscopy–energy dispersive X-ray spectroscopy to investigate the phase transformation and the mechanism underlying the volatilization of Pb and Zn at different times and temperatures. The Pb–Zn volatilization kinetics of a low-grade oxysulfur Pb–Zn ore by a one-step pyrometallurgical process in an argon atmosphere was studied, and the effects of different temperature conditions on the Zn volatilization process were investigated. The results showed that the Zn-containing phase in the raw material was decomposed to ZnO and ZnS upon heating. Moreover, ZnO was reduced via carbothermal reduction, whereas ZnS was reduced via a CaO-assisted carbothermal reaction and volatilized in the form of gaseous Zn. In the Pb-containing phase, PbSO4 generated PbO, Pb, and PbS in the presence of Fe, FeS, and CaO. PbO was volatilized in the form of gaseous Pb through carbothermal reduction and interactions between PbS and PbO. The Pb–Zn volatilization reaction conformed to the shrinking core model with a constant size, and the volatilization-based removal of Pb and Zn process was controlled by internal diffusion. A macroscopic kinetic model of the reaction was established on the basis of experimental data. The apparent activation energy of Pb and Zn volatilization was 163.90 and 328.19 kJ/mol, respectively. This study promotes the utilization of the low-grade oxysulfur Pb–Zn ore through a pyrometallurgical method to provide theoretical support for large-scale industrial treatments.

Volatilization behavior of lead, zinc and sulfur from flotation products of low-grade Pb-Zn oxide ore by carbothermic reduction

Existing methods are difficult to directly treat the tailings of Lanping Pb-Zn deposit because of low Pb + Zn content. According to the characteristics of high CaO content (11%) in the flotation products of Lanping low-grade Pb-Zn oxide ore, a carbon thermal reduction method based on rotary hearth furnace (RHF) process was developed. When reaction temperature was above 1000 °C, CaO could realize the transformation of metal sulfides to oxides. Increasing reducing atmosphere was favor of the efficient volatilization of Zn and Pb and the trapping of S. The volatiles in reducing agents could promote the volatilization of zinc. The reduction effect of anthracite and thermal coal was better than that of charcoal. The volatilization rates of Zn and Pb exceeded 98% and 96%, respectively, under the conditions of 1250 °C, 30 min, 20% thermal coal addition and air atmosphere. High quality ZnO dust with a ZnO purity of 83% was obtained.

The role of the Co reduction and Zn evaporation of ZnCo-MOF carbonization in peroxymonosulfate activation for levofloxacin purification from wastewater

Nowadays, emerging pollutants have been attracting many interests from the researchers. Many attentions are being paid to sulfate based advanced oxidation process for purification of emerging pollutants degradation, what depended on the activity in peroxymonosulfate (PMS) activation. In this work, the Zinc and Cobalt bimetallic zeolite imidazole framework (ZnCo-MOF) was conducted as precursor for preparing a novel magnetic ZnxCoy-CN-T through carbothermal reduction. The ZnxCoy-CN-T was further used to activate PMS for degrading levofloxacin (LEV) as a typical emerging pollutant. XRD, SEM, XPS and Raman spectra analysis were used to characterize the ZnxCoy-CN-T. Carbothermal reduction of ZnCo-MOF at 900 °C leads to the generation of zero-valent cobalt and the volatilization of Zn. Meanwhile, the volatilization of Zn not only brings about the adjacent diffusion of the Co atom but also constructs porous carbon (CN) for anchoring the well dispersed Co nanocluster. The Zn1Co5-CN-900 performed the high activity in PMS activation for LEV degradation with favorable efficiency and rate of 98.3% and 0.228 min−1 within 60 min, respectively. The Zn1Co5-CN-900 could be recycled five times with preferable stability and magnetism. The possible degradation pathways were proposed by identifying the intermediate products through liquid chromatography-mass spectrometry (LC-MS) analysis. In summary, a kind of zero-valent cobalt nanocluster anchored on CN was designed to construct a promising Zn1Co5-CN-900/PMS system for LEV degradation with favorable activity and reusability.

Tailoring Ni3ZnC0.7/graphite heterostructure in N-rich laminated porous carbon nanosheets for highly efficient microwave absorption

Bimetallic transition carbide nanoparticles (Ni3ZnC0.7) encapsulated with graphitic shells were successfully embedded into N-rich laminated porous carbon nanosheets (NC–ZnNi1.5) by one-step pyrolysis of bimetallic organic frameworks. It was found that C atoms penetrated octahedral interstitial spaces of the Ni lattice to form Ni3ZnC0.7. The charge states and distribution of metal atoms were influenced by the interstitial C atoms, which promoted polarization relaxation and facilitated dielectric loss. Simultaneously, the volatilization of Zn influenced recrystallization and rearrangement of the crystalline domains, facilitated graphitization and established a 3D conductive network to optimize the conductive loss. Besides, multi-level heterogeneous interface and nitrogen doping also further optimized the impedance matching. Benefiting from these advantages, the minimum reflection loss of NC-ZnNi1.5 was −69.1 dB at 12.7 GHz, and the effective absorption bandwidth was 6.5 GHz. The mechanism of bimetallic carbide's dielectric loss was explained in detail, providing a new pathway for the development of multi-component carbon-based microwave absorbers in the future.

Separation and recovery of zinc, lead and iron from electric arc furnace dust by low temperature smelting

Electric arc furnace dust (EAFD), an important secondary resource, is categorized as hazardous solid waste which contains multiple heavy metals such as zinc, lead and chromium. Smelting-Reduction is considered as an effective method to recover metal elements from EAFD. To efficiently separate the zinc, lead, iron and slag from EAFD, a novel and clean process developed to enhance reduction and lower smelting temperature through sodium carbonate was proposed herein. Thermodynamic analysis and laboratory experiments were carried out to determine the feasibility and reliability of this new process. The optimal conditions were determined as temperature of 1450 °C, sodium carbonate dosage of 4%, C/O of 0.8, holding time of 30 min and basicity of 0.8, and the corresponding volatilization of Zn and Pb could be 99.78% and 89.47% respectively; besides, the reduction of iron could reach 98.98%. Simultaneously, the recovery of iron reached 98.62% and the grade of iron amounted to 93.8%. The melting reduction process of zinc, lead and iron could be divided into three stages according to both the experimental results and the thermodynamic analysis. The short process which is characteristic of high efficiency and low energy consumption, aims to provide a clean and sustainable approach to utilize EAFD.

Research for the recovery of Zn and Pb from electric arc furnace dust through vacuum carbothermal reduction

Isothermal kinetic methods were used to investigate reduction process in the Zn and Pb during the vacuum carbothermal reduction of electric arc furnace dust (EAFD). During the experiments, the volatilization ratios of Zn and Pb in EAFD increased with the increase of temperature and holding time, which was 96.29 % and 83.91 % for Zn and Pb respectively at a temperature of 1000 °C and holding time of 60 min. The main phase changes of Zn and Pb in the reduction process were ZnFe2O4 → ZnO → Zn and PbSO4 → PbO → Pb, and the generated Zn and Pb gases escaped and were collected via condensation. In the kinetic study, the volatilization of Zn was controlled by three-dimensional diffusion (Jander) with an apparent activation energy of 19.97 kJ/mol, whereas the volatilization of Pb was controlled by the interfacial chemical reaction with an apparent activation energy of 85.68 kJ/mol. The results show that higher purity of valuable metals Zn and Pb could be obtained, laying a theoretical foundation for the treatment of EAFD pollution.

Na2O induced stable heavy metal silicates phase transformation and glass network depolymerization

The pollution of heavy metals and chlorine salts widely exists in solid/hazardous waste, while the stable heavy metal silicates limit the heavy metals removal. This work proposed mechanism of Na2O induced stable heavy metal silicates phase transformation and glass network depolymerization to promote heavy metals chlorination volatilization. Medical waste incineration slag (MWI S) containing heavy metal silicates was used as typical sample. Compared with the control, Cu and Zn volatilization efficiencies sharply increased from 77.54% to 92.22% and 18.70% to 93.82% at 3% Na2CO3, 1200 °C, 40 min. It showed that Na2O successfully induced phase transformation from stable Zn2SiO4 and CuSiO3 to ZnO and CuO easy to react with chloride by destroying the Si–O of Zn–O–Si and Cu–O–Si, respectively. Meanwhile, Na2O effectively destructed Si–O bond to depolymerize the glass network, resulting in the percentage of Q0 and Q1 increase from 25.14% to 38.29%, reducing melt viscosity and improvement of volatilization environment to form bigger bubbles. Medical waste incineration fly ash (MWI FA) was applied as Na source to further verify that the mechanism was significantly enhance Cu and Zn volatilization efficiencies. This study provided new method to reduce heavy metal residues in glass products prepared by melting treatment of solid/hazardous wastes.

Effects of S and Mineral Elements (Ca, Al, Si and Fe) on Thermochemical Behaviors of Zn during Co-Pyrolysis of Coal and Waste Tire: A Combined Experimental and Thermodynamic Simulation Study

The transformation behaviors of Zn during co-pyrolysis of waste tires and coal were studied in a fixed-bed reaction system. The effects of pyrolysis temperature and the Zn content of coal mixture on the Zn distributions in the pyrolytic products (coke, tar and gas) were investigated in detail. It is found that the relative percentages of Zn in the pyrolytic products are closely related to the contents of S and mineral elements (Ca, Al, Si and Fe) in the coal. The thermodynamic equilibrium simulations conducted using FactSage 8.0 show that S, Al and Si can interact with Zn to inhibit the volatilization of Zn from coke. The reaction sequence with Zn is S > Al > Si, and the thermal stability of products is in the order of ZnS > ZnAl2O4 > Zn2SiO4. These results provide insights into the migration characteristics of Zn during co-pyrolysis of coal and waste tires, which is vital to the prevention and control of Zn emissions to reduce the environmental burden.

Effects of protective materials on the sintering properties of Zn4Sb3

ABSTRACT High brittleness materials such as ceramics and semiconductors are prone to fracture during cooling. Improving the sintering quality of such materials has been a problem explored by industry and scientific research. Here, the high brittleness semiconductor Zn4Sb3 was prepared by hot-press sintering. It was found that adding protective aluminum sheets with a similar expansion coefficient of Zn4Sb3 can significantly improve the sintering success rate of Zn4Sb3. The density and compositional homogeneity of the Zn4Sb3 were also significantly improved by the addition. The finite element simulation found the greatest increase in density when the thickness ratio of the sintered sample to the aluminum sheet was 1:1. The increase in density is due to the reduced stress during the cooling process and more uniform stress distribution on the sample. The improvement in composition homogeneity is due to the higher thermal conductivity of the aluminum sheets, which results in a smaller temperature difference inside the sample. In addition, the protective effect of the aluminum sheets reduces the volatilization of Zn. Materials with similar melting points have similar thermal expansion coefficients. High-quality sintering of brittle materials will no longer be difficult as long as a suitable sample protection material is found.

Thermodynamic and Experimental Study on Migration Characteristics of Heavy Metals during the Melting Process of Incineration Fly Ash

The migration characteristics of heavy metals during the melting process were one of the key factors for safe treatment and resource utilization of incineration fly ash (IFA). In this paper, the material variation of heavy metal elements of Pb, Zn, Cu, and Fe during the IFA melting process was simulated by HSC 6.0 chemistry software. The effects of melting temperature, alkalinity, atmosphere, chlorine content of raw materials, and an iron bath added to the migration characteristics, and phase transformation of selected heavy metal elements was investigated. The simulation results were also verified by experimental results. The results showed that, with the increase in temperature, the gas phase proportion of Pb, Zn, Cu, and Fe gradually increased. The alkalinity had little effect on the proportion of elements Fe and Cu in the liquid slag (LS) phase and the element Pb in the gas phase, but the increase in alkalinity could inhibit the proportion of element Zn in the gas phase. Zn mainly existed in the gas phase, and the atmosphere had little influence on the distribution of Zn. In reducing atmosphere (RA), elements Fe and Cu, which entered the liquid metal (LM) phase, were promoted, while the volatilization of Pb was restrained, which was conducive to the recovery of heavy metals. The melting process of IFA with water-washing and dechlorination had an inhibitory effect on the volatilization of Zn and Pb, but had little effect on Fe and Cu. The proportion of element Zn in the gas phase reduced from 85.84% to 9.89%. With the iron bath added in the IFA melting process, 98.42% of Cu and 82.28% of Pb entered the LM phase as metal simple substances, and 76.3% of Zn entered the gas phase as Zn (g) and ZnCl2 (g). In the experimental verification, the distribution proportions of the four heavy metals in the gas phase, LS phase, and LM phase were consistent with the simulation results.

Resolving impact volatilization and condensation from target rock mixing and hydrothermal overprinting within the Chicxulub impact structure

This work presents isotopic data for the non-traditional isotope systems Fe, Cu, and Zn on a set of Chicxulub impactites and target lithologies with the aim of better documenting the dynamic processes taking place during hypervelocity impact events, as well as those affecting impact structures during the post-impact phase. The focus lies on material from the recent IODP-ICDP Expedition 364 Hole M0077A drill core obtained from the offshore Chicxulub peak ring. Two ejecta blanket samples from the UNAM 5 and 7 cores were used to compare the crater lithologies with those outside of the impact structure. The datasets of bulk Fe, Cu, and Zn isotope ratios are coupled with petrographic observations and bulk major and trace element compositions to disentangle equilibrium isotope fractionation effects from kinetic processes. The observed Fe and Cu isotopic signatures, with δ56/54Fe ranging from −0.95‰ to 0.58‰ and δ65/63Cu from −0.73‰ to 0.14‰, mostly reflect felsic, mafic, and carbonate target lithology mixing and secondary sulfide mineral formation, the latter associated to the extensive and long-lived (>105 years) hydrothermal system within Chicxulub structure. On the other hand, the stable Zn isotope ratios provide evidence for volatility-governed isotopic fractionation. The heavier Zn isotopic compositions observed for the uppermost part of the impactite sequence and a metamorphic clast (δ66/64Zn of up to 0.80‰ and 0.87‰, respectively) relative to most basement lithologies and impact melt rock units indicate partial vaporization of Zn, comparable to what has been observed for Cretaceous-Paleogene boundary layer sediments around the world, as well as for tektites from various strewn fields. In contrast to previous work, our data indicate that an isotopically light Zn reservoir (δ66/64Zn down to −0.49‰), of which the existence has previously been suggested based on mass balance considerations, may reside within the upper impact melt rock (UIM) unit. This observation is restricted to a few UIM samples only and cannot be extended to other target or impact melt rock units. Light isotopic signatures of moderately volatile elements in tektites and microtektites have previously been linked to (back-)condensation under distinct kinetic regimes. Although some of the signatures observed may have been partially overprinted during post-impact processes, our bulk data confirm impact volatilization and condensation of Zn, which may be even more pronounced at the microscale, with variable degrees of mixing between isotopically distinct reservoirs, not only at proximal to distal ejecta sites, but also within the lithologies associated with the Chicxulub impact crater.