Leaching Of Zn Research Articles

The best-modified BCR and Tessier with microwave-assisted methods for leaching of Cu/Zn and their δ 65Cu/δ 66Zn for tracing sources in marine sediment fraction

The optimum condition of modified BCR and Tessier with microwave-assisted (m-a) methods for leaching of Cu and Zn in the sediment Certified Reference Material (CRM) was investigated and then applied to those in marine sediments. Samples were leached by modified BCR and Tessier with (m-a) methods to perform Cu and Zn analysis in each sediment fraction (CRM) by means of ICP-MS. The irradiation power (336 watts) of 50%-2 min (fraction 1), 50%-3 min (fraction 2), 50%-1 min (fraction 3), and 50%-3 min (fraction 4) were observed in the optimum condition of the microwave. The best-modified BCR with (m-a) method was in the range 1.43–10.8% RSD (90.8% recovery) for Cu and 0.40–1.29% RSD (98.6% recovery) for Zn. The optimum condition in the modified Tessier with (m-a) method was also observed in the irradiation power (336 watts) of 50%-1 min (fraction 1), 30%-3 min (fraction 2), 30%-3 min (fraction 3), 50%-1 min (fraction 4), 30%-2 min (fraction 5). The best range precision (accuracy) in the optimized condition with (m-a) was recorded as leaching Cu in the range of 0.62–1.65% RSD (98.8% recovery) and Zn in the range of 1.35–6.06% RSD (92.7% recovery). Both of the best-modified methods were then applied to marine sediment of the Java Sea and measured their Cu and Zn isotopes fractionations by the recommended MC-ICP-MS. Considering treated Cu and Zn isotope fractionations by δ 65 Cu calculated in the range 3–4.5‰ reflecting the source of their Cu and Zn from natural sediments. • Cu and Zn concentrations and their isotopes were analyzed in the marine sediment. • Modified BCR and Tessier of leached Cu and Zn were applied using the microwave. • Both the best-modified BCR and Tessier were found in the optimum condition of CRM. • Those methods successfully leach Cu and Zn in the marine sediment of the Java Sea.

Optimizing co-combustion synergy of soil remediation biomass and pulverized coal toward energetic and gas-to-ash pollution controls

The co-combustion synergy of post-phytoremediation biomass may be optimized to cultivate a variety of benefits from reducing dependence on fossil fuels to stabilizing heavy metals in a small quantity of ash. This study characterized the thermo-kinetic parameters, gas-to-ash products, and energetically and environmentally optimal conditions for the co-combustions of aboveground (PG-A) and belowground (PG-B) biomass of Pfaffia glomerata (PG) with pulverized coal (PC). The mono-combustions of PG-A and PG-B involved the decompositions of cellulose and hemicellulose in the range of 162–400 °C and of lignin in the range of 400–600 °C. PG improved the combustion performance of PC, with the blends of 30 % PG-A and 70 % (PAC37) and 10 % PG-B and 90 % PC (PBC19) exhibiting the strongest synergy. Both PG-A and PG-B interacted with PC in the range of 160–440 °C, while PC positively affected PG in the range of 440–600 °C. PC decreased the apparent activation energy (Eα) of PG, with PBC19 having the lowest Eα value (107.85 kJ/mol). The reaction order models (Fn) best elucidated the co-combustion mechanisms of the main stages. Adding >50 % PC reduced the alkali metal content of PG, prevented the slagging and fouling depositions, and mitigated the Cd and Zn leaching toxicity. The functional groups, volatiles, and N- and S-containing gases fell with PAC37 and PBC19, while CO2 emission rose. Energetically and environmentally multiple objectives for the operational conditions were optimized via artificial neural networks. Our study presents controls over the co-circularity and co-combustion of the soil remediation plant and coal.

Improved leaching of Cu, Sn, Pb, Zn, and Al from waste printed circuit boards by electro-generated Cl2 in HCl solution

This paper investigated the improved leaching of Cu, Sn, Pb, Zn, and Al from waste printed circuit boards (WPCBs) by electro-generated Cl2 in HCl solution through multiple leaching cells in series, double intake pipes, and bubble stone for leaching. The leaching agents in the leaching cell include Cl2(aq), HCl, HClO, and Cl3-. The leaching rate and leaching speed of Zn, Sn, Al, and Pb exceeded that of Cu. Leaching time and HCl concentration have a strong impact on the dissolution of Cu, whereas the effect of the electrolytic current and the leaching temperature is comparably weak. The series of leaching cells improved the effective utilization of Cl2 and increased the treatment capacity of the WPCBs. Bubble stones significantly enhanced the efficiency and rate of leaching. Reduction of the size of the Cl2 gas bubbles improved the leaching kinetics. The leaching rate of Cu reached 87.22%, whereas the leaching rate of Zn, Sn, Al, and Pb exceeded 90% after 100 min. Our experimental data provide a reference for electrolytic leaching recovery of metals from WPCBs, and our method improves the metal leaching and electrolytic efficiency in practice.

Facile synthesis of oxygen vacancies enriched ZnFe2O4 for effective photocatalytic peroxodisulfate activation

Water pollution is a global environmental problem that needs to be solved urgently. Among them, visible light-assisted catalytic peroxodisulfate (PDS) activation, as an efficient advanced oxidation technology, has great potential in organic wastewater treatment. Therefore, it is crucial to develop efficient photocatalysts based on PDS activation. Here, introducing defects in ZnFe2O4 to construct abundant oxygen vacancies (ZFOV) could not only promote the photocatalytic degradation of TCH, but also enhance magnetic nanoparticles-activated PDS. It was shown that the ZFOV/PDS/vis system could degrade TCH by ∼ 65 % within 30 min, about 1.23 times greater than that of ZFO/PDS/vis system. More importantly, the degradation rate was still over 58 % after three reuse cycles and extremely low leaching of Zn and Fe were observed. The effects of pH, PDS concentration, humic acid, anions and cations on TCH degradation in the presence of ZFOV/PDS/vis systems were also investigated in detail. Combining experimental results revealed that oxygen vacancies acted as catalytically centers which supplied abundant local electrons for the adsorbed S2O82− reaction to produce OH and SO4− via a single electron transfer process. Additionally, oxygen vacancies could also boost electron transfer and take part in the Fe2+/Fe3+ redox cycle. Our study might open up new avenues for designing high efficiency photocatalyst by means of surface engineering and PDS activation.

Selective Leaching of Zn from ZnFe2O4 Modified by CaO in the H2SO4 Solution

Selective Leaching of Zn from ZnFe2O4 Modified by CaO in the H2SO4 Solution

Recycling of municipal sewage sludge incineration fly ash based on (NH4) 2SO4 roasting-acid leaching and filling PP matrix process.

Sludge incineration is one of the most efficient sludge treatment methods. The fly ash produced by incineration must be handled further since it has a significant number of heavy metals. In this study, the chemical composition of sewage sludge incineration fly ash (SSA) generated from Zhejiang in various months was identified by XRD, X-ray fluorescence spectrometer (XRF), and SEM analyzes. The SSA were treated by a (NH4)2SO4 roasting-acid leaching process to determine its effect on the elimination performance of heavy metals. The SSA content on the mechanical properties and heavy metal leaching of modified SSA-filled PP composite were also studied. Results show (NH4)2SO4 roasting-acid leaching process has a good effect of eliminating heavy metals, with the highest leaching of Zn of 86.4%. The presence of sodium stearate modifier increases activation index of SSA and then improves the compatibility of SSA particles in PP, resulting for the composites have relatively excellent mechanical properties. For the toxicity characteristic leaching procedure (TCLP) test, modified SSA particles can be effectively encapsulated with PP resins, which have a considerable inhibitory effect on heavy metal leaching. This process from this study provides a reference for sewage sludge treatment by using modified SSA as a polymer filler to achieve the immobilization of heavy metals and the resource recycling.

Utilization of bioactivated incineration bottom ash in cement binder for mortar harmless treatment and performance improvement

Municipal solid waste incineration bottom ash (IBA) is a common waste containing heavy metals and compounds, and it cannot be recycled until it is treated. This study reports that microbially induced carbonate precipitation (MICP) technology is used to treat a binder of bottom ash with ordinary Portland cement (IBA-OPC, namely IBP), and the IBP after biotreatment is called MTIP. The leaching behavior and splitting tensile strength of IBP and MTIP were investigated. The pozzolanic test was used to analyze the potential of bioactivated IBA as a binder. Additionally, the immobilization efficiency of heavy metals in the samples was studied by microtopography and energy dissipation. The results show that the leaching of Cr, Cu, Zn, Cd, and Pb can be reduced by 70–90% by biomineralization. After biotreatment, the carbonate bound state of heavy metals in IBP increases, while the exchangeable bound state decreases. The strength of MTIP is 10.87% higher than that of IBP at 28 days. By analysis, it also can replace a part of the binder of cement for reducing carbon dioxide emissions. This provides a sustainable idea for the biotreatment of IBA in cement binder.

Photocatalytic oxidative desulfurization of dibenzothiophene solution and real sample of fuel by using Mn-doped ZnO under visible irradiation

In this study, manganese was doped to ZnO by the hydrothermal method and calcined at different temperatures consist of: 3%MZ800, 6%MZ800, 9%MZ800, 9%MZ300, and 9%MZ400. The structural and optical properties of the samples were characterized using XRD, SEM, TEM, EDS, BET, DRS, and atomic spectroscopy analysis. Photocatalytic oxidative desulfurization of the solutions containing sulfur compounds was investigated by using the synthesized samples. 9%MZ400 showed the most desulfurization efficiency (95.99 ± 0.8%) for dibenzothiophene solution and (94.96 ± 1.3%) for AW 402 as a real sample of fuel in the presence of H2O2 and CH3COOH under visible-light irradiation (200 W tungsten). The leaching of Zn and Mn metal ions from photocatalyst isn’t occurred in this process. The optimum amounts of H2O2, CH3COOH and dosage of photocatalyst were obtained in desulfurization process. Also kinetics of desulfurization and stability of photocatalyst were investigated.

Mobility and crop uptake of Zn in a legacy sludge-enriched agricultural soil amended with biochar or compost: insights from a pot and recirculating column leaching test

The application of organic amendments to contaminated soils is a remediation method to regulate metal(loid) leaching to waters and uptake to crops. Here, wood-derived biochar and/or green waste compost was amended to a Zn-rich agricultural soil (~ 450mgkg-1 total Zn, derived from legacy sludge application). A pot experiment grew barley and pea crops in amended soil for 100days, simultaneously measuring Zn, pH, and dissolved organic carbon (DOC) in pore waters and Zn uptake to plants. An assessment was made of leaching of Zn via a linked column test that recirculated soil leachates to amendments multiple times to chart the confounding impacts of pH and DOC on Zn mobility. Concentrations of Zn in pore waters in the pot test were reduced from 2mgl-1 in soil without amendment to 1mgl-1 following the addition of 5% (vol.) biochar and compost, which was reduced further (0.5mgl-1) in the presence of crops. DOC appeared largely unaffected by soil amendment when mixed into soil, though was universally increased by the presence of the barley crop, whilst pH was variable (pH 4-6) and not clearly correlated with any intervention. Barley head mass was significantly increased after 5% biochar and both doses of compost amendment. Barley Zn content was maintained or enhanced by all soil amendments. The leaching column test revealed that biochar raised pH above that of the soil and compost amendment. Zn leachate concentrations were also reduced from after biochar amendment. Notably, compost resulted in net mobilisation of Zn from soil. This study demonstrates that the addition of biochar and compost to a Zn-rich agricultural soil was able to reduce pore water Zn considerably, especially in the presence of a barley crop. Compared to compost, biochar was the more efficient sorbent of Zn.

Metal leaching test of commercially available faucets in the Japanese market in 2016-2020.

In this study, metal leaching was investigated in commercially available faucets in Japan to clarify their compliance to Japanese regulations. We purchased 37 faucets from the market and analyzed the leaching of cadmium, mercury, selenium, lead (Pb), arsenic, hexavalent chromium, boron, zinc (Zn), copper, manganese, and nickel. The leaching tests were performed with and without a conditioning treatment, that simulated approximately 1-month intermittent use of faucets on weekdays, and the results were compared to estimate the changes in metal leaching during the use of faucets. The results revealed that metal leaching from most of the faucets complied with Japanese regulations. However, the levels of Pb leaching from several faucets produced by certain manufacturers exceeded the Japanese standard. The conditioning treatment was generally effective in reducing metal leaching. However, the reductions in Pb and Zn leaching tended to be lower than those of the other metals. Nickel is not legally regulated in Japan; although the number of cases where nickel concentration in leachate exceeded the water quality management target value was greater, such cases were limited to faucets primarily made of copper alloys. We believe that these results will be helpful to improve the public health associated with metal leaching from faucets.

The effect of sulfur on the leaching of Cr3+, Cr6+, Pb2+ and Zn2+ from fly ash glass

This work assessed the capture and subsequent release of potentially harmful Cr(VI), Cr(III), Pb(II) and Zn(II) ions in and from dechlorinated fly ash glass. Differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy – energy dispersive spectroscopy and inductively coupled plasma spectrometry along with other analytical techniques were used to explore the mechanism by which sulfur affected the immobilization and long-term leaching behavior of heavy metals in fly ash glass. Working with a CaO–MgO–Al2O3–SiO2–SO3 system, increasing the sulfur content was found to promote the leaching of Cr but had only a minimal effect on the loss of Pb and Zn. The concentrations of Pb and Zn in the leachate were found to remain at essentially nil over time while the Cr level increased up to 64 h and then decreased. The presence of Sulfur ions degraded the glass network and this promoted the leaching of S2−, Cr3+/Cr6+, Pb2+ and Zn2+. In addition, the S2− ions reacted with Pb2+ and Zn2+ to form needle-shaped and flocculent sulfide precipitates, thus trapping the Pb2+ and Zn2+. Si4+, Ca2+, Al3+ and Fe3+ were also found to migrate into the leaching solution where they combined to form a dendritic flocculent that adsorbed and encapsulated Cr. This phenomenon greatly reduced the concentration of Cr in the leachate. Thus, sulfur prevented the leaching of Cr, Pb and Zn via different mechanisms.

The Effect of Zn Content and Granulation Temperature on Zn Leaching in an Fe-Saturated (FeXZn(1−X))2SiO4 System

The zinc in the fayalite slag of copper smelters, in which Zn-containing raw materials are used, is mainly found to be in oxidic phases, such as glassy iron silicate. During the slag water granulation process, the molten slag is heated, whereby the granulated slag achieves varying granulation temperatures. Therefore, in this study, we aimed to characterize and assess the leaching behavior of a synthesized Fe-saturated (FeX,Zn(1−X))2SiO4 system to understand the dependance of the zinc leaching behavior on the parameters of the ZnO content (1–10 wt.%) and granulation temperature (1300 or 1400 °C). It was found that the Zn leaching increased with the increasing Zn content and granulation temperature, using both batch and static pH leaching methods. Zn leaching was further increased at pH 5 using diluted nitric acid under oxidation conditions. Among the oxides in the samples—fayalite, spinel, and glass—glass was found to contribute to Zn leaching, owing to its weathering during pH-titration.

Growth mechanism of double cone-shaped nano zinc oxide prepared from zinc oxidation flue dusts by acid leaching

Cone-shaped nano zinc oxide was prepared by acid leaching-alkali precipitation using zinc oxidation flue dusts as raw materials. The dynamic conditions of acid leaching and the growth mechanism of ZnO crystal were also discussed. It was shown that the optimum acid leaching conditions were H2SO4 concentration 2 mol/L, liquid–solid ratio 20:1, reaction time 4 h, reaction temperature 90 °C and Zn leaching rate was 94.98%. Then, the nano ZnO was prepared by acid leaching solution in an open hydrothermal system at low temperature. The formation process of nano ZnO crystals undergoes crystallization-dissolution-recrystallization under low temperature and alkaline conditions. Double cone-shaped ZnO nanoparticles could be obtained at 62 °C with n(Zn2+)/n(OH−) ratio of 1:5 and reaction time of 1 h. The average size of ZnO nanoparticles was about 100 nm.

Promoted acid leaching of Zn from hazardous zinc-containing metallurgical dusts: Focusing on transformation of Zn phases in selective reduction roasting

As hazardous wastes from metallurgical processes, high zinc dust (HZD) was considered as a potential alternative resource of Zn. The acid leaching of HZD was a principal step and therefore was highly relevant to efficient utilization. Unfortunately, zinc ferrite (ZnFe2O4) in HZD was difficult to be leached by hydrometallurgical methods. Therefore, in this study, to enhance the recovery of zinc, selective reduction roasting was used to decompose ZnFe2O4. The transformation of Zn phases during the reduction process was investigated by thermodynamic calculation, XRD analysis. The results showed that ZnFe2O4 was converted into acid-soluble ZnO in H2 at 600 °C, while the further reduction of ZnO to Zn(g) and the volatilization of ZnO was avoided. However, the soluble ZnSO4 in HZD was also reduced to acid-insoluble ZnS. Consequently, a novel method of reduction roasting combined with water leaching was proposed to pretreat HZD. In water leaching, the solid-liquid ratio was1:10 (g/mL). When H2SO4 concentration was 80 g/L, the leaching ratio of Zn was 94.24% after pretreatment, higher than that of direct leaching of HZD (87.76%). Therefore, acid leaching of Zn was promoted by water leaching and reduction roasting pretreatment, which will bring considerable benefits to the high zinc dust recycling enterprises.

Benefits of pre-treating MSWI fly ash before alkali-activation

The significant amount of heavy metals and soluble salts contained in municipal solid waste incineration fly ash (MSWI FA) and the corresponding risk of leaching make them classified as hazardous waste. Nowadays, the ashes are usually landfilled, but another application can be the inertization and valorization of MSWI FA in building materials. Geopolymer can be a potential material because it can naturally entrap heavy metals physically and chemically inside its matrix. This research investigated how the use of electrodialytic treatment compared to a water washing procedure, considered as pre-treatments for MSWI FA, influenced a metakaolin-based geopolymer as an encapsulation matrix for MSWI FA. Geopolymers with metakaolin and 5, 10, 20 wt% of raw or pre-treated MSWI FA were compared with a sample containing only metakaolin for environmental, mechanical, and physical properties. The formation of aluminosilicate gel was confirmed for all geopolymers, although with varying degrees of impurities. The results show low compressive strength for the sample with washed ash but good mechanical strength for geopolymers with raw and electrodialytic treated ash compared to metakaolin-based geopolymer or with geopolymer with washed ash. A decrease in leaching for all the metals in the samples confirms the encapsulation capacity of geopolymers. The electrodialytic pre-treatment decreases, particularly the leaching of Cr, Zn and chloride in geopolymers, confirming the potential use of this pre-treatment to improve the environmental and mechanical characteristics of geopolymers with MSWI FA.

Nanostructuring Matters: Stabilization of Electrocatalytic Oxygen Evolution Reaction Activity of ZnCo2O4 by Zinc Leaching

Despite the enormous attention paid to cobalt oxide materials as efficient water splitting electrocatalysts, a deep understanding of their activity discrepancy is still elusive. In this work, we showed that stabilization of the internally generated oxygen evolution reaction (OER) active phase (oxyhydroxide) is crucial for ZnCo2O4 electrocatalysts. A systematic evaluation of the bulk and nanostructured ZnCo2O4 system concomitant with nanostructured Co3O4 showed that leaching of Zn is the driving force behind the near-surface transformation to the oxyhydroxide phase. The relative contribution to this near-surface reconstruction was found to be surface-sensitive. The electrochemical observations combined with Raman and impedance spectroscopy revealed that the good catalytic activity could be attributed to the formation of the cobalt oxyhydroxide phase, which was created by the dissolution of Zn from the nanostructured surface. Moreover, this study sheds light on previous contradicting postulates regarding the discrepancy of the OER activity of ZnCo2O4. Our finding regarding the formation of the OER active phase in spinel Zn-Co oxide will motivate researchers to focus more on the near-surface reconstruction behavior of cobalt-based oxide electrocatalysts in the future.

Bioavailability of metals in coastal lagoon sediments and their influence on benthic foraminifera

Coastal lagoons experience removal and leaching of metals due to seasonal fluctuation of salinity coupled with pH and dissolved oxygen variability. Benthic foraminifers are susceptible to seasonal variation in physicochemical conditions. Assessment of bioavailable fraction of selected metals in sediments along the salinity gradient of the largest brackish lagoon in Asia- Chilika was carried out. Further, population density and abnormality index of foraminifera in the sediments were calculated to understand the influence of bioavailable metal on benthic foraminifera. Metal concentrations were higher in the low salinity regions and decreased towards the high salinity regions. This suggests river discharge controls the metal input and distribution in the lagoon. Overall, metal concentrations are high in the residual fraction (F4) followed by interplay within the reducible (F2) or oxidizable (F3) fractions, except for Mn. The seasonal fluctuations of pH and cyclic oxygen deficiency intensified the leaching of Fe, Cr, Cu, Pb, and Zn in the bioavailable fraction in the low salinity region of the lagoon. The presence of metals in bioavailable fractions impacted the normal growth of the abundant Ammonia species. Despite low bioavailable metal concentrations, higher morphological abnormalities were observed in the high salinity regions due to higher energy conditions near the sea. Therefore, abnormalities in the benthic foraminifera are attributed to bioavailability of metals from sediments and natural stress conditions in the coastal lagoon environment.

Climate influence on zinc isotope variations in a loess–paleosol sequence of the Chinese Loess Plateau

Zinc (Zn) is an essential micronutrient, and its isotopes are increasingly applied to understand trace metal biogeochemical cycling. Atmospheric deposition from anthropogenic or natural origins can perturbate the nutrient supply globally. However, our understanding on Zn isotope variations in natural mineral dust and during dust–climate interaction is still rare. This study presents Zn isotope data and leaching experiments with ammonium acetate buffering solution (pH = 5) on a loess–paleosol profile (S0–L3) from the Yimaguan section in the central Chinese Loess Plateau. The loess–paleosol sequence records the contributions from Asian mineral dust accumulation and chemical weathering, and the response to glacial–interglacial climate changes. Bulk loess–paleosol samples display limited Zn/Al (3.5 × 10-4 – 4.5 × 10-4) and δ66Zn variations (0.17–0.30‰). The mean δ66Zn of paleosol (0.19 ± 0.01‰, 2SD/√n, n = 11) is slightly lower than that of loess (0.24 ± 0.01‰, 2SD/√n, n = 13). Correlations with magnetic susceptibility and grain size distribution suggest that bulk δ66Zn variations between loess and paleosol are not sensitive to glacial–interglacial source fluctuations or wind sorting, but could result from loess pedogenesis.The leachable Zn fractions have high δ66Zn values (0.80–1.29‰) and display good positive correlations with Ca, Sr, Mg, Fe and Mn (r > 0.7), suggesting that carbonates are enriched in heavy Zn isotopes. Although Zn contents in carbonates are low (<3%) and dissolution of carbonates alone cannot explain the bulk Zn/Al variations (∼7% of Zn loss), significant carbonate weathering and biotic activities during loess pedogenesis could modify soil conditions (pH) and provide dissolved bicarbonate ions and organic ligands, which may facilitate the transport of heavy Zn isotopes by soil liquids. Conversely, the bulk δ66Zn of loess developed during glacial times were not modified by the low degree of chemical weathering, and thus the mean value of 0.24‰ for loess can be regarded as the average composition of the upper continental crust.

Experimental immobilization of Zn, Pb and Cd by additives to highly contaminated soils

Abstract The immobilization effect of soil amendments on leaching and bioavailability of Pb, Zn and Cd in highly contaminated soils under industrial impact was studied by collecting the soils in the surroundings of Zn-Pb Smelter “Miasteczko Śląskie” in southern Poland as an example. Various amounts of four additives (phosphate fertilizer, limestone powder, bentonite rock and bog iron ore) were tested in laboratory experiments to compare the effectiveness of three dominant mechanisms of immobilization: precipitation of phosphates, pH increase, and sorption. The contents of metals before immobilization were determined by extraction in CaCl2, EDTA and aqua regia. Cadmium and zinc are mainly represented by soluble, bio-available forms extractable in CaCl2, while lead by potentially bioavailable speciations extractable by EDTA. Most effective in the immobilization of these metals were the amendments increasing soil pH: limestone powder and phosphate fertilizer. Bog iron ore and bentonite were less effective because the soil pH was too low for efficient cation adsorption.

Selective Leaching of Zn from Cu-Based Alloy Scraps and Concurrent Purification of Cu

Selective Leaching of Zn from Cu-Based Alloy Scraps and Concurrent Purification of Cu