Extractable Zn Research Articles

Secondary and Multi-micronutrient (S, B & Zn) Doses on Yield and Residual Effect on Rice-groundnut Cropping System in Alfisols of Odisha, India

Orissa is the fourth largest state in India covering an area of 15.57 m ha out of which the net sown area is 6.13 m ha. Out of 8 broad soil groups found in the state, red and laterite groups of soil occupy more than 75% of total cultivable area. Low productivity of crops in red and laterite soils are associated with deficiency of Ca, Mg, S, B and Mo (Mitra and Sahu, 1988). The DTPA extractable Zn also indicates that red and laterite soils of Orissa is deficient in available Zn and respondent to Zn application to rice crop (Anonymous, 2002; Mandal et al., 2009). Next to Zn, the deficiency of B is wide spread in many districts of the state as well as contrary (Sharma et al., 2006). Rice-Groundnut is the most prevailing cropping pattern in red and Lateritic soils of Orissa. In spite of recommended dose of NPK fertilizer, the farmers get low yield. A field experiments were carried out with rice-groundnut cropping systems in two successive cropping seasons each, to study the effect of S, B and Zn on grain yield, nutrient uptake and their accumulation. The experimental design included ten treatments, T1: control, T2 : S 40 kg/ha, T3 : B 1 kg/ha, T4 : Zn 5 kg/ha, T5 : FYM 5 t/ha, T6 : S+B, T7 : S+Zn, T8 : B+Zn, T9 : S+B+Zn and T10 : S+B+Zn+FYM replicated thrice in randomized block design. Integrated use of S + B + Zn with FYM was the ideal combination for rice-groundnut cropping system as it was more sustainable, recorded the highest yield and SYI value along with higher accumulation and uptake of nutrients. The results revealed that red and lateritic soils are poor in S and B need integrated use of S, B and Zn along with recommended dose of NPK for getting synergistic and best effect in rice-groundnut cropping system.

Fractal Analysis of Mining Wastewater Time Series Parameters: Balkhash Urban Region and Sayak Ore District

The population life and health quality are significantly reduced due to water resources pollution caused by heavy metals, especially in urban agglomerations located close to metal ore mining and processing facilities. The greatest environmental pollution occurs during the extraction of Cu, Zn, and Pb. In this study, a fractal R/S analysis of wastewater discharge indicators time series from a metal ore mining facility located in the Sayak ore district in the Republic of Kazakhstan (turbidity, electrical conductivity, flow magnitude, and pH level) was carried out. A sharp increase in the flow rate was recorded from 10 to 15 July 2024 and an increase in the electrical conductivity from 4 to 26 July 2024. However, the latest type of indicator assessment does not exceed the critical level for life. The presence of electrical conductivity indicators time series long-term memory and persistence was also recorded (the Hurst exponent for the electrical conductivity time series is fixed in the 0.56 to 0.59 range and does not go below the threshold value for randomness according to the Anis-Lloyd formula). Thus, the value-changing process is controlled and stable, and minor changes in turbidity indicate that these releases do not significantly harm the environment. Despite this, the results obtained do not allow for a comprehensive analysis of the state of releases as the data from all deposits is not available. Therefore, due to the time constraints of the data provided for analysis, it is difficult to fully assess the impact of specific metal ore mining facilities on the environmental safety of the Balkhash urban region. In addition, many studies indicate very high risks of chronic diseases for the population living in this region. The findings of this study enable us to conclude that the application of fractal analysis and the calculation of fractal characteristics for time series of emissions can serve as an indicator of the environmental status within the given area. This information can be used by environmental services to build reliable environmental pollution monitoring systems.

Effect of Fertigation of Water-Soluble Fertilizers on Growth, Yield of Cowpea and Nutrients Availability in Soil under Rice-cowpea Cropping Sequence

A investigation was carried out to study the Growth and yield of cowpea and primary nutrients availability in soil as influenced by fertigation of water-soluble fertilizers under rice-cowpea cropping sequence. Hybrid rice was tested under aerobic condition during Kharif 2015-16 and 2016-17 with 16 treatments replicated thrice in randomized block design. The results indicated that, the treatment, 100% RDF through water soluble fertilizer at 8 DI was recorded significantly higher growth and yield determinants, higher seed yield (12.94 q ha-1) and haulm yield (26.17 q ha-1) of cowpea. Significant higher organic carbon (0.57 %) was recorded with the application 100% STCR dose with WSF through fertigation at 8 DI and higher available N (146.38 kg N ha-1 ), P2O5 (122.67 kg P2O5 ha-1 ) and K2O (130.17 kg K2O ha-1 ) content in soil recorded 100% water soluble fertilizers (WSF) applied at 4 DI. However, exchangeable calcium [3.51 cmol (p+) kg-1], magnesium [2.55 cmol (p+) kg-1], available sulphur [12.50 ppm] in soil were recorded with 100% conventional fertilizers applied plots through PoP. Significantly higher DTPA extractable Fe (18.45 mg kg-1) noticed with 100% STCR of WSF at 8 DI. However, significantly higher DTPA extractable Zn (1.44 mg kg-1) and Cu (0.57 mg kg-1) was recorded with the application of 100% RDF with WSF at 4 DI. Significantly higher DTPA extractable Mn (22.78 mg kg-1) noticed with 100% STCR of WSF at 4 DI.

Geochemical Interaction and Bioavailability of Zinc in Soil Under Long‐Term Integrated Nutrient Management in Pearl Millet–Wheat System

ABSTRACTThe degree and severity of zinc (Zn) deficiency in soil reduced the agricultural yield and quality, thus encouraging malnutrition in humans worldwide. The study was hypothesized to increase the bioavailability and release of Zn in soil and Zn biofortification in wheat grains under integrated nutrient management (INM). The long‐term (54 years) experiment laid out in a split‐plot design comprising single (W) and dual (PW) applications of farmyard manure (FYM) (0, 5, 10, and 15 Mg ha−1) and nitrogen (0, 60, and 120 kg ha−1) was studied to understand the distribution of different Zn fractions in soil and their relationship to wheat grain yield and Zn uptake. A laboratory incubation study was performed on surface soils to evaluate the release kinetics of native Zn at field capacity. The different fractions of Zn in soil increased with increasing frequency and levels of FYM application. Residual Zn constituted the maximum proportion (89.03%) of total soil Zn. A high positive correlation (p < 0.01) of diethylenetriaminepentaacetic acid (DTPA)‐extractable Zn and total grain Zn content were observed with different Zn fractions. The release kinetics of native soil Zn increased up to 10 days and became almost constant, indicating the establishment of chemical equilibria between the soil solid and solution phase. Thus, long‐term INM ensured higher wheat production (6.08 Mg ha−1) and Zn biofortification (38.95 mg kg−1) to combat Zn malnutrition and achieve the United Nations’ sustainable development goals on “zero hunger” and “good health and well‐being.”

Sr, Mn, and Zn extraction and separation from zinc electrolyte crystallization sediment with Ca and Sr sulfate cocrystallization structure: Reduction roasting reconstruction mechanism

Zinc electrolyte crystallization sediment (ZECS) generated in the zinc hydrometallugy industry contains valuable metals of strontium (Sr), manganese (Mn), and zinc (Zn), which has economical value but poses potential detrimental to the environment. However, the extraction and recovery of Sr is extremely difficult due to the thermodynamically stable Ca and Sr sulfate cocrystallization structure in ZECS. The destruction of refractory sulfate cocrystallization structure is a prerequisite for Sr extraction, and the carbothermal reduction roasting method is demonstrated to be efficient for the phase reconstruction. In this study, a stepwise Sr, Mn, and Zn recovery process from ZECS via carbothermal reduction roasting-acid leaching-selective precipitation-multistage extraction was proposed. In the reduction roasting procedure, all the sulfates including CaSO4, SrSO4, and Ca0.7Sr0.3SO4 are reduced to soluble sulfides. Meanwhile, most MnO2 is converted to a low-valence Mn product (MnO) that is soluble in acid, and the reduced Zn(g) is volatilized which can be collected from the flue dust. In the acid leaching procedure, the leaching efficiencies of Sr, Ca, and Mn are as high as 97.34 %, 97.44 %, and 95.49 % respectively, while 99.50 % Si in the form of silica is enriched in the leaching residue. After that, high-purity Sr solution was obtained after selective precipitation for Mn removal and D2EHPA multistage extraction for Ca removal. 97.41 % Mn in the leaching solution is precipitated by adjusting the pH value to 9.5 with NaOH solution. After four-stage extraction, 79.60 % Sr and only 0.35 % Ca are retained in the aqueous phase. The purified solution contains 2.88 g/L Sr, 0.052 g/L Ca, and 0.014 g/L Mn, which can be used to prepare industrial SrCO3 product via the carbonation operation. Thermodynamic behavior and reduction roasting reconstruction mechanism of Ca and Sr sulfate cocrystallization structure in ZECS were discussed in this work. The distributions of main metal elements (Sr, Ca, Mn, and Zn) in ZECS during the carbothermal reduction roasting-acid leaching-selective precipitation-multistage extraction process were also systematically studied.

Comparative Study of Steel Mill Dust Leaching with Phosphoric Acid and Sodium Hydroxide

Steel mill dust (SMD), produced by electric arc furnaces, is a highly polluting industrial waste due to its high content of metals (Zn, Fe, and Pb) and fine particle size (ca. 5.4 µm). This residue can be valorized to recover Zn using pyro and hydrometallurgical methods, with hydrometallurgy offering greater selectivity and lower energy costs. However, composition of SMD presents a challenge in identifying an optimal leaching agent. This study investigates the preferential extraction of Zn using two leaching agents, namely 150 g L−1 (1.5 M) phosphoric acid (H3PO4) and 240 g L−1 (6 M) sodium hydroxide (NaOH), in a two-stage leaching process (80 °C). Metallic Zn from the alkaline pregnant solution was recovered by electrodeposition (750 A/m2, graphite anode, stainless-steel cathode) and smelting (450 °C). The samples of SMD contained 26.3% Zn, 20.1% Fe, and 0.9% Pb, in compounds such as magnetite (Fe3O4), zincite (ZnO), and franklinite (ZnFe2O4). Each leaching agent successfully attained a 99% Zn recovery, demonstrating the proposed procedure’s high efficacy. However, H3PO4 leached also Fe and corroded the cathode during electrodeposition, thereby restricting the final recovery of metallic Zn. NaOH demonstrated greater selectivity for Zn over Fe and Pb, producing high-purity Zn deposits on the cathode by electrodeposition and 99% metallic zinc by smelting.

Evolution of Cu and Zn speciation in agricultural soil amended by digested sludge over time and repeated crop growth

Metals such as Zn and Cu present in sewage sludge applied to agricultural land can accumulate in soils and potentially mobilise into crops. Sequential extractions and X-ray absorption spectroscopy results are presented that show the speciation changes of Cu and Zn sorbed to anaerobic digestion sludge after mixing with soils over three consecutive 6-week cropping cycles, with and without spring barley (Hordeum vulgare). Cu and Zn in digested sewage sludge are primarily in metal sulphide phases formed during anaerobic digestion. When Cu and Zn spiked sludge was mixed with the soil, about 40% of Cu(I)-S phases and all Zn(II)-S phases in the amended sludge were converted to other phases (mainly Cu(I)-O and outer sphere Zn(II)-O phases). Further transformations occurred over time, and with crop growth. After 18 weeks of crop growth, about 60% of Cu added as Cu(I)-S phases was converted to other phases, with an increase in organo-Cu(II) phases. As a result, Cu and Zn extractability in the sludge-amended soil decreased with time and crop growth. Over 18 weeks, the proportions of Cu and Zn in the exchangeable fraction decreased from 36% and 70%, respectively, in freshly amended soil, to 28% and 59% without crop growth, and to 24% and 53% with crop growth. Overall, while sewage sludge application to land will probably increase the overall metal concentrations, metal bioavailability tends to reduce over time. Therefore, safety assessments for sludge application in agriculture should be based on both metal concentrations present and their specific binding strength within the amended soil.

Zinc supply effects on wheat production in a low precipitation zone

AbstractZinc (Zn) fertilization of hard red and soft white winter wheat (Triticum aestivum L.) is uncommon in the low precipitation zone of the inland Pacific Northwest. It is uncommon because there have been no indications of deficiency. Soil test data, however, show Zn levels have been declining over time. We conducted a four‐site‐year experiment to evaluate effects of fertilization on early‐season tissue Zn concentration (TZC), dry matter accumulation (DMA), Zn uptake (ZNU), the grain test weight (TWT), protein content (PRO), and yield (YLD) of two regionally adapted cultivars. Planting occurred late in September or early in October. Zinc fertilizer, placed with the seed while planting, was applied at rates of 0 and 5 kg Zn ha−1. Application of 5 kg Zn ha−1 increased TZC and ZNU at one of two sites. There were corresponding trends of increased DMA and improved YLD. Response to fertilization occurred on a relatively shallow soil that had a diethylenetriamine‐pentaacidic acid–extractable Zn test level of 0.3 mg kg−1.

The Effect of Various Parameters in the Sulfuric Acid Leaching of Low Grade Zinc Oxide Ore of Niğde-Türkiye

The aim of this study was to investigate the main parameters affecting the leaching of low grade zinc oxide ores with sulfuric acid. The influence of leaching time (5 to 480 minutes), sulfuric acid concentration (25 to 125 g/L), leaching temperature (25 to 90 °C), particle size (-104 µm, -82 µm, -60 µm, -49 µm) and solid/liquid ratio (1/10, 1/7.5, 1/5, 1/4) was investigated. The effects of these process parameters were studied with to achieve maximum zinc extraction with minimum iron extraction and acid consumption. The optimum parameters for sulfuric acid leaching of zinc ore were determined to be 60 min leaching time, 75 g/L sulfuric acid concentration, 80 oC leaching temperature, 1/10 solid/liquid ratio and -60 µm particle size. Under these optimum conditions, Zn extraction (%), Fe extraction (%) and acid consumption (ton H2SO4/ dissolved ton Zn) were obtained 88.68%, 25.83% and 5.47 ton H2SO4/ dissolved ton Zn respectively.

Recycling Process of Spent Alkaline and Zn-C Batteries for the Re-Utilization in Rechargeable Zn-Ion Battery

The Zn, Mn and C extraction processes from spent primary batteries and the synthesis of recycled Zn film, MnO2 and MnO2/C for Zn-ion battery application were developed in the project. The Zn, Mn and C extraction process involved the acid leaching of Zn and Mn ions from the spent alkaline and Zn-C battery electrodes in the lab-scale was initially investigated using various leaching conditions. The acid leaching using 0.5-2 M HCl and H2SO4 at ambient temperature providing Zn extraction efficiencies in a range of 72.3-95.3%. By introducing an inexpensive reducing agent namely sodium sulfide (Na2S), sodium metabisulfite (Na2S2O5) or hydrogen peroxide (H2O2) in 2M H2SO4, the Mn extraction efficiency for Mn was increased from 21.9% (with no reducing agent) up to 48.4%, 82.8% and 98.9%, respectively. The upscale leaching study was subsequently performed in a 100-L pilot scale reactor demonstrated the Zn and Mn extraction efficiencies of 71% and 65%, respectively. Using the leaching solutions from the upscale hydrometallurgical route, Zn-film fabrication via electrodeposition process, and the MnO2 and MnO2/C synthesis via hydrothermal techniques were performed. Additionally, the one-step synthesis of MnO2/C via one-step hydrothermal method with no acid leaching was also explored in this study. The recycled Zn, MnO2, MnO2/C and C residual were subsequently used as the anode and cathode main components in the CR2032 and pouch-cell rechargeable Zn-ion batteries. The recycled MnO2 and MnO2/C provided similar performance as the commercial products, which indicating the recycled MnO2, MnO2/C could be effectively utilized in the Zn-ion battery, while the utilization of recycled Zn-film provided slightly lower performance compared to that of the commercial Zn foil.

Effect of Different Zinc Sources and Application Methods on Content and Uptake of Micronutrients of Basmati Rice

Zinc (Zn) is an essential trace element for plants, animals and human’s health. Zn deficiency is widely spread in paddy soils of India and has negative impact on national rice production. Field experiment on rice crop was conducted in sandy loam soil at crop research center Chirodi of SVBP University of Agriculture and Technology, Meerut., during Kharif season of 2011 and 2012 toevaluate the “Effect of different sources and application methods of zinc on content and uptake of micronutrients in basmati rice crop in sandy loam soil. The experiment was laid out in randomized block design with three replications. The experiment comprised of twelve treatments viz.; T1 (control), T2 (recommended NPK @120:60:60 kg ha-1) T3 (5 kg Zn through ZnSO4.7H2O+RDF), T4(5 kg Zn through mono ZnSO4.7H2O),T5 (0.1% Zn spray through ZnSO4.7H2O+RDF ),T6 (0.1% Zn spray through ZnSO4.7H2O + RDF),T7 (0.012% Zn spray through chelated Zn at tillering + RDF),T8 (0.05% Zn spray through ZnSO4.7H2O at tillering +0.05% at panicle initiation+ RDF), T9 (0.05% Zn spray through mono ZnSO4.7H2O at tillering + 0.05% at panicle initiation +RDF),T10 (0.006% Zn spray through chelated Zn at tillering + 0.006% at panicle initiation+ RDF ), T11 (micronutrient mixture@ 25kg ha-1 + RDF), T12 (vermicompost @ 3tha-1+ RDF).The experimental soil was low in organic carbon and available nitrogen and medium in phosphorus and higher in potassium with slightly alkaline in pH. The status of DTPA extractable Zn 1.23 mg Kg-1,Fe 14.85 mg Kg-1 Cu 2.43 mg Kg-1 Mn 10.91 mg Kg-1 in the surface soil. Nutrient assimilation at different stages by the rice crop varied significantly due to application of different treatments in the study. Maximum zinc content 85.78 and 93.57 ppm and uptake 288.60 and 341.85 g/ha at 30 DAT during 2011 and 2012 found in T12 which was significantly higher than the rest of the treatments while minimum zinc content recorded in T1 was significantly lower than the rest of the treatments during both the years. Similar trends were also recorded at 60 DAT, grain and straw growth stages of rice plant. The zinc content of plant sample in T11 and T3 was also higher and statistically at par to the level of zinc content recorded in T12. The Cu, Fe, and Mn content and uptake at different growth stages of rice plant sample in T11 and T3 was also higher and like the level in T12. Among the method of Zn application, soil application resulted in higher biomass, micronutrient content and uptake in the grain and straw. Foliar application caused greater effect on zinc content and uptake and as well as content and uptake of Cu, Fe and Mn in rice plant at different growth stages during both the years. Among the sources of Zinc, ZnSO4.7H2O proved to be the most efficient source of Zn for rice production.

Study on the impact of adopting organic practices on the absorption and extractability of Cu and Zn in commercial coffee samples

Although coffee is not a primary source of minerals in the diet, due to its frequent consumption, it can be considered an important source of some micronutrients, highlighting those with antioxidant properties such as Cu and Zn. The availability of nutrients in foods consumed through infusion is related to solubility, which is influenced by the metabolization of these elements by the plant. Several factors can impact this metabolism, including cultivation. This study investigated the influence of cultivation on the absorption and extractability of Cu and Zn in conventional and organic commercial coffee. It was observed that cultivation influences the absorption of the minerals studied in opposite ways: while organic samples have higher levels of Zn, conventional samples have higher levels of Cu. Cultivation does not influence the extractability of Zn in coffee infusions, therefore indicating little influence on the metabolization of this element. Copper metabolism, on the other hand, is influenced by cultivation, with Cu exhibiting greater affinity and lower extractability in organic coffee samples compared to conventional ones.

Greener and Sustainable Production: Production of Industrial Zinc (II) Acetate Solution and Recovery of Some Metals (Zn, Pb, Ag) from Zinc Plant Residue by Ultrasound-Assisted Leaching

Zinc plant residue (ZPR) contains significant amounts of valuable metal (Zn, Pb, Ag, etc.) compounds, as well as various heavy metals and harmful compounds that pollute the environment. Processing such residues allows for the recovery and reuse of valuable metals, which is crucial for sustainable resource management. This study investigated a two-stage leaching process of Zn, Pb, and Ag recovery from ZPR. The first stage of ultrasonic-assisted leaching of ZPR was applied to produce an industrial selective zinc acetate solution. Leaching experiments were carried out with an ultrasonic device in the presence of acetic acid, known as organic acid. Under optimum leaching conditions, the extraction of Zn and Fe metals was obtained as 76.13% and 1.32% Fe, respectively. According to the Brunauer–Emmett–Teller (BET) analysis results on the original sample and ultrasonic leaching residue (ULR), the BET surface area and micropore area increased. However, the mean adsorption pore width decreased. In the second stage, conventional sodium chloride leaching was applied to recover lead and silver from the remaining solid after the first stage. Under the optimum conditions in this stage, 80.12% of Pb and 96.2% of Ag were extracted. The presence of coordination between Zn2+/AcO− (acetate) and Pb2+/Cl− complexes in the leaching solution was revealed by Raman spectroscopy. Finally, according to the characterization analysis of the final leaching residue, it was determined that iron oxides and silicate species accumulated in the solid. In conclusion, a significant reduction in the rate of pollution and toxic metals in ZPR was noticed.Graphical

Residual effect of micronutrients and sulfur enriched phyto-biochars soil applied to fodder maize on yields, tissue concentration and uptake of nutrients by rice and post-harvest soil properties

The residual effect of low doses of lantana, pine needles and wheat straw phyto-biochars pyrolyzed at 300 °C and 450 °C and enriched with 0, 50, 75 and 100% of recommended doses of fertilizers (RDF) of micronutrients and S was studied on the yields, nutrient concentration and uptake of second crop, i.e. rice (Oryza sativa L.) after fodder maize to validate their nutrient slow-release characteristics. The residual effect of phyto-biochars averaged over different RDF increased rice grain yield significantly under lantana and pine needles phyto-biochars pyrolyzed at 300 °C, but decreased with pine needles biochar pyrolyzed at 450 °C as compared to the control. The highest grain yield (9.43 g pot−1) was under pine needles phyto-biochar pyrolyzed at 300 °C and enriched initially with 75% of RDF, which was 7.8 per cent higher than that with 75% of RDF applied through conventional fertilizer sources. The residual effect of some treatments significantly increased the readily oxidizable C and extractable Zn, Cu, Fe, Mn, B and S in the soil after rice harvest. For fodder maize + rice crops together, pine needles phyto-biochar pyrolyzed at 300 °C or lantana phyto-biochar pyrolyzed at 450 °C with enrichment of 75% RDF of micronutrients and S gave the higher apparent per cent utilization of Zn, Fe, Mn, and S, but numerically closer per cent utilization values for Cu and B in comparison to the conventional chemical fertilizer sources.

From waste to added-value product: A case of efficient separation and recovery of zinc and iron from spent galvanizing acid

Spent galvanizing acid solution contains high concentrations of zinc salts, ferrous salts, and residual acids, exhibiting extremely high value-added recovery potential. However, achieving the efficient extraction and separation of Zn over Fe becomes particularly challenging under elevated Zn ion concentration. Here, the key extraction parameters, such as modifier ratio, Cyanex 923 concentration and ratio of organic phase to aqueous phase (O/A), are investigated. The stripping and regeneration of extractant, extraction mechanism, as well as high-value recovery of Zn and Fe resources are also comprehensively expounded. After the two-stage extraction, the extraction efficiency of Zn and Fe is 98.92 ​% and 2.09 ​%, respectively. Moreover, the stripping efficiency of Zn reaches 92.3 ​% with O/A ratio of 1 : 2, using oxalic acid as stripping agent. The predominant extracted species is confirmed to be ZnCl3−, resulting in the formation of HZnCl3∙R3PO complex. More importantly, the regenerated extractant can be recycled back into the extraction process, and the reproduced HCl, high-value recovered ZnO and Fe2O3 can be used for different industrial fields. These findings lay a solid foundation for the efficient separation and comprehensive recovery of high-concentration spent galvanizing acid solution.

Bioenergy crop rotation for phytoremediation of heavy metal contaminated soils at Mahd AD'Dahab mine, Kingdom of Saudi Arabia

Phytoremediation is a viable approach in order to mitigate toxic soil levels and, therefore, the associated impacts of HMs. This approach requires the assessment of contaminated sites and the selection of reportedly efficient phytoremediators, which might contribute to facilitating the practical implementation of phytoremediation in polluted soils. In a twelve-month microcosm experiment, Indian mustard (Brassica juncea) and rapeseed (Brassica napus) plants were planted over the winter season. Subsequently, maize (Zea maize) was planted after the harvest of these plants. Oil crop rotation systems might promote tested HM removal (Cu, Cd, Fe, Ni, Mn, Zn, and Pb) from the Mahd AD'Dahab mine-contaminated soil and provide higher biomass than single crops. The results indicated that both the rapeseed maize and Indian mustard maize rotation showed the highest phytoextraction efficiency compared to a single crop. The extraction of Zn, Pb, Ni, Mn, Fe, Cu, and Cd are 18, 27, 29, 24, 23, 24, and 28%, respectively, for Indian mustard-maize rotation, although 17, 27, 31, 24, 21, 23, and 26% respectively for rapeseed-maize rotation. The short rotation strategy could be helpful in landscaped and controlled access to the polluted sites. The utilization of short-rotation phytoremediation has the potential to emerge as a financially viable approach for the management of polluted areas. This method involves enhancing biomass yield through the implementation of phytomanagement techniques such as fertilization, irrigation, and coppicing, thereby capitalizing on the benefits associated with both biomass production and landscape management.

Recovery of valuable metals from manganese purification sludge (SPS) containing Mn-Ni-Co sulfide and preparation of battery-grade Ni-Co-Mn sulfate solution

The manganese production industry produces a large amount of sulfide purification sludge (SPS) every year, representing a hazardous solid waste but also a valuable secondary resource for Ni, Co, and Mn. In this paper, the recovery of Ni, Co, and Mn from the SPS was achieved by (i) leaching with a solution of hydrogen peroxide, (ii) selectively extracting nickel, cobalt and manganese, (iii) solvent extraction for zinc removal, and finally obtained the battery-grade Ni-Co-Mn sulfate solution. During the hydrogen peroxide solution leaching stage, the leaching efficiency of Co, Mn, and Ni reached 98.5%, 98.6%, and 95.6%, respectively. A synergistic extraction system (SES) consisting of decyl 4-picolinate and dinonylnaphthalene sulfonic acid was used to selectively extract Ni, Co, and part of Mn, and the extraction of Ni and Co was >99.8% and 95.5%, respectively. The loaded organic was subjected to four-stage countercurrent scrubbing using a 5 g/L H2SO4 solution, resulting in nearly 100% removal of Ca and Mg. After that, 150 g/L H2SO4 was used to strip Ni, Co, and Mn from the loaded organic to obtain a crude Ni-Co-Mn sulfate solution. Finally, D2EHPA was utilized for the extraction of impurity Zn from the stripping solution to obtain a battery-grade Ni-Co-Mn sulfate solution with <5 × 10−4 g/L of Zn. Compared to traditional technology, the novel process not only enables the recovery of valuable Ni, Co, and Mn in SPS but also facilitates their direct preparation into battery-grade nickel‑cobalt‑manganese sulfate solution, which has the advantages of a short process and high added value.

Characterization, Concentration, and Speciation of Metal Elements in Copper Slag: Implications for Secondary Metal Recovery

The treatment of large amounts of copper slag is an unavoidable issue resulting from the high demand for copper during the global transition to a sustainable development path. Metal-rich copper slag might serve as a potential source of metals through secondary recovery. In this study, two copper slags (CS1 and CS2) with different metallurgical properties were characterized, focusing on secondary metal recovery. The X-ray diffraction (XRD) results show that fayalite (Fe2SiO4) and magnetite (Fe3O4) were the main crystalline phases in both CS1 and CS2. In addition, CS2 exhibited a more stable amorphous silicate network than CS1, which was attributed to the differences in the content of Si-O-3NBO linkages. The sequential extraction of Zn, Cu, Fe, and Pb from the slags was also explored, with the Cu content in CS1 being substantially lower than that in CS2. All metals were distributed in the F5 residue fraction. Cu was the most mobile metal as a result of the large proportion of soluble fractions (F1–F3), followed by Zn and Fe. This study explored the chemical speciation of Zn, Cu, Fe, and Pb from copper slags, which has practical implications for secondary metal recovery from such materials.

Charging behavior of ZnMn2O4 and LiMn2O4 in a zinc- and lithium-ion battery: an ab initio study

In the field of sustainable energy storage systems, zinc-ion batteries (ZIB) employing aqueous electrolytes have emerged as viable successors to the widely used lithium-ion batteries, attributed to their cost-effectiveness, environmental friendliness, and intrinsic safety features. Despite these advantages, the performance of ZIBs is significantly hindered by the scarcity of suitable cathode materials, positioning manganese zinc oxide (ZnMn2O4) as a potential solution. In this study, we describe the ZnMn2O4 (ZMO) compound focusing on its properties variations during Zn extraction and potential battery applications. For the sake of comparison, we also analyze the same properties of the LiMn2O4 in its tetragonal phase (TLMO), for the first time, motivated by a recent discovery that the substitution of Zn ions by Li in ZMO forms isostructural TLMO compound at room temperature. The study was conducted within the density functional theory (DFT) framework, where the structural, electronic, magnetic, electrochemical, and spectroscopic properties of ZMO and TLMO are investigated under various conditions. Although both systems crystallize in tetragonal structures, they demonstrate distinct electronic and magnetic properties due to different oxidation states of the Mn. Computationally optimized lattice parameters align closely with experimental values. The TLMO exhibits a narrower band gap compared to ZMO, indicating enhanced electrical conductivity. In addition, TLMO presented a lower diffusion energy barrier than ZMO, indicating better ionic conductivity. To evaluate the potential application of these materials in battery technologies, we further explored their volume changes during charging/discharging cycles, simulating Zn or Li ions extraction. TLMO underwent a significant volume contraction of 5.8% upon complete Li removal, while ZMO experienced a more pronounced contraction of 12.5% with full Zn removal. By adjusting ion extraction levels, it is possible to reduce these contractions, thereby approaching more viable battery applications. Voltage profiles, constructed from DFT-based simulation results, unveiled an average voltage of 4.05 V for TLMO, closely matching experimental values. Furthermore, spectroscopy results provide insights into the electronic transitions and validate the computational findings, consolidating our understanding of the intrinsic properties of ZMO and TLMO.

Mechanism Analysis and Experimental Research on Leaching Zn from Zinc Oxide Dust with an Ultrasound-Enhanced NH3-NH4Cl-H2O System

Zinc oxide dust (ZOD) is an industrial solid waste produced in the production process of wet smelting Zn, with large output and great pollution to the environment. The recycling of metallurgical solid waste such as zinc oxide dust is very important to achieve the sustainable development of the circular economy. An experimental study of zinc (Zn) leaching from zinc oxide dust using an ultrasound-enhanced ammonia–ammonium chloride system was performed. The effects of ultrasonic power, leaching time, total ammonia concentration, and other factors on the leaching rate of zinc from zinc oxide dust were investigated. The results revealed that the leaching rate of Zn reached up to 80.70% under the condition of ultrasound power of 1000 W, reaction time of 15 min, total ammonia concentration of 6 mol/L, [NH3]:[NH4+] of 1:1, L/S of 5:1, temperature of 45 °C, and stirring speed of 100 r/min. The conventional leaching was conducted under similar conditions, except that the time was controlled to 40 min and the zinc leaching rate was 71.15%. The leaching rate of Zn in the ultrasound condition was improved by 9.55% compared with that in the conventional leaching process. XRD, laser particle size, and SEM-EDS analyses were conducted to study the leaching residues of ZOD. The analysis results showed that in the ultrasound condition, the largest leaching rate of soluble ZnO phases was achieved after 15 min of leaching. Under the ammoniacal system, it was difficult to leach ZnFe2O4, Zn2SiO4, and ZnS phases, which partly accounted for the low zinc leaching rate. Additionally, through ultrasound-enhanced treatment, the ZnO particles encapsulated in ZOD particles were broken into smaller sizes and exposed to the leaching solution. Thus, the leaching rate of Zn was improved. The experimental results show that ultrasound can tremendously improve the effect of Zn extraction from ZOD, shorten reaction time, and help reduce energy consumption and environmental pollution, making it a promising application in the treatment of secondary Zn resources.