Extractable Mn Research Articles

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.

Separation of Co(II), Mn(II), and Ni(II) by solvent extraction with Cyanex 272 and D2EHPA from the sulfuric acid leaching solution of spent lithium-ion batteries

Spent lithium-ion batteries contain valuable metals such as cobalt, lithium, manganese and nickel. Smelting reduction of spent LIBs at high temperature results in metallic alloys. Therefore, it is necessary to recover the valuable metal ions present in the sulfuric acid leaching solutions of the metallic alloys. In this work, solvent extraction experiments were performed to separate the three metal ions, Co(II), Mn(II) and Ni(II) present in the leaching solutions of the metallic alloys. Synthetic sulfate solutions were prepared and commercial organophosphorous extractants were employed. First, both Co(II) and Mn(II) were completely extracted in one stage by using 40% saponified 0.3 M Cyanex 272, leaving Ni(II) in the raffinate. The small amount of Ni(II) co-extracted into Cyanex 272 was removed by two stages of cross-current scrubbing using pure CoSO4 solution. The effect of pH and CoSO4 concentration of the scrubbing solution on the scrubbing of Ni(II) was investigated. The Co(II) and Mn(II) present in the scrubbed Cyanex 272 were completely stripped by 0.05 M H2SO4 solution. Batch simulation experiments for the three stage of counter-current extraction with 1 M D2EHPA verified that Mn(II) and Co(II) were completely separated by selective extraction of Mn(II) into D2EHPA, leaving Co(II) in the raffinate. By consecutive extraction with Cyanex 272 and D2EHPA, pure solutions of Co(II), Mn(II) and Ni(II) with purity higher than 99.9% can be recovered from the starting solutions. A process was proposed for the treatment of sulfuric acid leaching solutions of spent LIBs containing Co(II), Mn(II) and Ni(II) by solvent extraction.

Effect of Ni and Fe Co-Application on the Soybean Crop Grown in Nickel and Iron Deficient Soils of Mirzapur District

ABSTRACT Considering the importance of nickel and iron nutrition for the soybean crop, their deficiency inhibits the yield drastically specially in the area where soybean crop is dominant. To encounter this problem, a pot experiment was conducted in glass house on low nickel and iron soil in Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, during 2019–20 and 2021–22. The study was carried out to investigate the effect of Ni (nickel) and Fe (iron) on the post-harvest soil parameters, growth, yield, nutrient uptake and nutrient content of soybean crop. There were 10 treatments with two levels of Ni (5 and 10 mg kg −1) and Fe (10 and 20 mg kg−1) with recommended dosage of fertilizers nitrogen, phosphorus, potassium (8.93, 35.71, and 17.86 mg kg−1) applied to all treatments except control. The result of the experiment revealed that the co-application of nickel and iron@10 mg kg−1 and 20 mg kg−1 (RDF + Ni10Fe20), resulted in the increase in plant height, greeness index, no of seed per pod, no of pod per plant, seed yield, and stover yield. Similar, findings for the post- harvest soil parameter indicated that there was increase in pH, electrical conductivity, and organic carbon content of soil. DTPA (Diethylenetriaminepentaacetic acid) extractable Ni, Fe, Zn, and Cu, also found highest in treatment where nickel and iron@10 mg kg−1 and 20 mg kg−1 (RDF + Ni10Fe20) were applied in soil, but in case of DTPA extractable Mn, the highest amount was found in treatment where nickel and iron@10 mg kg−1 and 10 mg kg−1 (RDF + Ni10Fe10) was applied in soil. The soil microbial biomass carbon and urease activity was also found highest in the treatment where nickel and iron@10 and 20 mg kg−1 was applied in soil. The minimum plant height, greeness index, no of seed per pod, no of pod per plant, seed, and stover yield was recorded in treatment where only RDF(T1) was applied. Similar, result recorded for the post-harvest soil parameters. So, overall findings of the pot experiment revealed that the conjoint application of nickel and iron has resulted in better yield of soybean crop.

Long-Term Amendment with Sewage Sludge: Effects on Nutrient Value and Trace-Metal Content in Different Parts of Maize Plants

Agricultural soils play a key role in the achievement of a circular nutrient economy. The use of sewage sludges as fertilizers is important for such an achievement, assisting in the maintenance of soil health and nutritional crop value. This study was established, after 23 years of a fertilization experiment, in calcareous soil under a maize monoculture. The treatments included mineral fertilization as a control (MIN, 225 kg N ha−1) and two sludge treatments, where doses followed a threshold sludge nitrogen criterion (SNC, 170 kg org-N ha−1) or a threshold soil phosphorus criterion (SPC; when the soil Olsen-P value exceeded 40–60 kg P ha−1, the sludge application was stopped). A detailed study was performed on Cd, Cu, F, Mn, Pb, and Zn soil extractable with diethylenetriaminepentaacetic acid (DTPA), as well as the nutrient and heavy metal concentration of different fractions of the maize plant (grain, cob, and the rest of the plant). Extractions were also quantified. No biomass-yield differences were observed in the different parts of the maize plant in the year of sampling. Sludges increased the soil DTPA extraction of Cd, Cu, Fe, and Zn and diminished Mn extraction, without differences in extractable Pb. The SNC, when compared with MIN, showed increased P cob concentrations, and in grain, it showed increased Fe, Cr, and Co concentrations. The SPC figures of the studied parameters were, in general, between both treatments (MIN and SNC), although Cr extractions in grain diminished vs. SNC. Based on the results, the SPC can be recommended as it also avoids excessive available-P build up.

Selective extraction of Li and Mn from spent lithium-ion battery smelting slag: Insights from isomorphous replacement in minerals

Recycling the high content of valuable metal elements contained in spent lithium-ion batteries (SLIBs) has attracted significant interest. By leveraging the concept of substitution of isomorphous replacement in earth minerals, this study proposes a novel approach for the selective extraction of Li and Mn from the artificial spodumene-type lithium-rich slag comprising LiAlSi2O6 and Mn2SiO4 through two-step selective roasting process with Na2SO4 and CaCl2, respectively. The thermodynamic calculations confirmed the feasibility of selective Li extraction by Na2SO4 roasting, with the experimental results showing that over 99 % Li was preferentially extracted as LiNaSO4. In the subsequent CaCl2 roasting step for Mn recovery, the Mn2SiO4 was effectively transformed into soluble Na2MnCl4, achieving a maximum Mn extraction efficiency of 86.5 %. The leaching kinetics of the Na2SO4 roasting products were investigated, revealing that the leaching of Li was governed by diffusion and chemical reactions in line with the shrinking core model. Characterization methods such as XRD, SEM, XPS, and TG-DSC were employed to reveal the phase transformation mechanisms of Li and Mn during Na2SO4 and CaCl2 roasting, respectively. The proposed process introduces a novel paradigm for its remarkable selective recovery of Li and Mn from SLIBs smelting slag.

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.

A process for preferential recovery of lithium and manganese from spent NCM by vacuum carbothermal reduction method

In this study, a process was developed for the preferential recovery of lithium and manganese from spent ternary lithium batteries using the vacuum carbothermal reduction method. Firstly, the electrolyte and PVDF in the cathode and anode wafers of the spent ternary lithium batteries were removed. Subsequently, lithium in the cathode powder was preferentially recovered under vacuum conditions using the anodic powder as a reducing agent. The findings show that at 1623 K and 25 %for 2 h, the reduction process generates Li2O, (NiO)m-(MnO)n, Ni, and Co as the ultimate products. Reduction roasting enables the preferential extraction of 99.99 % Li and 99.82 % Mn, which condense on the condensation tray as Li2O and MnOx, while Ni and Co are present in the residue as oxides and monomers. In summary, the whole process of the vacuum carbothermal reduction method achieves efficient extraction of Li and Mn while avoiding the subsequent recovery of Ni, Co, and Mn. It also minimizes Li loss and Mn contamination during the recovery of Ni and Co. Additionally, by utilizing the cathode material from waste LIBs. This process realises the use of waste for waste management, resulting in significant cost savings in recycling and reducing environmental harm.

Kinetic and Mechanistic Modelling of Pyrimethanil Fungicide Adsorption onto Soils of Varying Physico-chemical Properties.

Pesticide transport in the environment is impacted by the kinetics of its adsorption onto soil. The adsorption kinetics of pyrimethanil was investigated in ten soil samples of varying physicochemical properties. The highest adsorption was in the soil having the maximum silt and CaCO3 contents, pH and electrical conductance but the lowest amorphous Fe oxides and CaCl2 extractable Mn. Pseudo-second order kinetics and intra-particle diffusion model best accounted the adsorption kinetics of pyrimethanil. The equilibrium adsorption estimated by pseudo-second order kinetics (q02) was significantly and positively correlated with CaCl2 extractable Cu content (r = 0.709) while rate coefficient (k02) had a negative correlation with crystalline iron oxides content (r = -0.675). The intra-particle diffusion coefficient (ki.d.) had inverse relationship with CaCl2 extractable Mn content in soils (r = -0.689). FTIR spectra showed a significant interaction of pyrimethanil with micronutrient cations. Adsorption kinetic parameters of pyrimethanil could be successfully predicted by soil properties. The findings may help to evolve fungicide management decisions.

Extraction Strategies from Black Alloy Leachate: A Comparative Study of Solvent Extractants

Recycling spent lithium-ion batteries (LIBs) is crucial to prevent environmental pollution and recover valuable metals. Traditional methods for recycling spent LIBs include hydrometallurgy and pyrometallurgy. Among these methods, solvent extraction can selectively extract valuable metals in spent LIB leachate. Meanwhile, spent LIBs that underwent pyrometallurgical treatment generate a so-called ‘black alloy’ of Ni, Co, Cu, and so on. These elements in the black alloy need to be separated by solvent extraction and there have been few studies on extracting valuable metals from black alloy. Therefore, it is necessary to examine the extraction behavior of elements in black alloy and optimize the solvent extraction process to recover valuable metals. In this paper, four types of organic extractants are used to extract metals from simulated black alloy leachate: di-(2ethylhexyl) phosphoric acid (D2EHPA), bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A), and neodecanoic acid (Versatic acid 10). Based on the pH isotherms, D2EHPA would be the most reasonable for Mn extraction and impurity removal. Cyanex 272 would be more suitable for Co separation than PC88A, and Versatic acid 10 is preferred for Cu extraction over other metals. In conclusion, the optimal combination of extractants is suggested for the recovery of valuable metals.

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.

Preparation of a hydrogel sorbent based on agar-polyethylene glycol stabilized with iminodiacetic acid using electron irradiation method and its use for dispersive micro-solid phase extraction of Mn(II)

An agar/polyethylene glycol hydrogel was synthesized and modified with iminodiacetic acid (IDA-agar/PEG), and its ability as a biocompatible sorbent for extraction of manganese (II) ions from different environmental and food samples was investigated. The prepared IDA-agar/PEG hydrogel was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The crucial parameters of manganese (II) extraction before its determination by flow injection flame atomic absorption spectrometry were optimized. At optimized conditions, a detection limit of 0.12 μg L−1, a limit of quantification of 0.41 μg L−1, and the relative standard deviations of 3.5 % (intra-day) and 5.5 % (inter-day) for six replicate quantifications of Mn (5.0 μg L−1) were obtained. The linearity range (LR) and preconcentration factor (PF) were determined as 0.4–50.0 µg/L and 187.5, respectively. The IDA-agar/PEG hydrogel sorbent was successfully employed for the dispersive micro-solid phase extraction (DMSPE) of Mn(II) in waters, soil, vegetables, and nuts with good recoveries (97.2–101.0 %).

Soil Chemical Properties and Nutrient Dynamics under Different Legume-based Agroforestry Systems in Semi-arid Conditions of Haryana

Background: In order to support livelihoods, enhance food security, restore ecosystem services, and reduce pressure on forests, soil fertility can be improved by utilizing alternative land-use systems, such as agroforestry. Methods: The present study was conducted to investigate the effect of different agroforestry systems on soil chemical properties and nutrient availability (macro and micro) during different seasons in Hisar, Haryana. Different systems include Poplar (Populus deltoides), Eucalyptus (Eucalyptus tereticornis), Melia (Melia composita), Shisham (Dalbergia sissoo) based agroforestry system (Cowpea-Wheat) and sole cropping of Cowpea-Wheat (as control). Soil samples were collected from 0-15 and 15-30 cm of soil depth during five seasons i.e., winter, spring, summer, rainy and autumn. Result: Soil EC, SOC and available macronutrients and micronutrients were significantly affected by the depth of sampling, systems and seasons while soil pH was not significantly affected by seasons. Lower soil pH and EC was observed from agroforestry systems as compared to sole cropping. Soil Organic Carbon, availability of N, P, K and S was significantly higher under tree based systems as compared to control. Maximum DTPA extractable Mn, Zn and Cu was observed under poplar based system while highest DTPA extractable Fe was observed under Melia based system during both the years. Significantly higher SOC and nutrient availability was observed during autumn, rainy and spring seasons as compared to winter and summer seasons, while reverse trend was observed for soil pH and EC among the seasons. Soil Organic Carbon, availability of macro and micronutrients decreased with increase in soil depth. Overall, the soil chemical properties and nutrient status of soil were comparatively better under tree based systems than sole cropping of Cowpea-Wheat.

Complete recovery of valuable metals from chlorinated titanium-white waste acids: Focus on solvent extraction for recovery and preparation of battery-grade manganese sulfate (MnSO4·H2O) from lab to pilot scale

Chlorination titanium-white waste acid (CTWA) is known to contain a substantial number of valuable metals, including Mn, which can be utilized in the manufacturing of high-value battery cathode materials. Based on the concept of complete resource recovery and zero pollution, a novel process for metal recovery from CTWA has been developed. D2EHPA was used to extract Sc, V from CTWA. Al was completely removed by slowly adding 1.5 mol/L NaOH until the solution pH reached 4.20 and stabilized for 0.5 h. This process resulted in a limited loss of 11 % for Fe and 5 % for Mn. An oxidative precipitation method was proposed to process the Al-free solution to preparate a pure and easily filterable FePO4 product, which can be used in the production of battery materials. Additionally, the loss of Mn in this process was less than 0.5 %. After removing Fe and Al, the pre-extraction feed has an O/A ratio of 2.5:1, a temperature of 40 °C, and an equilibrium pH of 4.5 ∼ 5.0, it is possible to extract Mn at over 99.50 % using a 5-stage extraction. The loaded phase is scrubbed with 5 g/L H2SO4, O/A = 5:1. It is then cyclically stripped with 75 g/L H2SO4, O/A = 8:1, to obtain a battery-grade MnSO4 solution. The stripped solution can be 100 % crystallized to obtain battery-grade MnSO4·H2O products after removing heavy metals using BaS and removing oil with activated carbon. The recovery of Mn in the extraction process was 97.59 %. The pilot test was conducted to demonstrate that the extraction process can be efficiently and continuously produced. The process achieved the recovery of valuable metals from CTWA and the preparation of corresponding products. This process is comprehensive and environmentally friendly, which has an industrial foundation.

Valorisation of sulphide tailings: A novel dilute reagents-based Mn extraction process

The surging demand for manganese (Mn) and the concomitant scarcity of its primary resources have ignited interest in the extraction of this pivotal metal from unconventional sources, notably mining tailings. This study delves into the efficacy of dilute reagents as a judicious and discerning method for extracting Mn from sulphide tailings, concurrently offering environmental amelioration and substantial economic advantages. Specifically, the investigation concentrates on the adept and selective leaching of Mn from rhodochrosite (MnCO3) mineral under optimized conditions. Under the optimized conditions of 5 % HCl, a liquid-to-solid ratio of 5, a 90-minute leaching period, and a temperature at 50 °C, an exemplary 95 % leaching of MnCO3 was achieved while incurring a modest 12 % leaching of Fe, the principal impurity in the sample. Subsequent to the leaching process, MnO was efficiently extracted from the solution, exhibiting a purity surpassing 96 %, facilitated by the introduction of a diluted ammonium hydroxide solution (0.1 M NH4OH) at a solution pH of 9.8 and a temperature of 48 °C. The proposed methodology for reprocessing sulphide tailings offers numerous benefits, including cost-effective recovery and extraction, resulting from dilute reagents used and promoting a circular economy in mining. This research substantiates a significant stride towards the sustainable utilization of mining by-products, concurrently addressing both economic and environmental imperatives.

Study on the influence mechanism of carbothermal reduction and selective leaching of valuable metals in spent lithium batteries

AbstractBACKGROUNDExploring an innovative method for precious metal recovery from spent batteries, our study combines hydrometallurgy and pyrometallurgy, focusing on pivotal carbothermal reduction. This crucial phase enhances the leachability of metals by significantly reducing their valence. To evaluate the effect of novel carbon (C) materials on this reduction process, our study synthesized two types of nanoporous Cs, Al‐PCP‐800 and ZIF‐8‐800, found in electrode materials. Their carbothermal reduction efficacy was compared to activated (A)C using thermogravimetric analysis.RESULTSThe experimental findings revealed that ZIF‐8‐800 exhibits superior reducibility, initiating and reaching peak weight loss rate at a lower temperature of 692.01 °C with a peak of 32.27%/°C. Under the optimized conditions (roasting temperature 750 °C, time 3 h, C content 20%, 2.75 mol L−1 H3PO4 concentration, 40 °C leaching temperature, liquid‐to‐solid ratio of 6 mL g−1, leaching time 10 min) the leaching efficiency of lithium (Li) and manganese (Mn) reached 100%, indicating complete extraction with ZIF‐8‐800. However, cobalt (Co) and nickel (Ni) leaching with ZIF‐8‐800 was low (3.22%, 2.06%). Al‐PCP‐800 showed slightly less leaching efficiency for Li and Mn, but higher efficiency for Co and Ni. Activated C led to incomplete Li and Mn extraction, with higher Co and Ni leaching, diminishing the process's selectivity.CONCLUSIONThe study confirms that the C material in carbothermal reduction significantly impacts metal leaching efficiency and selectivity. ZIF‐8‐800 was the most effective for Li and Mn leaching, outperforming Al‐PCP‐800 and AC in selectivity. This underscores ZIF‐8‐800's potential to improve metal recovery from spent batteries. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

4D-Printed Elution-Peak-Guided Dual-Responsive Monolithic Packing for the Solid-Phase Extraction of Metal Ions.

Four-dimensional printing (4DP) technologies are revolutionizing the fabrication of stimuli-responsive devices. To advance the analytical performance of conventional solid-phase extraction (SPE) devices using 4DP technology, in this study, we employed N-isopropylacrylamide (NIPAM)-incorporated photocurable resins and digital light processing three-dimensional printing to fabricate an SPE column with a [H+]/temperature dual-responsive monolithic packing stacked as interlacing cuboids to extract Mn, Co, Ni, Cu, Zn, Cd, and Pb ions. When these metal ions were eluted using 0.5% HNO3 solution as the eluent at a temperature below the lower critical solution temperature of polyNIPAM, the monolithic packing swelled owing to its hydrophilic/hydrophobic transition and electrostatic repulsion among the protonated units of polyNIPAM. These effects resulted in smaller interstitial volumes among these interlacing cuboids and improvements in the elution peak profiles of the metal ions, which, in turn, demonstrated the reduced method detection limits (MDLs; range, 0.2-7.2 ng L-1) during analysis using inductively coupled plasma mass spectrometry. We studied the effects of optimizing the elution peak profiles of the metal ions on the analytical performance of this method and validated its reliability and applicability by analyzing the metal ions in reference materials (CASS-4, SLRS-5, 1643f, and Seronorm Trace Elements Urine L-2) and performing spike analyses of seawater, groundwater, river water, and human urine samples. Our results suggest that this 4D-printed elution-peak-guided dual-responsive monolithic packing enables lower MDLs when packed in an SPE column to facilitate the analyses of the metal ions in complex real samples.

Temperature-induced changes in DTPA-extractable trace elements: Predicting the potential impact of climate change on the availability of soil elements

The extraction of trace elements from soil with DTPA is a widely used protocol across laboratories. There is a possible “hidden” discrepancy regarding the results obtained from the extractions, i.e., ambient laboratory temperature and soil properties. In this study, the possible influence of these factors on the extractability of the available forms of Cu, Fe, Pb, Mn, Ni, and Zn, measured with DTPA were studied. Α series of extractions was carried out on a soil sample under normal laboratory temperatures, which fluctuated throughout the year, from 15 to 33.9 °C. In other 144 soil samples, the prevailing physico-chemical properties of soil were evaluated (pH, organic C, clay, CaCO3) that affected the percentage of DTPA extractability relative to the pseudo-total determined content. A strong positive correlation of all metals versus increased ambient temperature was found. Cu had an R2 of 0.897, Fe 0.970, Mn 0.957, Ni 0.938, Pb 0.876, and, Zn 0.922, all highly significant. Extracted Mn exhibited a 6.5-fold increase at the highest temperature of 33.9 οC compared to the lowest. Similar increasing trend was observed for Fe, and Ni, and smaller for Cu, Zn, and Pb. Inherent soil properties affected the percentage of extractability relative to the total content: extractability of Cu, Fe, Mn, and Ni was affected negatively by pH, and the extractability of the studied metals with CaCO3 content. Other soil properties (organic C and clay/sand content) also had an effect, not as pronounced as that of pH and CaCO3. This signifies the necessity of employing standard conditions for routine extractions such as DTPA so that data may be comparable. Also these identified discrepancies may have consequences in the extractability and availability of soil micronutrients and toxic elements regarding climate change. This study aspires to play the role of an initial step towards more robust investigations that would suggest ways of correcting temperature and soil characteristics discrepancies across laboratories.

Sulfide-modified magnetic titanium dioxide microparticles for the adsorption and solid-phase extraction of toxic metals in aqueous samples

In this work, sulfide-modified magnetic titanium dioxide microparticles (magnetic TiO2-µPs@S) were synthesized and studied for adsorption-based removal and extraction of Cd(II), Co(II), Cu(II), Mn(II), and Ni(II) ions in aqueous solutions before FAAS analysis. The magnetic TiO2-µPs@S was well characterized by UV-vis, FTIR, XRD, SEM, and EDS techniques, and the material was well functionalized, pure, and had a slightly rod-like morphology. Under optimized conditions, initial concentration of 10 mg/L, sample solution pH of 7, adsorbent dose of 0.5 g/L, agitation speed of 200 rpm, and contact time of 45 min, the magnetic TiO2-µPs@S exhibited an adsorption capacity of 24.0, 34.9, 37.6, 38.5, and 27.9 mg/g for Cd(II), Co(II), Cu(II), Mn(II), and Ni(II), respectively. Then after, the desorption experiment was conducted using 5 mL of 0.2 M HNO3 as an eluting solvent. The method showed excellent linearity (R 2 ≥ 0.998) in 0.05–10 mg/L concentration range. The limits of detection and quantification of the developed method were found to be in the range of 0.14–0.81 and 0.47–2.73 µg/L, consecutively, indicating high sensitivity of the proposed method, and <3% RSD was obtained. Furthermore, its practical applicability was assessed on tap water, lake water, and wastewater samples, and satisfactory percent recovery values, 84.5–114%, were acquired. These results indicate the potential applicability of the developed method. In general, the magnetic TiO2-µPs@S can be used as an effective adsorbent for removing heavy metals, and the adsorbent-based solid-phase extraction can be considered a promising technique for extracting and enriching heavy metals from aqueous solutions.

An innovative method for the efficient and selective extraction of Co, Ni, Cu, and Mn from oceanic cobalt-rich crusts by ammonium sulfate roasting: Behavior, roasting kinetics and mechanism

The exploitation of deep-sea mineral resources is an unavoidable choice for sustainable human development, given the diminishing or even depletion of land-based mineral resources and the increasing demand for critical metals in global industrialization. This work presents a new method for the selective extraction of Co, Ni, Cu, and Mn from oceanic cobalt-rich crusts through the ammonium sulfate roasting-water leaching process. The metal oxides in oceanic cobalt-rich crusts were transformed to sulfates or ammonium sulfate salts by sulfation roasting and then by selective decomposition roasting to transform Fe2(SO4)3 to Fe2O3, while the other metals remained in sulfate forms. Under the sulfation roasting temperature of 450 ℃ for 120 min and the mass ratio of (NH4)2SO4 to cobalt-rich crusts of 1.2:1, the decomposition roasting temperature of 650 ℃ for 90 min and the air flow rate of 2 L/min, the leaching efficiencies of Mn, Co, Ni, and Cu reached 98.3 %, 93.7 %, 88.7 %, and 66.3 %, while the Fe leaching efficiency was only 0.9 %. The analysis of the mechanism shows that the Mn in oceanic cobalt-rich crusts first formed (NH4)2Mn2(SO4)3 during roasting and then decomposed to MnSO4; Co, Ni, and Cu first formed (NH4)2Co2(SO4)3, (NH4)2Ni2(SO4)3, (NH4)2Cu3(SO4)4 and then decomposed to their respective sulfates; Fe first formed (NH4)3Fe(SO4)3 and finally decomposed to Fe2O3. Ammonia released during the roasting process can be absorbed with dilute sulfuric acid and then regenerated (NH4)2SO4 with an ammonia recovery of 87.3 %. The process proposed in this study is not only efficient, clean, and selective, but also achieves full component recovery from oceanic cobalt-rich crusts, with obvious environmental and economic advantages over the traditional reduction roasting-acid/ammonia leaching.

Effect of Chloride and Ferrous Ions on Improving Copper Leaching from Black Copper Ores

Although the importance of black copper ores is well established, many topics remain to be studied. This manuscript describes the efforts to improve copper recovery from refractory ores on a pilot scale. Preliminary tests provided the water dose to form a stable and compact agglomerate of 89 L per ton of ore and an acid dosage of 40 kg per ton of ore. The column leaching method resulted in an effluent with 1.63 g/L Cu, a pH of 1.04, and a redox potential of 675 mV (average). Despite the similarities observed in the results, reductant agents were essential to dissolve the MnO4 present in the black copper ore. Thus, the best Mn extraction results were 67.7% using the MnO2:FeSO4 ratio of 1:3. Additionally, the kinetics of leaching are slower than in an industrial operation. The copper ore under study required more than 65 days of leaching to reach the maximum copper recovery. Finally, the total recovery of copper (including washing and resting time) indicates that the maximum value was reached for ore pretreated with NaCl, H2SO4, and FeSO4, concluding that the use of agents favored leaching.