Metal Extraction Efficiency Research Articles

Recovery of Metals from the "Black Mass" of Waste Portable Li-Ion Batteries with Choline Chloride-Based Deep Eutectic Solvents and Bi-Functional Ionic Liquids by Solvent Extraction.

Lithium-ion portable batteries (LiPBs) contain valuable elements such as cobalt (Co), nickel (Ni), copper (Cu), lithium (Li) and manganese (Mn), which can be recovered through solid-liquid extraction using choline chloride-based Deep Eutectic Solvents (DESs) and bi-functional ionic liquids (ILs). This study was carried out to investigate the extraction of metals from solid powder, black mass (BM), obtained from LiPBs, with various solvents used: six choline chloride-based DESs in combination with organic acids: lactic acid (1:2, DES 1), malonic acid (1:1, DES 2), succinic acid (1:1, DES 3), glutaric acid (1:1, DES 4) and citric acid (1:1, DES 5 and 2:1, DES 6). Various additives, such as didecyldimethylammonium chloride (DDACl) surfactant, hydrogen peroxide (H2O2), trichloroisocyanuric acid (TCCA), sodium dichloroisocyanurate (NaDCC), pentapotassium bis(peroxymonosulphate) bis(sulphate) (PHM), (glycine + H2O2) or (glutaric acid + H2O2) were used. The best efficiency of metal extraction was obtained with the mixture of {DES 2 + 15 g of glycine + H2O2} in two-stage extraction at pH = 3, T = 333 K, 2 h. In order to obtain better extraction efficiency towards Co, Ni, Li and Mn (100%) and for Cu (75%), the addition of glycine was used. The obtained extraction results using choline chloride-based DESs were compared with those obtained with three bi-functional ILs: didecyldimethylammonium bis(2,4,4-trimethylpentyl) phosphinate, [N10,10,1,1][Cyanex272], didecyldimethylammonium bis(2-ethylhexyl) phosphate, [N10,10,1,1][D2EHPA], and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, [P6,6,6,14][Cyanex272]/toluene. The results of the extraction of all metal ions with these bi-functional ILs were only at the level of 35-50 wt%. The content of metal ions in aqueous and stripped organic solutions was determined by ICP-OES. In this work, we propose an alternative and highly efficient concept for the extraction of valuable metals from BM of LiPBs using DESs and ILs at low temperatures instead of acid leaching at high temperatures.

Ingenious approach for retrieving valuable metals from gypsum via dehydration–rehydration two-step phase transition

Retrieving valuable metals (VMs) from industrial waste is an attractive approach to reduce the continuous consumption of metallic resources and prevent the environmental contamination by heavy metals. However, metal extraction efficiencies are extremely low due to their entrapment in crystal lattices. Herein, a universal strategy for extracting VMs from gypsum (CaSO4·2H2O), a common industrial waste, was reported using a two-step phase transition of dehydration–rehydration; metal extraction was achieved by designing an appropriate phase transition route and controlling the phase transformation kinetics. As the phase transition route to CaSO4·0.5H2O (path-0.5) proceeded faster than that to CaSO4 (path-0), higher extraction efficiencies were realized for Cr (99.9%) and Cd (98.8%) from gypsum. Mechanistic investigations indicated that during the selected path-0.5 dehydration, water molecule loss from gypsum initiated a direct solid-state transformation, triggering the first rearrangement of local atoms and excluding partially incorporated metals from the CaSO4·0.5H2O lattice. The subsequent rehydration from CaSO4·0.5H2O to CaSO4·2H2O, with a phase transition rate faster than that of path-0, triggered the secondary atom rearrangement. The synergism between the two atomic rearrangements finally led to the complete release of trapped metals. Additionally, this strategy was used for retrieving other metals (e.g., Pb, Zn, Hg, As, and Sr) from gypsum, thereby potentially offering a new approach for designing an appropriate phase transition route for extracting VMs from other hydrous minerals.

Switchable metal extractant integrated miniaturized 3D-printed device: A semi-online multi-metal separation system for matrix-free ICP-MS analysis

BackgroundThis study tackles the critical challenges in metal analysis by presenting an innovative miniaturized metal extraction device prototype. This device features a functional nanocomposite (FNC) enhanced 3D-printed polylactic acid (PLA) metal extractant (FNC@3D PLA). The research is motivated by the constraints of traditional solid-phase extraction (SPE) methods, specifically their limitations in handling competitive metal ion environments and matrix interference during inductively coupled plasma mass spectrometry (ICP-MS) analysis. The designed prototype aims to overcome these challenges and enhance the extraction efficiency of diverse metals. ResultsThe FNC, designed to incorporate various functional groups critical for metal ion extraction efficiency, was meticulously engineered through the reaction of acid-treated and delaminated graphitic carbon nitride nanosheets (Thiol-gCN NSs) with 3-mercaptopropyl trimethoxysilane (MPTMS). The competitive metal ion extraction efficiency of FNC@3D PLA was demonstrated, showcasing notable limit of detection values of 3.2 ± 0.7 ng mL−1 and 8.57 ± 3.05 ng mL−1 for Cu and Ag, respectively. Furthermore, the miniaturized 3D-printed metal-preconcentration setup incorporating FNC@3D PLA exhibited favorable intraday relative standard deviation (RSD) percentage (%) values ranging from 1.23 to 8.6 for both Cu and Ag. Interday RSD % between 1.41 and 8.14 were observed under spiked real urine sample conditions. The sustainability and robustness of the proposed approach were underscored by substantial recovery % values exhibited by FNC@3D PLA, even after eight consecutive regeneration processes. SignificanceThis study significantly contributes to the advancement of analytical methodologies by providing a reliable and efficient platform for metal extraction and preconcentration in practical metal analysis applications. Developed FNC@3D PLA system demonstrates its potential to address the challenges associated with SPE in metal analysis, especially in complex sample matrices. We believe implications of this research can be extended to various fields, from environmental monitoring to clinical diagnostics, where accurate and reliable metal analysis is paramount.

Comparing nitric acid treatment and microwave digestion for efficiency of metal extraction from bioprocess samples

Metal ions may act as enzyme cofactors and influence the kinetics of biochemical reactions that may also influence the biological production of therapeutic proteins and quality attributes such as glycosylation. Because sample preparation is a significant step in the reliable analysis of metals, we compared two sample preparation procedures for metal analysis of bioreactor culture media samples by ICP-MS: (i) samples were diluted in 2 % nitric acid (treatment with nitric acid, TNA); and (ii) samples were mixed with equal volume of 5 % nitric acid and closed vessel digestion was performed in a microwave (closed vessel digestion, CVD). In the comparison of extraction efficiencies between TNA and CVD procedures, CVD showed better extraction for Ca and Cu among bulk metals (∼30 %) and for Ni among the trace metals (∼65 %) for the bioreactor broth supernatant samples. For the cell pellet samples, the CVD procedure was found to be better for extraction of Fe (∼65 % more) among bulk metals, Zn (∼20 % more) among minor metals and Co (∼60 % more) and Ni (∼45 % more) among trace metals. Differences between the two procedures were less than 10 % and TNA was better for all other metals quantified from both supernatant samples and cell pellet samples. The current study helps bring more clarity to the methodology on comprehensive metal analysis to monitor and maintain trace metal content for biologics production.

Removal of heavy metals from Industrial brownfields by Hydrolysate from waste chicken feathers in intention of circular Bioeconomy

Contamination of soils with heavy metals is a problem which has a significant negative impact not only on the environment but also on the presence and quantity of soil bacteria; the basis of healthy soil. Currently, new types of biodegradable chelating agents which could effectively wash heavy metals from soils and would replace the used EDTA-based agents are being sought and tested. However, it would be advantageous to use waste materials in accordance with the circular bioeconomy. Therefore, the hydrolysate prepared by the thermal pressure hydrolysis of waste chicken feather initiated by malic acid containing amino acids was tested as a new ecological and cheap chelating agent for the removal of heavy metals from industrial soil. The efficiency of the heavy metal extraction during twenty-four hours was at least the same and usually higher than the EDTA-based agents, especially for Cr, Ni and mainly for As, which could not be washed out by EDTA even with extended contact times of several days. Simultaneously, it was found that the hydrolysate revealed a significant biostimulating effect on soil bacteria, whose amount increased by several orders within five days. Simultaneously, the increased number of bacteria produced biosurfactants which significantly participated in the washing out of heavy metals, thereby increasing the efficiency of the hydrolysate.

Effect of Na2S+NaOH Pre-Identification Leaching on Oxidized Refractory Au-Ag Ores

This study was conducted to investigate the effect of the alkaline sulfide (Na2S+NaOH) pre-identification process on cyanide leaching performance in oxidized refractory gold-silver ores. The ore has intensive oxide, carbonate, and silicate content, and contains Au/Ag minerals containing electum, acanthite, and silver-bearing FePbZn Sulphate-Arsenate/Hydroxide minerals together with Fe, Pb, and Zn minerals. Niğde Ulukışla refractory Au/Ag ore has 8-9 g/T gold and 170-180 g/T silver grades. In mineralogical examinations, it was found that these metals were closed in minerals such as iron oxy/oxyhydroxide, calcite, and quartz or neighboring these minerals. In the cyanide soluble process after alkali sulfide preliminary procedure at room temperature, metal extraction yields were obtained as 62% for gold and 7% for silver. It is seen that silver is adversely affected by this process compared to the direct cyanidation process. However, after the hot alkali treatment process, metal extractions improved by approximately 25% of gold and 74% of silver. This increase in yield can be considered as converting Ag-oxyhydroxide into soluble Ag forms as a result of the effect of hot alkaline sulfur leaching on the cyanide process. The most important advantage of this decomposition process is to achieve high metal extraction efficiency in lower alkali concentrations.

Co-extractants based on the Hofmeister effect and the Van ‘t Hoff - LeChatelier effect to increase metal extraction efficiencies

This work evaluates the impact of the Hofmeister effect and the Van ‘t Hoff – LeChatelier effect on the extraction efficiency of cobalt and neodymium from aqueous phases to pseudo-protic ionic liquids. These metals are particularly relevant for the urban mining from for example electric vehicles. Cheap and readily available co-extractants were employed to investigate the impact of both effects either individually or in parallel on the extraction efficiency. A high driving force is required from either the Hofmeister effect or from both effects simultaneously to successfully increase the extraction of cobalt (more than tenfold). Lower driving forces are sufficient to successfully increase the extraction of neodymium (up to 100 %).

Efficient extraction of heavy metals from aqueous environments using magnetic effervescent Tablet-Assisted ionic Liquid-Based dispersive Solid-Phase microextraction

In this study, we successfully developed an effervescent tablet-assisted dispersive solid-phase microextraction approach using sulfanilic acid-modified magnetic graphene oxide (MGO@SA-DSPM) for the efficient removal of heavy metals (Pb(II), Cd(II), Zn(II), and Cr(II)). The study systematically investigated the impact of different variables on the extraction efficiency of heavy metals. Results demonstrated that the MGO@SA nanocomposite exhibited superior extraction yields for all four metals, with recovery rates of 100.6 % for Cd(II), 103.6 % for Zn(II), 99.39 % for Cr(III), and 87.08 % for Pb(II), surpassing those of the MGO composite (81.08 % for Cd(II), 101.5 % for Zn(II), 54.35 % for Cr(III), and 80.48 % for Pb(II)). The enhanced extraction efficiencies due to the introduction of additional functional moieties, such as sulphonyl (-SO3-) and amid (NH-CO) moieties, onto the surface of MGO through its modification with SA. This led to a significantly improved extraction process. Under optimized conditions, the MGO@SA-DSPM method achieved low limits of detection (LOD) ranging from 0.204 to 299 μg/L, and limits of quantification (LOQ) between 0.68 and 0.99 μg/L, along with satisfactory extraction recoveries (87.08 % − 103.6 %) and relative standard deviations of 1.36–1.99 % for all four heavy metals. In summary, the proposed MGO@SA-DSPM approach demonstrates promising potential for routine water quality monitoring.

High-efficiency process of aluminum removal from rare earth solutions using a readily industrialized ionic liquid

Aluminum (Al) is often associated with rare earth resources, and the removal of Al3+ from rare earth elements (REEs) is a difficult task due to its amphoteric properties. Aluminum ions (Al3+) enrich in Sm3+-Gd3+ solution with the traditional 2-Ethylhexylphosphoric acid mono-2-ethylhexyl ester (P507)-kerosene-HCl system, emulsifying the phases, polluting the rare earth products and reducing the separation efficiency. A readily industrialized ionic liquid (IL) was synthesized with methyltrioctylammonium chloride ([N1888]Cl) and industrial naphthenic acid (NA) for the purification of Al3+ from GdCl3 solution. Under the experimental conditions, the extraction properties of diluted [N1888][NA], diluted NA and saponified NA were comparatively investigated and the separation factors (βAl/Gd) of Al/Gd were 23.0, 3.5 and 1.3, respectively. The effects of the salting-out agent, extraction agent, pH value and phase ratio on metal extraction efficiency were optimized. Finally, the industrial GdCl3 feed with a high Al3+ impurity of 889 mg/L was lowered to 5 mg/L. The removal efficiency of Al3+ was 99.4%, and the purity of Gd3+ was 99.998%. It provides a potential method for Al3+ purification from rare earth solutions with advantages of high efficiency, raw materials availability and ready industrialization.

Extraction of Li, K, and Rb from zinnwaldite by chlorination roasting with CaCl2

The extraction of lithium, potassium, and rubidium from lithium mica zinnwaldite was investigated using high-temperature roasting with solid calcium chloride, followed by water leaching of the resulting sinters. This study examined the impact of roasting temperature, heating rate, roasting time, and the calcium chloride content within the roasting mixture on the extraction efficiency of alkali metals. Based on the observed phenomena, a comprehensive reaction mechanism for alkali metals chlorination was proposed.The crucial factors of the roasting process are the roasting temperature and the calcium chloride content within the roasting mixture. The optimal results were achieved when a mixture containing four times the stoichiometric amount of calcium chloride was roasted at 1000 °C for 20 min with a heating rate of 10 °C/min. Under these conditions, 77 % of lithium, 90 % of potassium, and 90 % of rubidium were successfully extracted.The proposed chlorination mechanism of zinnwaldite roasting involves three successive stages:a)Chlorination of alkali metals between 500 and 650 °C primarily via the surface reaction of calcium chloride with zinnwaldite before the mineral decomposition initiates.b)Decomposition of zinnwaldite between 650 and 850 °C, with a preferential chlorination of potassium and rubidium due to their better accessibility for the chlorinating agent after the structural disruption of the original mineral.c)Chlorination of lithium as a result of the reaction between calcium chloride andβ-spodumene, a decomposition product of zinnwaldite.During the roasting process, the emission of fluorinated gaseous compounds was observed, along with the reaction of chlorine with iron. This reaction consumes the chlorinating agent and eventually leads to the generation of chlorine gas as a result of the decomposition of chlorinated iron compounds.

Comparison of extraction abilities of deep eutectic solvents and aqueous acid solutions for extraction of rare earths and transition metals

In recent years, deep eutectic solvents have attracted increasing interest as effective extractants for the separation of both organic substances and metals from various objects. Acid-based deep eutectic solvents are most often used as extractants for the extraction of metals. In this work, for the first time, the extraction efficiency of transition metals and rare earth elements (Y, Zr, Nb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf and Ta) from mining tailings and Na, K, Ca, Mg, Cu, Fe, Mn, Pb, Ba, Ni and Sr from biodiesel samples using acidic deep eutectic solvents and saturated aqueous solutions of the same acids (malonic, malic, tartaric and citric) is compared. For this, deep eutectic solvents based on acids and their aqueous saturated solutions were prepared and studied. The prepared mixtures were analyzed by IR spectroscopy to confirm the formation of eutectic solvents. Properties such as the density and viscosity of the resulting mixtures were also investigated, as this can be of key importance for the efficiency of metal extraction. The extraction of rare earth metals from mining tailings took a long time (up to several days), while the extraction of metals from fuel took no more than 30 min. Atomic emission spectral methods were used as an analysis method. It is shown that the extraction efficiency with aqueous solutions is better than that with eutectic solvents, which casts doubt on the need for deep eutectic solvents use in this area.

Extraction efficiency of metals from low-nickel matte via NH4Cl roasting-water leaching process and synthesis of (Ni,Cu,Co)Fe2O4 photocatalyst

Extraction efficiency of metals from low-nickel matte via NH4Cl roasting-water leaching process and synthesis of (Ni,Cu,Co)Fe2O4 photocatalyst

Дезактивація рідких радіоактивних відходів Чорнобильської зони відчуження: шляхи вирішення

The purpose of the study: on the basis of information analysis of modern approaches and experimental studies, to develop effective methods of decontamination of radioactively contaminated waters of the Chernobyl Exclusion Zone. Research materials and methods. The object of our research was liquid radioactive waste stored in the sumps of one of the decontamination points for equipment and vehicles (PuSO) - the "Dibrova" facility. Modern research methods are applied - scanning electron microscopy, X-ray diffractometry, laser sedimentography. The mass fraction of cesium, strontium, cobalt, and manganese was determined by the atomic absorption method using an AA-8500 atomic absorption spectrophotometer (Nippon Jarrell Ash Co Ltd, Japan). The results. The effectiveness of the proposed sorbents based on nickel-potassium ferrocyanide-modified iron oxide micro- and nanotubes and iron (III) hydroxide nanoparticles, the size of which is mainly 1-100 μm, is shown. The choice of decontamination algorithm depends on the composition of liquid radioactive waste to be cleaned. To increase the degree of strontium extraction while maintaining the high efficiency of cesium and transition metal extraction, it is advisable to apply preliminary plasma chemical treatment followed by the use of sorbents based on iron oxides/hydroxides modified by ferrocyanides. Conclusions. The possibility and expediency of using the proposed method for the decontamination of liquid radioactive waste accumulated in the Chernobyl exclusion zone and for the current control of the condition of the storage sites of accumulated radioactive waste and radiation monitoring are shown.

Removal of polyvinylidene fluoride binder and other organics for enhancing the leaching efficiency of lithium and cobalt from black mass

The agglomeration and encapsulation of recoverable materials of interest (e.g. metals and graphite) as a result of the presence of polyvinylidene fluoride (PVDF) in spent lithium-ion batteries (LIBs) with mixed chemistries (black mass) lower the extraction efficiency of metals. In this study, organic solvents and alkaline solutions were used as non-toxic reagents to investigate the removal of a PVDF binder from a black mass. The results demonstrated that 33.1%, 31.4%, and 31.4% of the PVDF were removed using dimethylformamide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO) at 150, 160, and 180 °C, respectively. Under these conditions, the peel-off efficiencies for DMF, DMAc, and DMSO were 92.9%, 85.3%, and approximately 92.9%, respectively. Using tetrabutylammonium bromide (TBAB) as a catalyst and 5 M sodium hydroxide (NaOH) at room temperature (RT- 21 °C–23 °C), 50.3% of PVDF and other organic compounds were eliminated. The removal efficiency was enhanced to approximately 60.5% when the temperature was raised to 80 °C using NaOH. Using 5 M potassium hydroxide at RT in a TBAB-containing solution, ca. 32.8% removal efficiency was obtained; raising the temperature to 80 °C further enhanced the removal efficiency to almost 52.7%. The peel-off efficiency was 100% for both alkaline solutions. Lithium extraction increased from 47.2% to 78.7% following treatment with DMSO and to 90.1% following treatment with NaOH via leaching black mass (2 M sulfuric acid, solid-to-liquid ratio (S/L): 100 g L–1 at 50 °C, for 1 h without a reducing agent) before and after removal of the PVDF binder. Cobalt's recovery went from 28.5% to 61.3% with DMSO treatment to 74.4% with NaOH treatment.

Acid-free extraction of valuable metal elements from spent lithium-ion batteries using waste copperas

A large amount of hazardous spent lithium-ion batteries (LIBs) is produced every year. Recovery of valuable metals from spent LIBs is significant to achieve environmental protection and alleviate resource shortages. In this study, a green and facile process for recovery of valuable metals from spent LIBs by waste copperas was proposed. The effects of heat treatment parameters on recovery efficiency of valuable metals and the redox mechanism were studied systematically through phase transformation behavior and valence transition. At low temperature (≤460 °C), copperas reacted with lithium on the outer layer of LIBs preferentially, but the reduction of transition metals was limited. As the temperature rose to 460–700 °C, the extraction efficiency of valuable metals was greatly enhanced due to the generation of SO2, and the gas–solid reaction proceeded much fast than the solid–solid reaction. In the final stage (≥700 °C), the main reactions were the thermal decomposition of soluble sulfates and the combination of decomposed oxides with Fe2O3 to form insoluble spinel. Under the optimum roasting conditions, i.e., at a copperas/LIBs mass ratio of 4.5, and a roasting temperature of 650 °C and roasting time of 120 min, the leaching efficiencies of Li, Ni, Co and Mn were 99.94%, 99.2%, 99.5% and 99.65%, respectively. The results showed that valuable metals can be selectively and efficiently extracted from the complex cathode materials by water leaching. This study used waste copperas as an aid to recover metals and provided an alternative technical route for green recycling of spent LIBs.

Emission reduction treatment of chlorine-containing waste gas during the chlorination roasting process of lepidolite: thermodynamic analysis and mechanism investigation

It was vital for the chlorination roasting process to effectively reduce and avoid the production of chlorine-containing waste gas. In this paper, the chlorination roasting process of lepidolite was optimized and the reaction mechanism was studied emphatically. Thermodynamic investigations indicated that the direct interaction of calcium chloride with the alkali metal oxides in lepidolite played a dominant role in the chlorination process. The addition of calcium hydroxide achieved the goal of reducing the emission of chlorine-containing waste gas, which increased the chlorine content of the roasted product from 20% to 70% with the increase of calcium hydroxide dosage. The mechanism analysis revealed that the calcium oxide produced by the decomposition of calcium hydroxide consumed a lot of alumina and silicon dioxide in minerals, which improved the effective utilization rate of calcium chloride. Thus, the extraction efficiency of valuable metals was enhanced while the production of chlorine-containing waste gas was reduced dramatically. This study provided some theoretical guidance for the mechanism analysis of the lepidolite chlorination roasting process, and also contributed to a new method for the emission reduction treatment of chlorine-containing waste gas.

Endophytic Bacteria in Ricinus communis L.: Diversity of Bacterial Community, Plant−Growth Promoting Traits of the Isolates and Its Effect on Cu and Cd Speciation in Soil

Ricinus communis L. shows certain tolerance to and good accumulation ability with heavy metals. Endophytic bacteria−enhanced phytoremediation is an effective method to improve heavy metal extraction efficiency. Here, for better application of castor in phytoremediation, the Illumina high−throughput sequencing was carried out to reveal the endophytic bacterial community in the tissues of castor grown in two locations, and traditional microbial cultivation was used to isolate endophytic bacteria from castor. The dominant bacterial phyla were Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes and Acidobacteria, and Proteobacteria was absolutely dominate in all castor tissues. There were significant differences in the composition of endophytic bacterial communities between castor grown in two sites, with obvious variation in the relative abundance of the dominant phylum. The samples from two sites also had their own unique dominant bacterial genera. The analysis of alpha diversity illustrated that the diversity and species richness of endophytic bacteria community in different parts of castor sampled in Tonglushan mining area were lower than those in Gangxia village, Yangxin county. In total, there were 44 endophytic bacteria strains isolated from the tissues of castor, of which 42 strains possessed three or more growth−promoting properties. Most of these isolates were tolerant to Cu or Cd to varying degrees. Eight isolates were selected for further Cu mobilization and soil incubation experiments. Strains TR8, TR18, TR21, YL1, YS3 and YS5 could well solubilize Cu2(OH)2CO3 in medium. Strain YS3 had the best effect on increasing soil DTPA−Cu and DTPA−Cd contents by 8.4% and 6.9%, respectively. Inoculated endophytic isolates were conducive to the conversion of heavy metal forms from insoluble to relatively unstable, and could increase available phosphate content in soil (10.8–29.2%). Therefore, the plant growth−promoting endophytes screened from castor have great application prospects and can provide important support for the microbial−assisted phytoremediation of heavy metal−contaminated soil.

Optical and quantitative detection of cobalt ion using graphitic carbon nitride-based chemosensor for hydrometallurgy of waste lithium-ion batteries

A hydrometallurgy is one of the most important techniques for recycling waste LIBs, where identifying the exact composition of the metal-leached solution is critical in controlling the metal extraction efficiency and the stoichiometry of the regenerated product. In this study, we report a simple and selective optical detection of high-concentrated Co2+ using a graphitic carbon nitride (g–CN)–based fluorescent chemosensor. g-CN is prepared by molten salt synthesis using dicyandiamide (DCDA) and LiI/KI. The mass ratio of LiI/KI to DCDA modifies the resulting g-CN (CNI) in terms of in-plane molecular distances of base sites including cyano functional groups (─CN) and fluorescent emission wavelength via nucleophilic substitution. The fluorescent sensing performance of CNIs is evaluated through photoluminescence (PL) emission spectroscopy in a broad Co2+ concentration range (10−4–100 M). The correlation between the surface exposure of hidden nitrogen pots (base sites) and PL intensity change is achieved where the linear relationship between the PL quenching and the logarithm of Co2+ concentration in the analyte solution is well established with the regression of 0.9959. This study will provide the design principle of the chemosensor suitable for the fast and accurate optical detection of Co2+ present in a broad concentration range for hydrometallurgy for the recycling of waste LIBs.

A novel non-cyanide extraction method of gold for high As-Sb-bearing refractory gold ore based on Mn-oxide ore acidic oxidation

The present pre-processing of the As-and-Sb-bearing refractory gold ore has some flaws in the tediously flow, low treatment, and metal extraction efficiency. Based on these considerations, a whole wet gold extraction way combined Mn-oxide hydrochloric acid oxidation with acidic chlorination leaching for the As-and-Sb-bearing refractory gold ore was proposed in this study. The dissolution efficiencies of As, Sb, and Au leaching ratios, mineral phase transformation, and electrochemical behavior during the process were measured. It can be illustrated that the pre-oxidation of the gold ore by Mn-oxide oxidation controlled Au-extraction efficiency, and with the dissolution of 93.3 % As and 92.5 % Sb from the gold ore in the usage of Mn-oxide-assisted hydrochloric acid oxidation process, it obtains Au extraction ratio of 97.2 % by chlorination leaching. The pretreatment efficiency of the unmanageable gold ore is positively related to temperature and acidity increased due to the redox of Mn-oxides and As-Sb-Fe-sulphides. The wet process performs as an efficient non-cyanide method for gold extraction from the As-and Sb-bearing sulphide refractory gold ore.

On-line quantification of solid-phase metal extraction efficiencies using instrumented millifluidics platform

A semi-automated and fully integrated millifluidic platform has been developed for rapid development and study of Solid-phase extraction (SPE) processes. In this instrumented setup, the fluid coming out of the extraction mini-column is analysed directly using on-line X-ray fluorescence, enabling a real-time, fast and accurate measurement of the elemental concentrations within the flowing liquid. This platform aims at enhancing and facilitating the development of SPEs whose numerous experimental parameters make it time consuming to optimize and upscale. Hence, this approach solves the labour intensity issue and is as accurate as off-line Inductively Coupled Plasma, for instance. This is exemplified with a system, typical of the electronic wastes recycling industry, comprising of a mixture of Rare-Earth Elements (REEs) and Iron, whose separation is investigated as a function of various experimental parameters. It enabled us to study the performance of the newly released METALICAPT® commercial materials and to determine an optimized path towards the almost total separation of Iron from the initial mixture. Overall, the original SPE process reported herein demonstrates the platform’s reliability, performance and range of applicability.