Acidic Extraction Research Articles

Impregnation of preparative high‐performance solid phase extraction chromatography columns by organophosphorus acid compounds

The flexible and reversible preparation of columns for use in high-performance solid phase extraction chromatography by physisorption of organophosphorus acid extractants has been investigated in detail. Two extractants have been evaluated, bis (2-ethyl-1-hexyl) phosphoric acid (HDEHP) and 2-ethyl-1-hexyl (2-ethyl-1-hexyl) phosphonic acid (HEHEHP), but the developed procedure should be broadly applicable to other extractants. The liquid-liquid solubility of the extractants in feed solvents consisting of aqueous ethanol solutions of varying composition has been determined. The total amount of adsorbed extractant has been quantified by complete desorption and elution with ethanol followed by acid-base titrimetry. Column impregnation with feed solutions of varying concentration in the undersaturated region has been systematically evaluated, and the influence of a subsequent water wash step has been explored. It is shown that to achieve a robust and reproducible physisorption, the adsorbed amount of extractant should be determined after the wash step, and care must be taken when using indirect methods of measurement. Equilibrium Langmuir-type adsorption isotherms as a function of the extractant concentration in the feed solution have been determined. Adsorption of HEHEHP is higher than HDEHP for equal feed compositions, but the solubility of HEHEHP is lower, resulting in approximately identical maximum coverage levels. The ability of the resulting columns to separate rare earth elements have been verified for a mixture of eight metals using a combined isocratic and gradient elution of nitric acid.

Biostimulant Activity of <i>Sargassum</i> sp. Extracts on Early Growth of <i>Zea mays</i> L. and the Phytohormones Content Analysis

Seaweed has been gaining global interest in agriculture for the development of marine-based plant biostimulants. This research aimed to study the effect of three different liquid extracts of Sargassum sp., acidic, alkaline, and water extract, on the germination and early growth of maize and to evaluate the phytohormones content responsible for the growth. Phytohormones content including Indole-3-acetic acid (IAA), gibberellins (GA), kinetin and zeatin were analyzed using high-performance liquid chromatography (HPLC) and bioassay was performed twice on maize. Parameters observed on the bioassay were germination percentage, number of roots, shoot length, shoot weight and root weight under 4 different concentrations with 0.5; 1.5; 3.5; and 5% in the first bioassay and 3.5% concentration in the second bioassay. Both bioassays following randomized complete design and the data were analyzed using one-way ANOVA using post hoc test of Duncan Multiple Range Test (DMRT) at error probability of 5% in Genestat software. Phytohormones content in the seaweed extract indicated that alkaline extract was rich in IAA, gibberellin, and zeatin content, while water extract showed the highest kinetin content. The first bioassay indicated that lower concentration of the seaweed extracts gave better growth in all extracts, therefore a 3.5% concentration was chosen for the second bioassay with higher replication for each treatment. The second bioassay confirmed alkaline extract resulted in the highest germination while the highest seedling height, number of roots, shoot and root weight were resulted from acidic extract treatment. In conclusion, Sargassum sp. extracts obtained from acidic, alkaline, and water-based extraction methods, were able to improve the shoot and root growth of maize plants. The acidic extract showed the highest growth promotion among other extracts with the lowest phytohormones content.

Fast determination of trace metals in edible oils and fats by inductively coupled plasma mass spectrometry and ultrasonic acidic extraction

Trace elements play an important role in humans as some are essential for the proper functioning of the body while others may have negative impact in health. Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of nine elements (Cd, Cr, Cu, Fe, Mn, Ni, Ti, V e Zn) in olive oil, soy oil and margarine. Samples were treated with nitric acid solution (10 % v/v) and heated at 50 °C for 30 min. This mixture was placed in an ultrasonic bath for 20 min, in order to obtain quantitative extraction of trace-elements into the acid solution, which was directly aspirated into the ICP-MS to be quantified, using analytical curves constructed with aqueous standards. This simple sample preparation procedure along with an efficient sample introduction strategy (using a Meinhard K3 nebulizer and a twister cyclonic spray chamber) facilitated the overall analytical process. Internal standardization with Rh was used to correct matrix effects and signal fluctuations. Limits of detection in the ng g−1 range were achieved for all elements and were appropriate for the intended application. The method was tested by the analysis of samples before and after fortification with metalo-organic standards and recoveries between 88 and 117% were achieved. The method was found to lead to reliable results using a fast and simple procedure.

Ultrasonic-Assisted Extraction of Cannabidiolic Acid from Cannabis Biomass.

Industrial hemp (Cannabis spp.) has many compounds of interest with potential medical benefits. Of these compounds, cannabinoids have come to the center of attention, specifically acidic cannabinoids. The focus is turning toward acidic cannabinoids due to their lack of psychotropic activity. Cannabis plants produce acidic cannabinoids with hemp plants producing low levels of psychotropic cannabinoids. As such, utilization of hemp for acidic cannabinoid extraction would eliminate the need for decarboxylation prior to extraction as a source for the cannabinoids. The use of solvent-based extraction is ideal for obtaining acidic cannabinoids as their solubility in solvents such as supercritical CO2 is limited due to the high pressure and temperature required to reach their solubility constants. An alternative method designed to increase solubility is ultrasonic-assisted extraction. In this protocol, the impact of solvent polarity (acetonitrile 0.46, ethanol 0.65, methanol 0.76, and water 1.00) and concentration (20%, 50%, 70%, 90%, and 100%) on ultrasonic-assisted extraction efficiency has been examined. Results show that water was the least effective and acetonitrile was the most effective solvent examined. Ethanol was further examined since it has the lowest toxicity and is generally regarded as safe (GRAS). Surprisingly, 50% ethanol in water is the most effective ethanol concentration for extracting the highest amount of cannabinoids from hemp. The increase in cannabidiolic acid concentration was 28% when compared to 100% ethanol, and 23% when compared to 100% acetonitrile. While it was determined that 50% ethanol is the most effective concentration for our application, the method has also been demonstrated to be effective with alternative solvents. Consequently, the proposed method is deemed effective and rapid for extracting acidic cannabinoids.

Morus macroura Miq. Fruit extract protects against acetic acid-induced ulcerative colitis in rats: Novel mechanistic insights on its impact on miRNA-223 and on the TNFα/NFκB/NLRP3 inflammatory axis

Nod-like receptor pyrin domain-1 containing 3 (NLRP3) inflammasome/tumor necrosis factor alpha (TNFα)/nuclear factor kappa B (NFκB) inflammatory pathway is known to be involved in the pathogenesis of ulcerative colitis (UC). Inversely, miRNA-223 can exert counter-regulatory effect on NLRP3 expression. The mulberry tree (Morus macroura) fruit is attaining increased importance for its antioxidant and anti-inflammatory activity in addition to its high safety profile. Accordingly, we attempted to explore the possible protective effect of mulberry fruit extract (MFE) in acetic acid (AA)-induced UC rat model. Phytochemical constituents of MFE were characterized using high performance liquid chromatography coupled to mass spectrometry (HPLC-MS). In the in vivo study, three doses of MFE were orally given for seven days before intra-rectal induction of UC by AA on day eight. Screening study revealed that MFE (300 mg/kg) significantly reduced macroscopic and microscopic UC scores. Biochemically, MFE ameliorated oxidative stress, levels of TNFR1, NLRP3, p-NFκB p65, TNFα, IL-1β, and IL-18, caspase-1 activity, but enhanced miRNA-223 expression. In conclusion, our study provided a novel protective impact for MFE against UC, in which miRNA-223 and TNFα/NFκB/NLRP3 pathway are involved. These results provide a promising step that might encourage further investigations of MFE as a protective agent in UC patients.

Manipulation of fatty acid profile and nutritional quality of Chlorella vulgaris by supplementing with citrus peel fatty acid

Microalgae could be an excellent resource of functional and essential fatty acids. To achieve viable microalgal biomass production, mass cultivation of microalgae is required; however, the high cost of nutrients is the obstacle. An inexpensive and nutritious material is required to feed Chlorella vulgaris in the pharmaceutical and food sectors. Citrus peel waste with a valuable nutritional quality could be one of the promising and inexpensive candidates. In this study, the fatty acid extract from different citrus peels was used as the organic nutrient source for the cultivation of Chlorella. The proximate composition of bitter orange, sweet orange, grapefruit, and mandarin peels were determined, and their nutritional quality was evaluated. Total fatty acids from the citrus peel were prepared by acidic methanol hydrolysis and hexane extraction. Fourier transforms infrared (FT-IR) and gas chromatography–mass spectrometry (GC–MS) was used to analyze the fatty acid composition and nutrient composition. Fatty acids from the citrus peels were added to the Chlorella culture medium to study their influences on biomass, lipid production, fatty acid profile, and nutritional quality of Chlorella. The most predominant citrus peel fatty acids were linoleic, palmitic, oleic, linolenic, and stearic acids. The citrus peels contain polyunsaturated, saturated, and monounsaturated fatty acids. The most unsaturated fatty acids were omega-6, omega-3, omega-9, and omega-7. The citrus peel had acceptable atherogenicity, thrombogenicity, omega-6/omega-3, peroxidizability, hypocholesterolemic, and nutritive value indices. The major fatty acids of Chlorella were palmitic, linoleic, oleic, alpha-linolenic, gamma-linolenic, 4,7,10,13-hexadecatetraenoic, palmitoleic, 7,10-hexadecadienoic, 7,10,13-hexadecatrienoic, lauric and 5,8,11,14,17-eicosapentaenoic acids. Chlorella contains polyunsaturated, saturated, and monounsaturated fatty acids. The most unsaturated fatty acids contain omega-6, omega-3, omega-9, and omega-7. Chlorella had acceptable atherogenicity, thrombogenicity, omega-6/omega-3, hypocholesterolemic, peroxidizability, and nutritive value indices. Supplementation of Chlorella with citrus peels fatty acid increases total biomass, lipid content, and nutritional quality of Chlorella. The present research shows that citrus peels have good nutritional quality and could be used for the inexpensive cultivation of Chlorella biomass with potential utility for food application.

A Novel Endo-Polygalacturonase from Penicillium oxalicum: Gene Cloning, Heterologous Expression and Its Use in Acidic Fruit Juice Extraction.

An endo-polygalacturonase (endo-PGase) exhibiting excellent performance during acidic fruit juice production would be highly attractive to the fruit juice industry. However, candidate endo-PGases for this purpose have rarely been reported. In this study, we expressed a gene from Penicillium oxalicum in Pichia pastoris. The recombinant enzyme PoxaEnPG28C had an optimal enzyme activity at pH 4.5 and 45°C and was stable at pH 3.0-6.5 and < 45°C. The enzyme had a specific activity of 4,377.65 ± 55.37 U/mg towards polygalacturonic acid, and the Km and Vmax values of PoxaEnPG28C were calculated as 1.64 g/l and 6127.45 U/mg, respectively. PoxaEnPG28C increased the light transmittance of orange, lemon, strawberry and hawthorn juice by 13.9 ± 0.3%, 29.4 ± 3.8%, 95.7 ± 10.2% and 79.8 ± 1.7%, respectively; it reduced the viscosity of the same juices by 25.7 ± 1.6%, 52.0 ± 4.5%, 48.2 ± 0.7% and 80.5 ± 2.3%, respectively, and it increased the yield of the juices by 24.5 ± 0.7%, 12.7 ± 2.2%, 48.5 ± 4.2% and 104.5 ± 6.4%, respectively. Thus, PoxaEnPG28C could be considered an excellent candidate enzyme for acidic fruit juice production. Remarkably, fruit juice production using hawthorn as an material was reported for the first time.

A novel automatic flow-batch extraction induced by emulsion breaking platform for on-line copper determination in edible oil samples by atomic absorption spectrometry

A novel automatic flow-batch platform coupled with atomic spectrometry for on-line acidic extraction induced by emulsion breaking with heating (FB-EIEBH) for metal determination in edible oils (corn, sunflower and olive oil), was developed for the first time. The proposed system was demonstrated for copper determination in conjunction with flame atomic absorption spectrometry. The extraction of metal is accomplished after the oil emulsification with an aqueous solution consisted of Triton X-114 and nitric acid, in an on-line programmed manner. All the main parameters affecting the extraction procedure, such as oil dilution, type and concentration of surfactant and nitric acid as well as temperature and time for the emulsion breaking and phase separation, have been investigated and optimized. A mixture of oil/xylene at 10:2 proportion was found to be appropriate to use in the flow manifold. Optimum conditions were verified employing 8.0 mL of oil sample, 990 μL of extractant solution containing 10.0% m/v Triton X-114 and 10.0% v/v HNO3. Emulsion breaking and phases separation were completed at temperature 90 °C, and time 300 s. The detection and quantification limit for copper determination was found to be 5.8 μg L−1 and 19.3 μg L−1, employing aqueous standards, which are proved to produce similar performance characteristics with oil-based standards. Recovery tests were executed by appropriate additions of oil-based standard solution of copper and the recoveries ranged between 94.2 and 102.4%.

Microplastic sample purification methods - Assessing detrimental effects of purification procedures on specific plastic types

In search of effective, fast, and cheap methods to purify environmental samples for microplastic analysis, scientific literature provides various purification protocols. However, while most of these protocols effectively purify the samples, some may also degrade the targeted polymers. This study was conducted to systematically compare the effects of purification protocols based on acidic, alkaline, oxidative, and enzymatic digestion and extraction via density separation on eight of the most relevant plastic types. It offers insights into how specific purification protocols may compromise microplastic detection by documenting visible and gravimetric effects, analyzing potential surface degradation using Fourier transform infrared spectroscopy (FTIR) and bulk erosion on a molecular level using gel permeation chromatography (GPC). For example, protocols using strong acids and high temperatures are likely to completely dissolve or cause strong degradation to a wide range of polymers (PA, PC, PET, PS, PUR & PVC), while strong alkaline solutions may damage PC and PET. Contrarily, Fenton's reagent, multiple enzymatic digestion steps, as well as treatment with a zinc chloride solution frequently used for density-separation, do not degrade the eight polymers tested here. Therefore, their implementation in microplastic sample processing may be considered an essential stepping-stone towards a standardized protocol for future microplastics analyses.

Scandium Recovery Methods from Mining, Metallurgical Extractive Industries, and Industrial Wastes.

The recovery of scandium (Sc) from wastes and various resources using solvent extraction (SX) was discussed in detail. Moreover, the metallurgical extractive procedures for Sc recovery were presented. Acidic and neutral organophosphorus (OPCs) extractants are the most extensively used in industrial activities, considering that they provide the highest extraction efficiency of any of the valuable components. Due to the chemical and physical similarities of the rare earth metals, the separation and purification processes of Sc are difficult tasks. Sc has also been extracted from acidic solutions using carboxylic acids, amines, and acidic β-diketone, among other solvents and chemicals. For improving the extraction efficiencies, the development of mixed extractants or synergistic systems for the SX of Sc has been carried out in recent years. Different operational parameters play an important role in the extraction process, such as the type of the aqueous phase and its acidity, the aqueous (A) to organic (O) and solid (S) to liquid (L) phase ratios, as well as the type of the diluents. Sc recovery is now implemented in industrial production using a combination of hydrometallurgical and pyrometallurgical techniques, such as ore pre-treatment, leaching, SX, precipitation, and calcination. The hydrometallurgical methods (acid leaching and SX) were effective for Sc recovery. Furthermore, the OPCs bis(2-ethylhexyl) phosphoric acid (D2EHPA/P204) and tributyl phosphate (TBP) showed interesting potential taking into consideration some co-extracted metals such as Fe(III) and Ti(IV).

Theoretical study on the extraction behaviors of MoO22+ with organophosphorous extractants

99Mo is the parent isotope of 99mTc, which is commonly used in nuclear medicine, so the studies on the extraction of 99Mo have been attracted extensive attention. There are some experimental investigations about the extraction of Mo(VI) using the organophosphorous extractants including O-donor Cyanex 272 (HLa) and S-donor Cyanex 301 (HLb). We explored the coordination and complexing nature of Mo(VI) with HLa and HLb using scalar relativistic density functional theory. The electrostatic potentials and frontier molecular orbitals of HLa and HLb show that the former has stronger nucleophilic ability compared to the latter. All the MoO22+ complexes with HLa and HLb are tetra-coordinated structures. The values of Wiberg bond indices (WBIs) indicate that the Mo-S bonds have more covalency than Mo-O bonds. The energy decomposition analysis reveals that the interaction between MoO22+ ion with HLa is stronger than that with HLb, which is also supported by the thermodynamic energy. The thermodynamic energy indicates that [MoO2(H2O)2(NO3)]+ is the dominant initial species and reaction [MoO2(H2O)2(NO3)]++HL → [MoO2L(NO3)] + H++2H2O is the most preferred in the extraction process. This work elucidates the electronic structures and complexing nature of MoO22+ with Cyanex 272 and Cyanex 301 ligands and provides the useful theoretical information on designing acidic phosphorous extractants of MoO22+.

Functionalization of pectin-depleted residue from different citrus by-products by high pressure homogenization

In the valorisation of fruit and vegetable by-products by high pressure homogenization (HPH) into texturizing ingredients, the source of the by-product is an important determining factor. This study aims to demonstrate the valorisation potential of citrus residues after acidic pectin extraction (AR) and to investigate differences between citrus species (lemon, orange, grapefruit) and fruit parts (peel and pulp) as the source of the residues. Based on the results, pectin extraction is favourable in improving the storage modulus (G′) of the residue. However, residual pectin content in the different ARs, as indicated by pectic monosaccharides (e.g., GalA, Rha, Fuc), did not correlate to G′ after HPH. The G′ of all ARs suspensions, regardless of the source, improved significantly after HPH at 20 MPa. After HPH, fragmentation and subsequently aggregation of particles were observed from the particle size reduction and microscopy visualization. Particle morphology and size did not correlate with the G′ of the suspensions. Residual pectin's Rhamnogalacturonan-I contribution and degree of methyl-esterification, protein content, and glucose content related to hemicellulose were correlated to the G′ of the suspensions before HPH. However, after HPH, no correlation was found between G′ and these characteristics, likely due to changes on the structure of the particles. The results highlight the high potential of all the citrus ARs from the different sources to be functionalized as texturizing ingredients. However, the peel AR from grapefruit and lemon exhibited better rheological properties and may be considered as better sources compared to the other citrus by-products.

Separation of minor actinides from highly acidic solutions using diglycolamide modified mesoporous silica synthesized via a novel “ring-opening click” reaction

Solid-phase extraction represents a promising approach for partitioning of trivalent minor actinides (MAs) from high-level liquid waste, which is crucial for the decontamination of radioactive waste. However, highly acidic effluents poseaformidablechallengefor extraction materials. Herein, the diglycolamide ligands functionalized mesoporous silica robust matrixs were prepared, resulting in rapid and efficient separation of MAs from strong nitric acid media. This paper reports the first modification of SBA-15-type mesoporous silica through a “ring-opening click” reaction under mild conditions. Five modified silica materials with monolayer diglycolamide ligands containing different terminal groups were obtained using low temperature (0–25 °C) procedures. The rigid and open pore structure of SBA-15 is retained under such mild conditions, allowing facile diffusion and open access to the monolayer ligands. The functionalized product SBA-15-DEDGA exhibited a strong affinity for trivalent MAs in highly acidic solutions and could separate trace amounts of radioactive Am(III) from 1 to 8 M nitric acid solutions with high efficiency (> 98%) within 1 min; the largest distribution coefficient exceeded 5 × 104 mL/g. Solid-state nuclear magnetic resonance spectroscopy combined with X-ray photoelectron spectroscopy of Eu(III) revealed that the binding mechanism involves direct coordination of Eu(III) to a tridentate oxygen-binding site. Additionally, selective separation of americium from curium was achieved with separation factors up to 191 ± 20 through oxidation of Am(III) by sodium persulfate. The superlative and efficient sorption performance of these materials demonstrates their utility in the immobilization of trivalent actinides and the separation of americium from curium.

Almond hulls waste valorization towards sustainable agricultural development: Production of pectin, phenolics, pullulan, and single cell protein

This research aimed to valorize almond hulls based on a zero-waste strategy towards sustainable agricultural developments for the recovery and production of valuable compounds. For this purpose, the potential to produce four products, including pectin (AHP), phenolic compounds (AHPC), pullulan (PUL), and single-cell protein (SCP), was examined. The acidic extraction factors were optimized using a Box-Behnken design for the simultaneous extraction of AHP and AHPC, and the obtained results showed that the maximum AHP (26.32% w/w) and AHPC (6.97% w/w) yields were achieved at 90 °C, pH of 1.4, 58.65 min, and liquid–solid ratio (LSR) of 20.13 v/w as the optimum point. In the next step, the solid residues that remained from the AHP and AHPC extraction process (PESR) were treated with cellulase enzyme and ultrasound and were used for simultaneous microbial production of PUL (34.29–24.56 g/L) and biomass containing SCP (19.31–13.44% w/w). Furthermore, the obtained results showed that AHP was low methylated (26.40%), rich in galacturonic acid (67.88%), and high in molecular weight (595.299 kDa). Also, the investigations of structural properties of AHP and PUL confirmed the presence of chemical structures of these polysaccharides in the formed supernatants. In addition, the AHPC showed considerable antioxidant activity compared with ascorbic acid (ASC) and BHA.

Quantitation of propionic acid in emmental cheese products by direct solvent extraction.

Propionic acid (PA) is commonly present in Emmental cheese (EM) with relatively high concentration. Even though PA is allowed as GRAS in the USA, it may cause neurological disorders if it is consumed excessively. The maximum level of the preservative PA in cheese is set at 3.0g/kg by the Korean Food Code. Also, the minimum level of PA in EM (150mg / 100g) was set by Codex in 1967. Therefore, PA monitoring in EM, with relatively high level of intrinsic PA, is necessary to recommend the sound use of the PA in the EM ripened. The current official PA analysis method consisting of steam distillation and solvent extraction / evaporation, is too cumbersome to be handled in sample preparation process. In this study, acidic acetone-based direct extraction method was successfully applied to 12 EM samples for the determination of PA level.

Silicate minerals control the potential uses of phosphorus-laden mineral-engineered biochar as phosphorus fertilizers

Silicate minerals constitute the main components in silicon (Si)-rich biomass, affecting the phosphorus (P) adsorption and release competencies of mineral-engineered biochar; however, the mechanisms underlying their differences remain largely unresolved. To examine these interactions, we investigated the mineralogical compositions and quantified the P-adsorption capacities of Al-, Fe-, Mn-, Zn-, and Mg-engineered biochars from Si-rich rice husk material. The potential uses of P-laden mineral-engineered biochar for P fertilizers were assessed using citric acid extraction. The results from X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectrometry revealed that mixed metal (oxyhydr)oxides and metal-silicate compounds precipitated in the biochar structure and acted as the main P adsorbents. Micro-crystalline silicates derived from the biomass-induced metal-silicate precipitates in all engineered biochars, which effectively retained the aqueous P with varying excellent capacities (25.6–46.5 mg/g) but relatively slow kinetics (48 h). The suitability of the Zn-, Mg-, Mn-, and Fe-biochars as P-recycled fertilizers was confirmed by the high amounts of citric acid extractable P (19–69% of the total P). Varying amounts of Zn, Mg, and Mn (34–47% of the total host metals) were also released from the engineered biochar through ligand-promoted dissolution. Our data shed light on the novel potential utilization of Mn-, Mg- and Zn-biochars from Si-rich biomass for P retrieval and their use for P, Mg, and micronutrient (Mn and Zn) fertilizers. Regarding the P removal capacity, the mineral-engineered biochar needed a longer adsorption period than conventional metal-engineered biochar.Graphical

The selective recovery of rare earth from radioactive waste residue using improved oxamic acid for environmental and resource concerns

Because radioactive elements may migrate with rainwater and pollute the environment, the treatment of rare earth (RE) radioactive waste residue is of great significance. The process is helpful to recover RE and radioactive element, also reduce the volume of solid pollutants. In this paper, a novel oil-soluble oxamic acid extractant was synthesized to separate RE and Th from the waste residue. The low water soluble extractant 2-(didecylamino)-2-oxoacetic acid (DDOA) could be dissolved in common industrial diluent and used to remove low concentration of radioactive element Th from RE. The loading capacity of DDOA to Th is 2.81 g/L, which can meet the needs of treating ion adsorbed RE waste residue. The whole extraction process was carried out at lower acidities. After 3 times of stripping with 3 mol/L hydrochloric acid, the total stripping capacity of Th reached 98%. Slope analysis method indicates that 2 mol DDOA could extract 1 mol Th4+ in the extraction process. After five cycles, the extraction efficiency of Th could be maintained at 98%. After 4-stage extraction and 3-stage scrubbing, the concentration of Th in the RE aqueous phase outlet was lower than 0.22 mg/L, and the yield of RE was 95%. After oxalic acid precipitation, the recovery of RE could reach 80%. Overall, due to the high selectivity, better oil solubility, simplified fractional extraction, Th in radioactive slag could be efficiently removed and RE could be enriched.

Inhibition Role of Solvation on the Selective Extraction of Co(II): Toward Eco-Friendly Separation of Ni and Co

Ternary cathodes account for more than half of the market share for lithium-ion battery cathodes, and recycling draws considerable attention. The traditional extraction process used to separate and recover Co and Ni from spent ternary cathode leachates produces a large amount of saline wastewater; thus, a green method is urgently needed. In this work, we underscore the crucial role played by metal solvation during extraction, and this provides a new perspective for achieving green separation. The extraction mechanism can be described as follows: metal cations M2+ (M–Ni and Co) generate stable hydrated ions M(H2O)62+ upon solvation. However, Ni(H2O)62+ and Co(H2O)62+ exhibit different activities in reactions with acidic extractants (HA) and form different complexes, NiA2·2H2O and CoA2, respectively. Correspondingly, the coordinated water increases the electron density and steric hindrance of the center metal ions and thus inhibits the subsequent extraction. Therefore, a means of reducing solvation (adding lactic acid) was developed, and this approach exhibited good performance. The separation factor was improved by a factor of 192. These results open a new avenue for high-performance selective extraction of Co, which features a green recovery process and is suitable for future use in industrial production.

Separation and Recovery of Cobalt and Nickel from Sulfuric Acid Leach Liquor of Zinc Smelting Residue with Acidic Extractants

Separation and Recovery of Cobalt and Nickel from Sulfuric Acid Leach Liquor of Zinc Smelting Residue with Acidic Extractants

Phosphorus recovery and reuse potential from smouldered sewage sludge ash.

Smouldering treatment of sewage sludge - and recapturing phosphorus - provides important steps towards a circular economy. This study reveals that bulking sludge with sand or another organic waste, e.g., woodchips, created a material that was readily converted to ash by self-sustained smouldering. Simultaneous phosphorus and regulated potentially toxic element releases from ash were evaluated using leaching methods from the USEPA Leaching Environmental Assessment Framework (LEAF). Extraction potentials were also determined to evaluate direct recovery as an alternative to land application. Compared to the parent sludge, post-treatment ash from smouldering sludge with sand contained higher quantities of inorganic phosphorus in sorbed and mineral phases, which can provide beneficial slow phosphorus release to plants and avoid early phosphorus washout during land application. Ash also released lower initial and total quantities of potentially toxic elements than virgin sludge. As an alternative to land application, approximately 42% of retained phosphorus can be recovered directly using acidic extraction, and an additional 30% from emissions. In contrast, co-smouldering sludge with woodchips was more suited for direct recovery with 78% of phosphorus potentially recoverable via emissions capture and yield increasing to 99% with acidic extraction of resulting ash. Co-smouldering also produces a single post-treatment ash and can be readily operated continuously, which aligns with current incinerator configurations at wastewater treatment plants and makes adaptation highly feasible. With phosphorus reuse opportunities for land application and direct recovery, smouldering sewage sludge creates an important opportunity for a phosphorus circular economy as part of wastewater treatment sludge management.