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The solvation and transport of protons in aqueous solutions of phosphoric acid (PA), sulfuric acid (SA), and nitric acid (NA) were studied using ab initio molecular dynamics simulations. Systems with acid-to-water ratios of 1:1 and 1:3 were examined to understand the similarities and differences in transport mechanisms. The solvation structure of H3O+ in these systems is similar to that in slightly acidic water, with variations in the strength of hydrogen bonds (H-bonds) accepted by acid molecules. In aqueous PA systems, strong H-bonds between PA molecules are slightly affected by water, leading to significantly greater H3O+ diffusion compared to aqueous SA and NA systems. This enhanced diffusion is attributed to the participation of PA molecules in H3O+ transport, where the PA molecule can shuttle a proton for H3O+, facilitating a large displacement via collective proton hopping. This shuttling mechanism is prominent in aqueous PA but rare in aqueous SA and absent in aqueous NA. Moreover, the decomposition of H3O+ diffusion into vehicular and structural components indicates that the higher diffusion in aqueous PA is primarily due to the structural mechanism with the aid of PA molecules. In the aqueous NA systems, the vehicular diffusion is dominant at low water contents and the increase in water content improves the structural diffusion by forming connected H-bonds within water molecules. Our findings elucidate the role of acid molecules in proton transport within their aqueous solutions, thereby advancing the fundamental understanding of proton transport mechanisms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste copper sulphate solution was electrolyzed to provide sulphuric acid. • This study obtained leaching rates of 93 % of Ni, 91 % of Co, 89 % of Mn and 92 % of Li. • Recovery rates of 91 % of Ni, 91 % of Co, 86 % of Mn and 90 % of Li were achieved. • A novel method was developed without using any acid or reductant. • This work demonstrated the application of treating waste with waste. Effective recovery of Li, Co, Ni and Mn from cathode materials of spent lithium-ion batteries (LIBs) has become a global concern. In this study, electrolysis of copper sulfate to produce sulfuric acid and electrons were utilized to recover Li, Co, Ni and Mn from spent LIBs. The obtained results showed that 93 % of Ni, 91 % of Co, 89 % of Mn and 94 % of Li were leached and 99 % of Cu was deposited during leaching process by adopting the 0.225 mol/L of copper sulfate with a solid/liquid ratio of 15 g/L at a current density of 50 mA/m2 and 80 °C for 4.5 h. Then, a current efficiency of 72 % for the cathode and 30 % for the anode was achieved at a current density of 40 mA/m2, 70 °C and pH 2.5 during electrodeposition process. The Ni-Co deposition followed the principle of anomalous codeposition and the complete deposition time of Co, Ni and Mn were 3 h, 9 h and 10 h, respectively. Eventually, the Ni, Co, Mn, Li and Cu can be recovered as Ni-Co alloy, MnO 2 and Li 2 CO 3 and Cu metals with the corresponding recovery rates of 99.40 %, 91.00 %, 90.68 %, 85.59 % and 89.55 %, respectively. This study proposes a promising strategy for recycling cathode materials from spent LIBs without addition of chemical reductants and acids. [ABSTRACT FROM AUTHOR]

In this study, poly(lactic acid)‐poly(ethylene glycol)‐tetra‐n‐butylammonium hydrogen sulfate (PLA‐PEG‐HS) electrospun mats were fabricated by electrospinning as effective wound dressings against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), which are the most prevalent species of gram‐positive and gram‐negative bacteria, respectively. PLA is a polymer with high biocompatibility and biodegradability, but its structure is fragile. Therefore, we aimed to improve its structural properties using PEG as a plasticizer and to provide antibacterial properties with HS salt. The nanofibers characterized using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), and drying time tests. The addition of HS eliminated the beads in the PLA‐PEG nanofiber and improved the homogeneity of the fiber distribution. Concerning this result, when the liquid absorption capacity (LAC) test was evaluated, PLA‐PEG‐HS nanofiber production was achieved with the highest rate of 480.95%. The thermal properties of nanofibers increased with the addition of HS. Cytotoxicity test results of PLA‐PEG‐HS wound dressings showed high cell viability of 129.05% in L292 mouse fibroblast cells at the end of the 24th hour. PLA‐PEG‐HS nanofibers with 99.99% antibacterial activity against tow bacteria. Considering the modern wound dressing requirements, antibacterial wound dressing production has been successfully achieved. [ABSTRACT FROM AUTHOR]

In response to the problem that the conventional concentrated sulfuric acid catalyst for esterification reactions are prone to corrosion and generate large amounts of acid-containing wastewater, highly efficient gel resin-loaded ionic liquid solid acid (SA-ILs) catalysts were prepared by a one-pot method of loading ionic liquids onto gel resins. It is shown that the gel resin carrier has a strong water-absorbing structure, and the ionic liquids are covalently loaded on the gel resin carrier through chemical bonding, leading to SA-ILs catalysts with excellent acidity and good structural stability. With an optimal ionic liquid loading of 11% and acid density of 3.25 mmol·g−1,the synthesized SA-ILs catalysts showed good catalytic performance in the transesterification reaction between acetic acid and ethanol at 80 °C for 1.5 h. The catalyst dosage was 10 wt% of the total mass of acetic acid and ethanol, and the ethanol to acetic acid addition was at a molar ratio of 1.5:1. Ethyl acetate yields of up to 81% were achieved after the reaction. The catalyst also showed slightly decrease of the catalytic performance after reused for five cycles. The lower activation energy of the catalyst is proved to be the key to facilitate the catalytic transesterification reaction. [ABSTRACT FROM AUTHOR]

The incidence of "acid attacks" (vitreolage) is a global concern, with those affected often receiving lifelong medical care due to physical and psychological damage. The purpose of this study was to evaluate the effectiveness of several emergency skin decontamination approaches against concentrated (>99 %) sulphuric acid and to identify the effective window of opportunity for decontamination. The effects of four decontamination methods (dry, wet, combined dry & wet and cotton cloth) were assessed using an in vitro diffusion cell system containing dermatomed porcine skin. Sulphuric acid (H 2 SO 4) was applied to the skin with decontamination protocols performed at 10 s, 30 s, 8 min, and 30 min post exposure. Skin damage was quantified by tritiated water (3H 2 O) penetration, receptor fluid pH and photometric stereo imaging (PSI), with quantification of residual sulphur (by SEM-EDS) to determine overall decontamination efficiency. Skin translucency (quantified by PSI) demonstrated a time-dependent loss of dermal tissue integrity from 10 s. Quantification of dermal sulphur content confirmed the rapid (exponential) decrease in decontamination efficiency with time. The pH of the water effluent indicated complete neutralisation of acid from the skin surface after 90 s of irrigation. Wet decontamination (either alone or immediately following dry decontamination) was the most effective intervention evaluated, although no decontamination technique was statistically effective after 30 s exposure to the acid. These data demonstrate the time-critical consequences of dermal exposure to concentrated sulphuric acid: we find no practical window of opportunity for acid decontamination, as physical damage is virtually instantaneous. • Response to an acid exposure requires rapid intervention. • Immediate flushing with water reduces skin damage, other methods exacerbate damage. • Effectiveness of washing deteriorates as soon as 30 s following exposure to acid. [ABSTRACT FROM AUTHOR]

The development of a novel technology for extracting aluminum resources from coal fly ash through direct leaching with an ammonium hydrogen sulfate solution represents a significant advancement. A pivotal stage within this process is the reaction crystallization between NH 4 Al(SO 4) 2 ·12H 2 O solid and NH 3 ·H 2 O. Despite its many benefits, the fine particle size of the resultant product has impeded its widespread adoption. To tackle this challenge, this study concentrated on examining the growth mechanism of boehmite with larger particles in the presence of ammonia. Analysis revealed a distinct morphological evolution process for large-particle boehmite, progressing from a flaky morphology to a flower-like nanostructure with flaky features, and then further transitioning into particles displaying flower-like nanostructures and culminating in the formation of large particles with smooth surfaces. Initially, the early stages of crystallization were governed by kinetic factors, followed by a self-assembly phase, ultimately resulting in the final morphology of large particles, dictated by thermodynamic considerations. Density functional theory calculations underscored the significant role of H 2 O molecule adsorption in boehmite's growth trajectory, leading to the formation of pseudo-boehmite and inducing shifts in the X-ray diffraction peaks. The growth units remained integral throughout the entirety of the crystal growth process. [ABSTRACT FROM AUTHOR]

Scientific and technical developments toward improving bio-oil are under investigation, with an emphasis on research into upgrading bio-oil bitumen. The current study presents a new development of eco-friendly bio-oil bitumen produced using some local materials as well as studying its physical and rheological properties. Two bitumen sources with penetration grade of 40/50 were used, Dora and Nasiriyah, which were locally obtained from Dora and Nasiriyah refineries in Iraq. Biobitumen was prepared by vacuum distillation after esterification of waste cooking oil, which was freely collected from local households and cafeterias. Methanol, sulfuric acid (as a catalyst agent), and zeolite were used in the biobitumen preparation process. Physical and rheological properties were tested in evaluating the performance. The physical tests included viscosity, softening point, and penetration, and the rheological properties involved sweep frequency and creep tests using a dynamic shear rheometer (DSR). Three percentages (10%, 20%, and 30%) of biobitumen were blended with aged petroleum bitumen, which was obtained from excessive aging of the virgin bitumen by thin-film oven test (TFOT). It was found that a ratio of 1∶5 of biobitumen and aged petroleum bitumen exhibited the best performance. Results also highlighted that the new modified bitumen with biobitumen showed superior performance compared with that of traditional bitumen, taking into consideration the influence of biobitumen percentage and level of the age of the virgin bitumen. The current development and outcomes of the study can be considered as promising and encouraging for further investigations into sustainable and environmentally friendly production. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of chitosan addition on mortar performance during sulfuric acid attack. Twenty-four mortars were prepared using Brazilian portland cements, varying traces, and chitosan dosages ranging from 0% to 3%. Mortar expansion tests were performed to evaluate sulfuric acid attack resistance. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) were performed to evaluate the morphology, XDR was performed to confirm the FTIR results. Chemical structure and bending (3 points) and compressive tests were conducted to evaluate mechanical properties. The study demonstrated that mechanical properties as well the sulfuric acid-attack resistance are sensitive to the biopolymer incorporation, with noticeable effects even at low concentrations, 1% chitosan improves bending strength for CP V-ARI and CP V-ARI-RS in trace A, but decreases it for all cements in trace B, an outcome reflected in SEM images. FTIR results reveal lower levels of gypsum and ettringite formation in mortars with added biopolymer, except for CP V-ARI-RS. Tests on mortar expansion demonstrate that chitosan enhances sulfuric acid attack resistance by reducing mortar expansion by up to 60%. Practical Applications: The degradation of cement-based materials due to sulfuric acid-attack is a significant issue, as it leads to the formation of expansive products that progressively weaken concrete structures and increase its vulnerability to penetration by other substances. This research aims to investigate the impact of incorporating chitosan, a biopolymer, into mortar prisms in terms of sulfuric acid resistance. The study examines changes in mechanical properties, alterations in material structure, and the performance of mortars with and without chitosan when exposed to sulfuric acid attack. Findings indicate that both mechanical properties and resistance against sulfuric acid deterioration are influenced by the addition of biopolymer and chitosan enhances protection from sulfuric acid attack by reducing mortar expansion. This research has application on concrete structures subject to sulfate attacks present on soil and water. So, reservoirs, sewage treatment plants and pipes are some of the practical applications of this study. [ABSTRACT FROM AUTHOR]

Objective: Complications from diabetic foot wounds, including bacterial infection, ulceration and gangrene, are major causes of hospitalisation and are responsible for 85% of amputations in patients with diabetes. Given that orally administered investigational therapeutic Cytoreg (Cytorex de Venezuela SA, Venezuela), a defined aqueous mixture of hydrofluoric, hydrochloric, sulfuric, phosphoric, citric and oxalic acids, has been shown to increase levels of arterial blood oxygen in a Wistar rat model, oral and oral+topical Cytoreg were tested on patients with diabetic foot ulcers (DFUs) under a humanitarian, compassionate-use protocol. Method: All patients received oral Cytoreg (5.0 ml concentrate in fruit juice) for 30 days; half also received weekly wound washing with Cytoreg concentrate in isotonic saline (1:50 volume/volume) (oral+topical group). In addition to standard clinical observations, wounds were monitored against the Saint Elian checklist system for the diabetic foot. Results: A total of 10 patients took part in the study. Complete wound closure was observed in 4/5 patients in the oral+topical group; in the remaining patient, necrotic and fibrin tissues on the wound edges were eliminated. Half (2/4) of the patients receiving oral-only Cytoreg experienced complete wound closure; one patient in this group was removed prematurely because of an unrelated illness and was not replaced. During the study, no significant differences were observed between groups in either the oxygen saturation of the affected tissues or in insulin and glycaemia levels (p<0.05). Significant increases in arterial haemoglobin and arterial oxygen partial pressure (p<0.05) were observed, and significant decreases were measured in the levels of glycosylated haemoglobin, aspartate aminotransferase, glutamic-pyruvic transaminase, creatine and urea (p<0.05). Conclusion: The results of this study justify an expanded clinical study for the treatment of DFUs with Cytoreg. [ABSTRACT FROM AUTHOR]

Waste cotton fibers are an ideal raw material for extracting nanocellulose crystals (CNCs), benefitting from their high cellulose content. In this study, the waste cotton fibers from the calendering finishing process were used to extract CNCs by sulfuric acid, TEMPO oxidation, and phosphoric acid methods, aiming to create a new way to reutilize the waste cotton fiber and also to verify the practicability that the phosphoric acid method can replace sulfuric acid and TEMPO oxidation methods. The CNCs obtained from the three methods are all in cellulose I state with an average length of 200-500nm and diameter of 15-20nm, indicating that the waste cotton fiber can extract CNCs. However, the CNCs from the phosphoric acid method showed the highest thermostability but the lowest crystallinity, while the ones from the sulfuric acid and TEMPO oxidation methods had higher crystallinity but lower thermal stability. Overall, the three methods are all acceptable for preparing CNCs, but the phosphoric acid method has more significant potential due to its low cost, environmental friendliness, and safety. [ABSTRACT FROM AUTHOR]

Shale hydration and expansion during drilling can lead to wellbore instability, sticking, and frequent leakage accidents. To prevent these issues, an ionic liquid (IL) inhibitor solution was synthesized using DL‐alanine and 98% concentrated sulphuric acid as raw materials. The optimum composition and effect of the synthesized inhibitor in oilfield water‐based drilling fluids were evaluated through anti‐expansion, linear expansion rate, water washing resistance, and clay hydration dispersion experiments. The inhibition mechanism was investigated by thermogravimetric analysis, infrared spectroscopy, zeta potential, contact angle, and X‐ray diffraction analysis. The results show that the optimum IL consists of a 1:1 molar ratio of DL‐alanine to concentrated sulphuric acid synthesized under a reaction temperature and time of 70°C and 18 h, respectively. The resulting DL‐alanine IL exhibited the best inhibitory effect on the hydration, dispersion, and expansion of clay at a concentration of 0.5% in aqueous solution, and its linear expansion rate was only 18.49%. After adding a quantitative amount of clay to different concentrations of DL‐alanine IL aqueous solution, the expansion volume of the clay decreased and the water washing resistance significantly improved. These results provide a theoretical basis for improving the safety and efficiency of shale horizontal well drilling operations. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractThis study focuses on the synthesis, characterization, and potential applications of an amphiphilic nanocomposite composed of Poly(ε-caprolactone)-Poly(ethylene glycol)-Poly(ε-caprolactone) (PCL-PEG-PCL) and modified Maghnite (Algerian montmorillonite clay), referred to as PCL-PEG-PCL/Maghnite. The nanocomposite was synthesized via in-situ copolymerization of ε-caprolactone and polyethylene glycol, in the presence of intercalated Maghnite modified with tetrabutylammonium hydrogen sulfate (TBHSA). A variety of characterization techniques, including Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) were employed to analyze the structural properties of the resulting nanocomposite. Additionally, the antimicrobial activity assessment of the nanocomposites demonstrated their effectiveness against all the bacterial strains tested. Besides, the nanocomposite 10% demonstrated promising results as a gel for wound healing, confirming its effectiveness in promoting tissue regeneration and wound closure. [ABSTRACT FROM AUTHOR]

This study investigates the removal of major impurities, namely Fe, Al, Zn, and Mn, in a solution produced by sulfuric acid leaching of mixed hydroxide precipitate from the Ni and Co via solvent extraction using di(2-ethylhexyl) phosphoric acid (D2EHPA). The results of extraction experiments showed that the extracted Ni, Co, Fe, Al, Zn, Mn, and Mg increased as the equilibrium pH, D2EHPA concentration, and O/A ratio increased. The optimum extraction condition was achieved at a pH of 3.5, a 20% (v/v) D2EHPA concentration, and an O/A ratio of 1, with a complete (>99.9%) extraction of Al, Fe, Zn, and 97.33% Mn with co-extracted Ni and Co of 22.32% and 29.13%, respectively, in a single extraction stage. Complete Mn removal can be achieved in two extraction stages. Co-extracted Ni and Co can be scrubbed out using a mild sulfuric acid solution at a pH of 1.2 with only less than 2% of the Al, Fe, Zn, and Mn co-scrubbed. McCabe-Thiele diagrams of the scrubbing processes were constructed, and the results showed that Ni and Co can be scrubbed out using a mild acidic solution at a pH of 1.2, O/A ratio of 1, and temperature of 40°C for 10 min of mixing. Zn and Mn can be stripped completely using 0.5 M sulfuric acid solution at an O/A of 1 and temperature of 40°C for 10 min of mixing, while Fe and Al remained unstripped. Fe and Al can subsequently be stripped via reductive stripping. [ABSTRACT FROM AUTHOR]

Pig slurry can be used as an alternative source for nutrients, particularly nitrogen (N), for plants. However, after applying the pig slurry to the soil, gaseous loss of N this nutrient may occur, mainly in the form of ammonia. Hence this study aimed to evaluate the loss of N by volatilization after the application of pig slurry with an acidified pH. Ammonia volatilization was evaluated using pig slurry, with its pH modified to 5.0 using four acids (sulfuric acid, citric acid, ascorbic acid, and acetic acid). Additionally, pig slurry with natural pH and a control were also used. The work was conducted in a greenhouse, and collectors were used to capture the volatilized ammonia in a static free semi-open chamber. The application of pig slurry with natural pH (7.19) resulted in 61% loss of ammonia, whereas acidification with ascorbic acid (pH 5.0) caused a loss of only 26%. The application of pig slurry with pH above 7.0 caused N loss, indicating that using acids to maintain a pH of 5.0–6.0 could be an alternative to reduce N loss by ammonia volatilization. [ABSTRACT FROM AUTHOR]

A novel and controllable synthesis of thioacetals/thioketals and β-sulfanyl ketones mediated by the reaction of aldehyde/acetone with thiols has been developed. In this protocol, β-sulfanyl ketones can be generated without the prior preparation of α, β-unsaturated carbonyl compounds. A variety of thiols reacted with aldehyde/acetone and provided the corresponding thioacetals/thioketals and β-sulfanyl ketones in good to excellent yields, respectively. This protocol is operationally simple, mild, and atom-economical, providing controllable access to thioacetals/thioketals and thia-Michael addition products under mild conditions. [ABSTRACT FROM AUTHOR]

The research of this paper was carried out on the low-temperature (100 ± 2 °C) pressure (0.2–0.8 MPa) leaching of pyrite, chalcopyrite and their mixture. According to experiments on chalcopyrite dissolution, increasing the oxygen pressure from 0.2 up to 0.8 MPa had a slight effect on chalcopyrite dissolution. Oxygen pressure and initial sulfuric acid concentration in the range of 10–50 g/L had the greatest positive effect on the pyrite oxidation. The SEM and EDX mappings indicate the chalcopyrite and pyrite surfaces to be passivated by elemental sulfur. The oxidation degree of pyrite in its mixture with chalcopyrite increased significantly from 54.5 up to 80.3% in 0–240 min. The reaction time is relative to the dissolution of the individual mineral, while the dissolution of chalcopyrite remained virtually unchanged. The addition of Cu (II) and Fe (III) ions does not influence pyrite dissolution when chalcopyrite is added in a leaching process, which can be explained by the formation of an electrochemical link between the minerals. The positive effect of chalcopyrite addition is associated with a decreased formation of elemental sulfur on the surface of pyrite. The described method can be used for the hydrometallurgical processing of copper raw materials with increased pyrite content, as well as for the pretreatment of copper concentrates with gold-rich pyrite concentrates to increase the recovery of gold and silver. [ABSTRACT FROM AUTHOR]

Modulating the electronic structure of transition metal dichalcogenides (TMDs) via alloying is challenging despite the additional potential applications. In this study, a solvothermal reaction is used to synthesize composition‐tuned ReS2–VS2 (Re1‐xVxS2) alloy nanosheets featuring an expanded interlayer distance. Increasing x induces a phase transition from the semiconducting 1T″ phase ReS2 to the metallic 3R‐stacking 1T phase VS2. Alloying via homogeneous atomic mixing renders the nanosheets more metallic and with less oxidation than VS2. First‐principles calculations consistently predict the 1T″–1T phase transition of the atomically mixed alloy structures. The calculation also suggests that intercalation drives the 3R stacking of 1T phase VS2. The Re1‐xVxS2 nanosheets at x = 0.3–0.8 exhibit enhanced electrocatalytic activity toward water‐splitting hydrogen evolution reaction (HER) in an acid electrolyte. In situ X‐ray absorption fine structure measurements reveal that the metallicity of the alloys is fully retained during HER. The density of states and Gibbs free energy calculations show that alloying increases the metallicity and thus effectively activates the basal S atoms toward the HER, supporting the observed increased HER performance of the alloy nanosheets. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article presents the results of deformation characteristics and crack stress thresholds of cement stone under different acid treatment times. A series of true triaxial tests were conducted on cement stones under four sulfuric acid treatment times (0, 7, 14, and 28 days). The microstructures of cement stone under different acid treatment times were examined. In the range of 0 to 14 days, the damaging effect of sulfuric acid dominated, and the structural integrity was damaged by sulfuric acid. In the range of 14 to 28 days, the strengthening effect of calcium sulfate precipitate dominated, and the structural integrity was enhanced by calcium sulfate precipitate. The cement stone exhibited anisotropic deformation characteristics under true triaxial stress states. With an increase in acid treatment time, the deformation modulus of cement stone first decreased and then slightly increased. The crack stress thresholds first increased and then decreased with an increasing intermediate principal stress coefficient. With an increase in acid treatment time, the crack stress thresholds first decreased and then slightly increased. Substantially, the ratio of crack stress thresholds was analyzed. The proportion of the unstable crack growth stage and crack growth stage increased with minimum principal stress. Additionally, the proportion of the unstable crack growth stage and thecrack growth stage first increased and then decreased with increasing acid treatment time. However, the proportion of the stable crack growth stage had the opposite variation law to that of the unstable crack growth stage and crack growth stage. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are considered vital raw materials for the economy and are on the European Union's list of critical raw materials (CRMs). Europe is mainly dependent on REE imports. This dependence could be reduced if locally available primary or secondary resources would be processed. In Poland, there are, for instance, over 5 million metric tons of phosphogypsum (PG), a fine powdery byproduct from the fertilizer industry, available near the former Wizów Chemical Plant near Bolesławiec. This material that is considered a waste in Poland contains significant amounts of REEs that could theoretically be recovered and contribute to Europe's economy. This work is the first systematic analysis of REE leaching studies with sulfuric acid and PG from Wizów. Process parameters such as temperature, particle size, concentration of the leaching solution, and the addition of oxidant and reductant agents were tested to determine the most efficient process. Ultimately, a leaching efficiency of 99% was obtained. Lanthanum exhibited the highest leaching efficiency at almost 100%, followed by Yttrium, Neodymium, Terbium, and Dysprosium. The results of the laboratory experiments are promising and suggest that larger pilot or commercial experiments can be performed next. [ABSTRACT FROM AUTHOR]

This study focuses on the role of low-quality calcined Fanja (FNJ) clay in enhancing the behavior of cured cement mortar (CM) and its resistivity to chloride and sulfuric acid attack. Ordinary Portland cement was replaced with different quantities (10%, 25%, 35%, and 50% by weight) of FNJ, which was calcined at different temperatures (620 °C, 760 °C, and 900 °C). After 28 days of curing, all the hardened mortars were immersed in 5% sulfuric acid for up to 12 weeks. Additionally, a rapid chloride permeability test was conducted on the 91-day cured CM and CM-FNJ samples to evaluate the affinity of calcined FNJs to retard the chloride diffusion into CM. The results showed that all samples containing FNJ900 showed better physical and mechanical properties than the control sample, while CM with NFJ760 recorded nearly similar performance as CM-NFJ900. In contrast, the CM-FNJ620 mixtures showed lower properties than those of other mixtures. In addition to the pozzolanic reactivity of the calcined clay, the presence of hematite in the calcined clay strongly contributed to increasing the mechanical properties of the hardened mortar through forming calcium ferrosilicate hydrate binding phase, as confirmed by X-ray diffraction. Moreover, the existence of hematite increased the resistivity of CM against sulfuric acid attack as it acts as a buffer for an acidic medium. Compared with CM-FNJ900, the CM-FNJ760 is recommended for use as it exhibited a higher strength activity index and comparable resistance to accelerated chloride diffusion and sulfuric acid accompanied by lower energy demand and lower CO2 emission, achieving the concept of 'sustainability'. [ABSTRACT FROM AUTHOR]

Electroreduction of oxalic acid (OX) to glyoxylic acid (GO) is an extremely important and promising application in organic electrosynthesis. Pb cathodes, which exhibits good selectivity, need to be replace due to the severe deactivation and harmful to the environment. Herein, self‐doped titanium dioxide nanotube arrays (H‐TiO2NTs‐2) are synthesized as an alternative cathode for OX electroreduction to GO. Benefiting from two‐step anodization, the synthesized nanotube arrays are highly ordered with oriented openings. The ordered structure promotes the mass transfer of both OX and GO to ensure efficiently providing OX reactants for the diffusion‐controlled OX electroreduction and removal of GO products from the electrode to prevent the over‐reduction to glycolic acid. Additionally, the electroreduction treatment introduces more Ti3+ active sites and modulates the conduction band position of H‐TiO2NTs‐2, thereby enhancing the reduction driving force. Owing to the unique structural advantages, the Faraday efficiency of generating GO from OX reaches up to 81.3 % in an oxalic acid saturated electrolyte at 20 °C with a current density of 1500 A m−2. This designed H‐TiO2NTs‐2 holds broad application prospects in OX electroreduction. [ABSTRACT FROM AUTHOR]

Despite considerable progress, high-performing durable catalysts operating under large current densities (i.e., >1000 mA/cm2) are still lacking. To discover platinum group metal-free (PGM-free) electrocatalysts for sustainable energy, our research involves investigating layered topological magnetic materials (semiconducting ferromagnets) as highly efficient electrocatalysts for the hydrogen evolution reaction under high current densities and establishes the novel relations between structure and electrochemical property mechanisms. The materials of interest include transition metal trihalides, i.e., CrCl3, VCl3, and VI3, wherein a structural unit, the layered structure, is formed by Cr (or V) atoms sandwiched between two halides (Cl or I), forming a tri-layer. A few layers of quantum crystals were exfoliated (~50−60 nm), encapsulated with graphene, and electrocatalytic HER tests were conducted in acid (0.5M H2SO4) and alkaline (1M KOH) electrolytes. We find a reasonable HER activity evolved requiring overpotentials in a range of 30–50 mV under 10 mA cm−2 and 400−510 mV (0.5M H2SO4) and 280−500 mV (1M KOH) under −1000 mA cm−2. Likewise, the Tafel slopes range from 27 to 36 mV dec−1 (Volmer–Tafel) and 110 to 190 mV dec−1 (Volmer–Herovsky), implying that these mechanisms work at low and high current densities, respectively. Weak interlayer coupling, spontaneous surface oxidation, the presence of a semi-oxide subsurface (e.g., O–CrCl3), intrinsic Cl (or I) vacancy defects giving rise to in-gap states, electron redistribution (orbital hybridization) affecting the covalency, and sufficiently conductive support interaction lowering the charge transfer resistance endow the optimized adsorption/desorption strength of H* on active sites and favorable electrocatalytic properties. Such behavior is expedited for bi-/tri-layers while exemplifying the critical role of quantum nature electrocatalysts with defect sites for industrial-relevant conditions. [ABSTRACT FROM AUTHOR]

The extraction of rare earth elements (REEs) from mineral resources is of significant global importance due to their critical role in modern technologies. This study focuses on the leaching behavior of artificial cerium and lanthanum phosphates using nitric, sulfuric, and hydrochloric acids under varying conditions of acid concentration and temperature. Our experiments demonstrated that the maximum extraction efficiency of lanthanum and cerium was achieved with nitric acid solutions at concentrations of 12.5 mol/dm3, with 85.0% and 79.1% extraction efficiency, respectively. The leaching mechanism involved the protonation of phosphate anions, which disrupted the phosphate matrix, facilitating the dissolution of lanthanum and cerium into solution. Sulfuric acid, although less effective at room temperature, proved to be the most thermodynamically favorable leaching agent at higher temperatures due to the formation of stable sulfate complexes. Additionally, hydrochloric acid displayed high selectivity for cerium extraction, although its applicability is limited by complexation and environmental concerns. This study offers new insights into optimizing REE recovery from phosphates, demonstrating the advantages of sulfuric acid for industrial-scale leaching processes due to its economic and thermodynamic benefits. The novelty of this work lies in its systematic comparison of the three acids' effects on REE extraction, providing a comprehensive framework for selecting optimal leaching agents based on specific operational conditions. [ABSTRACT FROM AUTHOR]

This study investigates the impact of strontium (Sr) additions on the corrosion resistance of an LM6 (A413) aluminium alloy. By incorporating varying concentrations of Sr (0.01 wt.% and 0.05 wt.%), the morphological and corrosion behaviours of the alloy were analysed under different corrosive environments, including sulphuric acid, sodium hydroxide, and sodium chloride solutions. The results demonstrate that Sr modifications significantly enhance the alloy's corrosion resistance, with the most substantial improvement observed at 0.05 wt.% Sr. The analysis revealed that the weight loss of the alloy in sulphuric acid decreased by 2.5% with 0.05 wt.% Sr after 10 days of immersion, due to the formation of a stable passive oxide layer. In sodium hydroxide, however, the weight loss was reduced by 5% with 0.05 wt.% Sr after 10 days, indicating aggressive uniform corrosion. In the 3.5% sodium chloride solution, the corrosion rates remain relatively low, and the 0.05 wt.% Sr alloy showed a decrease in corrosion product formation over time, suggesting enhanced resistance. Detailed surface analyses, including 3D profiling and morphology assessments, revealed that Sr additions refine the eutectic silicon phase, transforming it from a coarse to a more desirable fibrous or lamellar structure, thus improving the alloy's overall performance. The innovative findings underscore the potential of Sr as an effective microstructural modifier for enhancing the durability and longevity of Al-Si alloys in corrosive environments. [ABSTRACT FROM AUTHOR]

The corrosion behavior of steels of various grades in sulfuric acid solutions with the addition of nitrogen-containing corrosion inhibitors has been studied. Compounds containing the 1,2,4-triazole moiety effectively protect low-carbon (St3, St20, 08PS), high-strength (70S2KhA), and stainless steels (1Kh18N9T) not only from corrosion but also from the hydrogen penetration into the metals in concentrated sulfuric acid solutions. In some cases, the degree of steel protection from corrosion by these compounds exceeded 99%. The possibility of creating mixed inhibitors for steel protection containing triazole derivatives and KI has been shown. The rate constants for the main steps of cathodic evolution and hydrogen penetration into steel in sulfuric acid solutions have been determined, and the subsurface concentrations of hydrogen in the metals have been calculated. Triazole derivatives were found to act as inhibitors of hydrogen absorption by steel in H2SO4 solution. The degree of protection of steel from hydrogen absorption can reach 97%. It has been shown that triazole derivatives act as complex inhibitors of steel corrosion in sulfuric acid solutions because, along with strong inhibition of metal corrosion, they prevent hydrogen absorption by steel. [ABSTRACT FROM AUTHOR]

Ion chromatography is the anion analysis benchmark. A miniature form, Open Tubular Ion Chromatography (OTIC), has attractive attributes for efficient ion separations. Here, we fabricate and characterize high‐density polyethylene (HDPE) open tubular anion exchange columns (OTCs). We attach positively charged latex particles onto negatively charged capillary surfaces. For efficient OTIC, column diameters need to be < ∼20 µm; functionalizing the bore is challenging. Methods to introduce acid groups to an HDPE capillary bore, e.g., sulfonation using chlorosulfonic or sulfuric acid solutions, with or without grafting of an aromatic ring through photo‐ or chemical grafting first, are explored. Following quaternary ammonium latex attachment, the ion exchange capacity and separating abilities of each OTC were measured as an index of OTC performance. Gradual loss of capacity was observed for many of these; high‐resolution mass spectrometry confirmed the leaching of detached oxidized/sulfonated oligomeric fragments and consequent poisoning of the latex sites. Ways to ameliorate this and/or to rejuvenate the columns are also described. [ABSTRACT FROM AUTHOR]

This study focuses on the simulation of the natural attenuation of groundwater contaminated by acid-leached uranium at a decommissioned uranium mining site. Although natural attenuation by mixing and dilution, pH buffering, adsorption, and reduction has been well described, little research on the simulation of the natural attenuation of groundwater U6+ and sulfuric acid in sandstone aquifers after mining has been performed. Using PHREEQC Version 3 software and the minteq.v4.dat database, in this paper, the thermodynamic adsorption equilibrium constants and adsorption site parameters were modified based on the experimental results of the mineral composition, chemical reactions, U6+ adsorption, and SO42− reduction reactions. This study provides a basis for establishing detailed environmental background data files, conducting laboratory experiments, and predicting the natural attenuation capability of sandstone aquifers at uranium mining sites and their surrounding areas. [ABSTRACT FROM AUTHOR]

For the construction of the international linear collider, mass production of niobium (Nb) superconducting cavities is essential. In the surface treatment of the Nb cavities, on-site analysis of electropolishing solution composed of hydrofluoric acid and sulfuric acid is desired. In this work, we analyzed the electropolishing solutions containing from 1.0 g L-1 to 10.0 g L-1 Nb by surface-enhanced laser-induced breakdown spectroscopy (surface-enhanced LIBS) that needs only a microvolume sample and simple operations. The sample solution was trapped on porous silicon (Si) fabricated by metal-assisted etching (metalassisted chemical etching) through a wiping process. Nb emission lines were detected with low laser energy irradiation (2.0 mJ per pulse) onto the substrate. A regression model was built by partial least squares regression, and the Nb concentrations of test samples were predicted with a mean absolute error of approximately 0.4 g L-1. To the best of our knowledge, this is the first report that applied LIBS to the analysis of the highly toxic electropolishing solution. The proposed method would be helpful for the quality control of surface treatment and the efficient use of solution. [ABSTRACT FROM AUTHOR]

The goal of this study is to provide new insights into the corrosion mechanism of core‐shell carbides containing steels. The corrosion behavior of two heat‐treated Cr–W–V–Mo‐rich stainless steels is evaluated using electrochemical techniques. The studied steels have different carbides microstructure, the first has core–shell carbides (Cr7C3–Cr23C6) in a ferritic matrix, while the second has conventional Cr23C6 carbides in a duplex matrix. The open‐circuit potential results show a nobler behavior of the duplex sample; it is noticed in the potentiodynamic polarization curves where the core–shell carbides containing steel have an oxidation peak at −0.37 V versus saturated calomel electrode with a current density of 0.19 mA cm−2, contrary to the duplex steel that shows a passive behavior. Electrochemical impedance spectroscopy demonstrates the presence of two degradation mechanisms in the core–shell carbide steel, while the other steel is governed by charge transfer only. These findings are supported by scanning electron microscopy examination that shows the preferential corrosion of the shell while the core and the duplex matrix are kept intact. The passive film stability is evaluated using Mott–Schottky analysis and it shows the presence of a higher defect density on the passive film of the core–shell carbides containing steel. [ABSTRACT FROM AUTHOR]

Methods of the pretreatment of reeds (grinding, hydrothermal treatment, treatment with acid or alkali solutions, organosolv, deep eutectic solvents) and their effect on the subsequent enzymatic hydrolysis by cellulase and hemicellulase complexes have been studied. Substrates with the highest reactivity were obtained by exposing the reeds to a weakly alkaline deep eutectic solvent (DES) and an alkali solution. The depth of enzymatic hydrolysis of these pretreated substrates was 63 and 59%, and the degree of conversion of polysaccharides (cellulose and hemicellulose) into monosaccharides taking into account the yield of the substrate at the preprocessing stage was 60 and 34%, respectively. After pretreatment of the reeds with acid DES, water steam, water, or a water/organic solution of sulfuric acid, the depth of enzymatic hydrolysis was 45, 25, 20, and 11% and the degree of polysaccharide conversion was 26, 18, 13, and 10%, respectively. The industrial enzyme preparation Agrocell Plus with a predominant content of cellobiohydrolases and endoglucanases was most effective in hydrolyzing the dust fraction of the reed, as was the reed pretreated with a solution of sulfuric acid or DES (acidic or alkaline). The industrial enzyme preparation Agroxil Plus, containing endoxylanase and cellobiohydrolases, was more effective in hydrolyzing the reed after hydrothermal pretreatment or alkali solution. The results of the hydrolysis of the reed pretreated with acidic or weakly alkaline DES under the action of individual (homogeneous) cellulases indicate that in both cases the key enzyme was cellobiohydrolase 1. [ABSTRACT FROM AUTHOR]

The formulation of ultra-high-performance concrete necessitates the use of a high cement content. The alkaline nature of cement makes it susceptible to acid attacks. In addition, its high C3A content causes its vulnerability to sulfate attack under the development of expansive ettringite, where porosity plays an important role. The main objective of this study was to figure out how mass loss and dimensional instability affected the rate of reaction and its relationship to acid concentration. It is noted that in contrast to sulfuric acid attack, sulfate attack on ultra-high-performance concrete (UHPC) is characterized by the accumulation of sulfate ions near the surface until reaching a critical concentration known as the threshold value. However, the reaction effect was not remarkable, as attributed to the extremely low porosity. The effect of curing was found to have a minimal influence on acid resistivity because it is a kind of spontaneous acid-base reaction that cannot be alleviated. In this research work, the UHPC's service life can be predicted when exposed to different concentrations of sulfuric acid. When comparing acid and sulfate attacks, the latter becomes negligible. Despite the use of silica fume and fly ash, the reactivity with sulfuric acid was found to occur spontaneously and rely on cement content and acid concentration. A concentration of 2.5% sulfuric acid is the threshold concentration after which a substantial change in the development of strength takes place. Both reactions were monitored on different types of samples over time using several techniques, such as XRD, TGA, and DSC and optical microscopy. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of acid corrosion on mechanical properties and fractal characteristics of red sandstone. The mineral composition of red sandstone was analyzed using X-ray diffraction. The mechanical properties and acoustic emission (AE) signals of red sandstone specimens corroded by sulfuric acid solution with pH values of 1, 3, and 5 for 30 days were determined by uniaxial compression test and AE technique. The energy dissipation law and the fractal damage characteristics of red sandstone specimens after acid corrosion were analyzed based on the energy and fractal theories. The results indicated that the compressive strength and elastic modulus of red sandstone specimens corroded by acid solution decreased. In addition, the peak strain increased, the cumulative AE ringing count decreased, and the duration of high-level AE ringing shortened. These phenomena became more pronounced as the acidity of the solution increased. The peak values of the total energy and the elastic strain energy of the acid-solution-corroded red sandstone specimens decreased. The energy absorption capacity and energy storage limit of rock specimens also decreased. The fractal dimension and the degree of fragmentation decreased with the dissipated energy used for fragmentation. This research provides valuable insights into the prevention and control of sub-surface geotechnical hazards in acid rain-prone areas. [ABSTRACT FROM AUTHOR]

Localized leaching method is a new reclamation leaching technique. Localized leaching method by using drip tapes allows water to be applied directly to the areas of salt accumulation. This study applied localized leaching method on a sandy loam soil in a pistachio orchard in Kerman, Iran to evaluate the impact of three treatments: adding gypsum soil remediation (G), soil remediation with sulfuric acid (SA) andirrigation water (IW) on soil remediation. Three treatments (IW, G and SA) in four repetitions were used to remove soluble salts from the Main Active Root Zone (MARZ) in a pistachio orchard which irrigated by a subsurface irrigation system. The localized leaching method consist of two T-tape pipelines at a distance of 40 cm located on both sides of the tree rows. Soil sampling was carried out before and after leaching from soil unit profiles with 80 cm (Length) × 120 cm (Depth) with 20 cm intervals. Concentrations of sodium (Na), magnesium (Mg), calcium (Ca) cations, and electrical conductivity (EC) were examined before and after leaching process. Results revealed that application of G-treatment compared to IW-treatment and SA-treatment led to more leaching of Na and Mg from the soil by 61% and 50%, respectively. The amount of leached Ca in both G-treatment and SA-treatments was less than that of IW-treatment. The leaching efficiency of total soluble salts for G, IW and SA treatments were 58%, 56% and 45%, respectively. Gypsum application could be recommended as a soil amendment. In addition, the localized leaching technique offers water-saving potential opposed to traditional leaching methods which applying water to the entire field. [ABSTRACT FROM AUTHOR]

Currently, less attention is paid to zinc–carbon batteries, although they are still widely used and are among the major types of batteries collected and recycled. The recycling technologies currently in use do not allow the complete recovery of resources, are not self-sufficient and require additional financing. Therefore, this paper aims to study the possibility of complete recycling of waste zinc–carbon batteries and to suggest the practical use of the final products generated in the recycling process. The possibility of complex processing of spent zinc–carbon batteries using mechanical separation and processing of the battery's components (steel case, zinc electrode, graphite electrode, polypropylene and paper insulators) is justified. The separation of spent electrolytes from other components of batteries with hydrochloric acid was studied. It was shown that the extraction of Zn2+ and NH4+ cations takes place following the addition of an equivalent amount of Na3PO4 solution and water-insoluble NH4ZnPO4 salt sedimentation. Waste agglomerate (mixture of MnO2, MnO(OH), and graphite) was regenerated to its initial composition (MnO2, graphite) at a temperature of 300–325 °C; manganese (III) hydroxide was oxidized to manganese (IV) dioxide. Thermal destruction of polypropylene and paper insulators with additional introduction of polyethylene into the primary mixture produced pyrolysis liquid, pyrocarbon and pyrolysis gas as products. The practical use of the products obtained and compliance with the environmental requirements of the suggested method of waste batteries recycling were shown. [ABSTRACT FROM AUTHOR]

Acute corrosive acid ingestion presents significant challenges in clinical and forensic pathology due to its severe and often fatal outcomes. This case series examines four autopsies involving fatal acid ingestion: three cases of hydrochloric acid (HCl) poisoning and one case of sulfuric acid (H2SO4) poisoning. Each case provides detailed autopsy findings, focusing on macroscopic and microscopic pathological changes. The first three cases of HCl poisoning revealed extensive tissue damage characterized by coagulative necrosis, particularly affecting the esophagus, stomach, and duodenum. Histological examination showed dense inflammatory infiltrate, submucosal edema, and significant hemorrhage, with patchy necrosis observed in the liver and kidneys. Pulmonary findings included alveolar edema and hemorrhage. The fourth case, involving H2SO4 ingestion, demonstrated more severe injuries with transmural necrosis and extensive hemorrhagic infiltration in the esophagus. The stomach exhibited full-thickness necrosis with a pronounced sulfurousodor, indicating severe chemical injury. Histopathological findings included extensive tissue dehydration and charring, with severe alveolar edema and hemorrhage in the lungs and extensive necrosis in the liver and kidneys. Comparative analysis of the histopathological changes highlighted the differences in tissue damage caused by these two acids. HCl primarily induced superficial necrosis with relatively preserved tissue architecture, while H2SO4 caused more extensive and deeper tissue damage due to its strong dehydrating and exothermic properties. Recognizing these differences is crucial for forensic pathologists in accurately diagnosing and differentiating cases of acid poisoning, ultimately enhancing diagnostic precision and clinical outcomes. This study underscores the severe and often fatal consequences of acute acid ingestion and aims to enhance the understanding of the pathological changes associated with such poisonings, thereby improving forensic and clinical evaluations. [ABSTRACT FROM AUTHOR]

A highly efficient, convenient and ecofriendly approach to access highly functionalized 2H‐chromenes via intramolecular aldehyde alkyne metathesis reaction was established starting from readily accessible alkyne‐tethered 2‐((3‐phenylprop‐2‐yn‐1‐yl) oxy)benzaldehydes and catalyzed by silica sulfuric acid (SiO2‐OSO3H, SSA) coupled with microwave irradiation. This reaction was well tolerated for various substituents including different functional groups and furnished the desired highly functionalized 2H‐chromene derivatives in good to excellent yields in a very short time. A systematic study of the conventional heating approach and microwave irradiation was performed to demonstrate the advantages of the microwave‐assisted condition in terms of high yield and shorter reaction time. [ABSTRACT FROM AUTHOR]

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The process of wet copper smelting is mainly used to extract copper from copper concentrate in Democratic Republic of the Congo (DRC). After roasting and two-stage acid leaching of copper sulfide concentrate containing 55% - 65% copper, the acid leaching residue contains 3% - 10% copper. Based on the process mineralogy analysis of calcine acid leaching residue of a copper concentrate in the DRC, pressure leaching method was used to recover copper from the acid leaching residue. The results show that copper in the acid leaching residue of calcine of copper concentrate mainly exists in the form of chrysocollite, chalcanthite and copper ferrite. The copper content of these three minerals accounts for 96.87% of the total copper content, and copper ferrite is the main difficult to leach mineral. During acid leaching, the amount of acid used has the greatest impact on copper leaching rate. The copper leaching rate is 94.52% and copper content in the residue can be reduced from 7.66% before treatment to 0.52% under the optimum leaching conditions including liquid-solid ratio of 4 mL/g, acid-ore ratio (the mass ratio of sulfuric acid dosage to acid leaching residue) of 65%, leaching time of two hours, and leaching temperature of 180 °C. [ABSTRACT FROM AUTHOR]

The experiments of medium temperature oxygen pressure leaching of Cu, Ni, Fe and S, and synchronous iron precipitation in complex sulfide copper nickel slag were carried out The main elements in sulfide copper nickel slag were found out, and the effects of oxygen pressure leaching conditions on the leaching rate of Cu, Ni, Fe and S were investigated. The leaching rate of copper, nickel, iron and sulfur is 98. 73%, 98.86%, 26.69%, 93.17%, respectively, the residual acid concentration in the leaching solution is 1.28 g/L, and the mass concentration of copper, nickel and iron in the leaching solution is 77.04, 18.80 and 0.67 g/L, respectively, under the optimum conditions including dosage of sulfuric acid (98%) of 20 g (i. e. 200 kg sulfuric acid per ton of copper-nickel slag), leaching temperature of 170 °C, oxygen partial pressure of 0.4 MPa, liquid-solid ratio of 5 mL/g, and leaching time of five hours. [ABSTRACT FROM AUTHOR]

Aiming at the high recovery value of silver concentrate and insufficient of existing treatment technology, applying the germanium-containing silver concentrate produced by zinc hydrometallurgy as research object, a process route of concentrated sulfuric acid curing and oxygen pressure acid leaching was put forward, focusing on the principle of the process, leaching behavior of Zn, Cu and Ge in the process of curing and oxygen pressure acid leaching of germanium containing silver concentrate and phase evolution in the leaching residue. The results indicate that low valence metal sulfide in germanium containing silver concentrate and the residual organic flotation chemicals on the concentrate surface can be oxidized and decomposed by pretreatment with concentrated sulfuric acid. Under the condition of high temperature oxidation and assisted leaching by Fe3+/Fe2+ variable ion pairs, the phase composition of the germanium- containing silver concentrate mainly evolves from dominated by iron sphalerite, sphalerite, gynopyrite and cuprous chloride to dominated by elemental sulfur, lead sulfate and ferrosite (MeFe3(SO4)2(OH)6 > Me: 1/2Pb, Na, K) in leaching residue Under the optimum oxygen pressure acid leaching conditions including reaction temperature of 150 °C, initial acidity of 150 g/L, reaction time of 180 min, partial oxygen pressure of 0.6 MPa, and liquid-solid ratk> of 7 mL/g, the leaching rate of Zn, Cu and Ge is 95.34%, 98.47% and 84.35%, respectively, and the enrichment of lead and sliver reaches 3.19% and 7 074 g/t, respectively, which reaiizes the deep leaching of Zn, Cu, and Ge, and efficient enrichment of Pb and Ag. [ABSTRACT FROM AUTHOR]

The nickel laterite ore from a mine in Philippines was analyzed for systematic process mineralogy. The results show that the ore sample contains 44.83% iron, 1.96% silicon, 1.18% magnesium, 1.02% nickel and 0.12% cobalt. It is a typical limonitic lateritic nickel ore. The main minerals in the samples are goethite, chrome spinel, quartz and other clay minerals, nickel and cobalt are mainly in iron minerals, and also in other minerals, and no nickel and cobalt minerals exist independently. Based on the characteristics of the minerals, the high- pressure sulfuric acid leaching process was chosen to treat the minerals. The leaching rate of nickel and cobalt is both 95% above, and the leaching rate of iron is less than 1% under the conditions including acid dosage of 29 g for 100 g mineral, temperature of 250 °C, liquid-solid ratio of 3 mL/g, and reaction time of 30 min, which realizes the selective leaching of nickel and cobalt The process mineralogical analysis of the leaching residue was carried out to analyze the causes of incomplete leaching of nickel and cobalt, During the leaching process, the acicular ferrite mineral phase in the raw ore is destroyed, and the nickel and cobalt endowed in it are leached into the solution, while the nickel and cobalt that are not leached are deposited in the chrome spinel, which is the main reason for the incomplete leaching of nickel and cobalt. The main sulfur-containing phase in the leaching residue is alunite produced by aluminum hydrolysis. In addition, the leaching slag may also contain part of the sulfate such as magnesium sulfate, both of which are closely combined with iron minerals. The sulfur-containing minerals in the leaching residue are tightly bound to iron minerals, so chemical desulfurization is required to remove the sulfur and realize its comprehensive utilization. [ABSTRACT FROM AUTHOR]

Aiming at the problems of low oxygen utilization rate and slow dissolution of sphalerite in the pressure leaching process of zinc concentrate, the strong oxidizability of Fe3+ in zinc leaching residue and the oxygen transport efficiency of Fe2+/Fe3+ redox ion pair were used to improve the efficient oxidation of S2- in sphalerite and the utilization rate of O2, so as to realize the synergistic enhanced leaching of zinc concentrate and zinc leaching residue. The results show that Fe3+ can improve the solubility of oxygen, and the back-and-forth valence behavior of Fe2+/Fe3+ accelerates the oxidative dissolution of sphalerite (ZnS) in the leaching system, and the leaching rate and leaching efficiency of zinc are significantly improved. Under the optimal process conditions of initial sulphuric acid concentration of 95 g/L, oxygen partial pressure of 0.8 MPa, temperature of 160 °C, reaction time of 120 min, and pH value of 3, and the addition of 6.1 g/L Fe3+ in the form of zinc leaching residue results in a high leaching rate of 98.60% of zinc, and 92.47% of iron is precipitated into the residue. The synergic Caching of zinc concentrate and zinc leaching residue is controHed by external diffusion with apparent activation energy of 15.61 kj/mol. The kinetic equation of synergc Caching process Is as follows; 1-(1-a)1/3=4.78X 10-3 X {[exp(-15610/8.314T)] Xc(H2SO4)1,21 XP(O2)0.33 Xc(Fe3+)0.43Xt} . [ABSTRACT FROM AUTHOR]

Address to the by-product sulfuric acid in the pyrometallurgical smelting process of copper sulfide concentrate is difficult to be applied on a large scale in the unsalable area of sulfuric acid, the oxygen pressure leaching process of copper sulfide concentrate was studied. The composition, phase and occurrence state of valuable elements of a copper sulfide concentrate raw material were analyzed. The feasibility of oxygen pressure leaching of copper sulfide concentrate was analyzed theoretically. The leaching effects of one-stage oxygen pressure leaching and two-stage oxygen pressure leaching process were studied. The results show that the copper leaching rate is 90.49%-92.25% by two-stage countercurrent oxygen pressure leaching. In the first stage, the temperature is 135140 °C, the total pressure is 1.3-1.4 MPa, the time is 2-2.5 h, the amount of dispersant is 4‰-5‰, and the amount of precipitation agent is 2.5%-3%. In the second stage, the temperature is 165-170 °C, the total pressure is 1.4-1.5 MPa, the time is 2.5-3 h, the amount of dispersant is 6‰-7‰, and the amount of precipitation agent is 3%-3.5%. The leaching solution from the first stage contains copper 90.78-92.34 g/L, iron 10.81-13.84 g/L and H2SO4 28-30 g/L, which can be sent to subsequent iron removal purification-electrowinning to produce electrocopper. [ABSTRACT FROM AUTHOR]

The pressure leaching process was employed to treat the copper-containing sulfide slag. The effects of initial sulfuric acid concentration, leaching temperature, liquid-solid ratio (L/S), oxygen partial pressure, and leaching time on the leaching efficiency of Co, Ni, Mn, Li, Al and Cu in the slag were examined through experiments. The results show that the single-step leaching rate of Co, Ni, Mn, Li, Al and Cu in the copper-containing sulfide slag is 99.80%, 99.10%, 98.42%, 98.49%, 93.89% and 96. 91%, respectively under the optimal conditions including initial sulfuric acid concentration of 120 g/L, leaching temperature of 140 °C, L/S of 5 mL/g, oxygen partial pressure of 1.1 MPa, and leaching time of three hours. The results show that the copper-containing sulfide slag is basically completely dissolved and the comprehensive leaching of valuable metals Is reaiized. In addition, the hydrolysis removal of Al and Cu is achieved through three rounds of pressure eaching of the inlflal leaching solution. [ABSTRACT FROM AUTHOR]

In this paper, the dihydrate–hemihydrate recrystallization method was employed to produce β-hemihydrate gypsum. The effects of thermodynamic conditions such as temperature, sulfuric acid concentration, and phosphoric acid concentration on the removal of F and P impurities were investigated. Kinetic studies revealed that the throughflow impeller, when compared to the conventional impeller, demonstrates a higher removal rate for soluble phosphorus, while having little impact on soluble fluorine. This study contributes to the utilization of PG resources. [ABSTRACT FROM AUTHOR]

Industrial sulfuric acid waste catalysts contain a large amount of vanadium, sodium, potassium, sulfur, and a small amount of aluminum, iron, and arsenic. They are often used as important raw materials for extracting vanadium and alkali metal salts. Rapid and accurate determination of relevant components in waste catalysts and leaching residues is crucial for their separation and extraction. On the basis of column chromatography separation, this article investigated the leaching rates of V, Na, S, and K in the samples after leaching treatment, which were 95.28%, 98.39%,98.88%, and 97.82%, respectively. SEM showed that the sediment dissolved and disappeared on the surface of the carrier and in the pores. At the same time, the inductively coupled plasma emission spectroscopy (ICP-OES) method was used for determination, and the spectral lines of each element (V 309.311 nm, Na 589.490 nm, K 766.490 nm, S 180.731 nm, Al 394.401 nm, Fe 238.204 nm, As 189.042 nm) were determined. The results showed that the mass concentration of each element was linear with emission intensity within a certain range, and the linear correlation coefficient of the calibration working curve was greater than 0.9999, except for arsenic, which was 0.999 7, The detection limit of each element was 0.004-0.017 µg/g, and the relative deviation (RSD,n=11) of the determination results excluding As was 2.2%. The other elements were less than 0.90%, and the recovery of the added standard was between 98. 9% and 102%. The accuracy and precision of the method can meet the requirements for testing various elements in industrial sulfuric acid waste catalysts, providing data reference for the content of each element in the leaching and separation process of waste catalysts. [ABSTRACT FROM AUTHOR]