Acid Mine Research Articles

New Insights into Thermal Degradation Products of Long-Chain Per- and Polyfluoroalkyl Substances (PFAS) and Their Mineralization Enhancement Using Additives.

The products of incomplete destruction (PIDs) of per- and polyfluoroalkyl substances (PFAS) represent a substantial ambiguity when employing thermal treatments to remediate PFAS-contaminated materials. In this study, we present new information on PIDs produced in both inert and oxidative environments from five long-chain PFAS, including three now regulated under the U.S. Safe Drinking Water Act, one cationic precursor compound, and one C10 PFAS. The data did not support the generation of tetrafluoromethane from any of the studied PFAS, and carbonyl fluoride was found only from potassium perfluorooctanesulfonate (K-PFOS) when heated in air in a narrow temperature range. Oxidative conditions (air) were observed to facilitate PFAS thermal degradation and accelerate the mineralization of K-PFOS. Spectroscopic data suggest that PFAS thermal degradation is initiated by the cleavage of bonds that form perfluoroalkyl radicals, leading to organofluorine PIDs (e.g., perfluoroalkenes). In air, perfluoroalkyl radicals react with oxygen to form oxygen-containing PIDs. The mineralization of PFAS was enhanced by adding solid additives, which were categorized as highly effective (e.g., granular activated carbon (GAC) and certain noble metals), moderately effective, and noneffective. Remarkably, simply by adding GAC, we achieved >90% mineralization of perfluorooctanoic acid at 300 °C and ∼1.9 atm within just 60 min without using water or solvents.

A Comparative Study of LiNCA Cathode Recycled from Spent Lithium-Ion Batteries and Synthesized from Metal Precursor

Spent lithium NCA (LiNCA) battery was recycled using organic and inorganic acids and the performances were compared against the cathode synthesized from precursor. The metals in the spent cathode were leached using sulfuric or citric acid and coprecipitated into ternary metal oxalate (TMO) after reduction and lithium separation. Subsequently, the coprecipitated solution was used for cathode synthesis. Leaching efficiencies for nickel, cobalt and aluminum using citric acid were 85.6, 94.1, and 99%, respectively, while the efficiencies using sulfuric acid were 96, 98, and 100%, respectively. TMO produced from coprecipitation had the same physical characteristics. It was important to acknowledge that all cathodes also had similar physical characteristics. The electrochemical tests showed that commercial cathodes had the highest capacity of 150 mAh/g. This was followed by those from precursors, sulfuric acid leaching, and citric acid leaching, which recorded 142, 135, and 130 mAh/g, respectively. Based on the cycle test at 1C, the sample from citric acid leaching was 86% after 20 cycles compared to others at 82–83%. The results suggested that spent LiNCA could be regenerated into new cathodes using acid with performance comparable to those synthesized from precursor. This presented a viable alternative for LiNCA cathode synthesis.

Assessment of Cationic Salts and Inorganic Acids as Washing Agents for Cs-137 Removal from Radioactively Contaminated Electric Arc Furnace Dust

Assessment of Cationic Salts and Inorganic Acids as Washing Agents for Cs-137 Removal from Radioactively Contaminated Electric Arc Furnace Dust

Excellent Performance of Sodium Ion Battery Cathode Materials Benefiting from the Inorganic Acid Regulating Strategy

Excellent Performance of Sodium Ion Battery Cathode Materials Benefiting from the Inorganic Acid Regulating Strategy

Investigation of Elemental Composition in White Wine Treated with Varying Doses of Bentonite

Investigation of Elemental Composition in White Wine Treated with Varying Doses of Bentonite

High cell density cultivation by anaerobic respiration

BackgroundOxygen provision is a bottleneck in conventional aerobic high cell density culturing (HCDC) of bacteria due to the low O2 solubility in water. An alternative could be denitrification: anaerobic respiration using nitrogen oxides as terminal electron acceptors. Denitrification is attractive because NO3− is soluble in water, the end-product (N2) is harmless, and denitrification is widespread among bacteria, hence suitable organisms for most purposes can be found. The pH must be controlled by injection of an inorganic acid to compensate for the pH increase by NO3−-consumption, resulting in salt accumulation if feeding the bioreactor with NO3− salt. We avoid this with our novel pH–stat approach, where the reactor is supplied with 5 M HNO3 to compensate for the alkalization, thus sustaining NO3−-concentration at a level determined by the pH setpoint. Here we present the first feasibility study of this method, growing the model strain Paracoccus denitrificans anaerobically to high densities with glucose as the sole C-source and NO3− as the N-source and electron acceptor.ResultsOur fed-batch culture reached 20 g cell dry weight L−1, albeit with slower growth rates than observed in low cell density batch cultures. We explored reasons for slow growth, and the measured trace element uptake indicates it is not a limiting factor. Bioassays with spent medium excluded accumulation of inhibitory compounds at high cell density as the reason for the slow growth. The most plausible reason is that high metabolic activity led to CO2/H2CO3 accumulation, thus suppressing pH, leading to a paucity in HNO3-feeding until N2-sparging had removed sufficient CO2. The three free intermediates in the denitrification pathway (NO3− → NO2− → NO → N2O → N2) can all reach toxic concentrations if the electron flow is unbalanced, and this did occur if cells were glucose-limited. On the other hand, accumulation of polyhydroxyalkanoates occurred if the cells were NO3−-limited. Carefully balancing glucose provision according to the HNO3 injected is thus crucial.ConclusionsThis work provides a proof of concept, while also identifying CO2/H2CO3 accumulation as a hurdle that must be overcome for further development and optimization of the method.

Adsorption and oxidation of β-carotene by montmorillonite bleaching clays

The role that clay mineral acidity, specific surface area (SSA) and pore size distribution (PSD) have on the adsorption and oxidation of β-carotene by montmorillonite bleaching clays was investigated. Five commercially available clay minerals were studied, including three acid-activated montmorillonites (AACs) (K10, K30 and 22B), one aluminium-pillared montmorillonite (Al-PC) and an untreated montmorillonite (SWy-3). Each underwent physicochemical characterisation. X-ray diffraction and N2 gas sorption techniques provided structural and textural information. Titration with n-butylamine in the presence of Hammett and arylmethanol indicators characterised the concentration and strength of clay acid sites. The kinetics of β-carotene adsorption were then measured as a means of comparing their adsorptive power. The tendency of each clay to oxidise β-carotene to a variety of carotenoid-oxidation-products (COPs) was examined by analysing extracts of each clay with ultra-high-performance liquid-chromatography mass-spectrometry (UPLC-MS). The AACs adsorption and oxidation of β-carotene exceeded that of SWy-3 and Al-PC. This was attributed to a greater number of stronger acid sites, and a higher SSA. The clay PSD was also shown to play a significant role. 22B, which had a narrower PSD than K10 or K30, showed a lower tendency to adsorb β-carotene despite having the greatest number of strong acid sites. Lastly, the AACs had a greater oxidative power than SWy-3 or Al-PC and produced COPs in greater abundance than the other clays. They also produced more COPs of a higher oxidation state relative to β-carotene. These findings provide helpful information for the selection of efficient adsorbents for use in vegetable oil bleaching.

Seaweed Nutritional Value and Bioactive Properties: Insights from Ascophyllum nodosum, Palmaria palmata, and Chondrus crispus.

This study investigates the nutritional composition and bioactive properties of Palmaria palmata (dulse), Ascophyllum nodosum (knotted wrack), and Chondrus crispus (Irish moss). Understanding the nutritional values of these seaweeds is very important due to their potential health benefits, especially their antioxidant properties and cytotoxic activities, which point to their ability to inhibit cancer cell proliferation. Comprehensive analyses were conducted to assess protein content, amino acid composition, mineral profile, fatty acids, polyphenols, total carotenoids, antioxidant activity, and cytotoxicity against cervical (HeLa), and colon (HCT-116) cell lines. P. palmata exhibited the highest protein content, while C. crispus was richest in calcium, iron, manganese, and zinc. Amino acid analysis revealed C. crispus as being particularly high in essential and non-essential amino acids, including alanine, glutamic acid, and glycine. A. nodosum and C. crispus were rich in polyunsaturated fatty acids (PUFAs), notably eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). A. nodosum showed the highest total carotenoid content. Polyphenol analysis highlighted the presence of compounds such as p-coumaric acid, gallic acid, and p-hydroxybenzoic acid across the species. Both the ethanolic and hexane A. nodosum extracts demonstrated the strongest antioxidant potential in DPPH• and ABTS+ assays. The cytotoxicity evaluation revealed high anticancer activity of A. nodosum and C. crispus hexane extract against HeLa and HCT-116, though it employed cell cycle arrest and apoptosis. A. nodosum hexane extract exhibited moderate selective anticancer activity against HCT-116. These findings underscore the nutritional diversity and potential health benefits of these macroalgae (seaweed) species, suggesting their suitability as functional foods or supplements, offering diverse nutritional and therapeutic benefits.

Inorganic Acid Resistance Performances of Magnesium Phosphate Cement: A Two-Year Observation.

Magnesium phosphate cement (MPC), a cementitious material that hardens through an acid-base reaction, is theoretically expected to exhibit strong acid resistance. However, studies on the durability of MPC in acidic environments remain limited. This study aims to systematically evaluate the acid resistance of MPC in common inorganic acid solutions across various pH levels. By measuring changes in compressive strength, mass loss, apparent changes, pH changes, and the microstructure evolution of MPC under acidic conditions, the mechanisms and influencing factors of its acid resistance are revealed. The results indicate that at pH levels of 1.0 and 2.0, MPC's resistance to H2SO4 and HCl erosion is markedly superior compared to its performance against H3PO4, as evidenced by compressive strength retention, mass loss, and visible erosion. At pH levels above 2.0, MPC demonstrates robust resistance to all tested corrosive media, with compressive strength retention ranging from 68.9% to 86.9%, irrespective of the acid source. Although new corrosion products form in these acidic environments, the adverse effects of NH4/P loss from struvite, along with the redissolution of corrosion products due to their higher solubility, increase porosity and subsequently reduce the mechanical strength. Nevertheless, considering that strength retention is significantly higher than that of other cement-based materials reported in the literature, MPC still exhibits good acid resistance and is suitable for environments requiring enhanced resistance to acid corrosion.

A novel method for leaching rare earth element from fluorescent lamp waste via acid fusion

Spent fluorescent lamps are alternatives to primary sources of rare earth elements. For recycling, the most common hydrometallurgical processes involve leaching with mineral acids, combined or not with alkaline fusion, which must be followed by another acidic leaching step for terbium, cerium, and lanthanum recovery. This study proposes a novel method employing acid fusion with potassium pyrosulfate (K2S2O7) and leaching with water at 25 °C. A full factorial design (23) was employed to study the following variables for the fusion process: temperature (450–550 °C), flux/sample mass ratio (2.2–3.0), and time (30–120 min). Under the optimal experimental conditions, the maximum recovery for La was 56.0 %. Recoveries were close to or greater than 70 % for Y, Ce, Eu, and Tb, at lower temperatures compared to those used in alkaline fusion, without the need for additional reagents and heating in the REE leaching step after fusion.

Study of the Dissolution of Tahoua Natural Phosphate by Mineral Acids: Hydrochloric Acid and Sulfuric Acid

The transformation of natural phosphorus into plant nutrient phosphorus, natural phosphates from Tahoua were dissolved in mineral acids, hydrochloric acid and sulfuric acid. Dissolution was effected at various concentrations (0.01M; 0.1M and 1M) and stirring times (1 hour, 3 hours and 5 hours). The results show that for all two acids (2), the dissolution rate is greater in concentrated acid solutions (1M) and for the 5-hour attack time. These rates are 38.37% and 34.87% respectively for sulfuric and hydrochloric acid solutions. Dissolution of Tahoua natural phosphate depends on the concentration of etching solutions and the etching time. With mineral acids (sulfuric and hydrochloric acid), for example, it increases with concentration. This dissolution offers interesting visions for perfecting phosphate fertilizers.

Simple and fast self-polymerization of benzidine using anodic exfloated graphene oxide nanosheet

Nowadays, researchers are looking for green synthesis methods of polymers that solve the disadvantages of polymerization with different initiators and traditional methods. In this work, the self-polymerization process of benzidine by anodic exfloated graphene oxide Nanosheet electrode (AEGO Nsh) is reported for the first time in the world. The self-polymerization of benzidine onto AEGO Nsh electrode was done by an easy and simple method by anodizing the graphite sheet followed by immersing the AEGO Nsh electrode inside the benzidine monomer dissolved in organic and inorganic acid media. The surface morphology of the self-polymerized benzidine (SPB) onto the AEGO Nsh (SPB/AEGO Nsh) electrode was investigated by phone camera and scanning electron microscope (FE-SEM) imaging. The chemical characterization of the SPB/AEGO Nsh electrode was verified through XPS and ATR-IR analysis. Additionally, the self-polymerization of benzidine onto AEGO Nsh electrodes was confirmed by electrochemical tests using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The results from these investigations unequivocally confirm the self-polymerization of benzidine onto the AEGO Nsh electrode.

Kinetic Study of Oxidation of Thiophene-2-Carbaldehyde by Imidazolium Dichromate Promoted By 1, 10-Phenanthroline

Kinetic study of oxidation of Thiophene-2-carbaldehyde by Imidazolium dichromate in aqueous acetic acid medium using 1,10-phenanthroline have been studied. In the absence of mineral acids, the oxidation kinetics of Thiophene-2-carbaldehyde acid by Imidazolium dichromate shows a first-order dependence on Imidazolium dichromate and fractional order on Thiophene-2-carbaldehyde. The variation of ionic strength, H+ and reaction product have in significant effect on reaction rate. Activation parameters have been studied for the reaction from the Arrhenius plot by studying the reaction at different temperatures.

Analysis of the nutritional composition of Bahraini breed camel (Camelus dromedarius) milk: fatty acid, mineral, phenolic, and antioxidant content

Camels live under extremely arid conditions, yet they can produce more milk than any other animal in the desert ecosystem. They also have a longer lactation duration as well as low nutrition requirements. This study aims to determine the fatty acids profile, minerals, antioxidant activity and total phenols/flavonoids content, in camel milk of the species Camelus dromedarius in Bahrain. Gas chromatography was employed to analyze the fatty acid methyl esters obtained after the extraction of fatty acids. Mineral concentrations were measured by an Inductively Coupled Plasma Optical Emission Spectrometer. Antioxidant measurements included total phenolic content by the Folin-Ciocalteu method, total flavonoid contents by AlCl3 colorimetric method, and total antioxidant activity by the ferric reducing antioxidant power assay. The fatty acids analysis (median(interquartile range) %) showed that the most predominant fatty acids were unsaturated fatty acids (50.40(6.76) %), which were slightly higher than saturated fatty acids (49.60(12.17) %). The most abundant saturated fatty acids were C16:0 (26.73(6.73) %), C18:0 (12.32(4.28) %), and C14:0 (10.55(2.86)%). Monounsaturated fatty acid 18:1n9 was 31.5(5.66) %, and 16:1n7 was 12.75(2.19)%, while the major omega-3 was C18:3n3 (3.91(0.71) %). The main omega-6 were C18:2n6 and C18:3n6, accounting for 1.30(0.35) % and 0.94(0.21) %, respectively. The mineral content of camel milk varied, with the presence of macro minerals such as calcium (699.60 mg/L), sodium (855.18 mg/L), magnesium (9.33 mg/L) and potassium (87.09 mg/L). The results showed that camel milk has considerable values of total antioxidant activity (4.75(1.71) mmol/g), total phenolic contents (20.24(11.18) mg GAE/L) and total flavonoid contents (31.74(20.72) mg CE/L). In conclusion, although the (poly)phenol content in camel milk is relatively lower compared to certain plant-based sources, it can represent a good source of antioxidants, in addition to a significant content in unsaturated fatty acids and minerals, further enhancing its nutritional value for human health.

Lipid-core nanocapsules containing simvastatin do not affect the biochemical and hematological indicators of toxicity in rats.

Our research group previously studied the effectiveness of lipid-core nanocapsules (LNC) containing simvastatin (SV-LNC) in treating cognitive impairment in rats. While our results were promising, we needed to evaluate the potential toxicity of the nanoparticles themselves. This study aimed to compare the biochemical and hematological parameters of adult Wistar rats receiving LNC or SV-LNC to those receiving low doses of simvastatin crystals dispersed in a saline solution over 45days. We discovered that LNC and SV-LNC, which are both nanometers in size with low polydispersity index, negative zeta potential, and high SV encapsulation efficacy, were not more toxic than SV crystals based on various biochemical markers of hepatic, pancreatic, renal, mineral, bony, alkaline phosphatase, glucose, and uric acid damage. Furthermore, LNC exhibited no toxicity for hematological parameters, including red and white blood cell counts. Based on this animal model of toxicological study, our findings suggest that long-term administration of LNC is a safe and promising nanocarrier.

Pork as a source of nutrients in a human diet - comparison of meat obtained from conventional and organic systems offered in the Polish market

Pork plays a key role as an important protein source of high biological value, essential fatty acids, vitamins (B group) and microelements such as zinc, selenium and iron in the human diet. Therefore, this study aimed to investigate and compare the chemical composition, fatty acid profile, mineral content and technological properties of organic and conventional pork loin, with particular emphasis on their availability in the Polish market. In the study, a hypothesis that organic meat has a more beneficial composition from a nutritional perspective and better technological properties was tested. The research material consisted of pork loin (musculus longissimus dorsi et lumborum) available on the Polish market. The technological properties (pH, colour, free water, shear force) and nutritional value (proximate composition, the fatty acid profile and mineral compounds) were assessed. Organic pork was darker and leaner, and had lower pH and water-holding capacity. It contained higher Cu, which resulted in a higher coverage of requirements for Cu. It was characterized by a more favourable fatty acid composition, including a higher concentration of monounsaturated fatty acids and a lower level of saturated fatty acids and better atherogenic and thrombogenic indexes, which indicates its better nutritional value than conventional pork.

Photoreactor based on original catalytic foam-filter for wastewater treatment

Water is essential for life on Earth, playing a crucial role in sustaining ecosystems and human health. However, the effectiveness of worldwide treatment processes is frequently inadequate, allowing some contaminants to persist and enter natural environments. This failure contributes to the deterioration of ecosystems and poses significant risks to biodiversity and public health. This work focuses on the development of an economic and realistic catalytic foam-filter activated by UV light to effectively remove contaminants in different types of wastewaters before their release in the environment or for water reuse. Using polydopamine, commercial open-cell polyurethane foams-filters are functionalized via a novel and simple dip-coating method, enabling the grafting of TiO2 on the surface of the foam. The resulting catalytic foam-filter is characterized and its photocatalytic activity is first assessed by studying the mineralization of formic acid (a model pollutant) in photoreactor operated in recirculation mode. The stability and recyclability of the catalytic foam-filter are investigated through multiple cycles of test and its performance is evaluated on a mixture of four highly relevant pollutants (atrazine, trimethoprim, 4-nonylphenol and bisphenol A). The results show that the catalytic coating of the foam-filter is highly stable, enabling a mineralization rate of 90 % of formic acid in 60 min, retaining the same efficiency after 15 cycles of reuse. The catalytic foam-filter is also efficient at removing contaminants from a mixture of pollutants, with removal rates ranging from 75 to 100 %. The reactor was modeled and validated by experimental data, enabling a change of scale. This study provides an initial framework for the use of bio-inspired materials in water treatment processes, with interesting mechanical and catalytic properties.

Recovery of bio-based volatile fatty acids from anaerobically treated winery wastewater using a closed-loop liquid-liquid hydrophobic membrane contactor system

This research evaluated a closed-loop hydrophobic liquid–liquid membrane contactor (MC) for the recovery of volatile fatty acids (VFAs) from the effluent of an up-flow anaerobic sludge blanket (UASB) bioreactor treating winery wastewater. Sodium bicarbonate was used as a stripping solution for its operational flexibility and compatibility with downstream bioprocesses. An electrochemical acidification cell (EAC) was tested to continuously adjust of pH of the feed solution to avoid the use of inorganic acids. VFA recovery was optimized under different flow rates and feed pH conditions using a synthetic VFA solution and validated with actual UASB effluent. Lower feed pH resulted in higher VFA recovery due to increased protonation of the acids. This effect was more pronounced when using synthetic VFA solutions compared to real UASB effluent. Specifically, the MC system recovered 16 ± 5 % of acetic acid at 0.3 ± 0.1 gCOD/m2h flux and 34 ± 4 % of butyric acid at 0.5 ± 0.1 gCOD/m2h flux at an unadjusted UASB effluent feed pH of 4.9, compared to 22 ± 3 % at 0.5 ± 0.1 gCOD/m2h flux and 46 ± 5 % at 0.7 ± 0.1 gCOD/m2h flux, respectively, at pH 2. The EAC effectively lowered the feed pH of UASB effluent to 3.9, achieving acetic acid recovery of 22 ± 3 % at a mass flux of 0.2 ± 0.1 gCOD/m2h, and butyric acid recovery of 45 ± 1 % at a mass flux of 0.6 ± 0.1 gCOD/m2h. These moderate recovery efficiencies are likely influenced by the lower pH gradient resulting from the use of sodium bicarbonate. However, the compatibility of sodium bicarbonate with bioprocesses offers the advantage that the proposed UASB-MC system can be seamlessly integrated with downstream bioprocesses to produce valuable end products for other markets, such as PHA for plastics and microbial proteins for animal feed.

Cu(I)-Induced 'Click Reaction' Involving Coordination and Covalent Assembly of Hybrid Borates for the Electrocatalytic CO2 Reduction.

The design and synthesis of hybrid borates by the organic ligand modification method are urgent and undeveloped areas of research. It is difficult to directly integrate organoboronic acids within inorganic borate chemistry by adopting the traditional preparation approaches. This work reports a facile synthetic method to synthesize a large family of pyrazole molecule-protected borates in a rapid and precise manner under mild conditions. A unique cyclic eight-membered B4O4-ring has been identified as the cluster core for all these hybrid borates with two different conformations (boat and crown). This strategy can be applied to a system of pyrazolyl molecules to generate such hybrid borates in two independent routes from organoboronic or inorganic boric acids. Furtherly, the mechanism of 'click reaction' between boric acid and pyrazole induced by copper ions has been proposed based on the synthetic conditions and the structure of intermediate. Due to the bimetallic Cu sites and the functional surfaces, these materials can be used as electrocatalysts for CO2 reduction reaction and efficiently enhance the selectivity of HCOOH and C2H4. Our strategy can be regarded as a typical template technique for organic molecule-protected borates.

Cu(I)‐Induced ‘Click Reaction’ Involving Coordination and Covalent Assembly of Hybrid Borates for the Electrocatalytic CO2 Reduction

AbstractThe design and synthesis of hybrid borates by the organic ligand modification method are urgent and undeveloped areas of research. It is difficult to directly integrate organoboronic acids within inorganic borate chemistry by adopting the traditional preparation approaches. This work reports a facile synthetic method to synthesize a large family of pyrazole molecule‐protected borates in a rapid and precise manner under mild conditions. A unique cyclic eight‐membered B4O4‐ring has been identified as the cluster core for all these hybrid borates with two different conformations (boat and crown). This strategy can be applied to a system of pyrazolyl molecules to generate such hybrid borates in two independent routes from organoboronic or inorganic boric acids. Furtherly, the mechanism of ‘click reaction’ between boric acid and pyrazole induced by copper ions has been proposed based on the synthetic conditions and the structure of intermediate. Due to the bimetallic Cu sites and the functional surfaces, these materials can be used as electrocatalysts for CO2 reduction reaction and efficiently enhance the selectivity of HCOOH and C2H4. Our strategy can be regarded as a typical template technique for organic molecule‐protected borates.