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22 pages, 1916 KiB  
Article
Freeze-Dried Probiotic Fermented Camel Milk Enriched with Ajwa Date Pulp: Evaluation of Functional Properties, Probiotic Viability, and In Vitro Antidiabetic and Anticancer Activities
by Sally S. Sakr and Hassan Barakat
Foods 2025, 14(15), 2698; https://doi.org/10.3390/foods14152698 - 31 Jul 2025
Viewed by 283
Abstract
Noncommunicable diseases (NCDs) like diabetes and cancer drive demand for therapeutic functional foods. This study developed freeze-dried fermented camel milk (FCM) with Ajwa date pulp (ADP), evaluating its physical and functional properties, probiotic survival, and potential benefits for diabetes and cancer. To achieve [...] Read more.
Noncommunicable diseases (NCDs) like diabetes and cancer drive demand for therapeutic functional foods. This study developed freeze-dried fermented camel milk (FCM) with Ajwa date pulp (ADP), evaluating its physical and functional properties, probiotic survival, and potential benefits for diabetes and cancer. To achieve this target, six FCM formulations were prepared using ABT-5 starter culture (containing Lactobacillus acidophilus, Bifidobacterium bifidum, and Streptococcus thermophilus) with or without Lacticaseibacillus rhamnosus B-1937 and ADP (12% or 15%). The samples were freeze-dried, and their functional properties, such as water activity, dispersibility, water absorption capacity, water absorption index, water solubility index, insolubility index, and sedimentation, were assessed. Reconstitution properties such as density, flowability, air content, porosity, loose bulk density, packed bulk density, particle density, carrier index, Hausner ratio, porosity, and density were examined. In addition, color and probiotic survivability under simulated gastrointestinal conditions were analyzed. Also, antidiabetic potential was assessed via α-amylase and α-glucosidase inhibition assays, while cytotoxicity was evaluated using the MTT assay on Caco-2 cells. The results show that ADP supplementation significantly improved dispersibility (up to 72.73% in FCM15D+L). These improvements are attributed to changes in particle size distribution and increased carbohydrate and mineral content, which facilitate powder rehydration and reduce clumping. All FCM variants demonstrated low water activity (0.196–0.226), indicating good potential for shelf stability. The reconstitution properties revealed that FCM powders with ADP had higher bulk and packed densities but lower particle density and porosity than controls. Including ADP reduced interstitial air and increased occluded air within the powders, which may minimize oxidation risks and improve packaging efficiency. ADP incorporation resulted in a significant decrease in lightness (L*) and increases in redness (a*) and yellowness (b*), with greater pigment and phenolic content at higher ADP levels. These changes reflect the natural colorants and browning reactions associated with ADP, leading to a more intense and visually distinct product. Probiotic survivability was higher in ADP-fortified samples, with L. acidophilus and B. bifidum showing resilience in intestinal conditions. The FCM15D+L formulation exhibited potent antidiabetic effects, with IC50 values of 111.43 μg mL−1 for α-amylase and 77.21 μg mL−1 for α-glucosidase activities, though lower than control FCM (8.37 and 10.74 μg mL−1, respectively). Cytotoxicity against Caco-2 cells was most potent in non-ADP samples (IC50: 82.22 μg mL−1 for FCM), suggesting ADP and L. rhamnosus may reduce antiproliferative effects due to proteolytic activity. In conclusion, the study demonstrates that ADP-enriched FCM is a promising functional food with enhanced probiotic viability, antidiabetic potential, and desirable physical properties. This work highlights the potential of camel milk and date synergies in combating some NCDs in vitro, suggesting potential for functional food application. Full article
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19 pages, 7574 KiB  
Article
Effect of Natural Fiber Characteristics on Properties of Cementitious Composites: A Comparison of Recycled Pulp from Beverage Cartons, Bamboo, and Eucalyptus Fibers
by Phouthanouthong Xaysombath, Nattakan Soykeabkaew, Darunee Wattanasiriwech and Suthee Wattanasiriwech
Constr. Mater. 2025, 5(3), 50; https://doi.org/10.3390/constrmater5030050 - 31 Jul 2025
Viewed by 132
Abstract
This study evaluates the influence of fiber type, geometry, and interfacial behavior on the physical and mechanical performance of cementitious composites reinforced with recycled pulp from beverage cartons (RPBC), bamboo fiber (BF), and eucalyptus fiber (EF) as the sole reinforcing agents. The BF [...] Read more.
This study evaluates the influence of fiber type, geometry, and interfacial behavior on the physical and mechanical performance of cementitious composites reinforced with recycled pulp from beverage cartons (RPBC), bamboo fiber (BF), and eucalyptus fiber (EF) as the sole reinforcing agents. The BF was rounded in shape and had the highest aspect ratio, while the ribbon-shaped EF exhibited the highest tensile strength index. The RPBC fibers were fibrillated and the shortest, with a ribbon shape. Flexural strength results showed that RPBCC achieved a maximum strength that was 47.6% higher than the control specimen (0% fiber), outperforming both BF- and EF-reinforced counterparts. This superior performance is attributed to the higher fibrillation level of the ribbon-shaped RPBC fibers, which promoted better fiber–matrix bonding. As the fiber content increased, the bulk density of EFC and BFC decreased linearly, while RPBC composites showed only a modest decrease in density. Porosity steadily increased in EFC and BFC, whereas a non-linear trend was observed in RPBCC, likely due to its unique morphology and fibrillation. Conversely, EFC exhibited significantly higher maximum fracture toughness (3600 J/m2 at 10 wt.%) compared to PBFCC (1600 J/m2 at 14 wt.%) and BFC (1400 J/m2 at 14 wt.%). This enhancement is attributed to extensive fiber pullout mechanisms and increased energy absorption during crack propagation. Overall, all composite types demonstrated flexural strength values above 4 MPa, placing them in the Grade I category. Those reinforced with 10–14% RPBC exhibited strengths of 11–12 MPa, categorizing them as Grade II according to ASTM C1186-02. Full article
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18 pages, 2786 KiB  
Article
Performance of Oriented Strand Boards Made with Jack Pine Strands Produced by an Innovative Strander-Canter
by Rosilei Garcia, Alain Cloutier, Irsan Alipraja, Roger E. Hernández and Ahmed Koubaa
Forests 2025, 16(8), 1227; https://doi.org/10.3390/f16081227 - 25 Jul 2025
Viewed by 164
Abstract
Canadian sawmills commonly use chipper-canters to process softwood logs into squared lumber and wood chips for pulp mills. However, the declining demand for newsprint and print paper has led to an oversupply of wood chips, resulting in economic losses and environmental concerns. To [...] Read more.
Canadian sawmills commonly use chipper-canters to process softwood logs into squared lumber and wood chips for pulp mills. However, the declining demand for newsprint and print paper has led to an oversupply of wood chips, resulting in economic losses and environmental concerns. To address this issue, a strander-canter capable of producing both softwood cants and strands for oriented strand board (OSB) presents a promising alternative. This study evaluates the feasibility of using jack pine strands generated by a novel strander-canter equipped with a cutterhead for OSB strand production. Strands were generated from frozen and unfrozen logs under varying cutting parameters and incorporated in the core layer of the panels. Industrial aspen strands were used for the surface layers. OSB panels were assessed for mechanical and physical properties following the CSA O325:21 standard. Strand size distribution and vertical density profiles were also analyzed. The results indicated that panels made from jack pine strands demonstrated bending and internal bond properties that were either comparable to or superior to those of the control panels. However, including jack pine strands in the core layer increased the thickness swelling of the panels. Full article
(This article belongs to the Special Issue Properties and Uses of Value-Added Wood-Based Products and Composites)
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17 pages, 2629 KiB  
Article
Recovery of High-Alkali-Grade Feldspar Substitute from Phonolite Tailings
by Savas Ozun, Semsettin Ulutas and Sema Yurdakul
Processes 2025, 13(8), 2334; https://doi.org/10.3390/pr13082334 - 23 Jul 2025
Viewed by 267
Abstract
Phonolite is a fine-grained, shallow extrusive rock rich in alkali minerals and containing iron/titanium-bearing minerals. This rock is widely used as a construction material for building exteriors due to its excellent abrasion resistance and insulation properties. However, during the cutting process, approximately 70% [...] Read more.
Phonolite is a fine-grained, shallow extrusive rock rich in alkali minerals and containing iron/titanium-bearing minerals. This rock is widely used as a construction material for building exteriors due to its excellent abrasion resistance and insulation properties. However, during the cutting process, approximately 70% of the rock is discarded as tailing. So, this study aims to repurpose tailings from a phonolite cutting and sizing plant into a high-alkali ceramic raw mineral concentrate. To enable the use of phonolite tailings in ceramic manufacturing, it is necessary to remove coloring iron/titanium-bearing minerals, which negatively affect the final product. To achieve this removal, dry/wet magnetic separation processes, along with flotation, were employed both individually and in combination. The results demonstrated that using dry high-intensity magnetic separation (DHIMS) resulted in a concentrate with an Fe2O3 + TiO2 grade of 0.95% and a removal efficiency of 85%. The wet high-intensity magnetic separation (WHIMS) process reduced the Fe2O3 + TiO2 grade of the concentrate to 1.2%, with 70% removal efficiency. During flotation tests, both pH levels and collector concentration impacted the efficiency and Fe2O3 + TiO2 grade (%) of the concentrate. The lowest Fe2O3 + TiO2 grade of 1.65% was achieved at a pH level of 10 with a collector concentration of 2000 g/t. Flotation concentrates processed with DHIMS achieved a minimum Fe2O3 + TiO2 grade of 0.90%, while those processed with WHIMS exhibited higher Fe2O3 + TiO2 grades (>1.1%) and higher recovery rates (80%). Additionally, studies on flotation applied to WHIMS concentrates showed that collector concentration, pulp density, and conditioning time significantly influenced the Fe2O3 + TiO2 grade of the final concentrate. Full article
(This article belongs to the Section Separation Processes)
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12 pages, 3566 KiB  
Article
Differential Regulation of Angiogenesis, Lymphangiogenesis, and Neural Tissue in Normal and Inflamed Dental Pulp: Immunohistochemical Analysis
by Nooruldeen Ammar Alani and Bashar Hamid Abdullah
Diagnostics 2025, 15(14), 1819; https://doi.org/10.3390/diagnostics15141819 - 19 Jul 2025
Viewed by 378
Abstract
Background/Objectives: Pulp inflammation impairs healing, yet the underlying vascular and neural mechanisms remain poorly understood. This study investigated the differential regulation of lymphatic vessels, blood vessels, and neural tissue in pulpitis to elucidate healing limitations in inflamed dental pulp. Methods: This study evaluated [...] Read more.
Background/Objectives: Pulp inflammation impairs healing, yet the underlying vascular and neural mechanisms remain poorly understood. This study investigated the differential regulation of lymphatic vessels, blood vessels, and neural tissue in pulpitis to elucidate healing limitations in inflamed dental pulp. Methods: This study evaluated 38 pulp samples (14 symptomatic irreversible pulpitis, 13 asymptomatic irreversible pulpitis, and 11 healthy controls) via immunohistochemistry, using D2-40 to identify lymphatic vessels, CD31 to mark blood vessels, and PGP9.5 to detect neural tissue. Vessel counts and neural tissue scoring were performed by blinded examiners and analyzed using appropriate statistical tests. Results: Dental pulp with symptomatic irreversible pulpitis exhibited significantly increased blood vessel density (50.3 vs. 39.2 in asymptomatic irreversible pulpitis and 25.8 in controls, p = 0.001, Cohen’s d = 1.82), while lymphatic vessel density remained unchanged across all groups (p ≥ 0.05), indicating impaired lymphangiogenesis despite inflammation. Neural tissue density was consistent across conditions, with a significant negative correlation between PGP9.5 expression and age (r = −0.5, p = 0.001). CD31 and D2-40 expression showed a positive correlation (r = 0.389, p = 0.016), suggesting coordinated vascular development. Conclusions: Our findings reveal a critical imbalance between enhanced angiogenesis and impaired lymphangiogenesis during pulpitis, potentially explaining the compromised healing capacity of inflamed dental pulp. This vascular dysregulation, combined with persistent neural tissue density, creates an environment in which inflammatory exudates accumulate with limited clearance. These insights indicate a need for new therapeutic strategies aimed at enhancing lymphangiogenesis to improve endodontic outcomes. Full article
(This article belongs to the Section Pathology and Molecular Diagnostics)
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21 pages, 2440 KiB  
Article
Dual-Purpose Utilization of Sri Lankan Apatite for Rare Earth Recovery Integrated into Sustainable Nitrophosphate Fertilizer Manufacturing
by D. B. Hashini Indrachapa Bandara, Avantha Prasad, K. D. Anushka Dulanjana and Pradeep Wishwanath Samarasekere
Sustainability 2025, 17(14), 6353; https://doi.org/10.3390/su17146353 - 11 Jul 2025
Viewed by 1177
Abstract
Rare earth elements (REEs) have garnered significant global attention due to their essential role in advanced technologies. Sri Lanka is endowed with various REE-bearing minerals, including the apatite-rich deposit in the Eppawala area, commonly known as Eppawala rock phosphate (ERP). However, direct extraction [...] Read more.
Rare earth elements (REEs) have garnered significant global attention due to their essential role in advanced technologies. Sri Lanka is endowed with various REE-bearing minerals, including the apatite-rich deposit in the Eppawala area, commonly known as Eppawala rock phosphate (ERP). However, direct extraction of REEs from ERP is technically challenging and economically unfeasible. This study introduces a novel, integrated approach for recovering REEs from ERP as a by-product of nitrophosphate fertilizer production. The process involves nitric acid-based acidolysis of apatite, optimized at 10 M nitric acid for 2 h at 70 °C with a pulp density of 2.4 mL/g. During cooling crystallization, 42 wt% of calcium was removed as Ca(NO3)2.4H2O while REEs remained in the solution. REEs were then selectively precipitated as REE phosphates via pH-controlled addition of ammonium hydroxide, minimizing the co-precipitation with calcium. Further separation was achieved through selective dissolution in a sulfuric–phosphoric acid mixture, followed by precipitation as sodium rare earth double sulfates. The process achieved over 90% total REE recovery with extraction efficiencies in the order of Pr > Nd > Ce > Gd > Sm > Y > Dy. Samples were characterized for their phase composition, elemental content, and morphology. The fertilizer results confirmed the successful production of a nutrient-rich nitrophosphate (NP) with 18.2% nitrogen and 13.9% phosphorus (as P2O5) with a low moisture content (0.6%) and minimal free acid (0.1%), indicating strong agronomic value and storage stability. This study represents one of the pioneering efforts to valorize Sri Lanka’s apatite through a novel, dual-purpose, and circular approach, recovering REEs while simultaneously producing high-quality fertilizer. Full article
(This article belongs to the Special Issue Technologies for Green and Sustainable Mining)
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28 pages, 5945 KiB  
Article
Liposomal Encapsulation of Carob (Ceratonia siliqua L.) Pulp Extract: Design, Characterization, and Controlled Release Assessment
by Aleksandra A. Jovanović, Dragana Dekanski, Milena D. Milošević, Ninoslav Mitić, Aleksandar Rašković, Nikola Martić and Andrea Pirković
Pharmaceutics 2025, 17(6), 776; https://doi.org/10.3390/pharmaceutics17060776 - 13 Jun 2025
Viewed by 511
Abstract
Background: Carob (Ceratonia siliqua L.) pulp flour is primarily used in the food industry. As a rich source of bioactive compounds, particularly polyphenols, it holds promise for pharmaceutical formulation research and development. Objectives: This study focused on developing liposomal particles loaded with [...] Read more.
Background: Carob (Ceratonia siliqua L.) pulp flour is primarily used in the food industry. As a rich source of bioactive compounds, particularly polyphenols, it holds promise for pharmaceutical formulation research and development. Objectives: This study focused on developing liposomal particles loaded with carob pulp extract using the proliposome method, followed by modifications through UV irradiation and sonication. Methods: The resulting liposomes were analyzed for encapsulation efficiency, vesicle size, polydispersity index (PDI), mobility, zeta potential, viscosity, surface tension, density, antioxidant activity, FT-IR spectra, and release kinetics under simulated gastrointestinal conditions. In addition, nanoparticle tracking analysis and transmission electron microscopy (TEM) were used for liposomal characterization. Results: The findings revealed a high encapsulation efficiency across all samples (>70%). The particle size and PDI measurements confirmed the presence of a multilamellar and uniform liposomal system before post-processing modifications. The medium value of zeta potential suggested a moderately electrostatically stabilized liposomal suspension. The sonicated liposomes demonstrated a higher concentration of vesicles in comparison to non-treated and UV-irradiated samples. TEM analysis revealed purified liposomal vesicles with preserved structural integrity. Encapsulation, as well as UV irradiation and sonication of liposomes, did not diminish the extract’s anti-DPPH activity. However, the ABTS radical scavenging potential of the pure extract was significantly lower compared to its encapsulated counterparts. UV irradiation and sonication notably reduced the anti-ABTS capacity of the extract-liposome system. Monitoring the release of bioactive compounds demonstrated controlled delivery from liposomal particles under simulated gastrointestinal conditions. Conclusions: Overall, liposomal formulations of carob pulp extract exhibit significant potential for further development as a functional food ingredient or for use in the prevention and treatment of various diseases. Full article
(This article belongs to the Special Issue Advanced Liposomes for Drug Delivery, 2nd Edition)
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16 pages, 3183 KiB  
Article
Relationship Between Density and Structure of Lignins Obtained from Different Feedstocks Pretreated with Protic Ionic Liquids
by Francisco Malaret, Pedro Y. S. Nakasu, Pedro Verdía Barbará, Cynthia Hopson and Jason Hallett
Processes 2025, 13(6), 1848; https://doi.org/10.3390/pr13061848 - 11 Jun 2025
Viewed by 554
Abstract
Lignin, one of the most abundant biopolymers on Earth, holds significant promise as a feedstock for applications such as resins, biofuels, foams, and carbon fibres. However, despite extensive research, lignin remains largely underutilised, with its primary use limited to combustion for energy. While [...] Read more.
Lignin, one of the most abundant biopolymers on Earth, holds significant promise as a feedstock for applications such as resins, biofuels, foams, and carbon fibres. However, despite extensive research, lignin remains largely underutilised, with its primary use limited to combustion for energy. While lignin’s structural features are well documented, there is a lack of consistent data on its key physical properties such as density. This study addresses that gap by providing experimentally determined values for skeletal and bulk densities of lignins obtained through different extraction methods, including Kraft; soda pulping; and particularly the ionoSolv process, using ionic liquids such as N,N-dimethyl butyl ammonium hydrogen sulphate ([DMBA][HSO4]). The results reveal correlations between lignin chemical structure and density in ionoSolv-extracted lignins from Eucalyptus Red Grandis, suggesting opportunities to tune the extraction parameters for targeted material properties. The skeletal density of the lignin samples ranged from 1.3370 to 1.4598 g/cm3, while the bulk density varied more widely—from 0.0944 to 0.5302 g/cm3—reflecting significant differences in particle packing and porosity depending on the biomass source and extraction method. These findings contribute valuable data for process design and scale-up, advancing the commercial viability of lignin-based products. Full article
(This article belongs to the Special Issue Ionic Liquid Applications in Sustainable Biomass Processing)
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26 pages, 4446 KiB  
Article
Exploring the Dual Nature of Olive Husk: Fiber/Aggregate in Lightweight Bio-Concrete for Enhanced Hygrothermal, Mechanical, and Microstructural Properties
by Halima Belhadad, Nadir Bellel and Ana Bras
Buildings 2025, 15(11), 1950; https://doi.org/10.3390/buildings15111950 - 4 Jun 2025
Viewed by 534
Abstract
This study investigates the potential of thermally treated olive husk (OH)—a heterogeneous agro-industrial by-product comprising olive stones, pulp, and fibrous residues—as a multifunctional component in lightweight bio-concrete. Uniquely, this work harnesses the intrinsic dual nature of OH as both a fibrous reinforcement and [...] Read more.
This study investigates the potential of thermally treated olive husk (OH)—a heterogeneous agro-industrial by-product comprising olive stones, pulp, and fibrous residues—as a multifunctional component in lightweight bio-concrete. Uniquely, this work harnesses the intrinsic dual nature of OH as both a fibrous reinforcement and a porous aggregate, without further fractionation, to evaluate its influence on the hygrothermal and mechanical behavior of cementitious composites. While prior studies have often focused selectively on thermal conductivity, this work provides a comprehensive assessment of all major thermal parameters; including diffusivity, effusivity, and specific heat capacity; offering deeper insights into the full thermal behavior of bio-based concretes. OH was incorporated at 0%, 10%, and 20% by weight, and the resulting concretes were subjected to a comprehensive characterization of their thermal, hygric, mechanical, and microstructural properties. Thermal performance metrics included conductivity, specific heat capacity, diffusivity, effusivity, time lag, and predicted energy savings. Hygric behavior was assessed through the moisture buffering value (MBV), while density, porosity, and mechanical strengths were also evaluated. At 20% OH content, thermal conductivity decreased to 0.405 W/m·K (a 72% reduction), thermal diffusivity dropped by 87%, and thermal effusivity reached 554 W·s0.5/m2·K, collectively enhancing thermal inertia and increasing the time lag by 77% (to 2.32 h). MBVs improved to 2.18 g/m2·%RH, rated as “Excellent” for indoor moisture regulation. Despite the higher porosity, the bio-concrete maintained adequate mechanical integrity, with compressive and flexural strengths of 11.68 MPa and 3.58 MPa, respectively, attributed to the crack-bridging action of the fibrous inclusions. Microstructural analysis (SEM/XRD) revealed improved paste continuity and denser C–S–H formation, attributed to enhanced matrix compatibility following oil removal via thermal pre-treatment. These findings demonstrate the viability of OH as a new bio-based, multifunctional additive for fabricating thermally efficient, hygroscopically active, and structurally sound concretes suitable for sustainable construction. Full article
(This article belongs to the Collection Advanced Concrete Materials in Construction)
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15 pages, 2858 KiB  
Article
Surface Physicochemical Property Differences Between Gold-Bearing and Gold-Free Pyrite for Efficient and Clean Processing of Refractory Pyritic Gold Ores
by Xujian Chai, Runqing Liu, Wenchao Dong, Wei Sun and Shangyong Lin
Minerals 2025, 15(6), 577; https://doi.org/10.3390/min15060577 - 29 May 2025
Viewed by 392
Abstract
Selective separation of gold-bearing pyrite from gold-free pyrite through flotation to improve the gold-to-sulfur ratio in the feed can significantly enhance the throughput of autoclaves, thus achieving efficient and clean processing of refractory pyritic gold ores. To achieve this expectation, this study examined [...] Read more.
Selective separation of gold-bearing pyrite from gold-free pyrite through flotation to improve the gold-to-sulfur ratio in the feed can significantly enhance the throughput of autoclaves, thus achieving efficient and clean processing of refractory pyritic gold ores. To achieve this expectation, this study examined the surface physicochemical differences between gold-bearing and gold-free pyrite under flotation conditions using cyclic voltammetry, polarization curve testing, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) simulations. Electrochemical tests showed higher reactivity in gold-bearing pyrite, with reactivity positively correlated to gold content. XPS results indicated more oxidation products on gold-bearing pyrite surfaces under identical conditions. DFT simulations revealed that the presence of gold reduced the oxygen adsorption energy on the pyrite surface while enhancing interactions between oxygen atoms and sulfur and iron atoms. Based on these findings, the selective separation of gold-bearing and gold-free pyrite in the flotation process can be explored through pulp aeration pre-oxidation combined with collectors demonstrating selectivity toward barren pyrite (e.g., dithiocarbamate collectors). This study provides theoretical foundations for the efficient exploitation and utilization of refractory gold-bearing pyrite resources. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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24 pages, 4281 KiB  
Article
Copper–Ammonia–Thiosulfate Leaching of High-Sulfide Concentrates: Process Optimization and Additive Effects on Gold Extraction
by Azizbek Bolikulovich Buronov, Blackie Korul Yayabu, Labone Lorraine Godirilwe, Batnasan Altansukh, Sanghee Jeon, Kazutoshi Haga and Atsushi Shibayama
Metals 2025, 15(6), 572; https://doi.org/10.3390/met15060572 - 22 May 2025
Viewed by 586
Abstract
This research focuses on finding an environmentally friendly method for extracting gold from a sulfide flotation concentrate. In this study, an ammonia–copper–thiosulfate leaching system was utilized for the extraction of gold. The flotation concentrate sample contains about 190 ppm of gold, 160 ppm [...] Read more.
This research focuses on finding an environmentally friendly method for extracting gold from a sulfide flotation concentrate. In this study, an ammonia–copper–thiosulfate leaching system was utilized for the extraction of gold. The flotation concentrate sample contains about 190 ppm of gold, 160 ppm of silver, and 6.89% of copper. To achieve an optimized gold extraction, various parameters, such as thiosulfate, ammonia and copper concentrations, pulp density, pH, stirring rate, temperature, and time, were investigated. About 87% of gold was leached under the following conditions: 0.5 M S2O32−, 1.0 M NH3, 0.1 M Cu2+, a stirring rate of 350 rpm, a pH of 12, a pulp density of 10% solids, a temperature of 25 °C, and a leaching time of 2 h. Additionally, to improve the economic effectiveness of the leaching system, thiosulfate consumption was investigated by utilizing different additives, such as diethylenetriamine (DETA), glycerol, and ammonium dihydrogen phosphate (ADP). The results showed that with the use of ADP, gold extraction increased from 87% to 91% while reducing copper dissolution. Additionally, the thiosulfate consumption also decreased from 0.37 M to 0.3 M. The inclusion of ADP was particularly effective, enhancing gold extraction efficiency and reducing reagent consumption, thereby making the process more sustainable. Considering the high economic value of gold, the optimization of recovery efficiency is prioritized over reagent costs in this study. Overall, this study indicates that the optimized ammonia–copper–thiosulfate leaching system with ADP additive is a promising environmentally friendly method for the extraction of gold. Full article
(This article belongs to the Section Extractive Metallurgy)
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21 pages, 8909 KiB  
Article
Isolation, Sphalerite Bioleaching, and Whole Genome Sequencing of Acidithiobacillus ferriphilus QBS3 from Zinc-Rich Sulfide Mine Drainage
by Kan Wang, Yuandong Liu, Run Liu, Wissal Belqadi, Weimin Zeng, Runlan Yu and Xueling Wu
Life 2025, 15(5), 792; https://doi.org/10.3390/life15050792 - 15 May 2025
Cited by 1 | Viewed by 527
Abstract
The genus Acidithiobacillus has been widely used in bioleaching, and novel strains in this genus, such as A. ferriphilus, have also been confirmed to possess bioleaching capabilities. In this study, an Acidithiobacillus ferriphilus strain, QBS3, was isolated from zinc-rich sulfide mine drainage [...] Read more.
The genus Acidithiobacillus has been widely used in bioleaching, and novel strains in this genus, such as A. ferriphilus, have also been confirmed to possess bioleaching capabilities. In this study, an Acidithiobacillus ferriphilus strain, QBS3, was isolated from zinc-rich sulfide mine drainage using the gradient dilution method. QBS3 is a Gram-negative, 1.3 µm rod-shaped bacterium with small red colonies. It showed a high iron oxidation efficiency of 0.361 g/(L·h) and a sulfur oxidation efficiency of 0.206 g/(L·d). QBS3 has sphalerite bioleaching ability; using QBS3 for pure sphalerite bioleaching, 18.8% of zinc was extracted in 14 days at 1% pulp density. Whole genome sequencing was performed on QBS3. Functional prediction showed that 9.13% of the genes were involved in replication, recombination, and repair. Bioleaching-related genes were analyzed, including iron and sulfur oxidation genes, and carbon and nitrogen fixation genes. For iron oxidation, the Cyc2→RusA pathway and Iro→RusB pathway were found in QBS3. In terms of sulfur oxidation, QBS3 has an incomplete SOX system and lacks the SDO gene, but Rho and Trx may complement the SOX system, enabling QBS3 to oxidize sulfur. QBS3 has multiple sets of carbon fixation genes, and nitrogen fixation genes were also identified. A hypothetical sphalerite bioleaching model is proposed; this study provides a theoretical basis for the zinc sulfide ore bioleaching industry. Full article
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15 pages, 6357 KiB  
Article
Study on Floatation Separation of Molybdenite and Talc Based on Crystal Surface Anisotropy
by Qidong Zhang, Xiaoli Li, Zhifang Hu, Bowen Gao and Chen Liu
Separations 2025, 12(5), 123; https://doi.org/10.3390/separations12050123 - 13 May 2025
Viewed by 331
Abstract
Talcose molybdenite resources are abundant but resource utilization is low. The floatation separation of molybdenite (MoS2) and talc is challenging due to their similar natural hydrophobicity and layered structures. This study investigates the surface properties and interaction mechanisms between these minerals [...] Read more.
Talcose molybdenite resources are abundant but resource utilization is low. The floatation separation of molybdenite (MoS2) and talc is challenging due to their similar natural hydrophobicity and layered structures. This study investigates the surface properties and interaction mechanisms between these minerals to improve their separation efficiency. Density functional theory (DFT) calculations confirm that the basal planes of both minerals are hydrophobic, while their edge surfaces are hydrophilic. Atomic force microscopy (AFM) and DLVO theory reveal that molybdenite and talc particles aggregate in neutral/acidic conditions but disperse in alkaline solutions due to altered surface forces. Floatation experiments demonstrate that pulp pH is the key controlling factor—alkaline conditions (pH > 10) effectively reduce hetero-aggregation, enabling selective molybdenite recovery. These findings provide critical insights into optimizing floatation processes for talcose molybdenite ores, enhancing resource utilization. Full article
(This article belongs to the Special Issue Advances in Novel Beneficiation Technology of Critical Minerals)
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24 pages, 1089 KiB  
Review
Bioleaching of Gold from Printed Circuit Boards: Potential Sustainability of Thiosulphate
by Zahra Ilkhani and Farid Aiouache
Recycling 2025, 10(3), 87; https://doi.org/10.3390/recycling10030087 - 3 May 2025
Viewed by 1321
Abstract
The rapid consumption and disposal of electronic waste due to technological innovations and changes in living commodities are causing the development of a significant environmental challenge. Among the components of these wastes, spent printed circuit boards are particularly considered to be among the [...] Read more.
The rapid consumption and disposal of electronic waste due to technological innovations and changes in living commodities are causing the development of a significant environmental challenge. Among the components of these wastes, spent printed circuit boards are particularly considered to be among the most valuable owing to their content of precious metals, such as gold first and potentially platinum, which may be available in a lower proportion. Effective methods as part of gold recovery strategies by industries and policymakers are developed and envisioned from economic and environmental perspectives. Currently, cyanidation dominates global gold production from e-waste due to its selectivity for gold. The high toxicity of cyanide, however, poses serious environmental issues, leading thiosulphate leaching to emerge as a non-toxic and promising alternative for gold extraction. Its industrial viability has been demonstrated by Barrick Gold Corporation at the Goldstrike site with the pretreatment of acidic or alkaline pressure oxidation. This review introduces bioleaching as a promising economic and environmentally friendly process for gold extraction. This review explores thiosulphate leaching of gold as an alternative to conventional cyanidation, with a particular focus on biothiosulphate production by adapted microorganisms. The factors that affect the pretreatment, chemical reaction mechanism, and design engineering are discussed. The consumption of thiosulphate was identified as one of the main challenges, restricting the reliability of the process. Various solutions for the reduction of its consumption and relevant process costs were discussed, with a particular examination from the engineering aspect of the process design and scalability to industrially relevant operating conditions by using bioreactors adapted to large pulp density loads of electrical waste. Full article
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18 pages, 6611 KiB  
Article
Optimization of Thiourea-Promoted Gold and Silver Leaching from Pyrite Cinders Using Response Surface Methodology (RSM)
by Yerkezhan Abikak, Bagdaulet Kenzhaliev, Ata Akcil, Seydou Dembele, Aigul Koizhanova, Nauryzbek Bakhytuly and Gulzhaina Kassymova
Processes 2025, 13(5), 1277; https://doi.org/10.3390/pr13051277 - 22 Apr 2025
Viewed by 778
Abstract
The cyanidation of precious metals from ores and secondary resources has been classified as a hazardous process due to the release of toxic gases. The use of environmentally friendly and cost-effective processes is a suitable alternative to cyanidation. Thiourea leaching has been shown [...] Read more.
The cyanidation of precious metals from ores and secondary resources has been classified as a hazardous process due to the release of toxic gases. The use of environmentally friendly and cost-effective processes is a suitable alternative to cyanidation. Thiourea leaching has been shown to be one of the best alternative reagents to cyanide. The present work aims to evaluate the efficiency of the thiourea leaching of gold and silver from pretreated pyrite cinders. The use of pre-chemical activation prior to leaching helped to increase the amount of free gold and silver particles. A preliminary leaching test led to the selection of Fe2(SO4)3 as a suitable oxidizing agent for Au and Ag leaching. To select suitable leaching parameters, the response surface methodology (RSM) was used to optimize some parameters that can considerably affect sulfuric acid–thiourea leaching and identify the greatest interaction between them. The optimized parameters of 30 g/L thiourea, 10% pulp density, pH = 1, and 50 °C over 4 h of leaching time allowed for Au and Ag recoveries of 98.31 and 88.57%, respectively. Full article
(This article belongs to the Special Issue Chemical Systems Dynamic Modeling and Simulation)
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