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Colloids Interfaces, Volume 9, Issue 2 (April 2025) – 10 articles

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15 pages, 2841 KiB  
Article
A Bio-Based Collector Derived from Vitamin E for Hematite Flotation
by Rocky Mensah, Tammitage Danesh S. Perera, Tina Hsia, Pouria Amani, San H. Thang and Mahshid Firouzi
Colloids Interfaces 2025, 9(2), 24; https://doi.org/10.3390/colloids9020024 - 11 Apr 2025
Viewed by 328
Abstract
The increasing demand for sustainable mining practices has driven the development of environmentally friendly reagents for mineral processing. This study investigates vitamin E sodium succinate (VE_SS), a novel bio-based collector, for its potential in hematite flotation. The performance of VE_SS was benchmarked against [...] Read more.
The increasing demand for sustainable mining practices has driven the development of environmentally friendly reagents for mineral processing. This study investigates vitamin E sodium succinate (VE_SS), a novel bio-based collector, for its potential in hematite flotation. The performance of VE_SS was benchmarked against sodium oleate (NaOL), a widely used conventional collector in mineral processing. To assess the flotation performance of VE_SS, micro-flotation experiments were conducted using hematite, sourced from a mine, and silica, a common associated gangue mineral. These tests were complemented by comprehensive surface characterizations, including contact angle measurements, zeta potential analysis, Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), to investigate the adsorption mechanisms of VE_SS in comparison to NaOL. The results demonstrate that VE_SS effectively enhances hematite recovery, achieving levels comparable to NaOL. Furthermore, VE_SS exhibited reduced sensitivity to pH, addressing a key limitation of NaOL, which performs well in neutral to alkaline conditions but shows significantly lower recovery under acidic pH. These findings highlight the potential of VE_SS as a bio-based alternative to conventional collectors, contributing to the advancement of more sustainable mineral processing practices. Full article
(This article belongs to the Special Issue Colloids and Interfaces in Mineral Processing)
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10 pages, 1581 KiB  
Article
Electronic Characteristics of Layered Heterostructures Based on Graphene and Two-Dimensional Perovskites: First-Principle Study
by Lev Zubkov, Pavel Kulyamin, Konstantin Grishakov, Savaş Kaya, Konstantin Katin and Mikhail Maslov
Colloids Interfaces 2025, 9(2), 23; https://doi.org/10.3390/colloids9020023 - 10 Apr 2025
Viewed by 239
Abstract
Layered perovskites have been actively studied due to their outstanding electronic and optical properties as well as kinetic stability. Layered perovskites with hexagonal symmetry have special electronic properties, such as the Dirac cone in the band structure, similar to graphene. In the presented [...] Read more.
Layered perovskites have been actively studied due to their outstanding electronic and optical properties as well as kinetic stability. Layered perovskites with hexagonal symmetry have special electronic properties, such as the Dirac cone in the band structure, similar to graphene. In the presented study, the heterostructure of single-layer all-inorganic lead-free hexagonal perovskite of the A3B2X9 type (A = Cs, Rb, K; B = In, Sb; X = Cl, Br) and graphene (Gr) was studied. The structural and electronic characteristics of A3B2X9 and the A3B2X9/Gr composite were calculated using density functional theory. It was found that graphene is not deformed, while the main deformation is observed only in perovskite. B-X bonds have different sensitivities to stretching or compression. The Fermi level of the A3In2X9/Gr composite can be shifted down from the Dirac point, which can be used to create optoelectronic devices or as spacer layers for graphene-based resonant tunneling nanostructures. Full article
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12 pages, 3037 KiB  
Article
Removing Fluoride from Water by Nanostructured Magnesia-Impregnated Activated Carbon
by Chen Yang, Chenliang Shen, Nan Zhang, Xusheng Zhang, Liang Zhao and Jianzhong Zheng
Colloids Interfaces 2025, 9(2), 22; https://doi.org/10.3390/colloids9020022 - 9 Apr 2025
Viewed by 245
Abstract
A facile method was employed to impregnate activated carbon, a commonly used water treatment medium, with nanostructured magnesium oxide for fluoride removal. Batch adsorption tests were conducted to evaluate the adsorption performance of the nanostructured magnesia-impregnated activated carbon (nMgO@AC) for fluoride removal. The [...] Read more.
A facile method was employed to impregnate activated carbon, a commonly used water treatment medium, with nanostructured magnesium oxide for fluoride removal. Batch adsorption tests were conducted to evaluate the adsorption performance of the nanostructured magnesia-impregnated activated carbon (nMgO@AC) for fluoride removal. The results demonstrated that this composite material exhibited a good adsorption capacity, with a maximum equilibrium uptake of approximately 121.1 mg/g for fluoride. Kinetic studies revealed that the adsorption process followed the pseudo-second-order adsorption kinetic model, reaching equilibrium in about 100 min. Within the initial pH range of 3 to 11, the adsorption efficiency of nMgO@AC for fluoride remained above 95%, indicating that the initial solution pH had a minimal effect on the material’s fluoride removal capability. The adsorption mechanism was elucidated by characterizing the material properties before and after adsorption using SEM, TEM, XRD and XPS. Initially, magnesium oxide reacted with water and rapidly transformed into magnesium hydroxide. Subsequently, a ligand exchange occurred between the hydroxide groups in magnesium hydroxide and fluoride ions in the aqueous solution, resulting in the effective removal of fluoride. The findings of this study suggest that nanostructured magnesia-impregnated activated carbon holds significant potential for the treatment of fluoride-containing wastewater, particularly for highly alkaline wastewater. Full article
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14 pages, 4232 KiB  
Article
Fenugreek Polysaccharide Gum as a Depressant in the Flotation Separation of Gold Ore with a High Content of Clay Minerals
by Qingqing Xing, Pingtian Ming, Xiaohui Wang, Fei Li, Zhen Wang and Kaile Zhao
Colloids Interfaces 2025, 9(2), 21; https://doi.org/10.3390/colloids9020021 - 31 Mar 2025
Viewed by 268
Abstract
A gold mine located in western China is facing the problem of a low concentrate grade, significantly hindering its economic benefits. Preliminary assessments indicate that this is caused by gangue minerals that are prone to floating and sliming, necessitating suppression in the flotation [...] Read more.
A gold mine located in western China is facing the problem of a low concentrate grade, significantly hindering its economic benefits. Preliminary assessments indicate that this is caused by gangue minerals that are prone to floating and sliming, necessitating suppression in the flotation process. The effect of fenugreek polysaccharide gum (FGM) upon the flotation separation of arsenopyrite (representative of Au-bearing minerals) and pyrophyllite (a typical gangue mineral) was investigated; its industrial potential was verified through actual ore flotation and pilot plant testing. Additionally, the selective inhibition mechanism of FGM on pyrophyllite was elucidated. The flotation tests of pure minerals indicated that pyrophyllite has a high natural floatability; thus, it cannot be separated from arsenopyrite at low alkaline pH (7–9); smaller pyrophyllite particle sizes, especially −0.038 mm fractions, significantly decreased the arsenopyrite recovery; FGM can eliminate this adverse effect to a large extent through its selective depression of the flotation of pyrophyllite. For real ore systems, FGM also exhibited superior performance compared with the commonly used silicate and SHMP; closed-circuit flotation tests showed that the gold grade of the concentrate increased by 3.90 g/t and the enrichment ratio increased by 2.53 with the addition of FGM. As of now, FGM has increased the profits by USD 1.715 M in the past two years by improving concentrate grade and recovery efficiency. According to the results of contact angle, zeta potential, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), the selective adsorption of FGM onto the pyrophyllite surface was the reason for the positive effect; the interaction primarily involved the Al sites on the pyrophyllite surface and the –OH on FGM molecules. Full article
(This article belongs to the Special Issue Colloids and Interfaces in Mineral Processing)
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18 pages, 12270 KiB  
Article
Sulfonate Thiacalixarene-Modified Polydiacetylene Vesicles as Colorimetric Sensors for Lead Ion Detection
by Angelina A. Fedoseeva, Indira Yespanova, Elza D. Sultanova, Bulat Kh. Gafiatullin, Regina R. Ibragimova, Klara Kh. Darmagambet, Marina A. Il’ina, Egor O. Chibirev, Vladimir G. Evtugyn, Nurbol O. Appazov, Vladimir A. Burilov, Svetlana E. Solovieva and Igor S. Antipin
Colloids Interfaces 2025, 9(2), 20; https://doi.org/10.3390/colloids9020020 - 28 Mar 2025
Viewed by 329
Abstract
We report the first synthesis of zwitterionic thiacalixarenes featuring imidazolium and sulfonate groups on the upper rim and alkyl (butyl or octyl) fragments on the lower rim of the platform. Despite their amphiphilic structure, these macrocycles exhibit limited water solubility. However, dynamic light [...] Read more.
We report the first synthesis of zwitterionic thiacalixarenes featuring imidazolium and sulfonate groups on the upper rim and alkyl (butyl or octyl) fragments on the lower rim of the platform. Despite their amphiphilic structure, these macrocycles exhibit limited water solubility. However, dynamic light scattering detected the formation of associates for derivatives with octyl moieties at a concentration of 0.1 mM. To develop stable materials for aqueous environments and to investigate the functionality of zwitterionic sulfonate-imidazolium groups along with the thiacalixarene platform, mixed organo-organic systems based on polydiacetylene polymer were created. Characterization of the modified polydiacetylene systems through various analytical methods revealed a significant colorimetric response to lead ions in aqueous media, surpassing that of the unmodified polydiacetylene polymer. Additionally, the modified polymers demonstrated efficacy in purifying aqueous media from lead ions, as evidenced by anodic stripping voltammetry (ASV) and microwave plasma atomic emission spectroscopy (MP AES). Full article
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24 pages, 3728 KiB  
Article
Surfactants Adsorption onto Algerian Rock Reservoir for Enhanced Oil Recovery Applications: Prediction and Optimization Using Design of Experiments, Artificial Neural Networks, and Genetic Algorithm (GA)
by Kahina Imene Benramdane, Mohamed El Moundhir Hadji, Mohamed Khodja, Nadjib Drouiche, Bruno Grassl and Seif El Islam Lebouachera
Colloids Interfaces 2025, 9(2), 19; https://doi.org/10.3390/colloids9020019 - 25 Mar 2025
Viewed by 517
Abstract
This study investigates the adsorption of surfactants on Algerian reservoir rock from Hassi Messaoud. A new data generation method based on a design of experiments (DOE) approach has been developed to improve the accuracy of adsorption modeling using artificial neural networks (ANNs). Unlike [...] Read more.
This study investigates the adsorption of surfactants on Algerian reservoir rock from Hassi Messaoud. A new data generation method based on a design of experiments (DOE) approach has been developed to improve the accuracy of adsorption modeling using artificial neural networks (ANNs). Unlike traditional data acquisition methods, this approach enables a methodical and structured exploration of adsorption behavior while reducing the number of required experiments, leading to improved prediction accuracy, optimization, and cost-effectiveness. The modeling is based on three key parameters: surfactant type (SDS and EOR ASP 5100), concentration, and temperature. The dataset required for ANN training was generated from a polynomial model derived from a full factorial design (DOE) established in a previous study. Before training, 32 different ANN configurations were evaluated by varying learning algorithms, adaptation functions, and transfer functions. The best-performing model was a cascade-type network employing the Levenberg–Marquardt learning function, learngdm adaptation, tansig activation function for the hidden layer, and purelin for the output layer, achieving an R2 of 0.99 and an MSE of 6.84028 × 10−9. Compared to DOE-based models, ANN exhibited superior predictive accuracy, with a performance factor (PF/3) of 0.00157 and the same MSE. While DOE showed a slight advantage in relative error (9.10 × 10−5% vs. 1.88 × 10−4% for ANN), ANN proved more effective overall. Three optimization approaches—ANN-GA, DOE-GA, and DOE-DF (desirability function)—were compared, all converging to the same optimal conditions (SDS at 200 ppm and 25 °C). This similarity between the various optimization techniques confirms the strength of genetic algorithms for optimization in the field of EOR and that they can be reliably applied in practical field operations. However, ANN-GA exhibited slightly better convergence, achieving a fitness value of 2.3247. Full article
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15 pages, 7244 KiB  
Article
Molecular Dynamics Study on the Lubrication Mechanism of the Phytic Acid/Copper Interface Under Loading Condition
by Min Guan, Dong Xie, Xiaoting Wang, Fengjuan Jing, Feng Wen and Yongxiang Leng
Colloids Interfaces 2025, 9(2), 18; https://doi.org/10.3390/colloids9020018 - 22 Mar 2025
Viewed by 275
Abstract
To investigate the lubrication mechanism of phytic acid (PA) solution, a “copper–PA solution–copper” confined model with varying concentrations was established. Molecular dynamics (MD) simulations were employed to model the behavior of compression and the confined shear process. By examining the variations in key [...] Read more.
To investigate the lubrication mechanism of phytic acid (PA) solution, a “copper–PA solution–copper” confined model with varying concentrations was established. Molecular dynamics (MD) simulations were employed to model the behavior of compression and the confined shear process. By examining the variations in key parameters such as dynamic viscosity, compressibility, radial distribution function, relative concentration distribution, and velocity distribution of PA solutions under different normal loads or shear rates, we elucidated the lubrication mechanism of PA solutions at the molecular level. The results demonstrate that under standard loading conditions, higher PA concentrations facilitate the formation of denser hydrated layers with decreased compressibility compared to free water, thereby significantly enhancing the load-bearing capacity. The shear stress at the solution–copper interface exhibits a substantial increase as the shear rate rises. This phenomenon originates from shear-driven migration of PA to the copper interface, disrupting the hydration layers and weakening hydrogen bonds. Consequently, this reduction in PA–water interactions amplifies slip velocity differences, ultimately elevating interfacial shear stress. The load-bearing capacity of the PA solution and the interfacial shear stress between the PA and copper are critical factors that influence the lubrication mechanism at the PA/Cu interface. This study establishes a theoretical foundation for the design and application of PA solution as a water-based lubricant, which holds significant importance for advancing the development of green lubrication technology. Full article
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26 pages, 1518 KiB  
Review
A Mini-Review on Enhancing Solubility in Topical Hydrogel Formulations Using Solid Dispersion Technology for Poorly Water-Soluble Drugs
by Zaid Dahma, Covadonga Álvarez-Álvarez and Paloma Marina de la Torre-Iglesias
Colloids Interfaces 2025, 9(2), 17; https://doi.org/10.3390/colloids9020017 - 21 Mar 2025
Viewed by 504
Abstract
The solubility behavior of drugs is a critical factor in formulation development. Approximately 40–45% of new drugs face market entry challenges due to low water solubility. Enhancing drug bioavailability is thus essential in developing pharmaceutical dosage forms. Many biopharmaceutical class II and IV [...] Read more.
The solubility behavior of drugs is a critical factor in formulation development. Approximately 40–45% of new drugs face market entry challenges due to low water solubility. Enhancing drug bioavailability is thus essential in developing pharmaceutical dosage forms. Many biopharmaceutical class II and IV drugs are commonly prescribed to treat inflammations, infections, and pain from various pathologies. Their oral administration has several drawbacks, including significant first-pass liver effects, low bioavailability, and adverse gastrointestinal effects. Topical application has gained relevance due to its advantages in delivering drugs directly to the target site, avoiding gastrointestinal irritation, and increasing their effectiveness. However, topical hydrogel formulations with poorly water-soluble drugs face challenges related to the skin’s permeability. Therefore, preparing topical hydrogels using solid dispersions (SDs) is an effective strategy to enhance the dissolution rate of poorly soluble drugs, thereby improving their topical bioavailability. In this review, the concepts of SDs, topical delivery systems, and topical hydrogel formulations incorporating SDs, as well as their preparation methods, characterization, and applications, will be discussed. Full article
(This article belongs to the Special Issue Biocolloids and Biointerfaces: 2nd Edition)
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14 pages, 1978 KiB  
Article
Determination of Particle Mixture Composition by Visible Spectroscopy
by Mauricio Escudey, Lizethly Cáceres-Jensen and Manuel Gacitúa
Colloids Interfaces 2025, 9(2), 16; https://doi.org/10.3390/colloids9020016 - 12 Mar 2025
Viewed by 486
Abstract
Limited methods exist to determine the composition of particle mixtures. This research presents a simple UV-vis-spectroscopy-based method for the separate quantification of particles mixtures considering the following: synthesized ferrihydrite, commercial Fe2O3, and natural allophane. Calibration curves and adsorption/scattering coefficients [...] Read more.
Limited methods exist to determine the composition of particle mixtures. This research presents a simple UV-vis-spectroscopy-based method for the separate quantification of particles mixtures considering the following: synthesized ferrihydrite, commercial Fe2O3, and natural allophane. Calibration curves and adsorption/scattering coefficients are determined for each particle at different wavelengths. This is the main input to solve equation systems and, ultimately, quantify particle concentration in binary mixtures. The limit of detection varies with wavelength and particle type, yielding values as low as 1.5, 0.2, and 1.6 mg L−1 for ferrihydrite (500 nm), Fe2O3 (450 nm), and natural allophane (450 nm), respectively. This study provides a simple, low-cost and straightforward method, compared to atomic-spectroscopy- or chromatography-based techniques, for resolving the composition of binary particle mixtures in suspension. Full article
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23 pages, 2278 KiB  
Review
Nanosized Being of Ionic Surfactant Micelles: An Advanced View on Micellization Process
by Olga S. Zueva, Mariia A. Kazantseva and Yuriy F. Zuev
Colloids Interfaces 2025, 9(2), 15; https://doi.org/10.3390/colloids9020015 - 28 Feb 2025
Viewed by 671
Abstract
An advanced model of ionic surfactant micellization has been developed. The structural and kinetic properties of micelles were analyzed in parallel from a universally accepted point of view and taking into account the principles of quantum mechanics, the phenomenon of ion pairing in [...] Read more.
An advanced model of ionic surfactant micellization has been developed. The structural and kinetic properties of micelles were analyzed in parallel from a universally accepted point of view and taking into account the principles of quantum mechanics, the phenomenon of ion pairing in the Stern layer, the symmetry considerations, and the chaos theory. It was shown that a micelle can be considered as a layered fullerene-like structure with a cavity in its center, possessing the solid-like properties of micelles in radial directions and the liquid-like properties in the perpendicular ones, allowing for water penetration between the surfactant head group and nearby methylene groups. The dimensions of the minimal fullerene-like structure formed by the terminal hydrogen atoms of surfactant methyl groups around the central cavity, unable to be occupied by surfactant tail fragments, were estimated. It was indicated that permanently occurring surfactant self-organization/disintegration needs a probabilistic description and revision of processes occurring in micellar systems built by ionic surfactants. It was noted that the probabilistic approach alters the mechanism of colloidal dissolution of hydrocarbon compounds and their solubilization by micelles. The advanced model proposes the same macroscopic properties of micelles as the classical one but modifies the structural characteristics of micelles on the nanoscale. Full article
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