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Data-Driven Optimization of Surfactants Adsorption for EOR Applications
Measurement Techniques for Interfacial Rheology of Surfactant, Asphaltene, and Protein-Stabilized Interfaces in Emulsions and Foams

Journal Description

Colloids and Interfaces

Colloids and Interfaces is an international, peer-reviewed, open access journal on colloids and interfaces chemistry published bimonthly online by MDPI.

Open Access— free for readers, no limits on space and color.
High Visibility: indexed within Scopus, ESCI (Web of Science), CAPlus / SciFinder, Inspec, and other databases.
Journal Rank: CiteScore - Q2 (Chemistry (miscellaneous))
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 22 days after submission; acceptance to publication is undertaken in 4.5 days (median values for papers published in this journal in the second half of 2024).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.

Impact Factor: 2.5 (2023); 5-Year Impact Factor: 2.6 (2023)

Imprint Information Journal Flyer Open Access ISSN: 2504-5377

Latest Articles

14 pages, 6056 KiB

Open AccessArticle

Preparation of Colloidal Silver Triangular Nanoplates and Their Application in SERS Detection of Trace Levels of Antibiotic Enrofloxacin

by Cao Tuan Anh, Dao Tran Cao and Luong Truc-Quynh Ngan

Colloids Interfaces 2025, 9(3), 31; https://doi.org/10.3390/colloids9030031 - 16 May 2025

Surface-enhanced Raman scattering (SERS) is a powerful technique for detecting trace amounts of chemicals due to its capacity to significantly amplify the Raman signal of the molecules of these substances. This is particularly relevant in food systems where monitoring antibiotic residues is critical [...] Read more.

Surface-enhanced Raman scattering (SERS) is a powerful technique for detecting trace amounts of chemicals due to its capacity to significantly amplify the Raman signal of the molecules of these substances. This is particularly relevant in food systems where monitoring antibiotic residues is critical for food safety. Traditional SERS substrates typically utilize colloidal silver nanospheres (AgNSs), but anisotropic silver nanoparticles with numerous sharp tips can further enhance SERS sensitivity, enabling lower detection limits suitable for food safety regulations. In this study, we describe a straightforward synthesis of colloidal silver triangular nanoplates (AgTNPls), featuring multiple sharp tips, using only four common reagents: silver nitrate, trisodium citrate, sodium borohydride (NaBH₄) and hydrogen peroxide (H₂O₂), all at room temperature. By carefully controlling the sequence of reagent addition, specifically introducing H₂O₂ after NaBH₄, we achieved a two-step synthesis. In the first step, AgNSs seeds form, and in the second, these seeds convert into AgTNPls, resulting in a colloid of relatively uniform AgTNPls with an edge length of approximately 52 nm. The resulting AgTNPls colloid, combined with an aluminum foil, produced an SERS substrate with high enhancement factor of 3.2 × 10⁹ (using rhodamine 6G as a test molecule). Applied to enrofloxacin (an antibiotic widely used in livestock and aquaculture) detection, this substrate achieved a detection limit as low as 0.39 µg/L (0.39 ppb), with enrofloxacin detectable at concentrations down to 5 µg/L. This highly sensitive SERS substrate holds great promise for rapid, accurate detection of antibiotic residues in food products, aiding regulatory compliance and food safety assurance. Full article

(This article belongs to the Special Issue Food Colloids: 3rd Edition)

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15 pages, 5965 KiB

Open AccessFeature PaperArticle

Gel Polymer Electrolytes with High Thermal Stability for Safe Lithium Metal Batteries

by Xianhui Chen, Xue Wang, Xing Li and Xing Xin

Colloids Interfaces 2025, 9(3), 30; https://doi.org/10.3390/colloids9030030 - 14 May 2025

The poor thermal stability of polypropylene (PP) separators poses risks of electrolyte leakage and battery short-circuiting, limiting their application in lithium metal batteries (LMBs). To address these challenges, a gel polymer membrane was designed using polymer blending technology. This membrane effectively retains the [...] Read more.

The poor thermal stability of polypropylene (PP) separators poses risks of electrolyte leakage and battery short-circuiting, limiting their application in lithium metal batteries (LMBs). To address these challenges, a gel polymer membrane was designed using polymer blending technology. This membrane effectively retains the electrolyte, provides a stable environment, enhances thermal stability, and significantly decreases the risk of battery explosions and side reactions between the lithium metal and the electrolyte. Compared to commercial PP separators, the developed blend-type gel polymer electrolyte (b-GPE) demonstrates a superior performance, including structural stability at temperatures up to 150 °C and a high lithium-ion transference number (

t_{{L i}^{+}}

) of 0.513. Furthermore, a cell with a LiCoO₂ cathode operated at a 1 C rate retains 97.4% of its capacity after 300 cycles. After exposure to 120 °C, the b-GPE-120 demonstrates that its performance is comparable to that of the b-GPE, such as a

t_{{L i}^{+}}

of 0.506, a high electrolyte absorption rate, and a wide electrochemical window of 5.2 V. Full article

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30 pages, 6442 KiB

Open AccessArticle

Impact of Carrageenan-Based Encapsulation on the Physicochemical, Structural, and Antioxidant Properties of Freshwater Snail (Bellamya bengalensis) Protein Hydrolysates

by Anand Vaishnav, Naresh Kumar Mehta, Mocherla Bhargavi Priyadarshini, Soibam Khogen Singh, Pratap Chandra Acharya, Satyajeet Biswal, Harjeet Nath, Syed Arshad Hussain, Prasenjit Pal, Jham Lal, Nongthongbam Sureshchandra Singh and Bikash Kumar Pati

Colloids Interfaces 2025, 9(3), 29; https://doi.org/10.3390/colloids9030029 - 13 May 2025

This study investigated the encapsulation of snail protein hydrolysates (SPHs) using carrageenan as a microencapsulating agent at concentrations of 1%, 2%, and 3%. SPHs were prepared from the soft tissue of freshwater snails (Bellamya bengalensis) through enzymatic hydrolysis using bromelain, resulting [...] Read more.

This study investigated the encapsulation of snail protein hydrolysates (SPHs) using carrageenan as a microencapsulating agent at concentrations of 1%, 2%, and 3%. SPHs were prepared from the soft tissue of freshwater snails (Bellamya bengalensis) through enzymatic hydrolysis using bromelain, resulting in a degree of hydrolysis of 48.05%. The encapsulation process was carried out using the spray-drying technique. Encapsulation with 3% carrageenan enhanced the yield, encapsulation efficiency (up to 84.96%), colloidal stability (up to −33.8 mV), and thermal stability (up to 75 °C). The particle size increased as the carrageenan concentration increased, reaching 206.9 nm at 3%, and the uniform polydispersity index (0.26) indicated stable encapsulation. While encapsulation reduces solubility and antioxidant activity (DPPH, FRAP, ABTS, and HRSA), it effectively protects SPH from environmental factors such as hygroscopicity and storage stability, thus maintaining high scavenging activity. Fourier transform infrared spectroscopy confirmed that carrageenan and SPH strongly interact. Scanning electron microscopy revealed that the particles had better shapes and smooth, cohesive surfaces. This study demonstrates the effectiveness of carrageenan as an encapsulating agent for SPH, enhancing its stability and bioactivity for potential applications in the food and nutraceutical industries as a bioactive additive and offering an alternative to conventional coating materials. Full article

(This article belongs to the Special Issue Food Colloids: 3rd Edition)

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19 pages, 5011 KiB

Open AccessArticle

One-Step Synthesis AlCo₂O₄ and Derived “Al” to Double Optimise the Thermal Decomposition Kinetics and Enthalpy of Ammonium Perchlorate

by Kaihua He, Yanzhi Yang, Zhengyi Zhao, Zhiyong Yan and Xuechun Xiao

Colloids Interfaces 2025, 9(3), 28; https://doi.org/10.3390/colloids9030028 - 10 May 2025

The solution combustion method is widely used because of its simple operation and ability to produce porous structures. The chemical composition and morphological structure of the material can be regulated by different oxidiser-to-fuel ratios (φ). In this work, AlCo₂O₄ derived [...] Read more.

The solution combustion method is widely used because of its simple operation and ability to produce porous structures. The chemical composition and morphological structure of the material can be regulated by different oxidiser-to-fuel ratios (φ). In this work, AlCo₂O₄ derived “Al” catalytic materials were successfully synthesised by adjusting the fuel-to-oxidiser ratio using a one-step solution combustion method. On the one hand, the aluminium nanoparticles act as a part of the metal fuel in the composite solid propellant and, at the same time, serve as a catalytic material. In contrast, the thermal decomposition performance of AP was significantly improved by the synergistic catalysis of AlCo₂O₄. Among the samples prepared under different fuel ratios, considering all aspects (high-temperature decomposition temperature, activation energy, and decomposition heat) comprehensively, the AlCo₂O₄ prepared with φ = 0.5 had a more excellent catalytic effect on AP thermal decomposition, and the T_HTD of AP was reduced to 285.4 °C, which is 188.08 °C lower. The activation energy of the thermal decomposition of AP was also significantly reduced (from 296.14 kJ/mol to 211.67 kJ/mol). In addition, the ignition delay time of AlCo₂O₄-AP/HTPB was drastically shortened to 9 ms from 28 ms after the addition of 7% AlCo₂O₄ derived “Al” catalytic materials. Composite solid propellants have shown great potential for application. Full article

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13 pages, 3492 KiB

Open AccessFeature PaperArticle

Magnetic Field Control of Liquid Crystal-Enabled Colloid Electrophoresis

by Joel Torres-Andrés, Guillermo Cassinello, Francesc Sagués and Jordi Ignés-Mullol

Colloids Interfaces 2025, 9(3), 27; https://doi.org/10.3390/colloids9030027 - 6 May 2025

Microswimmers are key for unveiling new physical phenomena underlying their propulsion, especially when driven inside complex fluids. Liquid crystals are anisotropic complex fluids that feature long-range orientational order. The propulsion of non-charged dielectric particles can be accomplished in these systems by breaking the [...] Read more.

Microswimmers are key for unveiling new physical phenomena underlying their propulsion, especially when driven inside complex fluids. Liquid crystals are anisotropic complex fluids that feature long-range orientational order. The propulsion of non-charged dielectric particles can be accomplished in these systems by breaking the particles’ fore-aft symmetry thanks to anisotropies in the conductivity and dielectric permittivity parameters of the liquid crystal. Under the application of an AC electric field, asymmetric osmotic flows are generated to propel non-spherical particles, whose direction of motion depends on the orientational order of the liquid crystal molecules around the inclusions. This means that, by controlling the LC orientation, one will be able to steer driven colloidal inclusions. In this experimental work, we show that a homogeneous magnetic field that is able to control the orientation of the liquid crystal molecules also allows us to determine the direction of motion of driven particles without significant changes in the propulsion mechanism. Additionally, we show that a radial configuration of the magnetic field lines can be used to generate topological defects in the liquid crystal orientational field that attract colloidal particles, leading to their clustering as rotating mills. The generated clusters were tested to study the collective motion of particles, suggesting the presence of particle–particle interactions. Full article

(This article belongs to the Special Issue State of the Art of Colloid and Interface Science in the Iberian Peninsula)

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16 pages, 2872 KiB

Open AccessArticle

Formulating Graphite-Filled PU Dispersions with Extended Shelf Life Using the Capillary Suspension Concept

by Katrin Dyhr and Norbert Willenbacher

Colloids Interfaces 2025, 9(3), 26; https://doi.org/10.3390/colloids9030026 - 2 May 2025

Stabilizing micron-sized particles in low-viscosity polymer dispersions is challenging when density differences are present. This study demonstrates that graphite particles in aqueous polyurethane dispersions can be efficiently prevented from sedimentation using the capillary suspension concept. Capillary suspensions are solid/liquid/liquid systems and the capillary [...] Read more.

Stabilizing micron-sized particles in low-viscosity polymer dispersions is challenging when density differences are present. This study demonstrates that graphite particles in aqueous polyurethane dispersions can be efficiently prevented from sedimentation using the capillary suspension concept. Capillary suspensions are solid/liquid/liquid systems and the capillary forces inferred from adding a second immiscible fluid can lead to drastic changes in texture and flow. Here, both spherical and flake-shaped graphite particles were used as fillers, with octanol as the secondary liquid. At low graphite concentrations, octanol increases the low-shear viscosity significantly attributed to the formation of loose particle aggregates immobilizing part of the continuous phase. Above a critical graphite concentration, capillary forces induce a self-assembling, percolating particle network, leading to a sharp yield stress increase (>100 Pa). The corresponding percolating particle network efficiently suppresses sedimentation; for the system including 28 vol% spherical particles, a shelf life of at least six months was achieved. Capillary forces do not affect the high-shear viscosity of suspensions; here, a hydrophobically modified polyether thickener can be used. Transfer of the stabilization concept presented here to other high-density particles like silver or metal oxides suspended in other polymer dispersions is straightforward and is applicable in various fields like flexible printed electronics. Full article

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17 pages, 4755 KiB

Open AccessArticle

Influence and Correction of Refraction Phenomenon in Liquid Contact Angle Measurement in Capillary Tube

by Weixiu Shi, Mengmeng Ran and Lisheng Pan

Colloids Interfaces 2025, 9(3), 25; https://doi.org/10.3390/colloids9030025 - 23 Apr 2025

By using clear vapor–liquid interface line images of the liquid inside the capillary, the measurement coordinate points of the vapor–liquid interface line were measured. A new method for measuring liquid contact angle has been proposed, which was used to calculate the actual coordinate [...] Read more.

By using clear vapor–liquid interface line images of the liquid inside the capillary, the measurement coordinate points of the vapor–liquid interface line were measured. A new method for measuring liquid contact angle has been proposed, which was used to calculate the actual coordinate points and fit the actual vapor–liquid interface line of the liquid. Finally, an angle measurement tool is used to measure the angle of the actual vapor–liquid interface line and obtain the actual contact angle of the liquid. Effectively reducing the influence of refraction on the contact angle by correcting the errors caused by the refractive index of different materials, it can be used for the precise measurement of the static contact angle of liquids. By measuring the static contact angle of the upper and lower liquid surfaces of the liquid column, it was found that the presence of refraction caused a difference of [1.84°, 5.61°] between the actual and measured values of the static contact angle. Full article

(This article belongs to the Special Issue Bubble and Drop 2025 (B&D 2025))

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15 pages, 2841 KiB

Open AccessFeature PaperArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessFeature PaperArticle

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

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

Open AccessArticle

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

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

Open AccessReview

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

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

Open AccessArticle

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

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

Open AccessFeature PaperReview

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

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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46 pages, 13796 KiB

Open AccessFeature PaperReview

Measurement Techniques for Interfacial Rheology of Surfactant, Asphaltene, and Protein-Stabilized Interfaces in Emulsions and Foams

by Ronald Marquez and Jean-Louis Salager

Colloids Interfaces 2025, 9(1), 14; https://doi.org/10.3390/colloids9010014 - 14 Feb 2025

Cited by 1

This work provides a comprehensive review of experimental methods used to measure rheological properties of interfacial layers stabilized by surfactants, asphaltenes, and proteins that are relevant to systems with large interfacial areas, such as emulsions and foams. Among the shear methods presented, the [...] Read more.

This work provides a comprehensive review of experimental methods used to measure rheological properties of interfacial layers stabilized by surfactants, asphaltenes, and proteins that are relevant to systems with large interfacial areas, such as emulsions and foams. Among the shear methods presented, the deep channel viscometer, bicone rheometer, and double-wall ring rheometers are the most utilized. On the other hand, the main dilational rheology techniques discussed are surface waves, capillary pressure, oscillating Langmuir trough, oscillating pendant drop, and oscillating spinning drop. Recent developments—including machine learning and artificial intelligence (AI) models, such as artificial neural networks (ANN) and convolutional neural networks (CNN)—to calculate interfacial tension from drop shape analysis in shorter times and with higher precision are critically analyzed. Additionally, configurations involving an Atomic Force Microscopy (AFM) cantilever contacting bubble, a microtensiometer platform, rectangular and radial Langmuir troughs, and high-frequency oscillation drop setups are presented. The significance of Gibbs–Marangoni effects and interfacial rheological parameters on the (de)stabilization of emulsions is also discussed. Finally, a critical review of the recent literature on the measurement of interfacial rheology is presented. Full article

(This article belongs to the Special Issue Rheology of Complex Fluids and Interfaces)

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17 pages, 2350 KiB

Open AccessFeature PaperArticle

Viral Clearance of Cupric-Modified Phyllosilicate Minerals Against Enveloped and Non-Enveloped Viruses

by Vaishali Sharma, Sneha Singh, Natalie M. Nold, Supreet Kaur, Bowen Li and Caryn L. Heldt

Colloids Interfaces 2025, 9(1), 13; https://doi.org/10.3390/colloids9010013 - 14 Feb 2025

The effectiveness of copper-based composites, specifically cupric ion (Cu²⁺)-modified phyllosilicate minerals, was evaluated in reducing the concentration of infectious agents in the environment while minimizing metal ion release. The phyllosilicate minerals, vermiculite, exfoliated and unexfoliated, and sepiolite, all modified with Cu [...] Read more.

The effectiveness of copper-based composites, specifically cupric ion (Cu²⁺)-modified phyllosilicate minerals, was evaluated in reducing the concentration of infectious agents in the environment while minimizing metal ion release. The phyllosilicate minerals, vermiculite, exfoliated and unexfoliated, and sepiolite, all modified with Cu²⁺, were compared with copper oxide for their antiviral activity against non-enveloped porcine parvovirus (PPV) and enveloped human coronavirus 229E (HCoV). Sepiolite effectively removed PPV and HCoV from the solution, regardless of Cu²⁺ presence, while vermiculite showed substantial viral clearance only when Cu²⁺ was present. The kinetics of viral clearance was fast, with complete clearance within one hour in many cases. To better understand the mechanism of virus clearance, EDTA was added at different times during the clearance study for PPV. EDTA prevented virus clearance in all vermiculite samples, whereas sepiolite containing copper still demonstrated substantial virus clearance. The addition of BSA before the virus binding was able to block binding in all cases. It was determined that binding is the key mechanism, and PPV can be eluted from the minerals with EDTA and still be infectious. This study provides the potent antiviral mechanisms of Cu²⁺-modified phyllosilicate minerals, offering insights for designing paints and plastics for high-touch surfaces to reduce viral transmission and enhance public health significantly. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces: 2nd Edition)

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11 pages, 2190 KiB

Open AccessFeature PaperArticle

Transient Electroosmosis on a Soft Surface

by Hiroyuki Ohshima

Colloids Interfaces 2025, 9(1), 12; https://doi.org/10.3390/colloids9010012 - 4 Feb 2025

Cited by 1

A general theory was developed for the time-dependent transient electroosmosis on a planar soft surface, i.e., a polyelectrolyte-coated solid surface in an electrolyte solution, when an electric field is suddenly applied. This serves as a simple model for the time-dependent electrokinetic phenomena occurring [...] Read more.

A general theory was developed for the time-dependent transient electroosmosis on a planar soft surface, i.e., a polyelectrolyte-coated solid surface in an electrolyte solution, when an electric field is suddenly applied. This serves as a simple model for the time-dependent electrokinetic phenomena occurring at biointerfaces. A closed-form approximate expression is derived for the electroosmotic velocity distribution within the polyelectrolyte layer as a function of both position and time. This analysis reveals that the temporal and spatial variations in the electroosmotic flow caused by the surface charges of the solid surface is confined to the region near the solid surface. In contrast, the variations due to the fixed charges within the polyelectrolyte layer extend over a wider region inside the polyelectrolyte layer. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces: 2nd Edition)

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