Special Issue "Selected Papers from XVI Polish–Ukrainian Symposium on Theoretical and Experimental Studies of Interfacial Phenomena and their Technological Applications"

A special issue of Colloids and Interfaces (ISSN 2504-5377).

Deadline for manuscript submissions: closed (30 December 2018)

Special Issue Editors

Guest Editor
Dr. Eugene V. Aksenenko

A.V. Dumanski Institute of Colloid Chemistry and Chemistry of Water, National Academy of Sciences of Ukraine, Kyiv (Kiev), Ukraine
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Interests: theoretical issues of adsorption on solid/fluid and fluid/fluid interfaces; quantum chemical calculations of supramolecular systems which simulate adsorbed clusters; thermodynamic models of adsorption; development of software for fitting the thermodynamic models of adsorbed layers to the experimental data
Guest Editor
Dr. Alexandra Szcześ

Department of Physical Chemistry-Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Sklodowska University, M.C.-Sklodowska Sq. 3/114 20-031 Lublin, Poland
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Phone: +48 81 537 7747
Interests: colloid and interface science; biomaterials and nanomaterials; liposomes
Guest Editor
Dr. Barbara Charmas

Faculty of Chemistry, Maria Curie-Sklodowska University, Lublin, Poland
Website | E-Mail
Interests: porous materials; nanomaterials and composites; mechanochemistry; cryoporometry DSC; thermal analysis

Special Issue Information

Dear Colleagues,

Successive Polish–Ukrainian Symposia are of great tradition and fame as an important scientific event, being the result of extensive and many years’ worth of collaboration between scientists from various research centers in Ukraine and Poland. The main aims of these symposia are the development of closer ties between Polish and Ukrainian research groups working in the field of theoretical and experimental studies of surface phenomena and their applications in practice.

The main topics of the symposia are: Sorption from gaseous and liquid phases, gas chromatography, ion exchange, heterogeneous catalysis, application of quantum mechanical methods for the study of the surface chemistry of dispersed materials, preparation of new adsorbents, ion exchangers and catalysts, and their application in various techniques, medicine and research practice.

The information of the event is posted on the Symposium web-site:
http://www.thomascat.info/Symposium.htm

Dr. Eugene V. Aksenenko
Dr. Aleksandra Szcześ
Dr. Barbara Charmas
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Theoretical problems of adsorption and colloid chemistry
  • Adsorption and adsorbents
  • Ion exchange. Chromatography
  • Catalysis and catalysts
  • Human health and environment protection

Published Papers (24 papers)

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Research

Open AccessArticle
Adsorption of Uranium (VI) from Aqueous Solutions by Amino-functionalized Clay Minerals
Colloids Interfaces 2019, 3(1), 41; https://doi.org/10.3390/colloids3010041
Received: 22 December 2018 / Revised: 20 March 2019 / Accepted: 22 March 2019 / Published: 23 March 2019
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Abstract
Silylation of clay minerals from Cherkasy deposit (Ukraine) montmorillonite (layer silicate) and palygorskite (fibrous silicate) was performed using organosilane (3-aminopropyl)triethoxysilane (APTES). Solvents with different polarity (ethanol, toluene) were used in synthesis. The structure of modified minerals was characterized by complex of methods (X-ray [...] Read more.
Silylation of clay minerals from Cherkasy deposit (Ukraine) montmorillonite (layer silicate) and palygorskite (fibrous silicate) was performed using organosilane (3-aminopropyl)triethoxysilane (APTES). Solvents with different polarity (ethanol, toluene) were used in synthesis. The structure of modified minerals was characterized by complex of methods (X-ray powder diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption at −196 °C and thermal analysis). Studies of adsorption characteristics of APTES-modified clay minerals were carried out in relation to uranium (VI). The results indicated that modified montmorillonite and palygorskite were effective materials for water purification from UO22+. Full article
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Open AccessArticle
Wetting Properties of Polyetheretherketone Plasma Activated and Biocoated Surfaces
Colloids Interfaces 2019, 3(1), 40; https://doi.org/10.3390/colloids3010040
Received: 29 December 2018 / Revised: 27 February 2019 / Accepted: 12 March 2019 / Published: 16 March 2019
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Abstract
Polyetheretherketone (PEEK) biomaterial is a polymer which has been widely used since the early 90s as a material for human bone implant preparations. Nowadays it is increasingly used due to its high biocompatibility and easily modeling, as well as better mechanical properties and [...] Read more.
Polyetheretherketone (PEEK) biomaterial is a polymer which has been widely used since the early 90s as a material for human bone implant preparations. Nowadays it is increasingly used due to its high biocompatibility and easily modeling, as well as better mechanical properties and price compared to counterparts made of titanium or platinum alloys. In this paper, air low-temperature and pressure plasma was used to enhance PEEK adhesive properties as well as surface sterilization. On the activated polymeric carrier, biologically-active substances have been deposited with the Langmuir-Blodgett technique. Thereafter, the surface was characterized using optical profilometry, and wettability was examined by contact angle measuring. Next, the contact angle hysteresis (CAH) model was used to calculate the surface free energy of the modified surface of PEEK. The variations of wettability and surface free energy were observed depending on the deposited monolayer type and its components. Full article
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Open AccessArticle
Titanium Silicates Precipitated on the Rice Husk Biochar as Adsorbents for the Extraction of Cesium and Strontium Radioisotope Ions
Colloids Interfaces 2019, 3(1), 36; https://doi.org/10.3390/colloids3010036
Received: 27 December 2018 / Revised: 24 February 2019 / Accepted: 1 March 2019 / Published: 12 March 2019
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Abstract
The aim of the work was the development of cheap and effective adsorbents based on titanium silicates deposited on the products of thermochemical processing of rice husk to extract cesium and strontium radioisotopes from aqueous media. Synthesis of adsorbents was carried out using [...] Read more.
The aim of the work was the development of cheap and effective adsorbents based on titanium silicates deposited on the products of thermochemical processing of rice husk to extract cesium and strontium radioisotopes from aqueous media. Synthesis of adsorbents was carried out using the cheapest and widely used titanium water-soluble reagent, titanium sulfate (an intermediate product of white rutile pigment production), as feedstock. After treatment with titanium sulfate and neutralization, hydrothermal treatment was carried out in various ways. The traditional method of processing in an autoclave was used, as well as the blowing at different temperatures by steam. The distribution coefficients and the adsorption capacity for cesium and strontium ions on these sorbents were studied. Along with the chemical composition of adsorbents obtained by those ways, the type and the temperature of hydrothermal treatment also affected the adsorption properties. It was found that the adsorbent obtained by hydrothermal treatment in an autoclave has the highest degree of cesium ions extraction (Kd = 27,500). The highest degree of strontium ions extraction (Kd = 2,095,000) has an adsorbent obtained by hydrothermal treatment with water vapor blowing. Full article
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Open AccessArticle
Sorption Membranes and Filter for Water Purification and Disinfection in Outdoor Conditions
Colloids Interfaces 2019, 3(1), 35; https://doi.org/10.3390/colloids3010035
Received: 27 December 2018 / Revised: 2 March 2019 / Accepted: 4 March 2019 / Published: 11 March 2019
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Abstract
The aim of this article was to develop a simple, cheap, light, highly efficient sorption membrane and filtering device for the purification of naturally polluted water with application in outdoor conditions. Sorption membranes have been prepared from cellulose pulp using paper and pulp [...] Read more.
The aim of this article was to develop a simple, cheap, light, highly efficient sorption membrane and filtering device for the purification of naturally polluted water with application in outdoor conditions. Sorption membranes have been prepared from cellulose pulp using paper and pulp technology. The sorbents were introduced into paper pulp as a filler (as activated carbon) or were chemically grafted to cellulose fibers. The absorption ability of such membranes assembled in a filter device has been investigated. The removal of weighted small mechanical particles, microorganisms, dissolved organic contaminants and colloids, and the undesirable ion impurities by the filter was investigated. Using a 10 × 10 cm filter, purification and disinfection of 18 liters of natural polluted water from a lake was done. Purification of dirty water occurs with gravity from a tank (bucket). Full article
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Open AccessArticle
Thermal Transformation of Caffeic Acid on the Nanoceria Surface Studied by Temperature Programmed Desorption Mass-Spectrometry, Thermogravimetric Analysis and FT–IR Spectroscopy
Colloids Interfaces 2019, 3(1), 34; https://doi.org/10.3390/colloids3010034
Received: 31 December 2018 / Revised: 22 February 2019 / Accepted: 5 March 2019 / Published: 11 March 2019
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Abstract
The studies of pyrolysis of caffeic acid (CA) and its surface complexes is important for the development of technologies of heterogeneous catalytic pyrolysis of plant- and wood- based renewable biomass components. In this work, the structure and thermal transformations of the surface complexes [...] Read more.
The studies of pyrolysis of caffeic acid (CA) and its surface complexes is important for the development of technologies of heterogeneous catalytic pyrolysis of plant- and wood- based renewable biomass components. In this work, the structure and thermal transformations of the surface complexes of CA on the surface of nanoceria were investigated using Fourier transform–infrared (FT–IR) spectroscopy, thermogravimetric analysis (TGA) and temperature-programmed desorption mass spectrometry (TPD MS). It was found that CA on the surface of cerium dioxide forms several types of complexes: bidentate carboxylates, monodentate carboxylates and complexes formed as a result of interaction with phenolic hydroxyl groups. This is due to the ability of nanosized cerium dioxide to generate basic hydroxyl groups that can deprotonate phenolic groups to form phenolates on the surface. The main pyrolysis products were identified. The possible ways of forming 3,4-dihydroxyphenylethylene, acetylene carboxylic acid, pyrocatechol and phenol from surface complexes of CA were suggested. It was established that on the nanoceria surface effectively occur the decarboxylation, decarbonylation, and dehydration reactions of the CA, which are the desirable processes in biomass conversion technologies. Full article
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Open AccessArticle
Development of Cu-Modified PVC and PU for Catalytic Generation of Nitric Oxide
Colloids Interfaces 2019, 3(1), 33; https://doi.org/10.3390/colloids3010033
Received: 22 December 2018 / Revised: 16 February 2019 / Accepted: 4 March 2019 / Published: 9 March 2019
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Abstract
Nitric oxide (NO) generating surfaces are potentially promising for improving haemocompatibility of blood-contacting biomaterials. In the present report, Cu-modified poly(vinyl chloride) (PVC) and polyurethane (PU) were prepared via polydopamine (pDA)-assisted chelation. The copper content on the PVC and PU modified surfaces, assessed by [...] Read more.
Nitric oxide (NO) generating surfaces are potentially promising for improving haemocompatibility of blood-contacting biomaterials. In the present report, Cu-modified poly(vinyl chloride) (PVC) and polyurethane (PU) were prepared via polydopamine (pDA)-assisted chelation. The copper content on the PVC and PU modified surfaces, assessed by inductively coupled plasma - optical emission spectrometry (ICP-OES), were about 3.86 and 6.04 nmol·cm−2, respectively. The Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) data suggest that copper is attached to the polymer surface through complex formation with pDA. The cumulative leaching of copper from modified PVC and PU during the five day incubation in phosphate buffered saline (PBS), measured by inductively coupled plasma mass spectrometry (ICP-MS), was about 50.7 ppb and 48 ppb, respectively which is within its physiological level. Modified polymers were tested for their ability to catalytically generate NO by decomposing of endogenous S-nitrosothiol (GSNO). The obtained data show that Cu-modified PVC and PU exhibited the capacity to generate physiological levels of NO which could be a foundation for developing new biocompatible materials with NO-based therapeutics. Full article
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Open AccessArticle
Removal of Rhodamine B (A Basic Dye) and Acid Yellow 17 (An Acidic Dye) from Aqueous Solutions by Ordered Mesoporous Carbon and Commercial Activated Carbon
Colloids Interfaces 2019, 3(1), 30; https://doi.org/10.3390/colloids3010030
Received: 10 January 2019 / Revised: 15 February 2019 / Accepted: 21 February 2019 / Published: 26 February 2019
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Abstract
In this work, adsorption of rhodamine B (RB) and acid yellow 17 (AY17) was investigated on ordered mesoporous carbon material obtained by soft-templating method with hydrochloric acid (ST-A). For comparison, the adsorption process on commercial activated carbon CWZ-22 was also carried out. The [...] Read more.
In this work, adsorption of rhodamine B (RB) and acid yellow 17 (AY17) was investigated on ordered mesoporous carbon material obtained by soft-templating method with hydrochloric acid (ST-A). For comparison, the adsorption process on commercial activated carbon CWZ-22 was also carried out. The sorbents were characterized by nitrogen adsorption/desorption isotherms and scanning electron microscopy. Langmuir and Freundlich adsorption isotherm models were applied to simulate the equilibrium data of RB and AY17. Adsorption isotherm data could be better described by the Langmuir model than the Freundlich model. The adsorption kinetics of RB and AY17 on studied carbons could be well depicted by using pseudo-second-order kinetic modeling. The adsorption capacity increased with temperature increase in the range of 298–315 K. In the whole diffusion process, the intraparticle diffusion was involved, but not the whole rate-controlling step. The calculated thermodynamic parameters, including Gibbs free energy (∆G), enthalpy (∆H), and entropy (ΔS) suggested that adsorption processes of RB and AY17 on ST-A and CWZ-22 were endothermic and spontaneous. Full article
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Open AccessArticle
Surface Complexation Modeling of Biomolecule Adsorptions onto Titania
Colloids Interfaces 2019, 3(1), 28; https://doi.org/10.3390/colloids3010028
Received: 15 December 2018 / Revised: 13 February 2019 / Accepted: 14 February 2019 / Published: 18 February 2019
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Abstract
The adsorption of nucleic acid components on the surface of nanocrystalline titanium dioxide (anatase, pHpzc = 6.5) in NaCl solutions was investigated using potentiometric titrations and multibatch adsorption experiments over a wide range of pH and ionic strengths. The Basic Stern surface [...] Read more.
The adsorption of nucleic acid components on the surface of nanocrystalline titanium dioxide (anatase, pHpzc = 6.5) in NaCl solutions was investigated using potentiometric titrations and multibatch adsorption experiments over a wide range of pH and ionic strengths. The Basic Stern surface complexation model was applied to experimental data to obtain quantitative equilibrium reaction constants. Adsorption results suggest that there is a considerable difference in the binding of nucleobases, nucleosides, and nucleotides with an anatase surface. Full article
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Open AccessArticle
Solid Phase Extraction of Trace Amounts of Praseodymium Using Transcarpathian Clinoptilolite
Colloids Interfaces 2019, 3(1), 27; https://doi.org/10.3390/colloids3010027
Received: 23 December 2018 / Revised: 8 February 2019 / Accepted: 8 February 2019 / Published: 14 February 2019
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Abstract
Sorptive properties of the Transcarpathian clinoptilolite towards Pr(III) were studied under dynamic conditions. The sorption capacity of clinoptilolite under optimal conditions (sorbent grain diameter of 0.20–0.31 mm; pH 9.0, temperature of preliminary precalcination of 350 °C, and flow rate of the Pr(III) salt [...] Read more.
Sorptive properties of the Transcarpathian clinoptilolite towards Pr(III) were studied under dynamic conditions. The sorption capacity of clinoptilolite under optimal conditions (sorbent grain diameter of 0.20–0.31 mm; pH 9.0, temperature of preliminary precalcination of 350 °C, and flow rate of the Pr(III) salt solution with the concentration of 1.0 μg·mL−1 through the sorbent of 5 mL·min−1) was equal to 47.5 mg·g−1. The best desorbent of Pr from the clinoptilolite was the 1 M solution of KCl acidified with HCl to a pH value of 3.0. The method of Pr(III) trace amounts preconcentration in a solid phase extraction mode with further determination of this REE via spectrophotometric technique was developed. The linearity of the proposed method was evaluated in the range of 2–100 ng·mL−1 with detection limit of 0.7 ng·mL−1. Full article
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Open AccessArticle
The Methanol Adsorption in Microporous Alumina Agglomerates
Colloids Interfaces 2019, 3(1), 22; https://doi.org/10.3390/colloids3010022
Received: 11 January 2019 / Revised: 28 January 2019 / Accepted: 29 January 2019 / Published: 31 January 2019
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Abstract
We have studied theoretical and experimental methods of methanol adsorption in micropores of aluminum oxide agglomerates obtained by gas-dispersion synthesis. It is shown that the necessity to use strict equations based on the theory of volume filling of micropores, which implies a physical [...] Read more.
We have studied theoretical and experimental methods of methanol adsorption in micropores of aluminum oxide agglomerates obtained by gas-dispersion synthesis. It is shown that the necessity to use strict equations based on the theory of volume filling of micropores, which implies a physical and formal analogy between the volume filling of micropores and capillary condensation, for qualitative and quantitative description of adsorption equilibrium in open slit-like micropores. The applicability of the proposed equations for the description of adsorption equilibrium in such systems is demonstrated on the example of experimental methanol adsorption/desorption isotherm on the aluminum oxide, which possesses a microporous structure. Full article
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Open AccessArticle
Influence of Biodestructors on the Wear Resistance of Polyester Geotextile Materials
Colloids Interfaces 2019, 3(1), 21; https://doi.org/10.3390/colloids3010021
Received: 28 December 2018 / Revised: 17 January 2019 / Accepted: 29 January 2019 / Published: 31 January 2019
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Abstract
Changes in the structure and properties of geotextile nonwoven materials after microbiological load under natural conditions have been studied. Microbiological research of samples was conducted after testing for 12 and 24 months. The results of the research of physical and mechanical materials properties [...] Read more.
Changes in the structure and properties of geotextile nonwoven materials after microbiological load under natural conditions have been studied. Microbiological research of samples was conducted after testing for 12 and 24 months. The results of the research of physical and mechanical materials properties prove their sufficient resistance to the influence of biodestructors. Full article
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Open AccessArticle
Colloidal Stability of Positively Charged Dispersions of Styrene and Acrylic Copolymers in the Presence of TiO2 and CaCO3
Colloids Interfaces 2019, 3(1), 20; https://doi.org/10.3390/colloids3010020
Received: 28 December 2018 / Revised: 25 January 2019 / Accepted: 28 January 2019 / Published: 30 January 2019
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Abstract
Increasing antibiotic resistance of several pathogenic microorganisms calls for alternative approaches to prevent spreading of bacterial diseases. We propose to employ for this purpose coatings obtained from positively charged latex dispersions. In this contribution we characterize aqueous mixed dispersions containing TiO2 or [...] Read more.
Increasing antibiotic resistance of several pathogenic microorganisms calls for alternative approaches to prevent spreading of bacterial diseases. We propose to employ for this purpose coatings obtained from positively charged latex dispersions. In this contribution we characterize aqueous mixed dispersions containing TiO2 or CaCO3 and methyl methacrylate-ethyl acrylate or styrene-ethyl acrylate copolymers synthesized using a cationic surfactant, cetyltrimethylammonium bromide as an emulsifier. Particle size, electrokinetic (ζ) potential of the mixed dispersions and the resulting thin films, as well as antimicrobial properties of the latter are described. The TiO2 and CaCO3 dispersions were stabilised with polyethyleneimine (PEI) and optimum pH for the mixed dispersions were chosen on the basis of ζ-potential measurements. For TiO2, the maximum ζ = +35 mV was found at pH 7.5, and for CaCO3, pH was set at 8.2 (ζ = +38 mV), to prevent its dissolution. In most 1:1 mixtures of TiO2 or CaCO3 with the cetyltrimethylammonium bromide (CTAB)-stabilised latex dispersions, two distinct particles populations were observed, corresponding to the bare latex and bare TiO2 or CaCO3 fractions. Films made of the mixed dispersions remained positively charged and showed antimicrobial activity similar or reduced with respect to the bare polymer films. Full article
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Open AccessArticle
Sorption Properties of Polydivinylbenzene Polymers Towards Phenolic Compounds and Pharmaceuticals
Colloids Interfaces 2019, 3(1), 19; https://doi.org/10.3390/colloids3010019
Received: 21 December 2018 / Revised: 20 January 2019 / Accepted: 23 January 2019 / Published: 28 January 2019
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Abstract
Highly cross-linked polymers are commonly used in purification and separation techniques because of their many useful features. In order to better adjust their porosity to adsorption of specific compounds, methods like surface functionalization or imprinting are used. In this work, a series of [...] Read more.
Highly cross-linked polymers are commonly used in purification and separation techniques because of their many useful features. In order to better adjust their porosity to adsorption of specific compounds, methods like surface functionalization or imprinting are used. In this work, a series of highly cross-linked polydivinylbenzenes (pDVB) were prepared using a suspension method. Toluene was applied as a pore-forming diluent. Some part of toluene (1 mL) was replaced with phenol (F), 2,4,6-trichlorophenol (T) or their mixture (M) to prepare polymers with porosity more suitable for phenols sorption. Another approach was an introduction of sulfone groups onto the polymer surface (pDVB-SO3H). The physicochemical characteristics of the synthetized adsorbents included CHN, FTIR, DSC and porosimetric analyses. Afterwards, to evaluate sorption properties of the prepared adsorbents towards phenols, ibuprofen and salicylic acid the solid phase extraction (SPE) experiments were performed. The polymers had the specific surface areas of about 440–560 m2/g created mainly by mesopores with widths ca. 3.75 and 4.75–7.15 nm. Materials obtained with the addition of porosity modifiers (phenol, trichlorophenol, mixture) had more uniform porous structure and their sorption capacity toward phenols increased ca. 5%. Similar sorption capacities were obtained for ibuprofen. Salicylic acid had low affinity to the surface of the tested polymers. Full article
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Open AccessArticle
Influence of the Synthesis Method on the Structural Characteristics of Novel Hybrid Adsorbents Based on Bentonite
Colloids Interfaces 2019, 3(1), 18; https://doi.org/10.3390/colloids3010018
Received: 21 December 2018 / Revised: 18 January 2019 / Accepted: 24 January 2019 / Published: 28 January 2019
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Abstract
New hybrid composite materials were prepared by polymerization of resorcinol–formaldehyde resins in the presence of bentonite with various contents of polymer and water, and then exposed to pyrolysis in an inert atmosphere at 800 °C. The influence of the filler and synthesis method [...] Read more.
New hybrid composite materials were prepared by polymerization of resorcinol–formaldehyde resins in the presence of bentonite with various contents of polymer and water, and then exposed to pyrolysis in an inert atmosphere at 800 °C. The influence of the filler and synthesis method on the morphological, textural and structural characteristics has been described. The materials were characterized using low temperature nitrogen adsorption–desorption, small angle X-ray scattering, scanning electron microscopy, Raman spectroscopy, differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The maximal values of the specific surface area of organo-bentonite and carbonized samples were 254 and 200 m2/g, respectively, which is much larger than that of the initial bentonite. The TGA and DSC experiments showed changes in the thermal stability of samples depending on their composition. The obtained data could provide a better understanding of the principles of preparing hybrid bentonite-containing composites that may provide an additional incentive to develop advanced technologies. Full article
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Open AccessArticle
Conversion of D-Fructose into Ethyl Lactate Over a Supported SnO2–ZnO/Al2O3 Catalyst
Colloids Interfaces 2019, 3(1), 16; https://doi.org/10.3390/colloids3010016
Received: 17 December 2018 / Revised: 17 January 2019 / Accepted: 22 January 2019 / Published: 25 January 2019
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Abstract
The study is directed to the search of a simple effective catalyst for ethyl lactate obtained from fructose as renewable raw material. A series of SnO2-containing oxides prepared by impregnation of alumina were characterized by several techniques in order to determine [...] Read more.
The study is directed to the search of a simple effective catalyst for ethyl lactate obtained from fructose as renewable raw material. A series of SnO2-containing oxides prepared by impregnation of alumina were characterized by several techniques in order to determine their textural and acid-base properties. The transformation of a 13% fructose solution in 98% ethanol over SnO2/Al2O3 catalysts using autoclave rotated with 60 rpm at 160 °C for 3 h was studied. It was found that doping SnO2/Al2O3 samples with ZnO improves selectivity towards ethyl lactate. The supported SnO2-ZnO/Al2O3 catalyst provides 100% fructose conversion with 55% yield of ethyl lactate at 160 °C. A possible scheme of fructose transformation into ethyl lactate on L-acid IVSn4+ sites is discussed. Full article
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Open AccessArticle
Wettability of DPPC Monolayers Deposited from the Titanium Dioxide–Chitosan–Hyaluronic Acid Subphases on Glass
Colloids Interfaces 2019, 3(1), 15; https://doi.org/10.3390/colloids3010015
Received: 30 December 2018 / Revised: 17 January 2019 / Accepted: 18 January 2019 / Published: 23 January 2019
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Abstract
The investigations were carried out to determine wettability of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers transferred from the liquid subphases containing chitosan (Ch), hyaluronic acid (HA), and/or titanium dioxide (TiO2) to a glass support by means of the Langmuir–Blodgett (LB) technique. [...] Read more.
The investigations were carried out to determine wettability of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers transferred from the liquid subphases containing chitosan (Ch), hyaluronic acid (HA), and/or titanium dioxide (TiO2) to a glass support by means of the Langmuir–Blodgett (LB) technique. For comparative purposes, the analysis of the plates surfaces emerged from the analogous subphases without the phospholipid film was also made. Characterization of the DPPC monolayers was based on the contact angle measurements using three test liquids (water, formamide, diiodomethane) and a simulated body fluid (SBF) solution in which the concentration of ions was close to that of human plasma. After deposition of the DPPC monolayers on the glass plates, a significant increase in the contact angles of all the probe liquids was observed compared to the plates pulled out from the given subphase without floating DPPC. The presence of phospholipid monolayer increased the hydrophobic character of the surface due to orientation of its molecules with hydrocarbon chains towards the air. In addition, the components of the subphase attached along with DPPC to the glass support modify the surface polarity. The largest changes were observed in the presence of TiO2. Full article
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Open AccessArticle
Adsorption and Decomposition of Peroxides on the Surfaces of Dispersed Oxides Fe2O3, Cr2O3 and V2O5
Colloids Interfaces 2019, 3(1), 13; https://doi.org/10.3390/colloids3010013
Received: 17 December 2018 / Revised: 12 January 2019 / Accepted: 16 January 2019 / Published: 17 January 2019
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Abstract
The adsorption of peroxides on dispersed oxides Fe2O3, Cr2O3 and V2O5 was studied. It is shown that the adsorption of peroxides is described by the Langmuir equation. The adsorption of benzoyl peroxide grows [...] Read more.
The adsorption of peroxides on dispersed oxides Fe2O3, Cr2O3 and V2O5 was studied. It is shown that the adsorption of peroxides is described by the Langmuir equation. The adsorption of benzoyl peroxide grows within Fe2O3 < Cr2O3 < V2O5. Adsorption-desorption equilibrium constants (K) for Cr2O3 and V2O5 are the same, but for Fe2O3 this value is 6 times higher. The decomposition of peroxides is observed in the solution and on the surface of adsorbents. The effective activation energy (E) of the thermal decomposition of peroxides in the studied systems is in the range of 80–140 kJ/mol. The activation energy of degradation of peroxides on the surface (Es) of the dispersed oxides studied is lower. The degradation reaction of peroxides on the surface of Fe2O3 and V2O5 has an oxidation-reducing nature, during which free radicals are produced. On the surface of Cr2O3, there is a heterolytic decay of peroxides. The parameters of the reaction of peroxides decomposition are found. The decomposition of peroxides in the presence of Fe2O3, Cr2O3 and V2O5 in styrene is accompanied by the formation of polystyrene both in the solution and on the surface of the adsorbent. Full article
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Open AccessCommunication
Luminescent Sol-Gel Glasses from Silicate–Citrate–(Thio)Ureate Precursors
Colloids Interfaces 2019, 3(1), 11; https://doi.org/10.3390/colloids3010011
Received: 9 December 2018 / Revised: 9 January 2019 / Accepted: 11 January 2019 / Published: 14 January 2019
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Abstract
Recent advancements in synthesis and analysis of the composites based on silica and carbon quantum dots have revealed great potential of such systems in bioimaging, sensor, as well as solid-state lighting applications. Most of the synthetic methods for obtaining such materials are still [...] Read more.
Recent advancements in synthesis and analysis of the composites based on silica and carbon quantum dots have revealed great potential of such systems in bioimaging, sensor, as well as solid-state lighting applications. Most of the synthetic methods for obtaining such materials are still relatively complex and costly. The aim of this work was to study the luminescent properties of silica-based composites prepared by the simple sol-gel method using low-cost silicate–citrate–(thio)ureate precursors. The glassy composites were prepared by acid hydrolysis of ethyl silicate (40%) in aqueous solution of citric acid ureates or thioureates with the citric acid-to-(thio)urea molar ratio of 1:1, 1:1.5 or 1:3. The results of spectrofluorimetric analysis have shown that heat-treated at 270 °C such silica gels upon UV excitation (with an optimum at λexc = 360 nm) emit light in a visible spectrum (400–600 nm). Upon this, photoluminescence efficiency of ureate-derived glasses (quantum yield 70.53% for 1:1.5 sample) appeared to be much higher than that for thioureate-derived glasses (quantum yield 11.25% for 1:3 sample) suggesting that the preparation conditions to obtain the glasses with optimal photoluminescence characteristics are quite different in case of urea and thiourea. Thus, citrate–ureate-derived silica glasses already demonstrate very good potential to be efficient materials for different fluorescence-related applications. Full article
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Open AccessArticle
Structural, Mineral and Elemental Composition Features of Iron-Rich Saponite Clay from Tashkiv Deposit (Ukraine)
Colloids Interfaces 2019, 3(1), 10; https://doi.org/10.3390/colloids3010010
Received: 8 December 2018 / Revised: 8 January 2019 / Accepted: 9 January 2019 / Published: 13 January 2019
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Abstract
Low-temperature nitrogen adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, as well as infrared spectroscopy were used to characterize structural features of raw and acid-treated saponite from Tashkiv deposit of Ukraine. It was determined that raw saponite is predominantly composed of [...] Read more.
Low-temperature nitrogen adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, as well as infrared spectroscopy were used to characterize structural features of raw and acid-treated saponite from Tashkiv deposit of Ukraine. It was determined that raw saponite is predominantly composed of trioctahedral saponite with an admixture of dioctahedral nontronite and associated minerals such as quartz, hematite, and anatase. Raw saponite clay was characterized by a high content of iron (19.3%) and titanium (1.1%). Iron is present in the form of hematite particles, isomorphic replacements in octahedral and tetrahedral sheets of a clay structure, or as a charge-balancing cation in the interlayer space. Titanium is homogeneously dispersed as submicrometer anatase particles. The porous structure of both saponite forms consists of micro-meso porous system with narrow slit mesopores dominating. As a consequence of the acid treatment, the specific surface area increased from 47 to 189 m2 g−1, the total pore volume from 0.134 to 0.201 cm3 g−1, and the volume of the micropores increased sevenfold. Using the data of our research allowed us to utilize these mineral resources wisely and to process saponite more efficiently. Full article
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Open AccessArticle
Characterization of Multimodal Silicas Using TG/DTG/DTA, Q-TG, and DSC Methods
Colloids Interfaces 2019, 3(1), 6; https://doi.org/10.3390/colloids3010006
Received: 10 December 2018 / Revised: 21 December 2018 / Accepted: 22 December 2018 / Published: 28 December 2018
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Abstract
The formation of hierarchical, multimodal porosity materials with controlled shape and size of pores is the essential challenge in materials science. Properties of silica materials depend largely on different features: crystal structure, dispersity, surface composition, and porosity as well as the method of [...] Read more.
The formation of hierarchical, multimodal porosity materials with controlled shape and size of pores is the essential challenge in materials science. Properties of silica materials depend largely on different features: crystal structure, dispersity, surface composition, and porosity as well as the method of preparation and possible modification. In this paper, multimodal silicas obtained using different additives are presented. A-50 and A-380 aerosils and wide-porous SiO2 milled at 300 rpm were used as the additives in the sol stage at 20 °C, the sol–gel stage followed by hydrothermal modification (HTT) at 200 °C, or in the mechanochemical treatment (MChT) process. The characterizations were made by application of N2 adsorption/desorption, SEM imaging, quasi-isothermal thermogravimetry (Q-TG), dynamic thermogravimetry/derivative thermogravimetry/differential thermal analysis (TG/DTG/DTA), and cryoporometry differential scanning calorimetry (DSC) methods. Results showed that such a one-step preparation method is convenient and makes it possible to obtain multimodal silicas of differentiated porous structures and surface chemistry. Full article
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Open AccessArticle
Equilibrium, Kinetic, and Thermodynamic Studies of Anionic Dyes Adsorption on Corn Stalks Modified by Cetylpyridinium Bromide
Colloids Interfaces 2019, 3(1), 4; https://doi.org/10.3390/colloids3010004
Received: 27 November 2018 / Revised: 21 December 2018 / Accepted: 22 December 2018 / Published: 23 December 2018
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Abstract
Corn stalks (CS) were modified by a cationic surfactant, cetylpyridinium bromide (CPB), and used as an adsorbent (CS-CP) to remove anionic dyes [Acid Red (AR) and Acid Orange (AO)] from aqueous solutions. The FTIR analysis and the obtained calculations based on the determination [...] Read more.
Corn stalks (CS) were modified by a cationic surfactant, cetylpyridinium bromide (CPB), and used as an adsorbent (CS-CP) to remove anionic dyes [Acid Red (AR) and Acid Orange (AO)] from aqueous solutions. The FTIR analysis and the obtained calculations based on the determination of the adsorption capacity of CS towards CPB confirmed that the cationic surfactant had been adsorbed on the surface of corn stalks. Adsorption of the anionic dyes on modified corn stalks was investigated in a series of batch adsorption experiments at 303–328 K. The adsorption data were analyzed using Langmuir, Freundlich, and Temkin models. The Langmuir model was found to be more suitable for the experimental data of the anionic dyes on CS-CP than other adsorption models. Kinetic studies revealed that the pseudo-second order model showed the best fit to the experimental data. The thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic. Mechanisms involving ion exchange and chemisorption might be responsible for the uptake of the anionic dyes on CS-CP. Obtained results imply that CS-CP could be applied as an effective adsorbent to remove anionic dyes from aqueous solutions. Full article
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Open AccessArticle
Dispersions of Metal Oxides in the Presence of Anionic Surfactants
Colloids Interfaces 2019, 3(1), 3; https://doi.org/10.3390/colloids3010003
Received: 22 November 2018 / Revised: 19 December 2018 / Accepted: 20 December 2018 / Published: 21 December 2018
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Abstract
We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up [...] Read more.
We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it. Full article
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Open AccessArticle
Effect of Both the Phase Composition and Modification Methods on Structural-Adsorption Parameters of Dispersed Silicas
Colloids Interfaces 2019, 3(1), 1; https://doi.org/10.3390/colloids3010001
Received: 28 November 2018 / Revised: 18 December 2018 / Accepted: 19 December 2018 / Published: 21 December 2018
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Abstract
Tripoli from two Ukrainian deposits was studied in its natural and modified forms. The investigation of natural and modified tripoli involves the identification of their phase compositions through X-ray diffraction and the analysis of their water vapor adsorption-desorption isotherms. The obtained results are [...] Read more.
Tripoli from two Ukrainian deposits was studied in its natural and modified forms. The investigation of natural and modified tripoli involves the identification of their phase compositions through X-ray diffraction and the analysis of their water vapor adsorption-desorption isotherms. The obtained results are evidence of changes in the structural-adsorption parameters of tripoli as a result of modification. Their treatment in boiling water or acid causes apparent alterations of contents of the main phases and sizes of their crystallites, whereas their calcination causes not only the dehydroxylation of surfaces and the agglomeration of phases, but even phase transformation in the case of carbonate tripoli. After analyzing water vapor adsorption-desorption isotherms of natural and modified tripolis, some correlations between their adsorption parameters, phase compositions, main phase contents and crystallite sizes have been found. Full article
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Open AccessFeature PaperArticle
Water Vapor Adsorption by Some Manganese Oxide Forms
Colloids Interfaces 2018, 2(4), 61; https://doi.org/10.3390/colloids2040061
Received: 19 October 2018 / Revised: 12 November 2018 / Accepted: 14 November 2018 / Published: 15 November 2018
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Abstract
Manganese oxide forms prepared by different methods differ by their compositions, phase ratios in polyphase samples, and crystallite sizes (XRD and TEM characterization). Among the phases, tunnel-structured β-MnO2 (pyrolusite), α-MnO2 (cryptomelane), ε-MnO2 (akhtenskite), and β-Mn2O3 (bixbyite) have [...] Read more.
Manganese oxide forms prepared by different methods differ by their compositions, phase ratios in polyphase samples, and crystallite sizes (XRD and TEM characterization). Among the phases, tunnel-structured β-MnO2 (pyrolusite), α-MnO2 (cryptomelane), ε-MnO2 (akhtenskite), and β-Mn2O3 (bixbyite) have been identified. Water vapor sorption isotherms showed substantial differences in the affinities of water molecules to oxide surfaces of the manganese oxide forms under study. The parameters of the BET equation and pore size distribution curves have been calculated. The manganese oxide forms have mesoporous structures characterized by uniform and non-uniform pore sizes as well as by moderate hydrophilic behavior. Full article
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