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Minerals
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Surfactants at Interfaces and Thin Liquid Films
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Surfactants at Interfaces and Thin Liquid Films

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (15 June 2020) | Viewed by 23100

Special Issue Editors

Prof. Dr. Jan Zawala

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Guest Editor
Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30-239 Krakow, Poland
Interests: surface chemistry; colloids systems; liquid films; coalescence; bubble attachment; hydrophobicity; adsorption; adhesion; multiphase flow; mass transfer; image analysis
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Przemyslaw B. Kowalczuk

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Guest Editor
Department of Geoscience and Petroleum, Norwegian University of Science and Technology, S.P. Andersens veg 15a, 7031 Trondheim, Norway
Interests: mineral processing; minerals engineering; flotation; physicochemistry of surfaces; colloids systems; hydrophobicity; minerals; surface properties; extractive metallurgy; leaching
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Thin liquid films, stabilized by surfactant adsorption layers, are the fundamental building blocks of any dispersed system with a liquid continuous phase. The stability of liquid films is a parameter of crucial importance for the properties of the dispersed system as a whole. Moreover, it controls the outcome of many important technological and industrial applications involving multiphase flows. One of the important examples of such processes is flotation separation, where the collision of gas bubbles with various interfaces, in the presence of reagents creating a favorable chemical environment, are the first fundamental step of the formation of bubble-particle aggregates and foam. We warmly invite you to contribute to the Special Issue “Surfactants at Interfaces and Thin Liquid Films”. Given the scientific scope of the journal, the topics of interest of this Special Issue should include the original papers related to basic and applied research on the physicochemical aspects of the flotation separation process, such as experimental and theoretical studies on the stability of liquid films (foam and wetting) under static and dynamic conditions, the kinetics of bubble attachment to solid surfaces, solid surface wettability, surfactant adsorption, bubble and drop interfaces, and the hydrodynamics of bubbles and drops in surfactant solution.

Dr. Jan Zawala
Dr. Przemyslaw B. Kowalczuk
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 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

  • liquid films
  • flotation
  • bubble attachment
  • surfactants
  • interface
  • wettability
  • particle
  • bubble

Related Special Issue

Published Papers (7 papers)

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Research

19 pages, 11834 KiB  
Article
β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 4. Impact on the Stability of Foam Films and Foams
by Georgi G. Gochev, Vamseekrishna Ulaganathan, Inga Retzlaff, Cécile Gehin-Delval, Deniz Z. Gunes, Martin Leser, Ulrich Kulozik, Reinhard Miller and Björn Braunschweig
Minerals 2020, 10(7), 636; https://doi.org/10.3390/min10070636 - 17 Jul 2020
Cited by 7 | Viewed by 2775
Abstract
The complexity and high sensitivity of proteins to environmental factors give rise to a multitude of variables, which affect the stabilization mechanisms in protein foams. Interfacial and foaming properties of proteins have been widely studied, but the reported unique effect of pH, which [...] Read more.
The complexity and high sensitivity of proteins to environmental factors give rise to a multitude of variables, which affect the stabilization mechanisms in protein foams. Interfacial and foaming properties of proteins have been widely studied, but the reported unique effect of pH, which can be of great interest to applications, has been investigated to a lesser extent. In this paper, we focus on the impact of pH on the stability of black foam films and corresponding foams obtained from solutions of a model globular protein—the whey β-lactoglobulin (BLG). Foam stability was analyzed utilizing three characteristic parameters (deviation time, transition time and half-lifetime) for monitoring the foam decay, while foam film stability was measured in terms of the critical disjoining pressure of film rupture. We attempt to explain correlations between the macroscopic properties of a foam system and those of its major building blocks (foam films and interfaces), and thus, to identify structure-property relationships in foam. Good correlations were found between the stabilities of black foam films and foams, while relations to the properties of adsorption layers appeared to be intricate. That is because pH-dependent interfacial properties of proteins usually exhibit an extremum around the isoelectric point (pI), but the stability of BLG foam films increases with increasing pH (3–7), which is well reflected in the foam stability. We discuss the possible reasons behind these intriguingly different behaviors on the basis of pH-induced changes in the molecular properties of BLG, which seem to be determining the mechanism of film rupture at the critical disjoining pressure. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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12 pages, 5583 KiB  
Article
Experimental Procedure for the Determination of the Critical Coalescence Concentration (CCC) of Simple Frothers
by Onur Guven, Khandjamts Batjargal, Orhan Ozdemir, Stoyan I. Karakashev, Nikolay A. Grozev, Feridun Boylu and Mehmet Sabri Çelik
Minerals 2020, 10(7), 617; https://doi.org/10.3390/min10070617 - 09 Jul 2020
Cited by 16 | Viewed by 2993
Abstract
In this study, the critical coalescence concentrations (CCC) of selected commercial frother solutions, namely polypropylene glycols (PPG 200, 400, and 600), tri propylene glycol (BTPG), triethylene glycol (BTEG), dipropylene glycol (BDPG), and as a reference, methyl isobutyl carbinol (MIBC), were determined using a [...] Read more.
In this study, the critical coalescence concentrations (CCC) of selected commercial frother solutions, namely polypropylene glycols (PPG 200, 400, and 600), tri propylene glycol (BTPG), triethylene glycol (BTEG), dipropylene glycol (BDPG), and as a reference, methyl isobutyl carbinol (MIBC), were determined using a bubble column based on light absorption. The results for all seven frothers showed that BTEG has the worst bubble inhibiting performance, and PPG 600 has the best bubble inhibiting performance. While critical coalescence concentration (CCC) was found as 3 ppm for PPG 600, it increased to 25 ppm for BTEG. In the case of MIBC, which was the reference point, the CCC value was found as 10 ppm, which was consistent with the literature. The surface tension isotherms of the frothers were determined and analyzed with one of the latest adsorption models. The results indicated that the polypropylene glycol frothers showed more surface activity compared to alcohol or other frothers investigated. This is due to the additional reorganization of the PPG molecules on the air/water interface, thus boosting its surface activity. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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13 pages, 9324 KiB  
Article
3-Mercaptopropionic/3-Mercaptoisobutyric Acids Used as Novel Selective Depressants for Improved Flotation of Chalcopyrite from Galena
by Ruohua Liu, Rui Xu, Li Wang, Feng Jiang, Jiao Jin, Zhiyong Gao, Honghu Tang and Wei Sun
Minerals 2020, 10(3), 258; https://doi.org/10.3390/min10030258 - 13 Mar 2020
Cited by 7 | Viewed by 2837
Abstract
The selective separation of chalcopyrite from galena (lead sulfide) through the flotation method is still a challenging task in the field of mineral engineering. Mercaptoacetic acid, though a common depressant of many gangue (commercially worthless) minerals, has shown to be less selective in [...] Read more.
The selective separation of chalcopyrite from galena (lead sulfide) through the flotation method is still a challenging task in the field of mineral engineering. Mercaptoacetic acid, though a common depressant of many gangue (commercially worthless) minerals, has shown to be less selective in the flotation separation of chalcopyrite and galena. This resent study therefore systematically investigated the selectivity of different mercapto acids (especially three types: 3-mercaptopropionic acid, 3-mercaptoisobutyric acid and mercaptoacetic acid) on the separation of chalcopyrite and galena by making the use of flotation experiments and first principle calculations. The calculation results demonstrated that the sulfhydryl and carboxyl groups existing on the molecular structure of three mercapto acids are the reactive and chelating centers to metal ions on sulfide mineral surfaces. Mercapto acids have higher binding energies to Cu2+ by 300–400 kJ/mol compared to Pb2+, indicating a higher affinity towards chalcopyrite. The order of reactivity and chelating ability noted was as follows: 3-mercaptopropionic acid > 3-mercaptoisobutyric acid > mercaptoacetic acid. Flotation results further showed that the selectivity of 3-mercaptopropionic acid or 3-mercaptoisobutyric acid was better than mercaptoacetic acid. The good agreement between the first principle calculations and the flotation results demonstrated that the former reagent could be served as a most selective depressant in the improved flotation separation of chalcopyrite and galena. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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9 pages, 1389 KiB  
Article
Critical Synergistic Concentration of Binary Surfactant Mixtures
by Jan Zawala, Agata Wiertel-Pochopien and Przemyslaw B. Kowalczuk
Minerals 2020, 10(2), 192; https://doi.org/10.3390/min10020192 - 20 Feb 2020
Cited by 16 | Viewed by 3809
Abstract
This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl [...] Read more.
This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl ether) was chosen as a model system. In addition to the cationic-non-ionic system, the mixture of anionic-non-ionic surfactants (sodium dodecyl sulphate and tri(propylene glycol) butyl ether) was investigated. The foam behavior of one-component solutions and binary mixtures was characterized as a function of surfactant concentration, number of carbons (n) in alkyl chain of CnTAB as well as type of surfactant. It was shown that synergism in foamability could be produced by the ionic-non-ionic systems, and the concentration below the synergism occurs, called the critical synergistic concentration (CSC), that can be easily predicted based on the surface tension data on individual components. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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13 pages, 4849 KiB  
Article
A Case Study of Enhanced Sulfidization Flotation of Lead Oxide Ore: Influence of Depressants
by Haiyun Xie, Rui Sun, Jizong Wu, Dongxia Feng and Likun Gao
Minerals 2020, 10(2), 95; https://doi.org/10.3390/min10020095 - 22 Jan 2020
Cited by 11 | Viewed by 2669
Abstract
The refractory lead oxide ore has become an important source of lead metal with the continuous depletion of lead sulfide minerals. Lead oxide ore is of poor floatability and there are few cases to concentrate it successfully. In this study, the sulfidization-xanthate flotation [...] Read more.
The refractory lead oxide ore has become an important source of lead metal with the continuous depletion of lead sulfide minerals. Lead oxide ore is of poor floatability and there are few cases to concentrate it successfully. In this study, the sulfidization-xanthate flotation method is applied for the beneficiation of lead oxide ore in Yunnan Province (China) with sodium hexametaphosphate and carboxymethyl cellulose as depressant. Chemical analysis and phase analysis was performed to explore the physicochemical property of raw ore, which provides a research basis for process design and operational control. The main influencing factors during the process, including grinding fineness, reagent types, and dosage, etc., have been studied through flotation tests. Zeta potential measurements and Fourier transfer-infrared spectrometry (FTIR) analysis were conducted to reveal the function mechanism of the reagents. Based on the determined experimental conditions, open circuit tests and closed circuit tests with one stage rougher, three-stage scavenger, and two-stage cleaner flotation, were carried out with the run-of-mine ore with a lead grade of 4.57%. Through close circuit bench test, the lead concentrate with a lead grade of 64.08% and recovery of 92.30% was obtained. This study is of special value, as it provides referencing significance for economically exploiting lead oxide ore. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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10 pages, 1166 KiB  
Article
Bubble Rise Velocity and Surface Mobility in Aqueous Solutions of Sodium Dodecyl Sulphate and n-Propanol
by Pavlína Basařová, Yuliya Kryvel and Jakub Crha
Minerals 2019, 9(12), 743; https://doi.org/10.3390/min9120743 - 29 Nov 2019
Cited by 4 | Viewed by 3220
Abstract
Aqueous solutions of simple alcohols exhibit many anomalies, one of which is a change in the mobility of the bubble surface. This work aimed to determine the effect of the presence of another surface-active agent on bubble rise velocity and bubble surface mobility. [...] Read more.
Aqueous solutions of simple alcohols exhibit many anomalies, one of which is a change in the mobility of the bubble surface. This work aimed to determine the effect of the presence of another surface-active agent on bubble rise velocity and bubble surface mobility. The motion of the spherical bubble in an aqueous solution of n-propanol and sodium dodecyl sulphate (SDS) was monitored by a high-speed camera. At low alcohol concentrations (xP < 0.01), both the propanol and SDS molecules behaved as surfactants, the surface tension decreased and the bubble surface was immobile. The effect of the SDS diminished with increasing alcohol concentrations. In solutions with a high propanol content (xP > 0.1), the SDS molecules did not adsorb to the phase interface and thus, the surface tension of the solution was not reduced with the addition of SDS. Due to the rapid desorption of propanol molecules from the bottom of the bubble, a surface tension gradient was not formed. The drag coefficient can be calculated using formulas for the mobile surface of a spherical bubble. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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18 pages, 5093 KiB  
Article
The Effect of the Ionic Strength of Process Water on the Interaction of Talc and CMC: Implications of Recirculated Water on Floatable Gangue Depression
by Malibongwe Manono, Kirsten Corin and Jenny Wiese
Minerals 2019, 9(4), 231; https://doi.org/10.3390/min9040231 - 15 Apr 2019
Cited by 11 | Viewed by 4102
Abstract
Previous studies speculate that hydroxo species present in flotation pulps at pH > 9, particularly those of polyvalent cations, selectively adsorb onto gangue minerals. Such species supposedly enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the [...] Read more.
Previous studies speculate that hydroxo species present in flotation pulps at pH > 9, particularly those of polyvalent cations, selectively adsorb onto gangue minerals. Such species supposedly enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the positively charged mineral surface and the negatively charged CMC molecule. Thus, the hydrophilicity of gangue minerals is enhanced, preventing the dilution of the concentrate. However, as there is little evidence to support these claims for complex process waters of increasing ionic strength, it is important to investigate. Adsorption data and mineral surface charge analyses provide a fundamental understanding of how electrolytes and their ionic strengths affect gangue mineral-depressant adsorption. It is strongly anticipated that decoupling these effects will allow process operators to tailor their process water quality needs towards best flotation operating regimes and, in the long run, effect closed water circuits. Thus, using talc as a proxy for naturally floatable gangue common in sulfidic Cu–Ni–PGM ores, this work investigates the influence of the ionic strength of process water on the adsorption of CMC onto talc for a perspective on how saline water in sulfidic ores would affect the behavior and therefore management of floatable gangue. In the presence of CMC, the microflotation results showed that the rate of talc recovery decreased with increasing ionic strength of process water. Increases in ionic strength resulted in an increase in the adsorption of CMC onto talc. Talc particles proved to have been more coagulated at higher ionic strength since the settling time decreased with increasing ionic strength. Furthermore, the zeta potential of talc particles became less negative at higher ionic strengths of process water. It is thus proposed that increases in the ionic strength of process water increased the zeta potential of talc particles, enhancing the adsorption of CMC onto talc. This in turn created a more coagulated nature on talc particles, increasing their hydrophilicity and thereby retarding floatability. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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