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Pawliszak P, Beheshti A, Møller A, Blencowe A, Beattie DA, Krasowska M. Increasing surface hydrophilicity with biopolymers: a combined single bubble collision, QCM-D and AFM study. J Colloid Interface Sci 2024; 667:393-402. [PMID: 38640658 DOI: 10.1016/j.jcis.2024.04.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/21/2024]
Abstract
HYPOTHESIS Naturally extracted polysaccharides, such as guar gum, are promising candidates for environmentally friendly flotation reagents. It is hypothesized that the kinetics of collision of sub- to millimeter gas bubbles with a hydrophobic graphite surface, and the stability of thin liquid film formed between the bubble and surface is affected by an adsorbed layer of guar gum. EXPERIMENTS A combination of gravimetric (quartz crystal microbalance with dissipation) and imaging (atomic force microscopy) techniques was used to investigate the adsorption of guar gum on graphite surface, while high-speed camera imaging allowed for direct observation of the bubble collision process with guar gum-modified graphite surfaces with millisecond resolution. FINDINGS Atomic force microscope topography images revealed a guar gum concentration-dependent interconnected network of guar gum molecules adsorbed at graphite surface. These adsorbed molecules at low surface coverage, changed the wettability of the graphite surface, resulting in a film drainage time longer by an order of magnitude, while at higher surface coverage successfully prevented bubble attachment to the graphite surface. Most importantly, the adsorbed layer changed the strength of the bubble's bouncing off the graphite surface. This enhanced bubble bouncing can be correlated with the film drainage time and used to predict a successful bubble-particle attachment.
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Affiliation(s)
- Piotr Pawliszak
- Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia; ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, Australia
| | - Amir Beheshti
- Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia; ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, Australia; School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Amalie Møller
- Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia; ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, Australia
| | - Anton Blencowe
- Applied Chemistry and Translational Biomaterials (ACTB) Group, Centre for Pharmaceutical Innovation (CPI), UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia 5000, Australia
| | - David A Beattie
- Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia; ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, Australia.
| | - Marta Krasowska
- Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia; ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, Australia.
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Ning S, Li G, Shen P, Zhang X, Li J, Liu R, Liu D. Selective separation of chalcopyrite and talc using pullulan as a new depressant. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126764] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Gao Z, Wang C, Sun W, Gao Y, Kowalczuk PB. Froth flotation of fluorite: A review. Adv Colloid Interface Sci 2021; 290:102382. [PMID: 33676242 DOI: 10.1016/j.cis.2021.102382] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/09/2021] [Accepted: 02/09/2021] [Indexed: 10/22/2022]
Abstract
Fluorite, as a scarce nonrenewable strategic non-metallic mineral resource, is the primary raw material for fluorine products used in diverse fields such as metallurgy, national defense, chemical and optical industries. With the increasing expansion of the related fields, the demand for high-quality fluorite continues to grow. Hence, the surge of interest in effectively utilizing fluorite resources has led to vast attention worldwide. So far, significant endeavors have been done to enhance the beneficiation of fluorite from relatively low-grade ores. It has been well appreciated that the froth flotation is of the most importance. However, to the best of the authors' knowledge, it lacks a thorough and critical review on the recent developments in fluorite flotation. This article begins with introducing the deposits and unique physical and chemical properties of fluorite from the perspective of the crystal structure. It is followed by a systematic review of common reagents involved in fluorite flotation, including collectors, depressants, regulators, modifiers, and frothers. Specifically, the synergistic effect of collectors and depressants on the recovery of fluorite is elaborated for the first time. Finally, the most widely seen fluorite-flotation cases, including separation of fluorite from quartz, calcite, barite, and sulfide, are summarized individually. The present review sheds new light on the deep understanding of fluorite flotation, the future synthesis of reagents, as well as their schemes in practical use. Meanwhile, such a novel rain of thought provided in this work has the potential to guide the flotation of other similar minerals extensively.
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Monkman GJ, Sindersberger D, Prem N, Diermeier A, Szecsey T. Dielectric behaviour of magnetic hybrid materials. PHYSICAL SCIENCES REVIEWS 2020. [DOI: 10.1515/psr-2019-0121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The objectives of this work include the analysis of electrical and magnetic properties of magneto-elastic hybrid materials with the intention of developing new techniques for sensor and actuator applications. This includes the investigation of dielectric properties at both low and high frequencies. The behaviour of capacitors whose dielectrics comprise magnetic hybrid materials is well known. Such interfacial magnetocapacitance can be varied according to magnetic content, magnetic flux density and the relative permittivity of the polymer matrix together with other dielectric content. The basic function of trapping electrical charges in polymers (electrets) is also established technology. However, the combination of magnetoactive polymers and electrets has led to the first electromagnetic device capable of adhering to almost any material, whether magnetically susceptible or not. During the course of this research, in addition to dielectrics, electrically conductive polymers based on (PDMS) matrices were developed in order to vary the electrical properties of the material in a targeted manner. In order to ensure repeatable results, this demanded new fabrication techniques hitherto unavailable. The 3D printing of silicones is far from being a mature technology and much pioneering work was necessary before extending the usual 3 d.o.f. to include orientation about and diffusion of particles in these three axes, thus leading to the concept of 6D printing. In 6D printing, the application of a magnetic field can be used during the curing process to control the particulate distribution and thus the spatial filler particle density as desired. Most of the devices (sensors and actuators) produced by such methods contain levels of carbonyl iron powder (CIP) embedded magnetic filler of up to 70 wt%. Contrary to this, a hitherto neglected research area, namely magnetoactive polymers (MAPs) having significantly lower magnetic particle concentrations (1 to 3 wt% CIP) were also investigated. With filler concentrations lower than 3 wt%, structures are formed which are completely absent at higher filler levels. CIP concentrations in the range of 1wt% demonstrate the formation of toroidal structures. Further development of coherent rings with a compact order results as filler concentrations increase towards 2 wt%. Above 3 wt% the structure eventually disintegrates to the usual random order found in traditional MAP with higher CIP content. Structured samples containing 1%–3 wt% CIP were investigated with the aid of X-ray tomography where solitary ring structures can be observed and eventually the formation of capillary doubles. Over wavelengths ranging from 1 to 25 µm, spectroscopic analysis of thin film MAP samples containing 2 wt% CIP revealed measurable magnetic-field-dependent changes in IR absorption at a wavenumber 2350 (λ = 4.255 µm). This was found to be due to the diamagnetic susceptibility of atmospheric carbon dioxide (CO2). Consequently, the first potential application for sparse matrix MAPs was found.
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Affiliation(s)
| | | | - Nina Prem
- Mechatronics Research Unit , OTH-Regensburg , Regensburg , Germany
| | | | - Tamara Szecsey
- Mechatronics Research Unit , OTH-Regensburg , Regensburg , Germany
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Recent advances in studies of bubble-solid interactions and wetting film stability. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.09.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Near-Field Optical Examination of Potassium n-Butyl Xanthate/Chalcopyrite Flotation Products. MINERALS 2018. [DOI: 10.3390/min8030118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Xie L, Wang J, Yuan D, Shi C, Cui X, Zhang H, Liu Q, Liu Q, Zeng H. Interaction Mechanisms between Air Bubble and Molybdenite Surface: Impact of Solution Salinity and Polymer Adsorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2353-2361. [PMID: 28191980 DOI: 10.1021/acs.langmuir.6b04611] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The surface characteristics of molybdenite (MoS2) such as wettability and surface interactions have attracted much research interest in a wide range of engineering applications, such as froth flotation. In this work, a bubble probe atomic force microscope (AFM) technique was employed to directly measure the interaction forces between an air bubble and molybdenite mineral surface before/after polymer (i.e., guar gum) adsorption treatment. The AFM imaging showed that the polymer coverage on the surface of molybdenite could achieve ∼5.6, ∼44.5, and ∼100% after conditioning in 1, 5, and 10 ppm polymer solution, respectively, which coincided with the polymer coverage results based on contact angle measurements. The electrolyte concentration and surface treatment by polymer adsorption were found to significantly affect bubble-mineral interaction and attachment. The experimental force results on bubble-molybdenite (without polymer treatment) agreed well with the calculations using a theoretical model based on the Reynolds lubrication theory and augmented Young-Laplace equation including the effect of disjoining pressure. The overall surface repulsion was enhanced when the NaCl concentration decreased from 100 to 1 mM, which inhibited the bubble-molybdenite attachment. After conditioning the molybdenite surface in 1 ppm polymer solution, it was more difficult for air bubbles to attach to the molybdenite surface due to the weakened hydrophobic interaction with a shorter decay length. Increasing the polymer concentration to 5 ppm effectively inhibited bubble attachment on mineral surface, which was mainly due to the much reduced hydrophobic interaction as well as the additional steric repulsion between the extended polymer chains and bubble surface. The results provide quantitative information on the interaction mechanism between air bubbles and molybdenite mineral surfaces on the nanoscale, with useful implications for the development of effective polymer depressants and fundamental understanding of bubble-solid interactions in mineral flotation. The methodologies used in this work can be readily extended to studying similar interfacial interactions in many other engineering applications such as froth flotation deinking and bitumen extraction in oil sands industry.
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Affiliation(s)
- Lei Xie
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Jingyi Wang
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Duowei Yuan
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Chen Shi
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Xin Cui
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Qi Liu
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Qingxia Liu
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
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Effect of adsorption of butyl xanthate on galena, PbS, and HOPG surfaces as studied by atomic force microscopy and spectroscopy and XPS. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.minpro.2015.10.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Formation and influence of the dynamic adsorption layer on kinetics of the rising bubble collisions with solution/gas and solution/solid interfaces. Adv Colloid Interface Sci 2015; 222:765-78. [PMID: 25147100 DOI: 10.1016/j.cis.2014.07.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 07/29/2014] [Indexed: 11/23/2022]
Abstract
BACKGROUND The DAL (dynamic adsorption layer) formation, that is, the establishment of uneven distribution of adsorption coverage over the rising bubble surface, with significantly diminished coverage at the upstream pole, is the factor of crucial importance for the bubble motion parameters and kinetic of the bubble collisions with various interfaces. The DAL presence can influence the stability of the thin liquid films formed by the colliding bubble at solution/gas and solution solid interfaces. AIM The purpose of this paper is to critically review the existing state of art regarding the influence of the DAL formation and existence on the bubble motion parameters as well as kinetics of coalescence at free solution surface and three phase contact (TPC) formation at solid/liquid interfaces of different hydrophilic/hydrophobic properties. CONCLUSIONS Despite the fact that up to now there is no direct experimental evidence showing DAL existence, it is documented by experimental data showing clear correlation between bubble local velocity variations and shape pulsations as well as lifetimes of the liquid film formed by the colliding bubble at gas/liquid and gas/solid interfaces.
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Beattie DA, Addai-Mensah J, Beaussart A, Franks GV, Yeap KY. In situ particle film ATR FTIR spectroscopy of poly (N-isopropyl acrylamide) (PNIPAM) adsorption onto talc. Phys Chem Chem Phys 2015; 16:25143-51. [PMID: 25330994 DOI: 10.1039/c4cp03161j] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The adsorption of poly(N-isopropyl acrylamide) (PNIPAM) onto talc from aqueous solutions has been studied using the in situ methodology of particle film attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. PNIPAM was observed to adsorb significantly onto the talc particle film at a temperature below its lower critical solution temperature (LCST). Peak shifts were seen in the adsorbed layer FTIR spectrum that match those observed when PNIPAM solution is heated above its LCST. This observation indicates that adsorption causes a conformational re-arrangement similar to that seen when PNIPAM undergoes a coil-to-globule transition, in this case presumably induced by hydrophobic interactions between PNIPAM and the talc basal plane surface. The kinetics of adsorption are seen to be complex, with potential influences of conformational rearrangement and differential adsorption kinetics for the two dominant surface regions of talc particles. The adsorbed PNIPAM was seen to be exceptionally resistant to removal, with no desorption occurring when a background electrolyte solution was flowed over the adsorbed layer. Spectra acquired of the adsorbed polymer layer heated above the LCST reveal that a further conformational rearrangement takes place for the adsorbed layer, finalizing the transition from coil-to-globule that was initiated by the interaction with the mineral surface.
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Affiliation(s)
- David A Beattie
- Ian Wark Research Institute, University of South Australia, Mawson Lakes SA 5095, Australia.
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Wu J, Delcheva I, Ngothai Y, Krasowska M, Beattie DA. Bubble-surface interactions with graphite in the presence of adsorbed carboxymethylcellulose. SOFT MATTER 2015; 11:587-99. [PMID: 25515526 DOI: 10.1039/c4sm02380c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The adsorption of carboxymethylcellulose (CMC), and the subsequent effect on bubble-surface interactions, has been studied for a graphite surface. CMC adsorbs on highly oriented pyrolytic graphite (HOPG) in specific patterns: when adsorbed from a solution of low concentration it forms stretched, isolated and sparsely distributed chains, while upon adsorption from a solution of higher concentration, it forms an interconnected network of multilayer features. The amount and topography of the adsorbed CMC affect the electrical properties as well as the wettability of the polymer-modified HOPG surface. Adsorption of CMC onto the HOPG surface causes the zeta potential to be more negative and the modified surface becomes more hydrophilic. This increase in both the absolute value of zeta potential and the surface hydrophilicity originates from the carboxymethyl groups of the CMC polymer. The effect of the adsorbed polymer layer on wetting film drainage and bubble-surface/particle attachment was determined using high speed video microscopy to monitor single bubble-surface collision, and single bubble Hallimond tube flotation experiments. The time of wetting film drainage and the time of three-phase contact line spreading gets significantly longer for polymer-modified HOPG surfaces, indicating that the film rupture and three-phase contact line expansion were inhibited by the presence of polymer. The effect of longer drainage times and slower dewetting correlated with reduced flotation recovery. The molecular kinetic (MK) model was used to quantify the effect of the polymer on dewetting dynamics, and showed an increase in the jump frequency for the polymer adsorbed at the higher concentration.
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Affiliation(s)
- Jueying Wu
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
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Kor M, Korczyk PM, Addai-Mensah J, Krasowska M, Beattie DA. Carboxymethylcellulose adsorption on molybdenite: the effect of electrolyte composition on adsorption, bubble-surface collisions, and flotation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11975-84. [PMID: 25232682 DOI: 10.1021/la503248e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The adsorption of carboxymethylcellulose polymers on molybdenite was studied using spectroscopic ellipsometry and atomic force microscopy imaging with two polymers of differing degrees of carboxyl group substitution and at three different electrolyte conditions: 1 × 10(-2) M KCl, 2.76 × 10(-2) M KCl, and simulated flotation process water of multicomponent electrolyte content, with an ionic strength close to 2.76 × 10(-2) M. A higher degree of carboxyl substitution in the adsorbing polymer resulted in adsorbed layers that were thinner and with more patchy coverage; increasing the ionic strength of the electrolyte resulted in increased polymer layer thickness and coverage. The use of simulated process water resulted in the largest layer thickness and coverage for both polymers. The effect of the adsorbed polymer layer on bubble-particle attachment was studied with single bubble-surface collision experiments recorded with high-speed video capture and image processing and also with single mineral molybdenite flotation tests. The carboxymethylcellulose polymer with a lower degree of substitution resulted in almost complete prevention of wetting film rupture at the molybdenite surface under all electrolyte conditions. The polymer with a higher degree of substitution prevented rupture only when adsorbed from simulated process water. Molecular kinetic theory was used to quantify the effect of the polymer on the dewetting dynamics for collisions that resulted in wetting film rupture. Flotation experiments confirmed that adsorbed polymer layer properties, through their effect on the dynamics of bubble-particle attachment, are critical to predicting the effectiveness of polymers used to prevent mineral recovery in flotation.
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Affiliation(s)
- Mohammad Kor
- Ian Wark Research Institute, University of South Australia , Mawson Lakes, SA 5095, Australia
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Mierczynska-Vasilev A, Beattie DA. The effect of impurities and cleavage characteristics on talc hydrophobicity and polymer adsorption. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.minpro.2012.11.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Adsorption of modified dextrins on molybdenite: AFM imaging, contact angle, and flotation studies. J Colloid Interface Sci 2012; 368:608-15. [DOI: 10.1016/j.jcis.2011.10.075] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/30/2011] [Accepted: 10/31/2011] [Indexed: 11/19/2022]
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Parkinson L, Ralston J. Dynamic aspects of small bubble and hydrophilic solid encounters. Adv Colloid Interface Sci 2011; 168:198-209. [PMID: 21880285 DOI: 10.1016/j.cis.2011.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 07/11/2011] [Accepted: 08/01/2011] [Indexed: 10/17/2022]
Abstract
The capture of solid particles suspended in aqueous solution by rising gas bubbles involves hydrodynamic and physicochemical processes that are central to colloid science. Of the collision, attachment and aggregate stability aspects to the bubble-particle interaction, the crucial attachment process is least understood. This is especially true of hydrophilic solids. We review the current literature regarding each component of the bubble-particle attachment process, from the free-rise of a small, clean single bubble, to the collision, film drainage and interactions which dominate the attachment rate. There is a particular focus on recent studies which employ single, very small bubbles as analysis probes, enabling the dynamic bubble-hydrophilic particle interaction to be investigated, avoiding complications which arise from fluid inertia, deformation of the liquid-vapour interface and the possibility of surfactant contamination.
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Beaussart A, Mierczynska-Vasilev AM, Harmer SL, Beattie DA. The role of mineral surface chemistry in modified dextrin adsorption. J Colloid Interface Sci 2011; 357:510-20. [DOI: 10.1016/j.jcis.2011.02.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 02/05/2011] [Indexed: 11/26/2022]
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Sedeva IG, Fornasiero D, Ralston J, Beattie DA. Reduction of surface hydrophobicity using a stimulus-responsive polysaccharide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:15865-15874. [PMID: 20853820 DOI: 10.1021/la101695w] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The adsorption of carboxymethyl cellulose (CMC) onto a hydrophobic self-assembled monolayer has been characterized using the quartz crystal microbalance (with dissipation monitoring, QCM-D). Adsorption was studied as a function of initial solution conditions. CMC adsorbs to a greater extent at high ionic strength (10(-1) M KCl as opposed to 10(-2) M KCl) or low pH (3 as opposed to 9). The solution conditions that yielded the lowest initial adsorbed amount (10(-2) M KCl, pH 9) were used as a reference to investigate the response of the adsorbed layer to a switch in solution conditions after adsorption (i.e., to higher ionic strength (10(-1) M KCl) or lower pH (pH 3)). The adsorbed layer released significant amounts of hydration water after each solution switch, as determined by the QCM-D measurements. This expulsion of hydration water was fully reversible. For the two solution switches, reducing the solution pH resulted in a more pronounced change in the amount of hydration water within the adsorbed CMC, accompanied by a distinct conformational change, as determined from a QCM D-f plot. In addition to studying adsorption using QCM-D, the effect of adsorbed CMC on surface hydrophobicity has been investigated using captive bubble contact angle measurements. The effect of the polymer on the contact angle of the surface was seen to be greatest when adsorbed at low pH or at higher ionic strength. CMC was also seen to have a significantly enhanced ability to reduce the surface hydrophobicity after both the ionic strength and pH switches, lowering the advancing water contact angle by 6 and 23° and the receding water contact angle by 10 and 40° for the ionic strength and pH switches, respectively. As with the change in hydration water content, the change in the contact angle of the polymer-coated surface following the solution switches was reversible.
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Affiliation(s)
- Iliana G Sedeva
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095, Australia
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Evolution of carboxymethyl cellulose layer morphology on hydrophobic mineral surfaces: Variation of polymer concentration and ionic strength. J Colloid Interface Sci 2010; 346:303-10. [DOI: 10.1016/j.jcis.2010.03.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 03/01/2010] [Accepted: 03/03/2010] [Indexed: 11/22/2022]
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Mierczynska-Vasilev A, Beattie DA. In situ atomic force microscopy of modified dextrin adsorption on hydrophobic and hydrophilic layered silicate minerals. J Colloid Interface Sci 2010; 344:429-37. [DOI: 10.1016/j.jcis.2010.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 01/04/2010] [Accepted: 01/07/2010] [Indexed: 10/20/2022]
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