Bubble–surface interactions with graphite in the presence of adsorbed carboxymethylcellulose

Soft Matter ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 587-599 ◽  
Author(s):  
Jueying Wu ◽  
Iliana Delcheva ◽  
Yung Ngothai ◽  
Marta Krasowska ◽  
David A. Beattie
Keyword(s):  
Contact Angle ◽  
Polymer Concentration ◽  
Adsorbed Layer ◽  
Surface Interactions ◽  
Bubble Surface ◽  
Graphite Surface ◽  
Mineral Surface ◽  
Film Rupture ◽  
Bubble Rise ◽  
Wetting Film

Bubble rise and collision against a graphite surface pre-treated with an adsorbed layer of carboxymethylcellulose. The adsorbed layer can prolong wetting film rupture, dramatically slow the dewetting of the mineral surface, and reduce the final contact angle of the bubble. Adsorption of CMC from a solution of higher polymer concentration amplifies the effect of the polymer.

Study of Tip-Surface Interactions in Scanning Tunneling Microscopy (STM) by Reflection Electron Microscopy (REM)

1990 ◽  
Vol 48 (1) ◽  
pp. 320-321
Author(s):  
W. Lo ◽  
J.C.H. Spence ◽  
M. Kuwabara
Keyword(s):  
High Resolution ◽  
Elastic Strain ◽  
Tunneling Current ◽  
Surface Damage ◽  
Surface Interactions ◽  
Graphite Surface ◽  
Scanning Tunneling ◽  
Large Area ◽  
Tunneling Microscopy ◽  
High Resolution Tem

Work on the integration of STM with REM has demonstrated the usefulness of this combination. The STM has been designed to replace the side entry holder of a commercial Philips 400T TEM. It allows simultaneous REM imaging of the tip/sample region of the STM (see fig. 1). The REM technique offers nigh sensitivity to strain (<10−4) through diffraction contrast and high resolution (<lnm) along the unforeshortened direction. It is an ideal technique to use for studying tip/surface interactions in STM.The elastic strain associated with tunnelling was first imaged on cleaved, highly doped (S doped, 5 × 1018cm-3) InP(110). The tip and surface damage observed provided strong evidence that the strain was caused by tip/surface contact, most likely through an insulating adsorbate layer. This is consistent with the picture that tunnelling in air, liquid or ordinary vacuum (such as in a TEM) occurs through a layer of contamination. The tip, under servo control, must compress the insulating contamination layer in order to get close enough to the sample to tunnel. The contaminant thereby transmits the stress to the sample. Elastic strain while tunnelling from graphite has been detected by others, but never directly imaged before. Recent results using the STM/REM combination has yielded the first direct evidence of strain while tunnelling from graphite. Figure 2 shows a graphite surface elastically strained by the STM tip while tunnelling (It=3nA, Vtip=−20mV). Video images of other graphite surfaces show a reversible strain feature following the tip as it is scanned. The elastic strain field is sometimes seen to extend hundreds of nanometers from the tip. Also commonly observed while tunnelling from graphite is an increase in the RHEED intensity of the scanned region (see fig.3). Debris is seen on the tip and along the left edges of the brightened scan region of figure 4, suggesting that tip abrasion of the surface has occurred. High resolution TEM images of other tips show what appear to be attached graphite flakes. The removal of contamination, possibly along with the top few layers of graphite, seems a likely explanation for the observed increase in RHEED reflectivity. These results are not inconsistent with the “sliding planes” model of tunnelling on graphite“. Here, it was proposed that the force due to the tunnelling probe acts over a large area, causing shear of the graphite planes when the tip is scanned. The tunneling current is then modulated as the planes of graphite slide in and out of registry. The possiblity of true vacuum tunnelling from the cleaned graphite surface has not been ruled out. STM work function measurements are needed to test this.

Electrochemical investigation of contact angle and of flotation in the presence of alkylxanthates. II. Galena and pyrite surfaces

1977 ◽  
Vol 30 (5) ◽  
pp. 981 ◽  
Author(s):  
JR Gardner ◽  
R Woods
Keyword(s):  
Contact Angle ◽  
Electrode Potential ◽  
Electrochemical Investigation ◽  
Pyrite Surface ◽  
Mineral Surface ◽  
Hydrated Iron Oxide ◽  
Mineral Particles ◽  
Lead Electrode ◽  
Nitrogen Bubble ◽  
Metal Xanthate

The contact angle between a nitrogen bubble and galena and pyrite surfaces immersed in methyl-, ethyl- or butyl-xanthates has been determined as a function of the electrode potential and of the quantity of xanthate species formed by interaction with the mineral surface. For galena, the initial chemisorbed xanthate layer was found to be hydrophobic when ethyl- or butyl-xanthates were employed, but hydrophilic for the methyl homologue. The presence of dixanthogen enhanced the contact angle but the metal xanthate diminished it. This conclusion was supported by contact angle studies at a lead electrode. For pyrite the surface was hydrophilic except when dixanthogen was formed, but a significant quantity was required on the mineral surface before a finite contact angle was observed. This behaviour is interpreted in terms of the presence of hydrated iron oxide on the pyrite surface. ��� The potentials at which particulate bed electrodes of galena and pyrite begin to float were determined for ethyl- and butyl- xanthates. The potentials correspond to the regions where chemisorption of xanthate takes place on galena and where significant quantities of dixanthogen are formed on pyrite. ��� With butylxanthate, flotation was inhibited when excessive quantities of xanthate species were present on galena or pyrite. The inhibition arose from flocculation of the mineral particles.

Flow of Hydrophobically Modified Water-Soluble-Polymer Solutions in Porous Media: New Experimental Insights in the Diluted Regime

SPE Journal ◽  
2010 ◽  
Vol 16 (01) ◽  
pp. 43-54 ◽  
Author(s):  
Guillaume Dupuis ◽  
David Rousseau ◽  
René Tabary ◽  
Bruno Grassl
Keyword(s):  
Oil Recovery ◽  
Polymer Concentration ◽  
Adsorbed Layer ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Improved Oil Recovery ◽  
Water Soluble Polymers ◽  
Resistance Factors ◽  
Soluble Polymers ◽  
Hydrophobically Modified

Summary The specific molecular structure of hydrophobically modified water-soluble polymers (HMWSPs), also called hydrophobically associative polymers, gives them interesting thickening and surface-adsorption abilities compared with classical water-soluble polymers (WSPs), which could be useful in polymer-flooding and well-treatment operations. However, their strong adsorption obviously can impair their injectivity, and, conversely, the shear sensitivity of their gels can be detrimental to well treatments. Determining for which improved-oil-recovery (IOR) application HMWSPs are best suited, therefore, remains difficult. The aim of this work is to bring new insight regarding the interaction mechanisms between HMWSPs and rock matrix and the consequences concerning their propagation in reservoirs. A consistent set of HMWSPs with sulfonated polyacrylamide backbones and alkyl hydrophobic side chains together with an equivalent WSP was synthesized and fully characterized. HMWSP and WSP solutions were then injected in model granular packs. As expected, with HMWSPs, high resistance factors (or mobility reductions, Rm) were observed. Yet, within the limit of the injected volumes, the effluent showed the same viscosity and polymer concentration as the injected solutions. A first significant outcome concerns the specificities of the Rm curves during HMWSP injections. Rm increases took place in two steps. The first corresponded to the propagation of the viscous front, as observed with WSP, whereas the second was markedly delayed, occurring several pore volumes (PV) after the breakthrough. This result is not compatible with the classical picture of multilayer adsorption of HMWSPs but suggests that injectivity is controlled solely by the adsorption of minor polymeric species. This hypothesis was confirmed by reinjecting the collected effluents into fresh cores; no second-step Rm increases were observed. Brine injections in HMWSP-treated cores revealed high residual resistance factors (or irreversible permeability reductions, Rk), which can be attributed to the presence of thick polymer-adsorbed layers on the pore surface. Nevertheless, Rk values strongly decreased when increasing the brine-flow rate. This second significant outcome shows that the adsorbed-layer thickness is shear-controlled. These new results should lead to proposing new adapted filtration and injection procedures for HMWSPs, aimed, in particular, at improving their injectivity.

scholarly journals Bubble Rise Velocity and Surface Mobility in Aqueous Solutions of Sodium Dodecyl Sulphate and n-Propanol

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 743
Author(s):  
Pavlína Basařová ◽  
Yuliya Kryvel ◽  
Jakub Crha
Keyword(s):  
Surface Tension ◽  
Aqueous Solutions ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Bubble Surface ◽  
Rise Velocity ◽  
Bubble Rise ◽  
Spherical Bubble ◽  
Surface Mobility ◽  
Bubble Rise Velocity

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.

Direct observation of the attachment behavior of hydrophobic colloidal particles onto a bubble surface

Soft Matter ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 695-702
Author(s):  
Nozomi Arai ◽  
Satoshi Watanabe ◽  
Minoru T. Miyahara ◽  
Ryoichi Yamamoto ◽  
Uwe Hampel ◽  
...  
Keyword(s):  
Contact Angle ◽  
Direct Observation ◽  
Single Particle ◽  
Colloidal Particles ◽  
Bubble Surface ◽  
Static Contact Angle ◽  
Attachment Behavior ◽  
Static Contact ◽  
Hydrophobic Particle

This article addresses the attachment behavior of a single particle onto a bubble from a microscopic view, in which a hydrophobic particle abruptly “jumps into” a bubble to satisfy its static contact angle.

Microbial Dissolution of Hematite and Associated Cellular Fossilization by Reduced Iron Phases: A Study of Ancient Microbe-Mineral Surface Interactions

Astrobiology ◽  
2009 ◽  
Vol 9 (8) ◽  
pp. 777-796 ◽  
Author(s):  
Kamal Kolo ◽  
Kurt Konhauser ◽  
Wolfgang Elisabeth Krumbein ◽  
Yves Van Ingelgem ◽  
Annick Hubin ◽  
...  
Keyword(s):  
Surface Interactions ◽  
Mineral Surface

scholarly journals Efficient Oil Removal of Polymer Flooding Produced Sewerage Using Super-Hydrophobic Mesh Filtration Method

2020 ◽  
Vol 4 (3) ◽  
pp. 32
Author(s):  
Wanli Kang ◽  
Xin Kang ◽  
Hongbin Yang ◽  
Hailu Gebremariam ◽  
Zhe Li
Keyword(s):  
Contact Angle ◽  
Crude Oil ◽  
Oil Recovery ◽  
Polymer Concentration ◽  
Polymer Flooding ◽  
Water Volume ◽  
Potential Candidate ◽  
Filtration Method ◽  
Static Contact ◽  
Copper Mesh

During the past 20 years, polymer flooding has become a successful enhanced oil recovery (EOR) technique for mature reservoirs with high water cut and recovery percent around the world. However, the high bulk viscosity of polymer solutions could slow down the separation rate of the crude oil emulsion and make it difficult to treat the produced fluid. Consequently, the efficient removal of oil from the polymer flooding produced sewerage has still drawn significant concern. In this research, a high flux super-hydrophobic copper mesh was prepared using two-stage processes to treat the sewerage from polymer flooding. The surface of the super-hydrophobic mesh was characterized using various techniques including scanning electron microscope (SEM), OCA 20-contact angle goniometer, etc. Accordingly, the static contact angle of the super-hydrophobic copper mesh reached up to 165°. Moreover, the performances of the mesh were systematically evaluated under different internal and external factors such as oil to water volume ratio, polymer concentration, shear rate, and pH. The corresponding configuration and separation mechanisms are further explained in detail. The prepared superhydrophobic mesh can be a potential candidate for sewerage with both a polymer solution and crude oil.

scholarly journals Effect of Bubble Surface Properties on Bubble–Particle Collision Efficiency in Froth Flotation

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 367 ◽  
Author(s):  
Shuofu Li ◽  
Kou Jue ◽  
Chunbao Sun
Keyword(s):  
Surface Properties ◽  
Froth Flotation ◽  
Surfactant Solution ◽  
Terminal Velocity ◽  
Bubble Surface ◽  
Particle Collision ◽  
Film Rupture ◽  
Collision Efficiency ◽  
Mineral Particles ◽  
Bubble Collision

In research on the particle–bubble collision process, due to the adsorption of surfactants and impurities (such as mineral particles, slime, etc.), most studies consider the bubble surface environment to be immobile. However, in the real situation of froth flotation, the nature of the bubble surface (degree of slip) is unknown. Mobile surface bubbles increase the critical thickness of the hydration film rupture between particles and bubbles, and enhance the collision between particles and bubbles. Sam (1996) showed that when the diameter of the bubble is large enough, a part of the surface of the bubble can be transformed into a mobile state. When the bubble rises in a surfactant solution, the surface pollutants are swept to the end of the bubble, so when the bubble reaches terminal velocity, the upper surface of the bubble is changed into a mobile surface. This paper analyzes the collision efficiency and fluid flow pattern of bubbles with mobile and immobile surfaces, and expounds the influence of surface properties on collision efficiency.

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