Hydrophobic attraction may contribute to aqueous flocculation of clays

Zbik, M.; Horn, Roger G.

doi:10.1016/s0927-7757(03)00250-4

Cited by 56 publications

(35 citation statements)

References 10 publications

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“…Although this seems unlikely due to the strong repulsive forces between coal and illite (as shown by the calculation results in Figure 1c), similar phenomena were observed in the coal-kaolinite (calculated force attractive) and coal-montmorillonite (calculated force repulsive) systems [8]. This is possibly due to the adhesion of the coal surface and clay platelet edges as Marek [26] reported, where clay platelets attach to hydrophobic (but not hydrophilic) surfaces by their edges as a result of the presence of nano-bubbles existing on the edges of the clay crystals. The deviation between the calculations and experiments was caused by using the general contact angles of illite on liquids.…”

Section: Coagulation Sedimentation Of Particlessupporting

confidence: 65%

“…In the pure coal and mixed coal-illite samples, the optimal supernatant turbidities (4.6 NTU for coal-coal and 9.8 NTU for coal-illite) were obtained when 1.5 mg/L APAM was added, with the turbidity increasing as more APAM was added. This demonstrates that calcium ions acted as bridges between particles and the anionic groups of flocculant when a suitable dosage of APAM was used; excessive APAM may increase repulsive electrostatic forces, which may be adverse to flocculation [26], as Figure 4b shows. Of interest is the fact that no obvious sedimentation was observed in the pure illite samples in all of the additional experiments.…”

Section: Flocculation Sedimentation Of Particlesmentioning

confidence: 93%

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Aggregation Mechanism of Particles: Effect of Ca2+ and Polyacrylamide on Coagulation and Flocculation of Coal Slime Water Containing Illite

Lin

Hou

et al. 2017

Minerals

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Abstract:Illite is one of the main components in coal slime water and it sometimes makes the water extremely difficult to clarify. In this study, the aggregation mechanism of coal and illite particles was investigated using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and settling experiments of slime water containing coal and illite. The results show that electrostatic energy plays a dominant role and manifests repulsive force in the long-range (>4 nm). However, the leading role becomes a hydrophobic force determined by the polar surface interaction energy in the short-range (<4 nm). A coagulant (Ca 2+ ) can lower the surface electric potential to make all particles easier to coagulate, while the surface hydrophobicity of coal and illite determines whether the particles aggregate. Cationic polyacrylamide (CPAM) can promote the sedimentation of particles flocs effectively and makes the supernatant clearer due to attractive electrostatic forces while anionic polyacrylamide (APAM) flocculates particles through the bridge mechanism. Although the hydration shell on the hydrophilic surface of illite appears to be harmful for either coagulation or flocculation, illite can accelerate sedimentation when it is attached to the coal due to its higher density.

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Section: Coagulation Sedimentation Of Particlessupporting

confidence: 65%

Section: Flocculation Sedimentation Of Particlesmentioning

confidence: 93%

Aggregation Mechanism of Particles: Effect of Ca2+ and Polyacrylamide on Coagulation and Flocculation of Coal Slime Water Containing Illite

Lin

Hou

et al. 2017

Minerals

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“…Moreover, Switkes et al [19] and Zhang et al [20] explored the effect of degassing on nanobubbles to find that formation of nanobubbles was strongly related with dissolved gas, indicating that there was gas contained in nanobubble. Although the mechanism of nanobubbles at interface remains unclear, its effect on some classic scientific problems and processes was taken into account by the scholars, such as the origin of long distance attraction between hydrophobic surfaces [21] , slippage of simple fluids near a wall [22,23] , microboiling behavior [24] , mineral flotation [25] , and the rupture of a wetting film [26] .As known, protein adsorption is an important phenomenon scientifically and practically, concerning artificial organs, issue engineering, biochip, biosensor, and so on [27] . Castner et al [28] drew the conclusion that to understand the biological response to a material, especially in vitro, one must fully understand the nature of the adsorbed protein film that formed on that material.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

In situ AFM observation of BSA adsorption on HOPG with nanobubble

Zhang

et al. 2007

Chin. Sci. Bull.

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Nanobubbles have been proven existent at the liquid/solid interface, and become a focus of research on varied interfacial processes. In the present work, by observing in situ with atomic force microscope (AFM), we found that nanobubbles could influence the adsorption process of bovine serum albumin (BSA) on hydrophobic surface of highly ordered pyrolytic graphite (HOPG). BSA could adsorb evenly, and coexist with nanobubbles at water/HOPG interface. After removing nanobubbles by injecting ethanol, some hollows were found in the BSA layers at the same positions of nanobubbles existing previously. These hollows were about 8 nm in depth and dozens of nanometers in diameter. The correlation coefficient between the areas of nanobubbles and that of the corresponding hollows reached 0.88-0.94, which strongly supported the assumption that the hollows were indeed caused by the nanobubbles. Moreover, the BSA molecules formed rings around the nanobubbles, suggesting the preference of BSA adsorption onto the contact line at water/HOPG interface.nanobubble, adsorption, bovine serum albumin (BSA), highly ordered pyrolytic graphite (HOPG), atomic force microscope (AFM)The water/solid interface is of special interest in terms of its ubiquitous presence and its important role in biological and colloidal systems [1] . Although bubbles at the nanoscale were believed impossible or unstable in classical theory [2] , and experimental studies have shown that nanobubbles do exist at water/solid interfaces [3][4][5] . In the last few years, more and more evidence, including atomic force microscope (AFM) observation, is found supporting the stable existence of nanobubbles [6][7][8][9][10][11][12][13][14][15][16][17][18] . Moreover, Switkes et al. [19] and Zhang et al. [20] explored the effect of degassing on nanobubbles to find that formation of nanobubbles was strongly related with dissolved gas, indicating that there was gas contained in nanobubble. Although the mechanism of nanobubbles at interface remains unclear, its effect on some classic scientific problems and processes was taken into account by the scholars, such as the origin of long distance attraction between hydrophobic surfaces [21] , slippage of simple fluids near a wall [22,23] , microboiling behavior [24] , mineral flotation [25] , and the rupture of a wetting film [26] .As known, protein adsorption is an important phenomenon scientifically and practically, concerning artificial organs, issue engineering, biochip, biosensor, and so on [27] . Castner et al. [28] drew the conclusion that to understand the biological response to a material, especially in vitro, one must fully understand the nature of the adsorbed protein film that formed on that material. There are vast literatures focusing on varied proteins on kinds of materials extensively, for example, protein C hordein and protein A on silicon surface, bovine serum albumin (BSA) onto titanium, fibrinogen assembles on both highly oriented pyrolytic graphite (HOPG) and PHYSICAL CHEMISTRY

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“…More details can be found elesewhere (Christenson and Claesson, 2001 ;Eriksson et al , 1989 ;Ruckenstein and Churaev, 1991 ). It is possible for the surface of particles dispersed in environmental waters to have some degree of hydrophobicity and the hydrophobic force has been postulated to contribute to the aqueous aggregation of clay particles (Zbik and Horn, 2003 ).…”

Section: Hydrophobic Interactionsmentioning

confidence: 99%