Polymer Adsorption and Particle Flocculation in Turbulent Flow

Wigsten, Anders L.; Stratton, Robert A.

doi:10.1021/bk-1984-0240.ch026

Cited by 9 publications

(5 citation statements)

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“…This suggests that the characteristic time for the adsorption of polymer on filler particles is of the order of seconds, in accordance with experimentally observed adsorption times for polymer adsorption under turbulent flow conditions (27) .…”

supporting

confidence: 89%

Physiocochemical and Hydrodynamic Aspects of Fines and Fillers Retention

van de Ven

1989

Trans. Of the IXth Fund. Res. Symp. Cambridge, 1989

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From the results of model studies on well-characterized systems, valuable conclusions can be drawn regarding several phenomena occurring in papermaking suspensions relevant to fines and fillers retention. We have shown that long range hydrodynamic interactions are operating between small particles (such as fillers) and spheroids (such as fibers) subjected to simple shear, preventing small particles from approaching large ones to within distances where colloidal forces become important. We can expect similar effects in papermaking suspensions, resulting in very low efficiencies for the deposition of fillers or fines on fibers. The efficiency can be improved by high molecular weight polymers which adsorb on the particles and can reduce the minimum distance of approach between a filler and a fiber. From model experiments on the deposition of T102 particles on cellophane, it can be concluded that the electrostatic forces also play an important role in fines and fillers retention. Usually no deposition occurs far below a critical deposition concentration (CDC) of electrolyte, slow deposition occurs just before the CDC and fast deposition above the CDC. Charged polymers, such as cationic polyelectrolytes, are most effective in retention because they can reduce the gap between a filler and a fiber during an encounter, and they ensure that electrostatic repulsion is negligible. Resides increasing the efficiency of deposition, retention aids can also increase the bond strength between a filler and a fiber, thus preventing or minimizing the rupture of fiber-filler bonds.

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supporting

confidence: 89%

Physiocochemical and Hydrodynamic Aspects of Fines and Fillers Retention

van de Ven

1989

Trans. Of the IXth Fund. Res. Symp. Cambridge, 1989

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“…For 1 mg/mL LSZ- and CC-induced PC liposome flocculation, the higher value of the activation energy and lower value of the kinetic constant are probably related to the protein surface coverage of the liposomes, which in the case of bridging flocculation plays an important role. It is well-known that a maximum flocculation occurs at θ = 0.5 (i.e., at 50%) surface coverage and that with further increase of the protein surface coverage the flocculation rate decreases . If the surface of the liposomes is completely covered by protein molecules, the bridging flocculation between protein-covered and protein-free liposomes can hardly occur.…”

Section: Discussionmentioning

confidence: 99%

Kinetics of Protein-Induced Flocculation of Phosphatidylcholine Liposomes

1997

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The influence of protein adsorption on membrane-membrane interactions was studied regarding the kinetic stability of phosphatidylcholine (PC) liposome dispersions. The rates of flocculation were measured by the decrease in the transmitted light intensities in time. To elucidate the experimental data, we proposed an analytical method relating light transmittance to the average size of liposome flocs. The obtained relaxation time and maximum light absorbance were connected to the kinetic constant and the flocculation activation energy. These model parameters were calculated for the flocculation processes of PC liposomes in the presence of lysozyme, cytochrome c, and bovine serum albumin as a function (i) of the protein concentration and (ii) of the ionic strength. In addition to the generally accepted concept that the stability of PC liposomes is due to the action of hydration repulsive force, here we found that in the presence of soluble proteins the steric factors and electrostatics play essential roles for the colloidal stability of egg PC liposome dispersions.

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“…3 considerably overestimates the aggregation rate compared to the experimental data. This is a common finding,8, 11, 12, 21, 22, 23, 25, 26, 41, 65–72 and the capture efficiency is frequently taken to be in the range 0.0001–0.5. In this case, if the capture efficiency was set to a constant value after flocculant addition, it had to be relatively small (∼0.06) to give a reasonable fit to the data, suggesting that particle collision (Eq.…”

Section: Model Developmentmentioning

confidence: 94%