Shear History Independence in Colloidal Aggregation

Langmuir ◽  
2012 ◽  
Vol 28 (31) ◽  
pp. 11337-11342 ◽  
Author(s):  
William R. Heinson ◽  
Christopher M. Sorensen ◽  
Amitabha Chakrabarti
Keyword(s):  
Colloidal Aggregation ◽  
History Independence ◽  
Shear History

Computer Simulation of Colloidal Aggregation Induced by Directionalism of Long Range van der Waals Forces

2007 ◽  
Vol 23 (08) ◽  
pp. 1241-1246 ◽  
Author(s):  
XIONG Hai-Ling ◽  
◽  
◽  
YUAN Yong-Zhi ◽  
LI Hang ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Long Range ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Colloidal Aggregation

scholarly journals Kinetics and proposed mechanism of the reaction of an immunoinhibition, particle-enhanced immunoassay

1997 ◽  
Vol 43 (12) ◽  
pp. 2384-2389 ◽  
Author(s):  
John C Thompson ◽  
Alan R Craig ◽  
Carol L Davey ◽  
David J Newman ◽  
Michele L Lonsdale ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Maximum Rate ◽  
Colloidal Stability ◽  
Kinetic Studies ◽  
Latex Agglutination ◽  
Equivalence Point ◽  
Colloidal Aggregation ◽  
Free Sample ◽  
Identical Fashion ◽  
Mechanism Of The Reaction

Abstract We report kinetic studies on the reaction of a latex agglutination immunoassay used to quantify phenytoin in serum. In this assay, polystyrene particles with a covalently attached analog of phenytoin react with an antiphenytoin monoclonal antibody to form light-scattering aggregates, with the rate of this reaction being decreased by addition of phenytoin from sample. In the absence of free (sample) phenytoin, this reaction did not exhibit a maximum rate of agglutination in the presence of excess antibody, i.e., an equivalence point. Furthermore, agglutination was inhibitable by free phenytoin even when the latter was added after agglutination of particles with antibody had begun. Most significantly, the immunoagglutination proceeded in an identical fashion with monovalent F(ab) fragment. These data are consistent with low-affinity immunospecific particle–antibody complexation, which then induces colloidal aggregation, without requiring immunospecific bridging by antibody molecules. The described mechanism is not generalizable to all latex agglutination immunoassays, although disturbance of colloidal stability may be a component in most assays.

scholarly journals Flocculation of Clay Suspensions by Anionic and Cationic Polyelectrolytes: A Systematic Analysis

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 999
Author(s):  
Ahmad Shakeel ◽  
Zeinab Safar ◽  
Maria Ibanez ◽  
Leon van Paassen ◽  
Claire Chassagne
Keyword(s):  
Light Scattering ◽  
Shear Rate ◽  
Settling Velocity ◽  
Rheological Analysis ◽  
Floc Size ◽  
Clay Concentration ◽  
History Of ◽  
Settling Column ◽  
Cationic Polyelectrolytes ◽  
Shear History

The characteristics of clayey suspensions, majorly composed of quartz microparticles, in the presence of anionic and cationic polyelectrolytes were investigated using different techniques. A wide range of clay concentrations was used, i.e., from 0.07 to 1000 g/L for different experimental techniques, based on the fact that the clay concentration possible to analyze with selected experimental methods was significantly different. The optimum flocculant to clay ratio was defined as the ratio that gives the fastest initial floc growth by static light scattering or fastest initial settling velocity by settling column experiments. In case of anionic polyelectrolyte, it was observed that the optimum flocculant dose depends on the amount of cations present in the system. For suspensions made with demi-water, a lower optimum flocculant dose (<1 mg/g) than for suspensions prepared in tap water (2.28 mg/g) was observed. At these lower salinities, the supernatant remained turbid in all the experiments and was, therefore, not a good measure for optimal anionic based flocculation. The equilibrium floc size at a given shear rate was found to be independent on the shear history of the floc and only dependent on the current applied shear. This was confirmed by both light scattering and rheological analysis. In case of cationic polyelectrolyte, the optimum flocculant ratio (5–6 mg/g) corresponded to the ratio that gives the lowest electrophoretic mobility for each clay concentration and to the ratio that gives the fastest settling velocity for the highest clay concentrations (12–15 g/L), where static light scattering measurements were not possible. All investigation techniques, therefore, proved to be good indicators for predicting the optimum flocculant to clay ratio. For the lowest concentrations (1.75–8.7 g/L) studied by settling column measurements, the optimum flocculant ratio was observed to increase with decreasing clay concentration, for fixed mixing conditions. The optimum flocculant to clay ratio was not always corresponding to the clearest supernatant and the size of flocs at optimum dosage was dependent on the mixing efficiency. The equilibrium floc size at a given shear rate was found to be dependent on the shear history of the floc and the current applied shear. This was confirmed by both light scattering and rheological analysis.

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