Heteroflocculation by Asymmetric Polymer Bridging

Ven, Theo G. M. van de; Alinče, B.

doi:10.1006/jcis.1996.0357

Cited by 48 publications

(41 citation statements)

References 5 publications

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“…For polymer bridging to occur there should be sufficient unoccupied space on the NPs for the polymer to attach to [141], and the thickness of the polymer layer must be larger than the thickness of the electrical double layer on the NP(s) [142,143]. Polymers may bind to NPs via electrostatic interactions, covalent bonding, or via functional or ligand groups.…”

Section: Bridgingmentioning

confidence: 99%

“…Polymers may bind to NPs via electrostatic interactions, covalent bonding, or via functional or ligand groups. Typically, the polymer has to be able to adsorb to the different types of NPs (or colloids/surfaces), but a phenomenon of asymmetric bridging has been described in which heteroaggregation still occurs although the polymer, in its pristine state, can only attach to one of the surfaces [142]. In asymmetric bridging the polymer first attaches to one of the surfaces, leading to a modification in polymer configuration and entropy, which enables it to attach to the other particle it may otherwise not have interacted with [142].…”

Section: Bridgingmentioning

confidence: 99%

“…Typically, the polymer has to be able to adsorb to the different types of NPs (or colloids/surfaces), but a phenomenon of asymmetric bridging has been described in which heteroaggregation still occurs although the polymer, in its pristine state, can only attach to one of the surfaces [142]. In asymmetric bridging the polymer first attaches to one of the surfaces, leading to a modification in polymer configuration and entropy, which enables it to attach to the other particle it may otherwise not have interacted with [142]. Although studies of asymmetric bridging in NPs-based systems are sparse, factors affecting morphology of polymers such as pH, ionic strength, and temperature [144][145][146] are expected to affect heteroaggregation occurring via polymer bridging.…”

Section: Bridgingmentioning

confidence: 99%

See 2 more Smart Citations

Heteroaggregation of nanoparticles with biocolloids and geocolloids

Wang

Adeleye

Huang

et al. 2015

Advances in Colloid and Interface Science

170

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The application of nanoparticles has raised concern over the safety of these materials to human health and the ecosystem. After release into an aquatic environment, nanoparticles are likely to experience heteroaggregation with biocolloids, geocolloids, natural organic matter (NOM) and other types of nanoparticles. Heteroaggregation is of vital importance for determining the fate and transport of nanoparticles in aqueous phase and sediments. In this article, we review the typical cases of heteroaggregation between nanoparticles and biocolloids and/or geocolloids, mechanisms, modeling, and important indicators used to determine heteroaggregation in aqueous phase. The major mechanisms of heteroaggregation include electric force, bridging, hydrogen bonding, and chemical bonding. The modeling of heteroaggregation typically considers DLVO, X-DLVO, and fractal dimension. The major indicators for studying heteroaggregation of nanoparticles include surface charge measurements, size measurements, observation of morphology of particles and aggregates, and heteroaggregation rate determination. In the end, we summarize the research challenges and perspective for the heteroaggregation of nanoparticles, such as the determination of α hetero values and heteroaggregation rates; more accurate analytical methods instead of DLS for heteroaggregation measurements; sensitive analytical techniques to measure low concentrations of nanoparticles in heteroaggregation systems; appropriate characterization of NOM at the molecular level to understand the structures and fractionation of NOM; effects of different types, concentrations, and fractions of NOM on the heteroaggregation of nanoparticles; the quantitative adsorption and desorption of NOM onto the surface of nanoparticles and heteroaggregates; and a better understanding of the fundamental mechanisms and modeling of heteroaggregation in natural water which is a complex system containing NOM, nanoparticles, biocolloids and geocolloids.

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Section: Bridgingmentioning

confidence: 99%

Section: Bridgingmentioning

confidence: 99%

Section: Bridgingmentioning

confidence: 99%

See 1 more Smart Citation

Heteroaggregation of nanoparticles with biocolloids and geocolloids

Wang

Adeleye

Huang

et al. 2015

Advances in Colloid and Interface Science

170

View full text Add to dashboard Cite

show abstract

“…Tadros [12] proposed the "diffusion-controlled adsorption kinetics model," stating that the flux of adsorption dominates when the surface concentration of polymer is lower than the equilibrium concentration, whereas desorption is the ruling phenomena when the surface concentration is higher than the equilibrium concentration. Moreover, the flocculant concentration also affects the conformation rate: polymers re-arrange relatively fast at low surface concentration but rather slowly on crowded surfaces, since neighbouring molecules interfere with the re-arrangement [4,13]. In addition, for flocculation to occur, polymer molecules have to collide with the fine particles in order to be adsorbed, and the polymer-coated particles have also to collide with each other [1].…”

Section: Introductionmentioning

confidence: 99%

The use of LDS as a tool to evaluate flocculation mechanisms

Rasteiro

Garcı́a

Ferreira

et al. 2008

Chemical Engineering and Processing: Process Intensification

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Flocculation studies of precipitated calcium carbonate induced by cationic polyacrylamides (C-PAMs) were carried out using light diffraction scattering (LDS). The effect of both polymer charge density and concentration on the flocculation process and on flocs density was investigated. As expected, results show that high charge density C-PAM induces flocculation by bridging and patching mechanisms simultaneously, while medium charge density C-PAM acts mainly according to the bridging mechanism. Consequently, the mass fractal dimensions of the flocs produced by high charge density C-PAM are higher. Results also show the effect of flocculant concentration: flocculation rate decreases and denser flocs are obtained as flocculant concentration increases. The results obtained so far allowed a preliminary quantitative evaluation of flocculation kinetics. In the flocculation curve, two regions corresponding to different kinetics were identified: a first region dominated by particle aggregation and a second region dominated by flocs stabilization. Therefore, LDS is considered a useful tool to evaluate flocculants performance. A strategy was developed that resulted in the use of LDS to retrieve, in a single test, information on the evolution with time of flocs dimension and structure, flocs resistance and flocculation kinetics. All the tests were performed under turbulent conditions similar to the ones prevailing in process equipment.

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“…Moreover, the flocculant concentration also affects the conformation rate: polymer re-arrangement is relatively fast at low surface concentration but rather slow on crowded surfaces since neighboring molecules interfere with the re-arrangement [3,9].…”

Section: Open Accessmentioning

confidence: 99%

Using Light Scattering to Screen Polyelectrolytes (PEL) Performance in Flocculation

et al. 2011

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Flocculation of precipitated calcium carbonate (PCC) was monitored using light diffraction spectroscopy (LDS). Four cationic polyacrylamides of high molar mass and with different degrees of branching, all copolymers of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (Q9), were tested. LDS supplied information about the kinetic curves for flocs growth and also for the flocs structure evolution. Flocculation kinetics, flocs size and structure, flocs resistance and reflocculation capacity could be correlated with the degree of branching of the polyelectrolytes (PEL). Furthermore, PEL with different degrees of branching corresponded to different values for the intrinsic viscosity, indicating differences in the polymer conformation, which explained well the performance differences in flocculation.

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Heteroflocculation by Asymmetric Polymer Bridging

Cited by 48 publications

References 5 publications

Heteroaggregation of nanoparticles with biocolloids and geocolloids

Heteroaggregation of nanoparticles with biocolloids and geocolloids

The use of LDS as a tool to evaluate flocculation mechanisms

Using Light Scattering to Screen Polyelectrolytes (PEL) Performance in Flocculation

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