Coagulation of bentonite suspension by polyelectrolytes or ferric chloride: Floc breakage and reformation

Barbot, Elise; Dussouillez, Philippe; Bottero, Jean‐Yves; Moulin, Philippe

doi:10.1016/j.cej.2009.10.001

Cited by 51 publications

(25 citation statements)

References 32 publications

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“…Ideal fractal structures are self‐similar throughout. Homoaggregation under controlled laboratory conditions produces aggregates of reasonably predictable fractal dimension (Barbot et al, 2010; Chakraborti et al, 2003; Hansen et al, 1999), whereas heteroaggregation typically forms natural fractals (statistically self‐similar over a limited range of length scales), making aggregation state more difficult to predict. The physical dimensions of the aggregates formed can affect the reactive surface area, reactivity, bioavailability, and toxicity.…”

Section: Colloid Science and Aggregationmentioning

confidence: 99%

Nanoparticle Aggregation: Challenges to Understanding Transport and Reactivity in the Environment

2010

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Unique forms of manufactured nanomaterials, nanoparticles, and their suspensions are rapidly being created by manipulating properties such as shape, size, structure, and chemical composition and through incorporation of surface coatings. Although these properties make nanomaterial development interesting for new applications, they also challenge the ability of colloid science to understand nanoparticle aggregation in the environment and the subsequent effects on nanomaterial transport and reactivity. This review briefly covers aggregation theory focusing on Derjaguin-Landau-Verwey-Overbeak (DLVO)-based models most commonly used to describe the thermodynamic interactions between two particles in a suspension. A discussion of the challenges to DLVO posed by the properties of nanomaterials follows, along with examples from the literature. Examples from the literature highlighting the importance ofaggregation effects on transport and reactivity and risk of nanoparticles in the environment are discussed.

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Section: Colloid Science and Aggregationmentioning

confidence: 99%

Nanoparticle Aggregation: Challenges to Understanding Transport and Reactivity in the Environment

2010

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“…Such a behavior was explained by the multi-scale structure of flocs: the primary particles bond each other to form small aggregates (flocculi) which themselves stick to each other to produce larger aggregates and flocs. Other papers report the same behavior concerning bentonite, [26][27][28] kaolin, 29 or humic acid. 30,31 Moreover, concerning the structure of flocs, several authors have observed a change of the fractal dimension during the growth phase of a flocculation process, indicating the formation of open and irregular structures poorly compacted.…”

Section: Introductionmentioning

confidence: 57%

“…The value of the fractal dimension itself, regardless of the definition used, varies with the nature of the material and the flocculation mechanism. 28,32 When a shear rate is applied, the fractal dimension may change depending on the floc strength and the breakage mechanism. 24 The change of the dispersed medium thus results from a competition between the aggregation, breakage and restructuring phenomena which all depend on the solid properties, the physico-chemical conditions and the hydrodynamic conditions.…”

Section: Introductionmentioning

confidence: 99%

Morphological properties of flocs under turbulent break‐up and restructuring processes

et al. 2017

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Bentonite flocculation was performed in a Taylor–Couette reactor coupled with an in situ method of image acquisition and analysis. A hydrodynamic sequencing is imposed to perform successive cycles of flocculation and breakage. Depending on the shear rate applied during the breakage step, one or two cycles are needed after the first flocculation step to recover a full reversibility on both size and shape factors. The breakup step produces flocculi that are the building blocks for the next. The re‐flocculation steps produce smaller sizes and more regular shapes than the initial growth step. The floc size is calibrated by the turbulence as the radius of gyration is close to the Kolmogorov microscale whereas the floc structure is determined by flocculi aggregates. An analysis of the change of the flocs morphology, despite of their diversity, can also be achieved thanks to some relevant moments of the distributions. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3706–3716, 2017

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“…Therefore models that assume flocs have one characteristic size and one porosity value fail to predict sludge settling and dewatering. The “chaotic” and multilevel structure of flocs is difficult to describe using concepts of conventional geometry; however, it can be well described in terms of fractal geometry (Barbot et al, 2010). Floc fractal dimensions can be relatively easily determined using floc images.…”

Section: Evolving Coagulation and Flocculation Rolesmentioning

confidence: 99%

Recent Research Every Utility Manager Needs to Know About

Speight¹,

Via²

2011

Journal AWWA

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Many utility managers do not have the time or funding to attend national conferences. Therefore, this article provides a way to highlight research findings that are of value in the daily operations of a utility. Being well‐informed about the advances in the field increases the value that a utility manager brings to his or her job each day. Research continues to improve the ability of conventional treatment processes to remove organic matter and other contaminants, such as arsenic. Inorganic contaminants, including nitrate, perchlorate, and ammonia, are a growing concern for many utilities. Biological treatment processes are emerging as a treatment option for inorganic contaminants and advances are improving removals with membrane and ion exchange technologies. Distribution system research has led to benchmarks for operations, better understanding of lead release, and characterization of microbial populations within pipe systems. Water utilities are entering the world of social media and implementing information technology advances such as cloud computing. Finally, for small systems in both developed and developing countries, research has demonstrated the value of operator training and performance‐based approaches in preventing disease.

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Coagulation of bentonite suspension by polyelectrolytes or ferric chloride: Floc breakage and reformation

Cited by 51 publications

References 32 publications

Nanoparticle Aggregation: Challenges to Understanding Transport and Reactivity in the Environment

Nanoparticle Aggregation: Challenges to Understanding Transport and Reactivity in the Environment

Morphological properties of flocs under turbulent break‐up and restructuring processes

Recent Research Every Utility Manager Needs to Know About

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