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Article: Collision frequencies of fractal aggregates with small particles by differential sedimentation

TitleCollision frequencies of fractal aggregates with small particles by differential sedimentation
Authors
KeywordsAirborne particle
Filtration
Mathematical model
Permeability
Sedimentation rate
Issue Date1997
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/est
Citation
Environmental Science And Technology, 1997, v. 31 n. 4, p. 1229-1236 How to Cite?
AbstractTwo groups of aggregates with fractal dimensions of 1.81 ± 0.09 and 2.33 ± 0.07 were generated by coagulation of latex microspheres (2.84 μm) in a Jar-test (paddle-mixing) device. The collision rates between these fractal aggregates (200-1000 μm) and small (1.48μm) particles were measured for individual aggregates that had settled through a suspension of the small particles. Aggregate permeabilities calculated from measured settling velocities were 3 orders of magnitude greater than predicted by a permeability model based on a homogeneous distribution of primary particles within the aggregates. Collision frequencies were 1 order of magnitude higher than predicted by a curvilinear model and about 2 orders of magnitude lower than predicted by a rectilinear collision model. The capture efficiencies of small particles by settling aggregates were <0.2% based on the total volume of water swept out by an aggregate. Fluid collection efficiencies, collision frequencies, and particle capture efficiencies of the fractal aggregates decreased with the magnitude of fractal dimensions. A fractal permeability model was developed by modifying the Brinkman correlation to describe the permeability as a function of aggregate size. This model was used in conjunction with a filtration model to predict capture rates and capture efficiencies of small particles by settling fractal aggregates. Based on these experiments and models, it is argued that the high aggregate permeabilities and the low overall particle capture efficiencies of fractal aggregates can be explained by flow through macropores formed between large clusters within the aggregates.
Persistent Identifierhttp://hdl.handle.net/10722/70528
ISSN
2015 Impact Factor: 5.393
2015 SCImago Journal Rankings: 2.664
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLi, Xen_HK
dc.contributor.authorLogan, BEen_HK
dc.date.accessioned2010-09-06T06:23:47Z-
dc.date.available2010-09-06T06:23:47Z-
dc.date.issued1997en_HK
dc.identifier.citationEnvironmental Science And Technology, 1997, v. 31 n. 4, p. 1229-1236en_HK
dc.identifier.issn0013-936Xen_HK
dc.identifier.urihttp://hdl.handle.net/10722/70528-
dc.description.abstractTwo groups of aggregates with fractal dimensions of 1.81 ± 0.09 and 2.33 ± 0.07 were generated by coagulation of latex microspheres (2.84 μm) in a Jar-test (paddle-mixing) device. The collision rates between these fractal aggregates (200-1000 μm) and small (1.48μm) particles were measured for individual aggregates that had settled through a suspension of the small particles. Aggregate permeabilities calculated from measured settling velocities were 3 orders of magnitude greater than predicted by a permeability model based on a homogeneous distribution of primary particles within the aggregates. Collision frequencies were 1 order of magnitude higher than predicted by a curvilinear model and about 2 orders of magnitude lower than predicted by a rectilinear collision model. The capture efficiencies of small particles by settling aggregates were <0.2% based on the total volume of water swept out by an aggregate. Fluid collection efficiencies, collision frequencies, and particle capture efficiencies of the fractal aggregates decreased with the magnitude of fractal dimensions. A fractal permeability model was developed by modifying the Brinkman correlation to describe the permeability as a function of aggregate size. This model was used in conjunction with a filtration model to predict capture rates and capture efficiencies of small particles by settling fractal aggregates. Based on these experiments and models, it is argued that the high aggregate permeabilities and the low overall particle capture efficiencies of fractal aggregates can be explained by flow through macropores formed between large clusters within the aggregates.en_HK
dc.languageengen_HK
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/esten_HK
dc.relation.ispartofEnvironmental Science and Technologyen_HK
dc.subjectAirborne particle-
dc.subjectFiltration-
dc.subjectMathematical model-
dc.subjectPermeability-
dc.subjectSedimentation rate-
dc.titleCollision frequencies of fractal aggregates with small particles by differential sedimentationen_HK
dc.typeArticleen_HK
dc.identifier.emailLi, X:xlia@hkucc.hku.hken_HK
dc.identifier.authorityLi, X=rp00222en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/es960771wen_HK
dc.identifier.scopuseid_2-s2.0-0030994796en_HK
dc.identifier.hkuros24186en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0030994796&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume31en_HK
dc.identifier.issue4en_HK
dc.identifier.spage1229en_HK
dc.identifier.epage1236en_HK
dc.identifier.isiWOS:A1997WR54600066-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLi, X=26642887900en_HK
dc.identifier.scopusauthoridLogan, BE=7202196555en_HK

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