Influence of azo dye-TiO2 interactions on the filtration performance in a hybrid photocatalysis/ultrafiltration process

Zhang, Jiwei; Wang, Ling; Zhang, Guoliang; Wang, Zhiyang; Xu, Lusheng; Fan, Zheng

doi:10.1016/j.jcis.2012.08.062

Cited by 46 publications

(17 citation statements)

References 37 publications

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“…Hence, the change of inter porosity during cake layer collapse appears more significant for estimating specific resistance values than accounting for differences between intra and intra porosities within cake layers. Comparing findings with other studies, fitted porosities are higher than the reported value of ~ 0.4 for C60 nanoparticles and Bentonite colloids [76,77], and specific resistances for both of DLA and RLA are slightly higher than what is reported for aggregated nanoparticles and SiO2 colloids of 460 nm [72,77,78]. Nevertheless, specific resistances of DLA and RLA are lesser than that of Bentonite colloids of 5000 nm; this is in line with predications of equations 19 and 20.…”

Section: Resistance Predictions and Interpretationssupporting

confidence: 84%

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Characterizations of Nanofluid Heat Transfer Enhancements

Johnson¹

2013

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Nanoparticle morphology is thought to be an important factor influencing heat and mass transfer rates in liquid systems. How nanoparticles mechanistically increase heat and mass transfer rates is not well understood. Both dispersed nanoparticles and aggregated nanoparticles are thought to play important roles. Dispersed nanoparticles and associated nanoparticle Brownian movements are purported to cause the enhancements by mixing mechanisms whereas aggregated nanoparticles are purported to cause enhancements by forming highly conductive paths. In this study, morphologies of nanoparticle were quantified in laboratory studies and related to laboratory measured heat and mass transfer rates. No mass transfer enhancements were found in the presence of nanoparticles. Thermal conductivity could be predicted with effective medium theory when aggregated nanoparticle aspect ratio was considered. Nanoparticle morphology is thought to be an important factor influencing heat and mass transfer rates in liquid systems. How nanoparticles mechanistically increase heat and mass transfer rates is not well understood. Both dispersed nanoparticles and aggregated nanoparticles are thought to play important roles. Dispersed nanoparticles and associated nanoparticle Brownian movements are purported to cause the enhancements by mixing mechanisms whereas aggregated nanoparticles are purported to cause enhancements by forming highly conductive paths. In this study, morphologies of nanoparticle were quantified in laboratory studies and related to laboratory measured heat and mass transfer rates.Grant research objectives were to answer fundamental questions related to mechanisms of nanofluid heat transfer enhancer enhancements. Activities in part (1) were designed to answer the question of: Are enhancements related to Brownian nanoparticle motion? Activities in part (2) were conducted to answer the question of: Are enhancements related to the extent of particle aggregation and morphology of aggregated particles, and if so, can the extent of particle aggregation and associated heat transfer enhancements be characterized using fractal dimensions of aggregated nanoparticles? Study parts (1) and (2) comprise the majority of the research effort to satisfy objectives associated with rational for funding support. Additional activities in the final year of the grant were completed once these major research objectives had been met. In study part (3), the morphology characterization techniques developed to study heat transfer mechanisms ...

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Section: Resistance Predictions and Interpretationssupporting

confidence: 84%

“…In addition, DLA resistance is found to be lesser than that of RLA. This is different from reports for C60 nanoparticles [76], but in agreement with others [72,[77][78][79] and equations 19 and 20.…”

Section: Resistance Predictions and Interpretationscontrasting

confidence: 69%

Characterizations of Nanofluid Heat Transfer Enhancements

Johnson¹

2013

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“…Most of the PMRs described in literature are slurry reactors equipped with polymer membranes [2][3][4]. However, polymer membranes have some serious drawbacks when their application in PMRs is considered.…”

Section: Introductionmentioning

confidence: 99%

Effect of process parameters on fouling and stability of MF/UF TiO2 membranes in a photocatalytic membrane reactor

Mozia

Szymański

Michalkiewicz

et al. 2015

Separation and Purification Technology

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“…However, it is still inconclusive whether equations 5 and 6 can predict aggregated nanoparticles filtration performance. Shown in Table I are the comparisons of aggregated nanoparticles and colloids filtration performance (Henry and Brant 2012; Zhang et al 2013;Waite et al 1999;Chellam and Xu 2006;Mendret et al 2009). Specific resistance of large Bentonite (5000 nm) and SiO 2 (460 ±10 nm) are higher than aggregated nanoparticles of C 60 , TiO 2 , and Hematite.…”

Section: Introductionmentioning

confidence: 99%

“…Specific resistance of large Bentonite (5000 nm) and SiO 2 (460 ±10 nm) are higher than aggregated nanoparticles of C 60 , TiO 2 , and Hematite. Predications of specific resistance for aggregated TiO 2 nanoparticle are not applicable using equations 5 and 6, as a negative specific resistance was reported and explained that aggregated TiO 2 nanoparticle at pH 6 altered membrane hydrophilicity and facilitated filtration processes (Zhang et al 2013). In addition, a higher specific resistance was indicated for DLA than that of RLA for C 60 nanoparticles (Henry and Brant 2012), in contrast to what equations 5 and 6 predict.…”

Section: Introductionmentioning

confidence: 99%

Aggregated Nanoparticle Morphology Effects on Membrane Filtration

Feng

Johnson

2014

Chemical Engineering Communications

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Nanoparticles are considered potential environmental contaminants because of reported toxicity to biota in the environment. As such, there is interest in understanding how to remove nanoparticles from waters. This study investigated membrane filtration behaviors of 70 nm alumina oxide (Al 2 O 3 ) nanoparticle when aggregated under diffusion limited aggregation (DLA) and reaction limited aggregation (RLA) regimes. In this study, nanoparticles were aggregated under conditions of high and low ionic strength to form aggregates of different morphology. Aggregates were filtered using a hydrophilic Polyvinylidene fluoride (PVDF) membrane with a pore size 0.22 µm and 100% nanoparticle removal efficiencies were obtained regardless of aggregation conditions used. Aggregate morphology was quantified by measured fractal dimensions. Fractal structure differences coincided with measured filtration resistance values. Low porosity aggregates provided a filtration resistance 43% greater than high porosity aggregates of the same effective size. Model predictions for measured specific resistance values were improved through incorporation of compressibility indexes. In order to obtain a porous structure with less resistance, a fast coagulation process is suggested for nanoparticle removal.

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Influence of azo dye-TiO2 interactions on the filtration performance in a hybrid photocatalysis/ultrafiltration process

Cited by 46 publications

References 37 publications

Characterizations of Nanofluid Heat Transfer Enhancements

Characterizations of Nanofluid Heat Transfer Enhancements

Effect of process parameters on fouling and stability of MF/UF TiO2 membranes in a photocatalytic membrane reactor

Aggregated Nanoparticle Morphology Effects on Membrane Filtration

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