Effect of Pore-Blocking Background Compounds on the Kinetics of Trace Organic Contaminant Desorption from Activated Carbon

This study examined the effect of pore-blocking (PB) background organic matter, which is known to hinder adsorption kinetics, on the rate of trace contaminant desorption. Adsorption, displaced desorption (DD) and nondisplaced desorption (NDD) kinetic tests were performed using powdered activated car...

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Bibliographic Details
Published in:Environmental science & technology 2008-07, Vol.42 (13), p.4825-4830
Main Authors: To, Priscilla C, Mariñas, Benito J, Snoeyink, Vernon L, Ng, Wun Jern
Format: Article
Language:English
Subjects:
Activated carbon
Adsorption
Applied sciences
Carbon offsets
Charcoal - chemistry
Chemical contaminants
Desorption
Diffusion
Environmental Modeling
Exact sciences and technology
Kinetics
Models, Chemical
Organic Chemicals - chemistry
Pollution
Studies
Water Purification - methods
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Summary:This study examined the effect of pore-blocking (PB) background organic matter, which is known to hinder adsorption kinetics, on the rate of trace contaminant desorption. Adsorption, displaced desorption (DD) and nondisplaced desorption (NDD) kinetic tests were performed using powdered activated carbon (PAC) that was preloaded with natural organic matter (NOM). Since the NOM contained both strongly competing (SC) and PB components, the proposed model separated the contributions of the SC and PB NOM to the overall diffusion coefficient of the target contaminant. By factoring out the SC NOM contribution, which increases the overall diffusion coefficient, it was found that the relationship used to model the effect of PB NOM on adsorption kinetics could also describe desorption kinetics. The results highlighted the substantial influence of competitive SC NOM on the kinetics of adsorption and desorption. SC NOM competition aids contaminant removal by offsetting the undesirable effects of pore blocking on adsorption kinetics. However, for desorption events, PB NOM serves a practical benefit of reducing the rate of release of adsorbed micropollutants, while SC NOM counters that gain by both displacing contaminants and accelerating their diffusion.
ISSN:0013-936X
1520-5851
DOI:10.1021/es800058s