TY - JOUR
T1 - Modeling packed bed sorbent systems with the Pore Surface Diffusion Model
T2 - Evidence of facilitated surface diffusion of arsenate in nano-metal (hydr)oxide hybrid ion exchange media
AU - Dale, Sachie
AU - Markovski, Jasmina
AU - Hristovski, Kiril
N1 - Funding Information:
Although the research described in the article has been funded in part by the U.S. Environmental Protection Agency 's STAR program through grant ( RD835175 ), it has not been subjected to any EPA review and therefore does not necessarily reflect the views of the Agency, and no official endorsement should be inferred.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2016/9/1
Y1 - 2016/9/1
N2 - This study explores the possibility of employing the Pore Surface Diffusion Model (PSDM) to predict the arsenic breakthrough curve of a packed bed system operated under continuous flow conditions with realistic groundwater, and consequently minimize the need to conduct pilot scale tests. To provide the nano-metal (hydr)oxide hybrid ion exchange media's performance in realistic water matrices without engaging in taxing pilot scale testing, the multi-point equilibrium batch sorption tests under pseudo-equilibrium conditions were performed; arsenate breakthrough curve of short bed column (SBC) was predicted by the PSDM in the continuous flow experiments; SBC tests were conducted under the same conditions to validate the model. The overlapping Freundlich isotherms suggested that the water matrix and competing ions did not have any denoting effect on sorption capacity of the media when the matrix was changed from arsenic-only model water to real groundwater. As expected, the PSDM provided a relatively good prediction of the breakthrough profile for arsenic-only model water limited by intraparticle mass transports. In contrast, the groundwater breakthrough curve demonstrated significantly faster intraparticle mass transport suggesting to a surface diffusion process, which occurs in parallel to the pore diffusion. A simple selection of DS = 1/2 DP appears to be sufficient when describing the facilitated surface diffusion of arsenate inside metal (hydr)oxide nano-enabled hybrid ion-exchange media in presence of sulfate, however, quantification of the factors determining the surface diffusion coefficient's magnitude under different treatment scenarios remained unexplored.
AB - This study explores the possibility of employing the Pore Surface Diffusion Model (PSDM) to predict the arsenic breakthrough curve of a packed bed system operated under continuous flow conditions with realistic groundwater, and consequently minimize the need to conduct pilot scale tests. To provide the nano-metal (hydr)oxide hybrid ion exchange media's performance in realistic water matrices without engaging in taxing pilot scale testing, the multi-point equilibrium batch sorption tests under pseudo-equilibrium conditions were performed; arsenate breakthrough curve of short bed column (SBC) was predicted by the PSDM in the continuous flow experiments; SBC tests were conducted under the same conditions to validate the model. The overlapping Freundlich isotherms suggested that the water matrix and competing ions did not have any denoting effect on sorption capacity of the media when the matrix was changed from arsenic-only model water to real groundwater. As expected, the PSDM provided a relatively good prediction of the breakthrough profile for arsenic-only model water limited by intraparticle mass transports. In contrast, the groundwater breakthrough curve demonstrated significantly faster intraparticle mass transport suggesting to a surface diffusion process, which occurs in parallel to the pore diffusion. A simple selection of DS = 1/2 DP appears to be sufficient when describing the facilitated surface diffusion of arsenate inside metal (hydr)oxide nano-enabled hybrid ion-exchange media in presence of sulfate, however, quantification of the factors determining the surface diffusion coefficient's magnitude under different treatment scenarios remained unexplored.
KW - Arsenic
KW - Groundwater
KW - Hybrid ion-exchange
KW - Modeling
KW - Nanomaterials
KW - Nanoparticles
KW - Pore surface diffusion
UR - http://www.scopus.com/inward/record.url?scp=84949673620&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84949673620&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2015.11.176
DO - 10.1016/j.scitotenv.2015.11.176
M3 - Article
C2 - 26672387
AN - SCOPUS:84949673620
SN - 0048-9697
VL - 563-564
SP - 965
EP - 970
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -