Title
2007 AIChE Annual Meeting
Start Date
November 4, 2007
End Date
November 9, 2007
Location
Salt Lake City, UT

Publications

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    Publication
    Aerosol-assisted nanoscale Fe/silica particles for dechlorination of trichloroethylene
    (AIChE, 2007-11-07)
    Zheng, Tonghua 
    ;
    Zhan, Jingjing 
    ;
    Piringer, Gerhard 
    ;
    McPherson, Gary L. 
    ;
    Lu, Yunfeng 
    ;
    John, Vijay T. 
    Nanoscale iron particles are a preferred option for the reductive dehalogenation of trichloroethylene (TCE) due to their environmentally benign nature, high efficiency and low cost. However, nanoscale zerovalent iron (ZVI) particles aggregate and in in-situ remediation technologies, it is difficult to transport these particles to the source of contamination. This study describes a novel approach to the preparation of ZVI nanoparticles that are efficient and effectively transport to contaminant sites. We describe the synthesis of silica supported iron nanoparticles using aerosol technology. While the encapsulated iron nanoparticles are reactive for groundwater trichloroethylene remediation, environmentally benign silica particles serve as effective carriers for nanoiron transport through soil. Encapsulation of iron into submicron silica particles protects ferromagnetic iron nanoparticles from aggregation and may increase their mobility through sedimentation. Additionally, the presence of surface silanol groups on silica particles allows control of surface properties via silanol modification using organic functional groups. Aerosol silica particles with functional groups such as ethyl tails on the surface preferentially adsorb hydrophobic TCE during environmental remediation. This increases the local concentration of TCE in the vicinity of iron nanoparticles, thus promoting the degradation of TCE by iron. These nanoscale iron/silica aerosol particles with controlled surface properties have the potential to be efficiently applied for in-situ remediation and permeable reactive barriers construction.
      58  1
  • No Thumbnail Available
    Publication
    Transport and partitioning of functional aerosol nanoparticles for remediation of trichloroethylene
    (AIChE, 2007-11-05)
    Zhan, Jingjing 
    ;
    Zheng, Tonghua 
    ;
    Piringer, Gerhard 
    ;
    McPherson, Gary L. 
    ;
    Lu, Yunfeng 
    ;
    Papadopoulos, Kyriakos D. 
    ;
    John, Vijay T. 
    Effective in-situ remediation of contaminated groundwater plume requires the successful delivery of reactive iron particles through soil. This study reports the transport characteristics of nanoscale zerovalent iron particles that are encapsulated in porous silica submicron particles through a novel aerosol-assisted technology. These particles resist aggregation characteristics that are typical of nanoscale zerovalent iron, and are highly reactive. They can be transported through model soils (Ottawa sands) more efficiently than commercially available reactive nanoscale iron particle (RNIP). To explore the fate of particles in sands, macroscopic and microscopic methods were used. Glass burette columns in vertical and horizontal configurations were used to simulate in-situ injection and natural groundwater situations, respectively. In both cases, the composite particles elute readily while RNIP is trapped at the inlet of the column. Capillary experiments further prove that RNIP clogs the pores between sand grains due to rapid aggregation, but pore plugging does not occur for the composite particles. The partitioning characteristic of the particles was investigated by a novel capillary video microscopy technique. Our results again indicate that the iron/silica composite nanparticles preferentially accumulate and localize at the TCE/water interface, making dechlorination more efficient. Such particles with enhanced mobility hold promise in new technologies for in-situ ground water remediation.
      39  1