title: Assessing the capacity of zero valent iron nanofluids to remediate NAPL-polluted porous media.
abstract: A variety of aqueous suspensions (nanofluids) of zero-valent nano-particles (nZVI) are prepared by wet chemistry techniques, their stability and longevity is evaluated by physic-chemical methods of characterization, and their reactivity toward the dechlorination of per-chloro-ethylene (PCE) is examined with tests in batch reactors. For assessing the mobility, longevity and reactivity of nZVI suspensions (nanofluids), under flow-through conditions, visualization multiphase flow and transport tests are performed on a glass-etched pore network. The nZVI breakthrough curves are constructed by measuring the transient variation of the iron concentration in the effluent with atomic absorption spectroscopy. The capacity of nZVI to remediate the bulk phase of PCE is quantified by detecting the mass loss rate of PCE ganglia trapped in glass-etched pore networks during the continuous injection of nZVI suspension or pure water. The nZVI injection in porous media is simulated as an advection- dispersion process by accounting for the attachment/detachment of nanoparticles on the pore-walls, and describing the kinetics of PCE dissolution and reaction by 1st order equations. Visualization experiments reveal that the gradual elimination of PCE ganglia by the injected nZVI is associated with the preferential "erosion" of the upstream interfacial regions. The step controlling the overall process kinetics might be either (i) the enhanced PCE dissolution or (ii) the direct reaction of bulk PCE with the nZVI deposited upon the ganglia interfaces. Inverse modeling of the experiments under the simplifying assumption of one active mechanism indicates that the estimated kinetic coefficients are increasing functions of the flow rate.
authors.affiliation: Foundation for Research and Technology Hellas-Institute of Chemical Engineering Sciences, Stadiou street, Platani, 26504 Patras, Greece. Electronic address: ctsakir@iceht.forth.gr.
authors.forename: Christos
authors.initials: C
authors.lastname: Tsakiroglou
authors.affiliation: Foundation for Research and Technology Hellas-Institute of Chemical Engineering Sciences, Stadiou street, Platani, 26504 Patras, Greece; Department of Chemical Engineering, University of Patras, 26504 Patras, Greece.
authors.forename: Katerina
authors.initials: K
authors.lastname: Terzi
authors.affiliation: Foundation for Research and Technology Hellas-Institute of Chemical Engineering Sciences, Stadiou street, Platani, 26504 Patras, Greece; Department of Chemical Engineering, University of Patras, 26504 Patras, Greece.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Sikinioti-Lock
authors.affiliation: Foundation for Research and Technology Hellas-Institute of Chemical Engineering Sciences, Stadiou street, Platani, 26504 Patras, Greece.
authors.forename: Kata
authors.initials: K
authors.lastname: Hajdu
authors.affiliation: Foundation for Research and Technology Hellas-Institute of Chemical Engineering Sciences, Stadiou street, Platani, 26504 Patras, Greece.
authors.forename: Christos
authors.initials: C
authors.lastname: Aggelopoulos
mesh_terms: D052918:Environmental Restoration and Remediation / Q000379:methods*; D060587:Groundwater / Q000032:analysis*; D007501:Iron / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D013535:Suspensions; D014877:Water Pollution, Chemical / Q000032:analysis*
chemical_list: D013535:Suspensions; D007501:Iron
keywords: Dechlorination; In situ remediation; Nanoparticles; Numerical modeling; Porous media; Zero valent iron