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...xperimental results and their implications for the reactive processes in the DNAPL source zone. The model was developed within the framework of a finite difference groundwater flow code MODFLOW-2000 (=-=Harbaugh et al. 2000-=-) and the reaction module RT3D (Clement 1997), which is an extension of method of characteristics based transport code MT3DMS (Zheng and Wang 1999). Here we implemented a Gilland-Sherwood type model o...

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...yelectrolytes because their small size is unsuitable for steric repulsions. Polymers typically adsorb strongly (effectively irreversible) to NPs while surfactants adsorption is more easily reversible(=-=Evans and Wennerstrom 1999-=-; Fleer et al. 1993). Poly(methacrylic acid)-b-poly(methylmethacrylate)-b-poly(styrene sulfonate) triblock copolymers (PMAA-PMMA-PSS), PSS homopolymer polyelectrolyte, sodium dodecylbenzene sulfonate ...

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...inite difference groundwater flow code MODFLOW-2000 (Harbaugh et al. 2000) and the reaction module RT3D (Clement 1997), which is an extension of method of characteristics based transport code MT3DMS (=-=Zheng and Wang 1999-=-). Here we implemented a Gilland-Sherwood type model of rate-limited DNAPL dissolution coupled to first order degradation of PCE by the NZVI particles(Saenton and Illangasekare 2007). The model consid...

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...ility. Recently, reactive nanoscale iron particles delivered in situ has been proposed and evaluated in the field with the goal of overcoming these limitations (Lowry 2007; Tratnyek and Johnson 2006; =-=Zhang 2003-=-). In principle, their small size (10-100 nm) provides an opportunity to deliver these remedial agents to subsurface contaminants in situ, and provides access to contamination trapped in the smallest ...

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...eactive processes in the DNAPL source zone. The model was developed within the framework of a finite difference groundwater flow code MODFLOW-2000 (Harbaugh et al. 2000) and the reaction module RT3D (=-=Clement 1997-=-), which is an extension of method of characteristics based transport code MT3DMS (Zheng and Wang 1999). Here we implemented a Gilland-Sherwood type model of rate-limited DNAPL dissolution coupled to ...

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...Franchi and O'Melia 2003; Phenrat et al. 2009a; Phenrat et al. 2008). Models are available to calculate the magnitude of all of the forces acting on a polymer or polyelectrolyte coated NZVI particle (=-=Israelachvili 1992-=-), (Brant et al. 2007; de Vicente et al. 2000) (Fritz et al. 2002) (Cayer-Barrioz et al. 2009). Table 5.1.1. Potential coatings from each class to be evaluated. Coating Charge Stabilization type Polym...

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...APL-water interface. KLi is contained in a modified Sherwood number Sh’ = KLi d50 2 Dmi -1 , where d50 is the median grain size and Dmi is the molecular diffusion coefficient in water of component i (=-=Imhoff et al. 1993-=-; Miller et al. 1990). In the system investigated here, many parameters remain constant and assuming that changes in NAPL saturation Sn are negligible during the experiments we formulated a correlatio...

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...nge when they are in the vicinity of the DNAPL and remain there. The NZVI properties and flow conditions required to achieve these criteria must be determined. Recent advances in particle filtration (=-=Tufenkji and Elimelech 2004-=-) can be used to develop hypotheses about the impact of specific NZVI properties and physical and hydrogeochemical conditions affecting NZVI transport and fate in water saturated porous media. Experim...

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...inimum well and are more easily disagglomerated than larger agglomerates. The higher seepage velocity also results in higher drag force that promotes greater detachment of the deposited agglomerates (=-=Bergendahl and Grasso 2000-=-; Torkzaban et al. 2007). In summary, assuming agglomeration and subsequent deposition, the higher seepage velocity promotes NZVI disagglomeration and detachment, both of which result in the lower obs...

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...ty and capillarity. The fluid properties in combination with characteristics of the soil both at the pore and macro-scale will determine how the DNAPL ultimately gets distributed (Illangasekare 1998; =-=Illangasekare et al. 1995-=-). In general, DNAPLs migrate through fingering and pools at capillary barriers (coarse-fine interfaces). The final entrapment architecture will contain both residual zones and pools. The pools that c...

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...ictated by the natural gradient and aquifer permeability. NZVI will therefore be subjected to a wide range of flow velocities during injection and migration that may affect the filtration efficiency (=-=Lecoanet and Wiesner 2004-=-). Based on filtration theory it is expected that higher injection rates will increase the radius of influence by decreasing the efficiency of all three attachment mechanisms (diffusion, interception,...

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...ow bypassing and inaccessibility. Recently, reactive nanoscale iron particles delivered in situ has been proposed and evaluated in the field with the goal of overcoming these limitations (Lowry 2007; =-=Tratnyek and Johnson 2006-=-; Zhang 2003). In principle, their small size (10-100 nm) provides an opportunity to deliver these remedial agents to subsurface contaminants in situ, and provides access to contamination trapped in t...

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...m source of groundwater contamination. Remediation is costly and poses significant technical challenges. Lifecycle treatment costs are estimated to exceed $2 billion for ~3000 contaminated DoD sites (=-=Stroo et al. 2003-=-). Even though the benefits of mass removal from a source zone in meeting regulatory goals are controversial, reducing entrapped DNAPL mass will lower the longevity of the source and reduce mass flux....

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...nt column end oxidation. 7.5.4 Effect of NZVI emplaced directly in the NAPL source zone The benefits of delivering NZVI directly to NAPL source zones have been speculated by several previous studies (=-=Gavaskar et al. 2005-=-; Liu et al. 2005b; Saleh et al. 2005a; Tratnyek and Johnson 2006; Zhang 2003) but has never been demonstrated. Delivering reactive NZVI particles in situ to reductively dechlorinate entrapped DNAPL h...

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...mmon non-toxic polymer used to stabilize NP dispersions. Adsorbed PVA reduces bacterial adsorption to surfaces(Koziarz and Yamazaki 1999). Cellulose is used to prepare stabilized nanoiron dispersions(=-=He and Zhao 2005-=-). Inexpensive and biodegradable. Used to prepare stabile nanoiron dispersions that partition to the TCE/water interface (Saleh et al. 2005a; Saleh et al. 2005b). PSS homopolymer is a common inexpensi...

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...l of nanoiron transport and targeting (inset). The effectiveness of this approach is limited because the particles may not transport a significant distance from the injection well (Quinn et al. 2005; =-=Saleh et al. 2007-=-; Schrick et al. 2004), may not locate themselves at or near the DNAPL-water interface, or may continue to 5transport down gradient away from the source zone. There are a number of reasons for this i...

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....................................... 107 List of Tables Table 5.1.1. Potential coatings from each class to be evaluated. ................................................ 7 Table 6.1. RNIP properties (=-=Liu et al. 2005-=-a; Liu et al. 2005b; Phenrat et al. 2007) ............ 11 Table 6.2. Property and structure of surface modifiers .......................................................... 15 Table 6.3. Physical prope...

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...nts and release H2 gas. The injection of NZVI can significantly decrease the ORP to very low values (e.g. < -500 mV), which may be an important indicator for the reactivity of injected NZVI particles(=-=Elliott and Zhang 2001-=-; Quinn et al. 2005). Currently assessing the results of injecting NZVI into the subsurface for groundwater remediation relies heavily on measuring ORP of water samples. Although the ORP measurement i...

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...solvent, which is subsequently reduced. For chlorinated hydrocarbons, the reduction typically results in the replacement of a chlorine atom with a hydrogen atom (Liu et al. 2005a; Liu and Lowry 2006; =-=Nurmi et al. 2005-=-). The reduction of the contaminant is surface-mediated, and the NZVI is the reductant. The attractiveness of NZVI is that the particles have a high surface-to-volume ratio and therefore have high rea...

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...lity required the use of hydrophilic supports (Schrick et al. 2004). Quinn et al. (2005) describes the emplacement and performance of an emulsified zero valent iron (EZVI) at NASA’s Launch Complex 34(=-=Quinn et al. 2005-=-). NZVI was injected into the subsurface at a TCE-contaminated aquifer, using a surfactant/vegetable oil emulsion to make the NZVI mobile. The technique demonstrated that TCE DNAPL was degraded using ...

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... of NZVI in the subsurface. Schrick et al (2004) was the first to report the low mobility of NZVI in water saturated porous media, and that enhanced mobility required the use of hydrophilic supports (=-=Schrick et al. 2004-=-). Quinn et al. (2005) describes the emplacement and performance of an emulsified zero valent iron (EZVI) at NASA’s Launch Complex 34(Quinn et al. 2005). NZVI was injected into the subsurface at a TCE...

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...lotted vs. ionic concentration Cs to obtained critical deposition concentration (CDC) and slope of the deposition curves (β) values via the best fit of these data (Table 7.1.4) according to Eq 7.1.1 (=-=Chen and Elimelech 2007-=-; 2008; Elimelech et al. 1995). ...

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...e NPs and/or to improve particle mobility in the environment due to steric, electrosteric, or electrostatic repulsions between the particles and between the particles and soil grains (He et al. 2009; =-=He et al. 2007-=-; Saleh et al. 2005a). Poly(aspartate), an anionic polypeptide, adsorbs to iron oxide 6surfaces via acid-base interactions through the carboxyl groups (Chibowski and Wisniewska 2002; Nakamae et al. 1...

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...f geochemistry on nanoiron migration Saleh et al., 2007 EES Phenrat et al., 2008 JNR Saleh et al., 2008 ES&T Phenrat et al., 2009, 2010 ES&T Kim et al., 2012 JCIS Elucidate DNAPL targeting mechanisms =-=Kim et al., 2009-=- ES&T Reactivity of modified nanoiron Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targetin...

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...hance dispersion stability of NZVI by providing additional electrosteric repulsions (a combination of osmotic and elastic repulsions ) against van der Waals attraction which can prevent agglomeration(=-=Phenrat et al. 2008-=-). In addition to electrosteric repulsion, the adsorbed macromolecule layer also serves as a lubricant. The macromolecule yields a higher local viscosity compared to the bulk, resulting in the reducti...

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...which can protonate or deprotonate depending on the pH in the solution (Itami and Fujitani 2005; Tombacz and Szekeres 2006). The reported pHpzc-edge of kaolinite edge sites ranges from pH 5.8 to 7.5 (=-=Kretzschmar et al. 1998-=-; Tombacz et al. 1999; Tombacz et al. 2004; Tombacz and Szekeres 2006). The positively charged edge sites on clay may serve as deposition sites for NZVI similar to the case of metal oxide surface impu...

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...made to remove fines in situ prior to injection of Z-Loy to improve transport. This included 1) a 20 PV flush with DI water. 2) Flushing with Ca 2+ and PEG together with K + to inhibit clay swelling (=-=Kjellander et al. 1988-=-; Liu et al. 2004). Ca 2+ (5 mM) and PEG (1g/L) with 10 mM K + were used to flush the columns for 4 PVs and allowed to react for 30 min. prior to inject Z-Loy dispersion (in DI water) at the approach ...

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...anding aggregation potential and transport.sThese properties were determined using electrophoretic mobility (EPM) measurements andsOhshima’s soft particle theory as described in Phenrat et al., 2008 (=-=Ohshima 1995-=-). Use of thesOhshima method requires data for the EPM for both the bare particles and for thespolyelectrolyte-coated particles as a function of the bulk solution ionic strength. The EPM wassmeasured ...

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... 107 List of Tables Table 5.1.1. Potential coatings from each class to be evaluated. ................................................ 7 Table 6.1. RNIP properties (Liu et al. 2005a; Liu et al. 2005b; =-=Phenrat et al. 2007-=-) ............ 11 Table 6.2. Property and structure of surface modifiers .......................................................... 15 Table 6.3. Physical properties of the sand used for the field-sca...

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...s and pH dependent edge charge due to surface hydroxyl groups (Al-OH, Si-OH) created from broken bonds which can protonate or deprotonate depending on the pH in the solution (Itami and Fujitani 2005; =-=Tombacz and Szekeres 2006-=-). The reported pHpzc-edge of kaolinite edge sites ranges from pH 5.8 to 7.5 (Kretzschmar et al. 1998; Tombacz et al. 1999; Tombacz et al. 2004; Tombacz and Szekeres 2006). The positively charged edge...

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...e and an average collector size (dg) of 300 μm. This trend contradicts 34classical filtration theory which contends that attachment efficiency is independent of approach velocity (Bai and Tien 1999; =-=Elimelech 1992-=-). However, this finding is consistent with a revised conceptual model of agglomeration and subsequent deposition on as proposed above (Figure 7.1.6). At higher approach velocity, fluid shear promotes...

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...behavior of polymer modified NZVI is governed the same underlying forces as other polymer and natural organic matter (NOM) modified nanoparticles (Amirbahman and Olson 1993; Franchi and O'Melia 2003; =-=Pelley and Tufenkji 2008-=-). Thus, a model was developed for polymer and NOM modified nanoparticles to predict the attachment efficiency of polymer modified NZVI based on the characteristics of the adsorbed polymer layer. We f...

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...ily disagglomerated than larger agglomerates. The higher seepage velocity also results in higher drag force that promotes greater detachment of the deposited agglomerates (Bergendahl and Grasso 2000; =-=Torkzaban et al. 2007-=-). In summary, assuming agglomeration and subsequent deposition, the higher seepage velocity promotes NZVI disagglomeration and detachment, both of which result in the lower observed attachment effici...

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...lower positive valent ions and pH dependent edge charge due to surface hydroxyl groups (Al-OH, Si-OH) created from broken bonds which can protonate or deprotonate depending on the pH in the solution (=-=Itami and Fujitani 2005-=-; Tombacz and Szekeres 2006). The reported pHpzc-edge of kaolinite edge sites ranges from pH 5.8 to 7.5 (Kretzschmar et al. 1998; Tombacz et al. 1999; Tombacz et al. 2004; Tombacz and Szekeres 2006). ...

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...ravelsfarther than the larger sized agglomerates formed for larger collector particles.sIn addition to affecting the size of the agglomerates formed, fluid shear can affectsdeposition and detachment (=-=Johnson et al. 2006-=-; Torkzaban et al. 2007).sThe hydrodynamic dragstorque acting on the deposited NZVI agglomerates is locally lower for agglomerates deposited onslarger sized collectors compared to the smaller sized co...

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...n the pH in the solution (Itami and Fujitani 2005; Tombacz and Szekeres 2006). The reported pHpzc-edge of kaolinite edge sites ranges from pH 5.8 to 7.5 (Kretzschmar et al. 1998; Tombacz et al. 1999; =-=Tombacz et al. 2004-=-; Tombacz and Szekeres 2006). The positively charged edge sites on clay may serve as deposition sites for NZVI similar to the case of metal oxide surface impurities. In addition, kaolinite clay can un...

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... between a particle and a collector (Cayer-Barrioz et al. 2009). It should be noted that electrosteric repulsions may result in reversible deposition in a secondary minimum (Franchi and O'Melia 2003; =-=Phenrat et al. 2009-=-a) which makes the attachment efficiency sensitive to fluid velocity (e.g. sliding and rolling as a result of the reduced frictional force) and solution chemistry (Cayer-Barrioz et al. 2009; Franchi a...

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...improve particle mobility in the environment due to steric, electrosteric, or electrostatic repulsions between the particles and between the particles and soil grains (He et al. 2009; He et al. 2007; =-=Saleh et al. 2005-=-a). Poly(aspartate), an anionic polypeptide, adsorbs to iron oxide 6surfaces via acid-base interactions through the carboxyl groups (Chibowski and Wisniewska 2002; Nakamae et al. 1989). Alkyl polyglu...

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............................. 48 Figure 7.3.1. (a) αpre from Bai and Tien’s correlation vs. αexp for latex particles coated with SRHA (Franchi and O'Melia 2003), latex particles coated with GFA and PHA (=-=Amirbahman and Olson 1993-=-), hematite particles coated with GFA, PFA, and PHA (Amirbahman and Olson 1995), hematite particles coated with GFA, PFA, and PHA (Amirbahman and Olson 1995), latex particles coated with SRHA(Pelley v...

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...ckground electrolyte and an average collector size (dg) of 300 μm. This trend contradicts 34classical filtration theory which contends that attachment efficiency is independent of approach velocity (=-=Bai and Tien 1999-=-; Elimelech 1992). However, this finding is consistent with a revised conceptual model of agglomeration and subsequent deposition on as proposed above (Figure 7.1.6). At higher approach velocity, flui...

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...03; Phenrat et al. 2009a; Phenrat et al. 2008). Models are available to calculate the magnitude of all of the forces acting on a polymer or polyelectrolyte coated NZVI particle (Israelachvili 1992), (=-=Brant et al. 2007-=-; de Vicente et al. 2000) (Fritz et al. 2002) (Cayer-Barrioz et al. 2009). Table 5.1.1. Potential coatings from each class to be evaluated. Coating Charge Stabilization type Polymers Polyethylene Glyc...

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...iron and Fe-oxide NPs and/or to improve particle mobility in the environment due to steric, electrosteric, or electrostatic repulsions between the particles and between the particles and soil grains (=-=He et al. 2009-=-; He et al. 2007; Saleh et al. 2005a). Poly(aspartate), an anionic polypeptide, adsorbs to iron oxide 6surfaces via acid-base interactions through the carboxyl groups (Chibowski and Wisniewska 2002; ...

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...ave a higher hydraulic conductivity. MRNIP2 followed the same transport pattern as a tracer, suggesting that density driven transport phenomenon as observed for another type of polymer modified NZVI (=-=Kanel et al. 2008-=-) is not significant for MRNIP2 under the transport conditions studied here. Polymer modified NZVI deposited in the regions where fluid shear is insufficient to prevent NZVI agglomeration and depositi...

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....................................... 107 List of Tables Table 5.1.1. Potential coatings from each class to be evaluated. ................................................ 7 Table 6.1. RNIP properties (=-=Liu et al. 2005-=-a; Liu et al. 2005b; Phenrat et al. 2007) ............ 11 Table 6.2. Property and structure of surface modifiers .......................................................... 15 Table 6.3. Physical prope...

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...Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targeting Modeling Fagerlund et al., 2012 JCH =-=Phenrat et al., 2010-=- JCH Phenrat et al. 2010 ES&T Phenrat et al., 2011 ES&T 0.18 m Intermediate and Large Scale Demonstration Effect of treatment on mass emission Field scale injection and monitoring (Task 4, 5-8) Shi et...

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...ame condition as above. As shown in Table 7.7.4, C/C0 is only 0.45, indicating that removing NOM from soil decreased ZLoy mobility through the sand. This agrees with several recently published works (=-=Johnson et al. 2009-=-) reporting enhanced transport of NZVI in the presence of NOM in porous media. The adsorbed NOM likely made the surface more negatively charged at neutral pH which increases the repulsive forces betwe...

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...batch to batch, depending on how well controlled the synthesis process is. The site conditions and 12composition of the site groundwater may also affect reactivity (e.g. presence of NOM or nitrate) (=-=Liu et al., 2007-=-). It is not possible to a priori determine the reactivity of a particular NZVI based solely on characterization of the iron (e.g. Fe(0) content, polymer content) and groundwater. As such, the reactiv...

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... between a particle and a collector (Cayer-Barrioz et al. 2009). It should be noted that electrosteric repulsions may result in reversible deposition in a secondary minimum (Franchi and O'Melia 2003; =-=Phenrat et al. 2009-=-a) which makes the attachment efficiency sensitive to fluid velocity (e.g. sliding and rolling as a result of the reduced frictional force) and solution chemistry (Cayer-Barrioz et al. 2009; Franchi a...

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...protonate depending on the pH in the solution (Itami and Fujitani 2005;sTombacz and Szekeres 2006). The reported pHpzc-edge of kaolinite edge sites ranges from pHs5.8 to 7.5 (Kretzschmar et al. 1998; =-=Tombacz et al. 1999-=-; Tombacz et al. 2004; Tombacz andsSzekeres 2006). The positively charged edge sites on clay may serve as deposition sites forsNZVI similar to the case of metal oxide surface impurities. In addition, ...

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...lecule layer also serves as a lubricant. The macromolecule yields a higher local viscosity compared to the bulk, resulting in the reduction of the frictional force between a particle and a collector (=-=Cayer-Barrioz et al. 2009-=-). It should be noted that electrosteric repulsions may result in reversible deposition in a secondary minimum (Franchi and O'Melia 2003; Phenrat et al. 2009a) which makes the attachment efficiency se...

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...ic Electrosteric Electrostatic Electrosteric Electrostatic Steric/ Hydration Relevance Common non-toxic polymer used to stabilize NP dispersions. Adsorbed PVA reduces bacterial adsorption to surfaces(=-=Koziarz and Yamazaki 1999-=-). Cellulose is used to prepare stabilized nanoiron dispersions(He and Zhao 2005). Inexpensive and biodegradable. Used to prepare stabile nanoiron dispersions that partition to the TCE/water interface...

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...situ prior to injection of Z-Loy to improve transport. This included 1) a 20 PV flush with DI water. 2) Flushing with Ca 2+ and PEG together with K + to inhibit clay swelling (Kjellander et al. 1988; =-=Liu et al. 2004-=-). Ca 2+ (5 mM) and PEG (1g/L) with 10 mM K + were used to flush the columns for 4 PVs and allowed to react for 30 min. prior to inject Z-Loy dispersion (in DI water) at the approach velocity of 1.25x...

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...et al. 1989). Alkyl polyglucosides are an emerging class of surfactant synthesized from renewable raw materials and are nontoxic, biocompatible, and biodegradable. They adsorb to metal oxide surfaces(=-=Matsson et al. 2004-=-). The latter, poly(aspartate) and alkyl polyglucosides are desirable due to their low cost and “green” nature and widely used as detergents in manufacturing. 5.2 Interaction potential affected by pol...

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...er interface (Saleh et al. 2005a; Saleh et al. 2005b). PSS homopolymer is a common inexpensive alternative used to stabilize NP dispersions. Polylysine is a biodegradable polypeptide and bactericidal(=-=Roddick-Lanzilotta and McQuillan 1999-=-). Poly(aspartic acid) should be biodegradable and less bactericidal. SDBS is a common anionic surfactant shown to enhance nanoiron mobility(Saleh et al. 2007) but resists biodegradation. Alkyl polygl...

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... based transport code MT3DMS (Zheng and Wang 1999). Here we implemented a Gilland-Sherwood type model of rate-limited DNAPL dissolution coupled to first order degradation of PCE by the NZVI particles(=-=Saenton and Illangasekare 2007-=-). The model considered mass transfer between the DNAPL and aqueous phase, using a lumped mass-transfer coefficient for component i over the DNAPL-water interface. KLi is contained in a modified Sherw...

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...lation vs. αexp for latex particles coated with SRHA (Franchi and O'Melia 2003), latex particles coated with GFA and PHA (Amirbahman and Olson 1993), hematite particles coated with GFA, PFA, and PHA (=-=Amirbahman and Olson 1995-=-), hematite particles coated with GFA, PFA, and PHA (Amirbahman and Olson 1995), latex particles coated with SRHA(Pelley viFigure 7.3.2. Figure 7.3.3 and Tufenkji 2008), and hematite and titanium dio...

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...n of water flow in the 2-D flow cell Water flow through the 2D flow cell was simulated to determine the velocity distribution in the layers in the cell. The two-dimensional groundwater flow equation (=-=Bear 2007-=-) based on Darcy’s Law was solved for the flow cell using COMSOL Multiphysics Software (COMSOL, Inc., Burlington, MA). Constant flow boundary conditions were set at the inlet and outlet ports represen...

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...and soil grains (He et al. 2009; He et al. 2007; Saleh et al. 2005a). Poly(aspartate), an anionic polypeptide, adsorbs to iron oxide 6surfaces via acid-base interactions through the carboxyl groups (=-=Chibowski and Wisniewska 2002-=-; Nakamae et al. 1989). Alkyl polyglucosides are an emerging class of surfactant synthesized from renewable raw materials and are nontoxic, biocompatible, and biodegradable. They adsorb to metal oxide...

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...ivity of modified nanoiron Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targeting Modeling =-=Fagerlund et al., 2012-=- JCH Phenrat et al., 2010 JCH Phenrat et al. 2010 ES&T Phenrat et al., 2011 ES&T 0.18 m Intermediate and Large Scale Demonstration Effect of treatment on mass emission Field scale injection and monito...

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...a. ........................................................................................... 48 Figure 7.3.1. (a) αpre from Bai and Tien’s correlation vs. αexp for latex particles coated with SRHA (=-=Franchi and O'Melia 2003-=-), latex particles coated with GFA and PHA (Amirbahman and Olson 1993), hematite particles coated with GFA, PFA, and PHA (Amirbahman and Olson 1995), hematite particles coated with GFA, PFA, and PHA (...

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...8). Models are available to calculate the magnitude of all of the forces acting on a polymer or polyelectrolyte coated NZVI particle (Israelachvili 1992), (Brant et al. 2007; de Vicente et al. 2000) (=-=Fritz et al. 2002-=-) (Cayer-Barrioz et al. 2009). Table 5.1.1. Potential coatings from each class to be evaluated. Coating Charge Stabilization type Polymers Polyethylene Glycol (PEG) Polyvinyl Alcohol (PVA) guargum Pol...

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...ect of NZVI on PCE dechlorination and dissolution from PCEDNAPL source zone A custom made glass flow cell that was used in similar studies to investigate effect of bio-activity in DNAPL source zones (=-=Glover et al. 2007-=-) was used in this study as a physical model. The flow cell had a total volume of 15 mL. The flow cell was carefully packed inside an anaerobic chamber, creating a two-zone system where a DNAPL pool c...

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... the action of gravity and capillarity. The fluid properties in combination with characteristics of the soil both at the pore and macro-scale will determine how the DNAPL ultimately gets distributed (=-=Illangasekare 1998-=-; Illangasekare et al. 1995). In general, DNAPLs migrate through fingering and pools at capillary barriers (coarse-fine interfaces). The final entrapment architecture will contain both residual zones ...

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...realistic conditions. Bench Scale Batch and Column Effect of geochemistry on nanoiron migration Saleh et al., 2007 EES Phenrat et al., 2008 JNR Saleh et al., 2008 ES&T Phenrat et al., 2009, 2010 ES&T =-=Kim et al., 2012-=- JCIS Elucidate DNAPL targeting mechanisms Kim et al., 2009 ES&T Reactivity of modified nanoiron Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distri...

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...ticles and clay particles. Natural aquifer materials typically contain metal oxide surface impurities (e.g. Fe-oxides or Al-oxides) that have a relatively high isoelectric point (pHiep = pH 7 ~ 9.5) (=-=Litton and Olson 1994-=-; Song et al. 1994) compared to silica (pHiep 2 ~ 3). Metal oxide impurities on mineral surfaces can behave as favorable deposition sites that limit nanoparticle mobility through the porous media at l...

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...ly due to flow bypassing and inaccessibility. Recently, reactive nanoscale iron particles delivered in situ has been proposed and evaluated in the field with the goal of overcoming these limitations (=-=Lowry 2007-=-; Tratnyek and Johnson 2006; Zhang 2003). In principle, their small size (10-100 nm) provides an opportunity to deliver these remedial agents to subsurface contaminants in situ, and provides access to...

Citation Context

...; He et al. 2007; Saleh et al. 2005a). Poly(aspartate), an anionic polypeptide, adsorbs to iron oxide 6surfaces via acid-base interactions through the carboxyl groups (Chibowski and Wisniewska 2002; =-=Nakamae et al. 1989-=-). Alkyl polyglucosides are an emerging class of surfactant synthesized from renewable raw materials and are nontoxic, biocompatible, and biodegradable. They adsorb to metal oxide surfaces(Matsson et ...

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...Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targeting Modeling Fagerlund et al., 2012 JCH =-=Phenrat et al., 2010-=- JCH Phenrat et al. 2010 ES&T Phenrat et al., 2011 ES&T 0.18 m Intermediate and Large Scale Demonstration Effect of treatment on mass emission Field scale injection and monitoring (Task 4, 5-8) Shi et...

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... et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targeting Modeling Fagerlund et al., 2012 JCH Phenrat et al., 2010 JCH Phenrat et al. 2010 ES&T =-=Phenrat et al., 2011-=- ES&T 0.18 m Intermediate and Large Scale Demonstration Effect of treatment on mass emission Field scale injection and monitoring (Task 4, 5-8) Shi et al., 2011 ES&T Johnson et al., 2012 ES&T Figure 6...

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...Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targeting Modeling Fagerlund et al., 2012 JCH =-=Phenrat et al., 2010-=- JCH Phenrat et al. 2010 ES&T Phenrat et al., 2011 ES&T 0.18 m Intermediate and Large Scale Demonstration Effect of treatment on mass emission Field scale injection and monitoring (Task 4, 5-8) Shi et...

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...Liu et al., 2007 ES&T Phenrat et al. 2009 ES&T Kim et al., EST (submit) Small Scale 2-D Nanoiron distribution Effect of heterogeneity Injection rate NAPL targeting Modeling Fagerlund et al., 2012 JCH =-=Phenrat et al., 2010-=- JCH Phenrat et al. 2010 ES&T Phenrat et al., 2011 ES&T 0.18 m Intermediate and Large Scale Demonstration Effect of treatment on mass emission Field scale injection and monitoring (Task 4, 5-8) Shi et...

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...improve particle mobility in the environment due to steric, electrosteric, or electrostatic repulsions between the particles and between the particles and soil grains (He et al. 2009; He et al. 2007; =-=Saleh et al. 2005-=-a). Poly(aspartate), an anionic polypeptide, adsorbs to iron oxide 6surfaces via acid-base interactions through the carboxyl groups (Chibowski and Wisniewska 2002; Nakamae et al. 1989). Alkyl polyglu...

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...were not depassivated. After 2 d aging, upon injection of NZVI stock solution, the ORP dropped quickly and was below -600 mV after about 1 h. The results are consistent with the previous aging study (=-=Sarathy et al. 2008-=-), which demonstrated that it usually took more than 12 h to depassivate the NZVI particles and the NZVI reactivity increased within 2 d. For the rest of our experimental results, all NZVI stock solut...

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...es. Natural aquifer materials typically contain metal oxide surface impurities (e.g. Fe-oxides or Al-oxides) that have a relatively high isoelectric point (pHiep = pH 7 ~ 9.5) (Litton and Olson 1994; =-=Song et al. 1994-=-) compared to silica (pHiep 2 ~ 3). Metal oxide impurities on mineral surfaces can behave as favorable deposition sites that limit nanoparticle mobility through the porous media at low pH (Song et al....