Low Adsorption of Magnetite Nanoparticles with Uniform

Article pubs.acs.org/IECR

Low Adsorption of Magnetite Nanoparticles with Uniform Polyelectrolyte Coatings in Concentrated Brine on Model Silica and Sandstone Esteban E. Ureña-Benavides,†,⊥ Edward L. Lin,† Edward L. Foster,‡ Zheng Xue,† Michael R. Ortiz,‡ Yunping Fei,† Eric S. Larsen,‡ Anthony A. Kmetz, II,§ Bonnie A. Lyon,§ Ehsan Moaseri,† Christopher W. Bielawski,‡ Kurt D. Pennell,§ Christopher J. Ellison,† and Keith P. Johnston*,† †

Department of Chemical Engineering, University of Texas, Austin, Texas 78712, United States Department of Chemistry, University of Texas, Austin, Texas 78712, United States § Department of Civil and Environmental Engineering, Tufts University, Medford, Massachusetts 02155, United States ‡

S Supporting Information *

ABSTRACT: In subsurface imaging and oil recovery where temperatures and salinities are high, it is challenging to design polymer-coated nanoparticles with low retention (high mobility) in porous rock. Herein, the grafting of poly(2-acrylamido-2methyl-1-propanesulfonic acid-co-acrylic acid) (poly(AMPS-co-AA)) on magnetic iron oxide nanoparticles was sufficiently uniform to achieve low adsorption on model colloidal silica and crushed Berea sandstone in highly concentrated API brine (8% NaCl and 2% CaCl2 by weight). The polymer shell was grafted via amide bonds to an aminosilica layer, which was grown on silica-coated magnetite nanoparticles. The particles were found to be stable against aggregation in American Petroleum Institute (API) brine at 90 °C for 24 h. For IO nanoparticles with ∼23% polymer content, Langmuir adsorption capacities on colloidal silica and crushed Berea Sandstone in batch experiments were extremely low at only 0.07 and 0.09 mg of IO/m2, respectively. Furthermore, upon injection of a 2.5 mg/mL IO suspension in API brine in a column packed with crushed Berea sandstone, the dynamic adsorption of IO nanoparticles was only 0.05 ± 0.01 mg/m2, which is consistent with the batch experiment results. The uniformity and high concentration of solvated poly(AMPS-co-AA) chains on the IO surfaces provided electrosteric stabilization of the nanoparticle dispersions and also weakened the interactions of the nanoparticles with negatively charged silica and sandstone surfaces despite the very large salinities.

■

EOR in carbonate reservoirs.27−31 Fatty acid amines and dodecylbenzenesulfonic acid, having been used for EOR in the absence of NP, may potentially be used as an NP stabilizer.32 Polymer chains on surfaces often tend to be extended and stabilize NPs if the polymer itself is solvated and soluble in the same media.33 Nonionic polymeric stabilizers, such as polyethylene glycol (PEG), polyacrylamide (PAM), and polyvinylpyrrolidone (PVP), have been widely utilized to stabilize NPs;3,34 however, these polymers exhibit lower critical solution temperature behavior and precipitate at high temperatures. Polymer desolvation at elevated temperatures becomes even more significant at the high salinities encountered in subsurface reservoirs. PVP and hydroxyethyl cellulose (HEC)-coated nanotubes were recently reported to be stable in high salinity brine at moderate temperatures but inevitably were dehydrated and precipitated at higher temperatures.3,35 Weakly acidic polyelectrolytes such as poly(acrylic acid) (PAA) remain soluble in 1 M NaCl at elevated temperatures but precipitate in the presence of divalent cations that interact strongly with carboxylates.5,36−38 In contrast, highly acidic sulfonated

INTRODUCTION Over the past decade, the interest in exploiting nanotechnology for imaging and oil recovery in subsurface reservoirs has grown markedly. Various types of nanoparticles (NP) including silica, carbon nanotubes, iron, and iron oxide have been designed for enhanced oil recovery (EOR),1−7 groundwater remediation,8−12 reservoir imaging,13−19 and CO2 capture.20 Superparamagnetic iron oxide nanoparticles may be utilized as contrast agents for cross-well electromagnetic imaging to map fluid flow patterns in reservoirs to guide oil production.21 Magnetite, Fe3O4, is of particular interest because it is inexpensive, relatively nontoxic, and has a high theoretical saturation magnetization of 127 emu/g. For magnetite to be transported several hundred meters through porous sandstone at high temperatures (up to 150 °C) and high salinities (over 1 M), the particles must be coated with polymer stabilizers that repel mineral surfaces. Concentrated divalent Ca2+ and Mg2+ ions often form salt bridges between the anionic polymers and anionic mineral surfaces, which must be minimized by carefully designing the polymer structure.10,14,17,18,22,23 A wide variety of polymers and surfactants have been adsorbed or grafted on NP surfaces to provide electrosteric stabilization against colloidal aggregation.24−26 Alternatively, a nonionic saponin surfactant, extracted from Zizyphus spinachristi, was utilized in conjunction with silica nanoparticles for © XXXX American Chemical Society

Received: September 3, 2015 Revised: December 1, 2015 Accepted: January 14, 2016

A

DOI: 10.1021/acs.iecr.5b03279 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

chemistry influence the level and uniformity of grafting of polyelectrolytes. Given that Si−OH groups are more reactive than iron oxide surfaces, it can be beneficial to add a thin silica layer to Fe2O3 and then aminate the silica shell.43−45 Upon grafting 3-aminopropyl triethoxysilane (APTES) to silicacoated maghemite nanoparticles, the amine density was 2.5times higher than in the case of grafting APTES directly onto bare Fe2O3.43,45 A further challenge is to devise new ways to graft high concentrations of highly charged polyelectrolytes to NP surfaces to overcome electrostatic repulsion of chains diffusing to the charged surfaces and enable reaction. Herein, we report a new thermal method for grafting poly(AMPS-co-AA) uniformly to amine-coated magnetite nanoparticles to achieve a remarkably low level of adsorption of the particles on colloidal silica, Ottawa sand, and high surface area crushed Berea sandstone in concentrated API brine. Relative to our earlier work, the level of amine functionalization with APTES was enhanced upon first forming a reactive thin silica layer on the magnetite.14,19 For further increasing the uniformity of polymer grafting, the amidation of the AA groups with the amines on the NP surface was performed at a high temperature of 90 °C. It was hypothesized that the thermal energy would be sufficient to drive the diffusion and reaction of the polyelectrolyte chains on the nanoparticle surface without the need to add salt to screen the electrostatic repulsion. Without added salt (which causes partial aggregation),14,19 the goal was to perform the grafting reaction on a fully stable colloidal dispersion to attempt to produce a more uniform polymer coating. At various stages, the magnetite nanoparticles were characterized with thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) to determine the composition, zeta potential to determine the surface charge, and dynamic light scattering (DLS) to determine the hydrodynamic diameter. Relative to our earlier work,14 these improvements led to a reduction in batch NP adsorption on colloidal silica by 4-fold and on crushed Berea sandstone by a factor of 3. The low adsorption values were also observed in dynamic flow experiments performed in columns packed with either Ottawa sand or crushed Berea sandstone.

polyelectrolytes with low affinities toward divalent cations, such as polystyrenesulfonate (PSS) and 2-acrylamido-2-methylpropanesulfonate (PAMPS), are soluble at high salinities and temperatures.37,39,40 When adsorbed or grafted onto NPs, the solvated polyelectrolyte chains remain extended and provide sufficient steric and electrosteric stabilization.14,16,19 Moreover, zwitterionic sulfobetaine polymers, also known to be soluble and stable at high salinities and temperatures,16,41 have been attached to magnetite by the “grafting through” approach and shown to stabilize NPs under these harsh conditions.16,41 Recently, our group has demonstrated electrosteric stabilization of iron oxide (IO) NPs in high salinity API brine (8% NaCl and 2% CaCl2 by weight) at temperatures up to 90 °C for a series of sulfonated random and block copolymers.13−15,19 Poly(AMPS-co-AA) random copolymers were found to be effective stabilizers for ∼100 nm IO NP dispersions at 90 °C for up to 30 days.15 The AA groups were found to adsorb to magnetite upon strong complexation (salt bridging) with multivalent cations, whereas the AMPS groups provided electrosteric stabilization. The degree of adsorption of IO NPs to silica microspheres could be tuned by covalently linking small molecule hydrophobic modifiers to the copolymer coating.13 However, upon dilution in a large oil reservoir, the adsorbed polymers may desorb from the surface of the NPs. In contrast, poly(AMPS-co-AA) with AMPS/AA ratios of 1:1 to 20:1 have been grafted to amine-coated IO NPs via amide bond formation with the AA monomers catalyzed by N-(3(dimethylamino)propyl)-N′-ethylcarbodiimide (EDC).14,19 Because the anionic charge on the surface increases during grafting, incoming chains will progressively be repelled. Thus, the reaction was performed at a high ionic strength (500 mM NaCl) to screen the charges to raise the graft density. However, the high salt content results in particle aggregation, which may have limited the uniformity of the grafted chains on the surface. The grafting was found to be permanent, as the polymer content remained constant upon a 22,500-fold dilution in 1 M NaCl, as characterized by TGA.19 Similarly, poly(AMPS-coAA)-grafted IO NPs were found to be stable in API brine at elevated temperatures of 90 °C for 1 month and exhibited relatively low adsorption on silica microspheres of 0.24 ± 0.11 mg of IO/mL at 1 mg/mL.14 A similar level of adsorption was observed in dynamic adsorption flow experiments through columns packed with Ottawa sand.19 The IO NP adsorption was found to decrease with increasing AMPS/AA ratio from 1:1 to 3:1, and then reached a plateau upon further increasing in AMPS fraction above 20:1.19 Additionally, anionic homopolymer PAMPS and a zwitterionic homopolymer poly(sulfobetaine [3-(methancryloylamino)propyl]-dimethyl(3sulfopropyl)ammonium hydroxide) (PMPDSA) could be tethered to IO NPs via an economic “grafting through” free radical polymerization method.16 For the zwitterionic IO NPs, adsorption on crushed Berea sandstone was found to be an order of magnitude lower than that of poly(AMPS-co-AA)grafted IO NPs.16 Poly(sulfobetaine methacrylamide), a zwitterionic stabilizer, grafted on silica and polystyrene NPs provided long-term colloidal stability at salt concentrations up to 120 000 mg/dm3 at 90 °C.42 To further increase IO NP mobility in porous media, even lower adsorption of NPs on mineral surfaces would be desired by designing a sufficiently thick and uniform polymer shell to mitigate interactions between bare IO surfaces and the mineral substrates. However, little is known about how the density of amine groups on IO nanoparticle surfaces and the grafting

■

EXPERIMENTAL SECTION Materials. Iron(II) chloride tetrahydrate, iron(III) chloride hexahydrate, citric acid monohydrate, 30% ammonium hydroxide, tetraethyl orthosilicate (TEOS), 3-amniopropyl triethoxysilane (APTES), glacial acetic acid, calcium chloride dihydrate, sodium chloride, hydrochloric acid, sodium hydroxide, acrylic acid, potassium persulfate, and sodium metabisulfite were obtained from Sigma-Aldrich (St. Louis, MO) and Fisher Scientific (Pittsburgh, PA) and used as received. The monomer 2-amino-2-methylpropanesulfonate (AMPS) was a gift from Lubrizol corporation and used as received. Uniform 8 μm silica microspheres with the trade name AngstromSphere Monodispersed Silica Powder (Catalog #SIO2P800-01-1KG) were purchased from Fiber Optic Inc. (New Bedford, MA) and were washed at least five times with pH 9 water and dried at 80 °C before use. Synthesis of Poly(2-acrylamido-3-methylpropanesulfonate-co-acrylic acid) (Poly(AMPS-co-AA)). The polymer with an AMPS/AA ratio of 3 was synthesized according to our previously reported procedure.14,19 A three-necked flask was loaded under a nitrogen atmosphere with 30.9 g (0.135 mol) of AMPS, 4.86 g (0.018 mol) of potassium persulfate, and 3.42 g (0.018 mol) of sodium metabisulfite; 3.0 mL (0.044 mol) of B


Article

Industrial & Engineering Chemistry Research acrylic acid was then added. The reactants were stirred at 80 °C for 16 h, after which the monomer ratio was confirmed by 1H NMR. Synthesis of Iron Oxide Nanoparticles (IO NPs). The nanoparticles were synthesized by coprecipitation of iron chlorides with a stoichiometric ratio of 1:2 Fe(II) to Fe(III) at 90 °C for 2 h by modifying our previous method.19 The mass of iron chlorides was chosen to be equivalent to 10 g of Fe. In our case, 8.60 g of iron(II) chloride tetrahydrate and 23.50 g of iron(III) chloride hexahydrate were added to a round-bottom flask along with 0.500 g of citric acid monohydrate and 400 mL of deionized (DI) water. The synthesized magnetite nanoparticles were then separated magnetically using a 0.5 T magnet from Eclipse Magnetics (catalog no. N426) followed by two 500 mL DI water washes also decanted magnetically. Once the magnetite nanoparticles were washed, 336 mL of a 3.85% wt citric acid solution was added to the solid magnetite residue. The latter solution, with a pH of 5.2, was prepared by mixing 17 g of citric acid monohydrate, 72 mL of 2.5 N NaOH, and 320 mL of DI water in a media bottle container. The IO NP mixture was bath sonicated for 10 min in a Fisher Scientific (Pittsburgh, PA) ultrasonic cleaner, model FS30D. The mixture was then heated to 80 °C in the same round-bottom flask used for the synthesis and magnetically stirred for 90 min. The resulting nanoparticle dispersion was cooled to room temperature, and the pH was adjusted to 10.1 using 2.5 N NaOH. The mixture was then centrifuged at 5000 rpm for 5 min to remove large clusters. The concentration of the final mixture was determined by a UV−vis spectrophotometer at 575 nm (Cary 3E, Varian). A typical yield of 45−55% was obtained in the supernatant at this step. Silica Coating of IO NPs. In an ice bath, a solution of 15 mL of TEOS was prepared in 260 mL of ethanol. The citratecoated nanoparticles obtained from the previous step were bath sonicated for 1 h in an ice/water mixture. The nanoparticle dispersion was then diluted to 0.1 wt %. The pH was adjusted to 7.2 using 1.0 N HCl, and the dispersion was equilibrated for 20 min in the ice water bath. The TEOS/ethanol solution was added slowly to the IO NP dispersion. The NP dispersion and TEOS solutions were combined at pH 7.2 and in an ice water bath to minimize the rate of TEOS hydrolysis and subsequent condensation during mixing. The pH was then increased to 12 using 1.5 N KOH. The sol−gel reaction was allowed to proceed for 3 h at room temperature. Once the reaction was complete, the pH was lowered to 10 with 1.0 N HCl, and the silica-coated NPs were separated magnetically and washed twice with DI water. The resulting NP dispersion was sonicated for 1 min/mL in 30 mL batches using a Branson digital sonifier, model 102c. The final mixture was centrifuged at 5000 rpm for 5 min to remove large aggregates. Amine Functionalization of IO NPs. The surface of TEOS-coated IO NPs was aminated following our earlier procedure.19 Briefly, 25 mL of APTES was mixed with 250 mL of 5 wt % acetic acid solution and allowed to oligomerize for 20 min under acid hydrolysis. The pH was raised to 8 with NaOH, and the silica-coated IO NPs were added. The reaction concentration was 5 mg of IO/mL. After 24 h of heating at 65 °C in a water bath, the reaction mixture was cooled to room temperature and stirred for another 24 h. Finally, the pH was adjusted to 5 with HCl and washed five times with DI water by magnetic separation. Grafting of Poly(AMPS-co-AA) to Amine-Functionalized IO NPs. The thermal grafting reaction at 90 °C was a

modification of our previous low temperature catalytic grafting procedure. Poly(AMPS-co-AA) (5.77 g) was dissolved with DI water and added to a round-bottom flask; the pH was adjusted to 5 using 11 mL of 2.5 N NaOH to yield a final polymer concentration of 145 mg/mL. The concentration of the aminecoated IO NP dispersion was adjusted to 20 mg of IO/mL, and then 50 mL were added to the polymer solution. The mixture was bath sonicated for 20 min. Argon was bubbled through the dispersion to remove air. Once degassed, the reaction mixture was placed in an oil bath at 90 °C and stirred vigorously for 72 h. At the beginning of the reaction, the septa inflated, so they were punctured with a needle connected to an argon line to release the pressure. The reaction mixture was allowed to cool to room temperature before it was centrifuged at 11,000 rpm (12,000g) for 10 min. The pellets were dispersed in 13−18 mL of DI water. The dispersed IO NPs were placed under probe sonication at 1.3 min/mL. The sonicated mixture was then centrifuged at 4,000 rpm for 5 min to remove the larger clusters. Adsorption of Poly(AMPS-co-AA)-Grafted IO NPs on Silica Microsphere. Adsorption of IO NPs on crushed Berea sandstone and 8 μm silica microspheres was measured in batch reactors as described in previous studies.14,19 The silica drying process was conducted at low temperature (below 200 °C) to avoid dehydroxylation of the silica surface. The concentration of the poly(AMPS-co-AA)-grafted IO was adjusted to 0.06 to 1 mg/mL in API brine. For silica adsorption, 2.5 mL of the IO dispersions was added to 1 g of the silica microspheres in a 1 dram screw-cap glass vial corresponding to 2.5 g of dispersion/ g of rock. For crushed Berea sandstone, 10 mL of the IO NPs dispersions was added to 0.2 g of the adsorbent in a glass vial, which equals 50 g of dispersion/g of rock. The glass vials were then sealed with Teflon tape and agitated horizontally overnight at room temperature on a LW Scientific Model 2100A Lab Rotator at 220 rpm. The mixture was then stood upright and left unperturbed for 24 h to allow the adsorbents to fully sediment. Column Study of Poly(AMPS-co-AA)-Grafted IO NPs. IO NP transport and retention experiments were performed using a one-dimensional column apparatus19 consisting of a syringe pump (model 22, Harvard Apparatus, Inc., Holliston, MA), a borosilicate glass column (10 cm length × 2.5 cm i.d.; Kontes, Vineland, NJ) and a fraction collector (CF-1, Spectrum Chromatography, Houston, TX). Acid-washed 80−100 mesh Ottawa sand (specific surface area = 0.01875 m2/g) or unwashed Crushed Berea sandstone of 60−170 mesh (specific surface area = 22.5 m2/g)46 was packed into the column in 1 cm increments. Immediately after packing, the column was purged with CO2 gas for 20 min, followed by injection of 10 pore volumes (PVs) of background solution containing API brine to completely saturate the column media. A nonreactive tracer test (2.0 M NaBr in DI water) was performed after complete saturation to assess water flow and hydrodynamic dispersion as previously described.11 Following the tracer test, approximately 3.5 PV of poly(AMPS-co-AA)-grafted IO NPs input suspension (2500 mg/L in API brine), adjusted to pH 7 with 1.0 M NaOH, was delivered to the column at a flow rate of 1.78 mL/min and 0.3 mL/min, which corresponds to a porewater (interstitial) velocity of approximately 12 m/day and 2 m/day, respectively. The IO NP injection was followed by at least 3.5 PV of NP-free background solution at the same flow rate. Quantification of influent and effluent IO NP concentration was performed using a UV−vis spectrophotometer C


Article


Figure 1. (a) Schematic diagram of the synthesis of poly(AMPS-co-AA) IO NPs. TEM images of (b) citrate IO NPs, (c) silica, and (d) poly(AMPSco-AA) coatings.

content was calculated from the HCl volume consumed in the intermediate region of the titration curve. Thermogravimetric Analysis (TGA). TGA was used to measure the organic content of the IO NPs after APTES functionalization and poly(AMPS-co-AA) grafting. All measurements were conducted using a Mettler-Toledo TGA/ SDTA851e instrument under N2 at a heating rate of 20 °C/ min from 25 to 800 °C. The percentage loss of weight was reported as the mass fraction of organic coating on the iron oxide. The amount of water in the samples was estimated by TGA as the difference between the initial weight and the weight at 120 °C. This number was used to calculate the polymer content on a dry basis. Transmission Electron Microscopy (TEM). The images were obtained on an FEI TECNAI Spirit Bio Twin operated at 80 kV. A dilute aqueous dispersion of the IO nanoclusters was deposited onto a 400 mesh Formvar-coated copper TEM grid and allowed to dry at room temperature overnight for imaging. Dilution Test. Polymer grafting was tested by an extreme dilution test similar to one reported previously.14 If the polymer was not grafted, it would desorb from the particles upon dilution, resulting in particle aggregation. First, 150 μL of sample was diluted in 15 mL of DI water and concentrated through a 300 kDa centrifugal filter. The resulting 150 μL was collected again and diluted in 15 mL of DI water once more; the polymer was allowed to desorb overnight, and then the sample was filtered again. The hydrodynamic diameter in brine was measured by DLS, and the amount of organic content of the washed IO NPs was determined by TGA.

(UV-1800, Shimadzu Scientific Instruments, Columbia, MD) operated at 600 nm. Figure S1 shows the UV absorbance spectra and a representative calibration curve. The accuracy of the UV method was confirmed through analysis of a subset of duplicate samples that were prepared using a Discover SP-D microwave digester (CEM Corporation, Matthews, NC) with concentrated nitric acid followed by quantification of total iron using an Optima 7300 DV inductively coupled plasma-optical emission spectrometer (ICP-OES, PerkinElmer, Waltham, MA). IO Concentration Measurements. The IO concentration was also determined by flame atomic absorption spectroscopy (FAAS). At least 100 μL of IO NP dispersion was digested in 12 M HCl for 24 h; the volume ratio of HCl:IO NP was 9:1. After digestion, the samples were diluted with 1% HNO3 to a concentration between 1 and 5 ppm of Fe. Particles that were coated with silica or polymer were filtered through a 20 nm syringe filter (Whatman ANOTOP 25). The FAAS was calibrated with ferric nitrate nonahydrate solutions in 1% nitric acid at concentrations from 1 to 5 ppm of Fe. The calibration was repeated every 10 samples. The concentration of the original suspension was calculated in terms of mg/mL of Fe3O4 based upon the Fe content measurements. Dynamic Light Scattering (DLS) Measurements. Dynamic light scattering (DLS) experiments were performed to measure the volume-averaged hydrodynamic size of IO NPs in DI water and API brine with a Brookhaven ZetaPlus system (Brookhaven Instruments Co.) at a measurement angle of 90°.19 The autocorrelation functions were fitted with the CONTIN algorithm. All measurements were collected over a 2 min period at a count rate of ∼500 kcps, and at least three measurements were collected for each sample. Zeta potential measurements were made as described previously.19 Amine Titration. The amount of surface amines was determined by conductometric titration following an earlier report.44 First, 200 μL of amine-coated IO NPs was diluted in 50 mL of DI water, and the pH was adjusted to 10 with 1 N NaOH. The conductivity and pH of the suspension was measured as it was titrated with 0.01 N HCl. The amine

■

RESULTS AND DISCUSSION Grafting of Poly(AMPS-co-AA) onto IO NPs. The poly(AMPS-co-AA)-grafted IO NPs were synthesized by adding the TEOS, APTES, and polymer layers to the citrate-coated IO NPs as shown in Figure 1. The size of the primary particles was similar after each step as expected from the TEM images. From these images, it was not possible to determine the size of the nanoclusters in suspension because the nanoclusters aggregated with each other during the TEM sample preparation. The IO D


Article


particles could be coated with silica despite the high surface coverage of citrate ligands. After amine functionalization with APTES on the surface of the silica-coated particles, the measured hydrodynamic diameter of the amine-coated particles in water was 97 ± 2 nm. Modest aggregation occurred during the amine coating, as the diameter increased by only a factor of 3. The zeta potential curve in Figure 2 indicates an isoelectric point at pH 9, as expected for the pKa of the amine surface. As the pH is decreased, protonation of the amine increased the zeta potential to a maximum of approximately 35 mV at pH 4. The decrease in zeta potential when the pH was lowered from 4 to 2 may be a complication resulting from partial dissolution of magnetite or from further deprotonation of silanol groups, as is evident for the zeta potentials of the TEOS-coated particles. The zeta potential curve is consistent with the results obtained by Campelj et al., who reported a maximum zeta potential of 40 mV and a point of zero charge of 9.43 With the amine coating, the IO NPs were stable for at least 4 days at pH 5 with no appreciable change in the mean hydrodynamic diameter. Grafting of poly(AMPS-co-AA) to IO NPs has been shown to enable electrosteric stabilization at high salinity and high temperature conditions.14,19 In our previous grafting approach with EDC at 25 °C, 3 wt % NaCl was used to screen the anions in the polyelectrolyte to lower the electrostatic barrier for the approach of the polymer chains to the IO surface. In the current study, we assumed that the thermal energy facilitates diffusion and reaction of the polymer chains at the surface without the need for any added salt. With this new grafting procedure, it did not appear that any of the iron oxide precipitated. The average hydrodynamic diameter of the poly(AMPS-co-AA)-coated particles in brine was 156 ± 5 nm (individual results for separate samples: 173, 144, 148, 144, 166, 162 nm, as shown in Table S2), which is only slightly larger than the mean diameter of the APTES-coated particles. On the basis of the 23% polymer content obtained by TGA, the minimum thickness of the polyelectrolyte layer was estimated to be 12 nm. The difference in hydrodynamic diameter of the amine- and polymer-coated NPs was 56 nm. If the particles did not aggregate, and the silica-coated clusters did not change shape, then the thickness of the polymer chains on the surface would be ∼28 nm. Thus, the DLS results suggested a modest amount of aggregation due to bridging by the polymer or van der Waals attraction, which is discussed in greater detail below. The cross-linked silica layer may have helped bind the primary particles within the clusters. The grafted polymer provides electrosteric stabilization of the nanoparticles by the highly acidic sulfonate groups, which bind weakly to Ca2+. In fact, the zeta potential curve shows values lower than −40 mV from pH 3 to 12. With the electrosteric stabilization, these particles were stable for several months in DI water and in API brine at room temperature. A dilution test was performed in an attempt to desorb any ungrafted polymer. After dilution of the grafted nanoparticles by 22,500-fold, the IO NPs were stable in API brine with a hydrodynamic diameter of 160 ± 15 nm after 1 day. TGA measurements of the poly(AMPS-co-AA)-grafted IO NPs after the dilution test showed an organic content of 42%. Thus, nearly all of the polymer chains on IO NPs were grafted. As a control, the dilution test was also performed on APTEScoated silica nanoparticles with adsorbed polymer (over 12 h) that was not covalently grafted. The dilution test resulted in immediate aggregation of APTES-coated silica nanoparticles in

NPs were synthesized in aqueous media by an alkali coprecipitation method under the same reaction conditions as our previous work.14,19 However, in the current study, the IO NPs were redispersed in a 3.85% citric acid solution and stored at pH 10 to enhance colloidal stability. The volume weighted hydrodynamic diameter distribution measured with DLS revealed small clusters of only 32 ± 6 nm (individual samples shown in Table S1) even though probe sonication was not used. The TEOS sol gel conditions were chosen to produce an 11 nm thick layer of silica assuming 100% yield,44,45 which corresponds to an NP diameter of 60 ± 7 nm, assuming that each cluster is individually coated by silica with 100% yield.45 The hydrodynamic diameter of the silica-coated particles (Table 1) was measured for 2 samples with an average of 30 Table 1. Summary of Colloidal Properties of IO Nanoclusters property hydrodynamic diameter (nm) zeta potential at pH 5 organic content (%wt) amine content (μmol/mg of IO)

poly(AMPS-coAA) IO

silica IO

amine IO

30 ± 2

97 ± 2

156 ± 5

−36 ± 6 10

28 ± 3 18 ± 2 2.5 ± 0.5

−47 ± 1 37 ± 5

a

Hydrodynamic diameters in water for silica IO and amine IO and in API brine for poly(AMPS-co-AA) IO.

± 2 nm. This relatively small hydrodynamic diameter suggests that the silica coating, along with the bath sonication, destabilized the initially larger iron oxide aggregates. The deprotonation of the highly acidic silanol (Si−OH) groups in the silica layer gave a zeta potential lower than −40 mV from pH 4 to 12 and an isoelectric point at pH 2 as shown in Figure 2. The charged silica-coated NP dispersion remained

Figure 2. Zeta potential of IO NPs at each stage. Red squares are IO NPs coated with silica (TEOS); blue diamonds are polymer-coated IO NPs, and green triangles are amine-coated IO NPs (APTES).

stable for several months at room temperature in DI water. After testing various TEOS levels, it was determined that 1 nm was the lowest silica thickness required to obtain a highly stable dispersion. The hydrodynamic diameter of the particles with a silica thickness of 1 nm measured by DLS was 41 ± 6 nm, whereas after 2 months of storage at room temperature, the mean diameter decreased to 22 ± 3 nm. However, we chose to perform polymer grafting on the particles with the 11 nm silica layer to ensure that the entire iron oxide surface was modified without bare spots. These experiments demonstrated that the E


Article


The polymer-coated samples showed two distinct peaks characteristic of the amide group at 1650 cm−1 and at 1540 cm−1. The former peak was attributed to the CO stretch and the latter peak to N−H bending. We hypothesized that the higher and more uniform amine densities, as a consequence of the silica sublayer, enabled more uniform grafting of poly(AMPS-co-AA), and ultimately greater stability of the IO NPs against adsorption on minerals. It has been previously reported that the sol−gel reaction of APTES on silica-coated NPs results in 2.5-times higher amine densities than the reaction on bare iron oxide NP.43,45 As shown in Figure 4, the surface amine density of the aminosilica-coated

API brine at room temperature, yielding a hydrodynamic diameter of 965 nm. The amidation reaction was expected to take place thermally without any catalyst based on previous studies.47−49 The free energy for amide bond formation is lower at high temperatures, which is thought to explain the stability of peptide bonds of enzymes and proteins in thermophilic organisms.49 In this study, a high concentration of IO NPs (20 mg/mL) coupled with a poly(AMPS-co-AA)/IO ratio of 6 g/g and an excess of 3.33 mol AA/mol NH2 helped drive the reversible grafting reaction. It should be noted that a single 200,000 Da polymer chain contains on average 250 AA units.14 In a hypothetical boundary condition where only 1 AA unit per polymer chain reacts with an NH2, the limiting reactant would be the polymer chains. There are 0.004 mol polymer chains/mol AA and 0.0133 mol polymer chains/mol NH2. Consequently, if all the polymer chains were grafted through a single grafting point, it would only require reacting 1.3% of all of the NH2 groups. However, an expected higher amide yield would produce multipoint grafting. The lack of a need for a catalyst has the advantage of simplifying the purification and scale-up procedures. Furthermore, modification of the protonated amines with EDC may reduce the colloidal stabilization. In addition, the addition of salt was not needed at high temperature because the polyelectrolyte chains had enough thermal energy to diffuse to the amines on the surface and react. Thus, the grafting could be performed on IO NPs in the colloidal state, which is beneficial for limiting aggregation as observed by the DLS results. The reaction at pH 5 enabled electrostatic attraction between the positively charged NP surface and the negatively charged polymer coils as the reaction began. In contrast, in our earlier work at low temperature, salt was needed to achieve high graft densities,14 which caused moderate precipitation of the particles. Furthermore, the particle size increased more during the grafting process, likely due to bridging of polymer on the precipitated particles. Surface Chemistry and Composition of IO NPs. The surface chemistry of IO NPs after the amine and polyelectrolyte grafting steps was characterized using ATR-FTIR, as shown in Figure 3. Si−O−Si stretch vibrations of silica were present in the amine-coated particles, as evidenced by the broad peak at 1040 cm−1. A peak was also observed at 1610 cm−1, which corresponds to N−H bending vibrations of the primary amine.

Figure 4. Conductometric titration of amine-coated IO clusters. The intermediate region corresponds to amine titration.

particles measured by conductometric titration with HCl was 2.5 ± 0.5 μmol/mg of IO, which corresponds to 35 ± 2 μmol/ m2 and 21 ± 1 amines/nm2. The surface area of the silicacoated clusters, based on the DLS hydrodynamic diameter (30 ± 2 nm), was used for these calculations. A control experiment was performed to determine the amine density after grafting directly to the citrate-coated particles (without a silica interlayer), which yielded an amine density of 1.4 μmol/mg of IO (or 32 μmol/m2, 20 amines/nm2). Thus, we found similar levels of grafting of the oligomeric APTES on silicacoated versus bare magnetite, unlike the case for APTES that was not oligomerized.45,50 The number of amine molecules per area was the same; however, because the silica layer was 11 nm thick, the total volume and surface area of the silica-coated IO NPs were higher, such that the amine content per mass of IO was nearly twice as large. The purpose of preoligomerizing APTES prior to grafting was to build a multilayer of amines and provide more sites for grafting of poly(AMPS-co-AA) onto the IO NP surface. One silanol group on a silica surface has an area of 0.47 × 0.47 nm2, corresponding to 4.6 silanol groups per nm2 for a monolayer on a silica surface.43,51 Conductometric titration gave 21 ± 1 amines/nm2, an equivalent of 4.6 monolayers of APTES and a 2 nm thick aminosilica layer. A typical amine density reported in the literature for silicacoated maghemite NP was 7.1 μmol/m2 (on the basis of the primary particle size), corresponding to 4.3 amines/nm2 for direct addition of APTES without preoligomerization.2,43,45 Our amine densities per nm2 of cluster surface area after grafting preoligomerized APTES were 5-fold higher, indicating multilayer grafting. If we based our calculations on the primary

Figure 3. FTIR of IO nanoclusters coated with silica, amine, and poly(AMPS-co-AA). F


Article


± 5%. Thus, we calculated that 23% of the NP mass was poly(AMPS-co-AA). Our previous work reported a total weight loss of 7 ± 3% at the amine-coating stage and 15 ± 3% for the poly(AMPS-co-AA)-grafted NP, which corresponds to ∼9% poly(AMPS-co-AA) in the final particle.14,19 The polymer content was 2.6-times higher with the new grafting method with the silica interlayer to control amine content and thermally driven amidation at 90 °C in the absence of added salt. The multipoint grafting of AA groups in the polymer layer limits the ability to accurately calculate its thickness. However, the minimum polymer layer thickness estimated from the polymer content was 12 nm assuming the poly(AMPS-co-AA) chains on the surface were at the bulk density of 1 g/mL. For this approximation, it was assumed that the chains are fully collapsed on the surface of the nanoparticles. The hydrodynamic diameter of the poly(AMPS-co-AA) employed herein, with a MW of 200 kDa, was 10 nm in DI water or API brine.14 Consequently, the thickness of the chains on the surface was greater than it would be for a polymer shell at a bulk density of 1 g/mL or for a monolayer with 10 nm long chains. Thus, the grafting process produced some bridging or aggregation of the IO nanoclusters. The poly(AMPS-co-AA) provides electrosteric stabilization to the magnetite nanoparticles, which will now be shown to provide minimal adsorption on mineral surfaces in API brine. Stability of Poly(AMPS-co-AA)-Coated IO NPs in Brine at High Temperature. The poly(AMPS-co-AA) chains provide stability to the IO NPs by electrosteric stabilization even at the harsh conditions of 90 °C in standard API brine; after 24 h, the measured hydrodynamic diameter was 183 ± 58 nm compared to 136 ± 25 in API brine at room temperature (Table S3).14,19 The stability at high temperature was expected given the very limited collapse of the pure polymer in solution at high temperature and salinity. In API brine, the charges on the polyelectrolyte layer are screened, and steric repulsion becomes the main stabilization mechanism with some degree of

particle size, rather than the cluster size, the graft density would only be 4.6 amines/nm2, similar to the value previously reported in the literature. However, it may be difficult for the oligomeric APTES to diffuse between the primary particles within the clusters to reach all the surface of primary particles, especially if the clusters are enclosed by a silica shell. Consequently, the cluster surface area was chosen to represent the amine density on the surface. The composition of the IO NPs was determined by TGA analysis at the various stages of the synthetic procedure as shown in Figure 5 and Table 1. For silica-coated particles, the

Figure 5. Thermogravimetric analysis of IO NPs coated with silica, amine, and poly(AMPS-co-AA).

10% weight loss may be attributed to absorbed water in the silica layer. For the amine-coated particles, the total weight loss was 18 ± 2%, arising from the release of water and aminopropyl groups. For the final poly(AMPS-co-AA)-coated particles, the total weight loss from polymer, water, and propylamines was 37

Figure 6. Batch adsorption test of poly(AMPS-co-AA)-grafted IO nanoclusters in API brine on silica (top) and crushed Berea sandstone (bottom). (a) Photographs showing low adsorption at IO concentrations ranging from 0.006 to 0.5 wt %. (b) IO nanoclusters adsorption isotherm. (c) Linearized Langmuir fit. G


Article

Industrial & Engineering Chemistry Research ⎛ 1 ⎞⎛ 1 ⎞ 1 1 1 = M p⎜ ⎟⎜ ⎟ + A /σa Ac /σa ⎝ kads/kdes ⎠⎝ Ac /σa ⎠ C

electrosteric repulsion. However, the IO NPs precipitated after 48 h in API brine at 90 °C, which was attributed to unreacted −NH2 on the NP surface. Monovalent ions, such as Na+, with low affinity to carboxylate and sulfonate anions only contribute to charge screening. In contrast, Ca2+ binds strongly to carboxylate groups and bridges polymer chains between particles and within the polymer layer of a single particle. Both cases lower stability as salt bridging within the polymer layer decreases osmotic repulsion and interparticle bridging forms aggregates.52,53 In the case of poly(AMPS-co-AA)-grafted particles, the AMPS unit has very low affinity for Ca2+, enabling solvation of the polyelectrolyte layer. Only 25% of the polymer units are AA, many of which have reacted to form amide linkages between the NP surface and the polymer chain; consequently, the small amount of residual AA units did not hinder colloidal stability. Batch Adsorption of Poly(AMPS-co-AA)-Coated IO NPs on Model Silica and Crushed Berea Sandstone. Batch adsorption tests were conducted with 8 μm model colloidal silica and crushed Berea sandstone at room temperature at pH 8 in standard API brine. The dispersions were shaken in the presence of the solid substrate for 16 h and then allowed to settle for 1 day to ensure equilibrium. As shown in the top four photographs of Figure 6a, the color of the silica remains very light compared to the solution, which is a semiquantitative indication of low adsorption levels considering that magnetite is a very strong inorganic pigment.19 Figure 6 and Table 2 show the specific adsorption data as a function of

where c is IO equilibrium concentration in g of IO/m , kads/kdes is the Langmuir equilibrium constant K, which is the ratio of the rates of adsorption and desorption with units of m3, Mp is the mass of one nanoparticle in g of IO, A is the adsorption at any given concentration in g IO/g, Ac is the adsorption capacity in g of IO/g, σa is the surface area of the adsorbent in m2/g, and the ratio of Ac/σa is the adsorption capacity in g/m2. A plot of σa /Ac versus 1/c gave a linear relation with correlation coefficients of 0.9997 and 0.9802 for silica and Berea sandstone, respectively. The adsorption capacities, calculated from the intercept of eq 1, were 0.07 and 0.09 mg/m2, and the Ks were 9.1 × 10−21 and 2.9 × 10−21 m3 for silica and Berea sandstone, respectively (Table 3). For poly(AMPS-co-AA)-grafted NPs Table 3. Langmuir Adsorption Isotherm Parameters for Iron Oxide Nanoparticles on Silica and Crushed Berea Sandstone adsorbent silica silica (previous)14 crushed Berea sandstone

silica

Berea

0.062 0.21 1.04 0.062 0.21 1.04

equilibrium IO concn (mg/mL) 0.051 0.193 1.01 0.053 0.187 0.992

± ± ± ± ± ±

0.003 0.001 0.01 0.009 0.009 0.005

% IO adsorbed 17 8 3 15 10 4

± ± ± ± ± ±

5 1 1 15 4 1

specific adsorption (mg of IO/m2) 0.04 0.06 0.09 0.03 0.05 0.10

± ± ± ± ± ±

kads/kdes (m3) −21

9.1 × 10 3.1 × 10−18 2.9 × 10−21

Ac/σa (mg/m2) 0.07 0.9 0.09

synthesized with our previous method on silica, Ac was 0.9 mg of IO/m2 with a K of 3.1 × 10−18 m3. Thus, for the new particles, Ac was lowered by more than an order of magnitude and in K by 3 orders of magnitude. According to Langmuir adsorption results, the equilibrium constant for adsorption (kads/kdes) of the nanoparticles was 3times larger for model silica than for crushed Berea sandstone. However, the adsorption capacity was larger for Berea sandstone compared to silica. Thus, at larger IO concentrations, when the adsorption capacity is approached, the adsorption is greater on Berea sandstone. The larger adsorption capacity may be due to the presence of very fine positively charged clay particles that interact with the anionic polymer. In Table 4, further comparisons are made between the new particles and our earlier ones grafted at room temperature. For silica at a reference concentration of 1 mg of IO/m2, the adsorption of 0.09 ± 0.04 mg/m2 was 2.7-times lower than the previously reported value. Here, the adsorption capacity was within experimental error of the Langmuir adsorption plateau of 0.07 mg/m2. For the previous particles, the adsorption continues to increase with concentration until a much higher plateau of 0.9 mg/mL is reached. In the case of Berea sandstone at a reference concentration of 0.1 mg of IO/mL, the value of 0.04 ± 0.02 mg/mL was a 4-fold improvement. As expected, the more uniform and larger amount of poly(AMPS-co-AA) on the newer magnetite nanoparticles provides greater steric and electrosteric stabilization and reduces the amount of adsorption onto silica and Berea sandstone. For investigating IO NP retention under dynamic conditions, one-dimensional column experiments were performed with a solution containing 2.5 mg of IO/mL in crushed Berea sandstone and Ottawa sand (Figure 7) saturated with API brine. In the fourth column of Table 4 and Figure 7a, the retention on Berea Sandstone was only 0.05 ± 0.01 mg/m2 (with 59% mass breakthrough), a marked improvement over the value of 0.18 mg/m2 (0.1% mass breakthrough) obtained for the previous particles. This nearly 4-fold decrease in retention was consistent with the lower specific adsorption

Table 2. Batch Adsorption Results of Poly(AMPS-co-AA)Grafted IO Nanoclusters on Silica and Crushed Berea Sandstone in API Brine initial IO concn (mg/mL)

(1) 3

0.01 0.01 0.04 0.02 0.02 0.02

the equilibrium concentration. The adsorption levels on silica and crushed Berea were exceptionally low, only 0.09 ± 0.04 mg of IO/m2 and 0.10 ± 0.02 mg of IO/m2 at 1 mg/mL. A control experiment using IO NPs with only physically adsorbed poly(AMPS-co-AA) at 2 mg of IO/mL in API brine gave a specific adsorption of 16.6 ± 1.3 mg of IO/m2 on silica, which is 180-times higher than for the covalently grafted particles. This much larger adsorption may be attributed to a smaller amount of polymer chains on the surface than for the case of covalently grafted polymer chains, where uncoated sites on the magnetite surface interact with silica. In addition, the polymer chains may desorb from the nanoparticle surface upon dilution.14 Finally, Ca2+ may form attractive salt bridges between the AA units (none of which are converted to amines) in the polyelectrolyte and the anionic silica surface, increasing the adsorption. The adsorption behavior of the IO NPs follows a Langmuir isotherm model as shown in Figure 6b. The data were fit according to the linearized version shown in eq 1 H


Article


Table 4. Batch Equilibrium Adsorption and Flow Retention of IO NPs Comparing Current and Previous Poly(AMPS-co-AA) Grafting Methods on Silica and Crushed Berea Sandstone in API Brine silica

current previous method14

crushed Berea sandstone

batch adsorption (mg of IO/m2) at 1 mg of IO/mL

batch adsorption (mg of IO/m2) at 0.1 mg of IO/mL

flow expt. retention (mg of IO/m2) at 2.5 mg of IO/mL

0.09 ± 0.04 0.24 ± 0.11

0.04 ± 0.02 0.13 ± 0.02

0.05 ± 0.01 (59% mass breakthrough) 0.18 (0.1% mass breakthrough)

levels (23% by TGA) favored by the high grafting temperature and colloidal stability during the grafting reaction. Unlike our previous studies with low-temperature grafting,14,19 it was not necessary to add high levels of salt or a catalyst. Another factor that improved the polymer grafting was the high density of amine surface grafting sites upon first coating the magnetite with a thin layer of silica interlayer prior to amination of the surface with APTES. The polymer-coated particles were colloidally stable at 90 °C in standard API brine for 24 h according to dynamic light scattering. The uniformity and high concentration of solvated poly(AMPS-co-AA) chains on the particle surfaces provided electrosteric stabilization between the NPs and weak interactions of the NPs with anionic silica and sandstone surfaces given the very low Ca2+ affinity to the strongly solvated highly acidic AMPS groups.14 High mobility (low retention) was observed for one-dimensional flow column studies conducted in either Ottawa sand or crushed Berea sandstone. Thus, the new polymer grafting technique, which does not require salt or catalyst, yielded IO NPs with reduced adsorption and improved mobility in porous media containing API brine.

Figure 7. Flow experiments of poly(AMPS-co-AA)-grafted nanoparticles in packed columns with (a) crushed Berea sandstone (60− 170 mesh, unwashed) and (b) Ottawa sand (80−100 mesh, acidwashed). Input concentration = 2500 ppm in API brine at room temperature.

measured in the batch experiments. In Ottawa sand, the particles were highly mobile (90% mass breakthrough); in fact, the breakthrough curve for the IO NPs was almost identical to that of the nonreactive tracer (Figure 7b). Previous work has shown reduced nanoparticle retention and increased mobility with increasing flow rate.54 The transport of the current batch of nanoparticles was also evaluated at a slower flow rate that is more representative of reservoir pore-water velocities (0.3 mL/min injection rate, 2 m/day seepage velocity) in crushed Berea sandstone. As shown in Figure S2, a slight delay was observed in breakthrough and slightly increased retention in the 2 m/day column compared to the faster flow rate column, which is consistent with previous studies in the literature. The low adsorption of the NPs on the mineral surfaces results from the strong steric repulsion as a consequence of the extension of the polyelectrolyte chains from the surface even in the high salinity brine.14 Previously, it was shown that poly(AMPS-co-AA)-coated NPs retain about half of their electrophoretic mobility even with 380 mM Na+ and 50 mM Ca2+. Furthermore, the pure polymer electrolyte is only partially collapsed at high ionic strength as shown by DLS.14 Thus, the polymer chains provided a significant degree of electrosteric as well as steric repulsion. The high acidity of the AMPS functionalities and resistance to Ca2+ binding were essential for avoiding polymer collapse.14,19,55 Relative to earlier studies,14,19 the lower adsorption of the NPs in this work was attributed to more uniform amine and polymer coating achieved on the NP surface.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.5b03279. Reproducibility of hydrodynamic diameter measurements of IO NP clusters coated with citrate, silica, amine, and polymer; sizes of polymer-coated IO NP clusters in API brine at RT and after aging for 24 h at 90 °C; UV absorbance spectra and calibration curve of poly(AMPS-co-AA)-grafted nanoparticles at 600 nm; and effect of flow rate on transport of poly(AMPS-co-AA)grafted nanoparticles in packed columns with crushed Berea sandstone (PDF)

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Present Address ⊥

E.E.U.-B.: Department of Chemical Engineering, University of Mississippi, University, MS 38677.

■

Notes

The authors declare no competing financial interest.

CONCLUSIONS For magnetite IO NPs with thermally grafted poly(AMPS-coAA) at an elevated temperature of 90 °C, the Langmuir adsorption capacities on colloidal silica and crushed Berea sandstone were ultralow at 0.07 and 0.09 mg of IO/m2, respectively. For colloidal silica, the Langmuir adsorption capacity was an order of magnitude lower than in our previous study14 as a consequence of more uniform polymer grafting

■

ACKNOWLEDGMENTS This work was supported by the Advanced Energy Consortium (member companies include Shell, Petrobras, Statoil, Schlumberger, BP America Inc., Total, and Repsol), the Department of Energy Center for Subsurface Energy Security, and the Welch Foundation (F-1319). I


Article


■

Copolymer Composition on Iron Oxide Nanoparticle Stability and Transport in Porous Media at High Salinity. Energy Fuels 2014, 28, 3655−3665. (20) Javadpour, F.; Nicot, J.-P. Enhanced CO2 Storage and Sequestration in Deep Saline Aquifers by Nanoparticles: Commingled Disposal of Depleted Uranium and CO2. Transp. Porous Media 2011, 89, 265−284. (21) Rahmani, A. R.; Bryant, S.; Huh, C.; Athey, A.; Ahmadian, M.; Chen, J.; Wilt, M. Crosswell Magnetic Sensing of Superparamagnetic Nanoparticles for Subsurface Applications. SPE J. 2015, 20, 1067− 1082. (22) Berlin, J. M.; Yu, J.; Lu, W.; Walsh, E. E.; Zhang, L.; Zhang, P.; Chen, W.; Kan, A. T.; Wong, M. S.; Tomson, M. B.; Tour, J. M. Engineered nanoparticles for hydrocarbon detection in oil-field rocks. Energy Environ. Sci. 2011, 4, 505−509. (23) Petosa, A. R.; Jaisi, D. P.; Quevedo, I. R.; Elimelech, M.; Tufenkji, N. Aggregation and deposition of engineered nanomaterials in aquatic environments: Role of physicochemical interactions. Environ. Sci. Technol. 2010, 44, 6532−6549. (24) Barbey, R.; Lavanant, L.; Paripovic, D.; Schüwer, N.; Sugnaux, C.; Tugulu, S.; Klok, H.-A. Polymer Brushes via Surface-Initiated Controlled Radical Polymerization: Synthesis, Characterization, Properties, and Applications. Chem. Rev. 2009, 109, 5437−5527. (25) Hiemenz, P. C.; Rajagopalan, R. Principles of Colloid and Surface Chemistry, revised and expanded; CRC Press, 1997; Vol. 14. (26) Sato, T.; Ruch, R. Stabilization of colloidal dispersions by polymer adsorption; Dekker: New York, 1980; Vol. 9. (27) Ahmadi, M. A.; Shadizadeh, S. R. Adsorption of Novel Nonionic Surfactant and Particles Mixture in Carbonates: Enhanced Oil Recovery Implication. Energy Fuels 2012, 26, 4655−4663. (28) Ahmadi, M. A.; Shadizadeh, S. R. Experimental investigation of adsorption of a new nonionic surfactant on carbonate minerals. Fuel 2013, 104, 462−467. (29) Ahmadi, M. A.; Shadizadeh, S. R. Induced effect of adding nano silica on adsorption of a natural surfactant onto sandstone rock: Experimental and theoretical study. J. Pet. Sci. Eng. 2013, 112, 239− 247. (30) Ahmadi, M. A.; Zendehboudi, S.; Shafiei, A.; James, L. Nonionic Surfactant for Enhanced Oil Recovery from Carbonates: Adsorption Kinetics and Equilibrium. Ind. Eng. Chem. Res. 2012, 51, 9894−9905. (31) Zendehboudi, S.; Ahmadi, M. A.; Rajabzadeh, A. R.; Mahinpey, N.; Chatzis, I. Experimental study on adsorption of a new surfactant onto carbonate reservoir samplesapplication to EOR. Can. J. Chem. Eng. 2013, 91, 1439−1449. (32) El-Batanoney, M.; Abdel-Moghny, T.; Ramzi, M. The effect of mixed surfactants on enhancing oil recovery. J. Surfactants Deterg. 1999, 2, 201−205. (33) Napper, D. H. Polymeric stabilization of colloidal dispersions; Academic Press: London, 1983; Vol. 7. (34) Wang, Y.; Zhu, H.; Becker, M.; Englehart, J.; Abriola, L.; Colvin, V.; Pennell, K. Effect of surface coating composition on quantum dot mobility in porous media. J. Nanopart. Res. 2013, 15, 1−16. (35) Hodge, R. M. HEC Precipitation at Elevated Temperature: An Unexpected Source of Formation Damage. SPE Drill. Completion 1998, 13, 88. (36) Lages, S.; Lindner, P.; Sinha, P.; Kiriy, A.; Stamm, M.; Huber, K. Formation of Ca2+-induced intermediate necklace structures of polyacrylate chains. Macromolecules 2009, 42, 4288−4299. (37) Newman, J. K.; McCormick, C. L. Water-Soluble Copolymers. 52. Sodium-23 NMR Studies of Ion-Binding to Anionic Polyelectrolytes: Poly (sodium 2-acrylamido-2-methylpropanesulfonate), Poly (sodium 3-acrylamido-3-methylbutanoate), Poly (sodium acrylate), and Poly (sodium galacturonate). Macromolecules 1994, 27, 5114− 5122. (38) Sinn, C. G.; Dimova, R.; Antonietti, M. Isothermal titration calorimetry of the polyelectrolyte/water interaction and binding of Ca2+: effects determining the quality of polymeric scale inhibitors. Macromolecules 2004, 37, 3444−3450.

REFERENCES

(1) Dickson, J. L.; Binks, B. P.; Johnston, K. P. Stabilization of Carbon Dioxide-in-Water Emulsions with Silica Nanoparticles. Langmuir 2004, 20, 7976−7983. (2) Espinoza, D.; Caldelas, F.; Johnston, K.; Bryant, S.; Huh, C. In Nanoparticle-stabilized supercritical CO2 foams for potential mobility control applications, SPE Improved Oil Recovery Symposium, 2010. (3) Kadhum, M. J.; Swatske, D. P.; Harwell, J. H.; Shiau, B.; Resasco, D. E. Propagation of Interfacially Active Carbon Nanohybrids in Porous Media. Energy Fuels 2013, 27, 6518−6527. (4) Ponnapati, R.; Karazincir, O.; Dao, E.; Ng, R.; Mohanty, K.; Krishnamoorti, R. Polymer-Functionalized Nanoparticles for Improving Waterflood Sweep Efficiency: Characterization and Transport Properties. Ind. Eng. Chem. Res. 2011, 50, 13030−13036. (5) Villamizar, L.; Lohateeraparp, P.; Harwell, J.; Resasco, D.; Shiau, B. Dispersion Stability and Transport of Nanohybrids through Porous Media. Transp. Porous Media 2013, 96, 63−81. (6) Worthen, A. J.; Bagaria, H. G.; Chen, Y.; Bryant, S. L.; Huh, C.; Johnston, K. P. Nanoparticle-stabilized carbon dioxide-in-water foams with fine texture. J. Colloid Interface Sci. 2012, 1. (7) Worthen, A. J.; Bryant, S. L.; Huh, C.; Johnston, K. P. Carbon dioxide-in-water foams stabilized with nanoparticles and surfactant acting in synergy. AIChE J. 2013, 59, 3490−3501. (8) Hong, Y.; Honda, R. J.; Myung, N. V.; Walker, S. L. Transport of iron-based nanoparticles: Role of magnetic properties. Environ. Sci. Technol. 2009, 43, 8834−8839. (9) Phenrat, T.; Saleh, N.; Sirk, K.; Tilton, R. D.; Lowry, G. V. Aggregation and sedimentation of aqueous nanoscale zerovalent iron dispersions. Environ. Sci. Technol. 2007, 41, 284−290. (10) Saleh, N.; Kim, H.-J.; Phenrat, T.; Matyjaszewski, K.; Tilton, R. D.; Lowry, G. V. Ionic strength and composition affect the mobility of surface-modified Fe0 nanoparticles in water-saturated sand columns. Environ. Sci. Technol. 2008, 42, 3349−3355. (11) Wang, Y.; Li, Y.; Costanza, J.; Abriola, L. M.; Pennell, K. D. Enhanced Mobility of Fullerene (C60) Nanoparticles in the Presence of Stabilizing Agents. Environ. Sci. Technol. 2012, 46, 11761−11769. (12) Xiao, Y.; Wiesner, M. R. Transport and Retention of Selected Engineered Nanoparticles by Porous Media in the Presence of a Biofilm. Environ. Sci. Technol. 2013, 47, 2246−2253. (13) Bagaria, H. G.; Neilson, B. M.; Worthen, A. J.; Xue, Z.; Yoon, K.; Cheng, V.; Lee, J. H.; Velagala, S.; Huh, C.; Bryant, S. L. Adsorption of Iron Oxide Nanoclusters Stabilized with Sulfonated Copolymers on Silica in Concentrated NaCl and CaCl2 Brine. J. Colloid Interface Sci. 2013, 398, 217. (14) Bagaria, H. G.; Xue, Z.; Neilson, B. M.; Worthen, A. J.; Yoon, K. Y.; Nayak, S.; Cheng, V.; Lee, J. H.; Bielawski, C. W.; Johnston, K. P. Iron oxide nanoparticles grafted with sulfonated copolymers are stable in concentrated brine at elevated temperatures and weakly adsorb on silica. ACS Appl. Mater. Interfaces 2013, 5, 3329−39. (15) Bagaria, H. G.; Yoon, K. Y.; Neilson, B. M.; Cheng, V.; Lee, J. H.; Worthen, A. J.; Xue, Z.; Huh, C.; Bryant, S. L.; Bielawski, C. W. Stabilization of Iron Oxide Nanoparticles in High Sodium and Calcium Brine at High Temperatures with Adsorbed Sulfonated Copolymers. Langmuir 2013, 29, 3195−3206. (16) Foster, E. L.; Xue, Z.; Roach, C. M.; Larsen, E. S.; Bielawski, C. W.; Johnston, K. P. Iron Oxide Nanoparticles Grafted with Sulfonated and Zwitterionic Polymers: High Stability and Low Adsorption in Extreme Aqueous Environments. ACS Macro Lett. 2014, 3, 867−871. (17) Kotsmar, C.; Yoon, K. Y.; Yu, H.; Ryoo, S. Y.; Barth, J.; Shao, S.; Prodanović, M. a.; Milner, T. E.; Bryant, S. L.; Huh, C. Stable citratecoated iron oxide superparamagnetic nanoclusters at high salinity. Ind. Eng. Chem. Res. 2010, 49, 12435−12443. (18) Ryoo, S.; Rahmani, A. R.; Yoon, K. Y.; Prodanović, M.; Kotsmar, C.; Milner, T. E.; Johnston, K. P.; Bryant, S. L.; Huh, C. Theoretical and experimental investigation of the motion of multiphase fluids containing paramagnetic nanoparticles in porous media. J. Pet. Sci. Eng. 2012, 81, 129−144. (19) Xue, Z.; Foster, E.; Wang, Y.; Nayak, S.; Cheng, V.; Ngo, V. W.; Pennell, K. D.; Bielawski, C. W.; Johnston, K. P. Effect of Grafted J


Article

Industrial & Engineering Chemistry Research (39) Hsieh, H.; Moradi-Araghi, A.; Stahl, G.; Westerman, I. In Watersoluble polymers for hostile environment enhanced oil recovery applications; Makromolekulare Chemie. Macromolecular Symposia; Wiley Online Library, 1992; pp 121−135. (40) McCormick, C. L.; Elliott, D. Water-soluble copolymers. 14. Potentiometric and turbidimetric studies of water-soluble copolymers of acrylamide: comparison of carboxylated and sulfonated copolymers. Macromolecules 1986, 19, 542−547. (41) Li, G.; Xue, H.; Cheng, G.; Chen, S.; Zhang, F.; Jiang, S. Ultralow Fouling Zwitterionic Polymers Grafted from Surfaces Covered with an Initiator via an Adhesive Mussel Mimetic Linkage. J. Phys. Chem. B 2008, 112, 15269−15274. (42) Ranka, M.; Brown, P.; Hatton, T. A. Responsive Stabilization of Nanoparticles for Extreme Salinity and High-Temperature Reservoir Applications. ACS Appl. Mater. Interfaces 2015, 7, 19651−19658. (43) Č ampelj, S.; Makovec, D.; Drofenik, M. Functionalization of magnetic nanoparticles with 3-aminopropyl silane. J. Magn. Magn. Mater. 2009, 321, 1346−1350. (44) Kralj, S.; Drofenik, M.; Makovec, D. Controlled surface functionalization of silica-coated magnetic nanoparticles with terminal amino and carboxyl groups. J. Nanopart. Res. 2011, 13, 2829−2841. (45) Kralj, S.; Makovec, D.; Č ampelj, S.; Drofenik, M. Producing ultra-thin silica coatings on iron-oxide nanoparticles to improve their surface reactivity. J. Magn. Magn. Mater. 2010, 322, 1847−1853. (46) Azam, M.; Tan, I.; Ismail, L.; Mushtaq, M.; Nadeem, M.; Sagir, M. Static adsorption of anionic surfactant onto crushed Berea sandstone. J. Pet. Explor. Prod. Technol. 2013, 3, 195−201. (47) Jursic, B. S.; Zdravkovski, Z. A Simple Preparation of Amides from Acids and Amines by Heating of Their Mixture. Synth. Commun. 1993, 23, 2761−2770. (48) Lanigan, R. M.; Sheppard, T. D. Recent Developments in Amide Synthesis: Direct Amidation of Carboxylic Acids and Transamidation Reactions. Eur. J. Org. Chem. 2013, 2013, 7453−7465. (49) Shock, E. L. Stability of peptides in high-temperature aqueous solutions. Geochim. Cosmochim. Acta 1992, 56, 3481−3491. (50) Campelj, S.; Makovec, D.; Drofenik, M. Preparation and properties of water-based magnetic fluids. J. Phys.: Condens. Matter 2008, 20, 204101. (51) Iler, R. K. The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica. WileyInterscience: New York, 1979. (52) Böhme, U.; Hänel, B.; Scheler, U. Influence of the Counterions on the Behaviour of Polyelectrolytes. In Trends in Colloid and Interface Science XXIV; Starov, V., Procházka, K., Eds.; Springer: Berlin Heidelberg, 2011; Vol. 138, pp 45−48. (53) Radeva, T. Physical chemistry of polyelectrolytes; CRC Press, 2001. (54) Ko, C.-H.; Elimelech, M. The “Shadow Effect” in Colloid Transport and Deposition Dynamics in Granular Porous Media: Measurements and Mechanisms. Environ. Sci. Technol. 2000, 34, 3681−3689. (55) Han, Z.; Zhang, F.; Lin, D.; Xing, B. Clay Minerals Affect the Stability of Surfactant-Facilitated Carbon Nanotube Suspensions. Environ. Sci. Technol. 2008, 42, 6869−6875.

K


Low Adsorption of Magnetite Nanoparticles with Uniform

Recommend Documents