Article pubs.acs.org/Langmuir
Metal-Foam-Based Ultrafast Electronucleation of Hydrates at Low Voltages Arjang Shahriari, Palash V. Acharya, Katherine Carpenter, and Vaibhav Bahadur* Texas Materials Institute & Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States S Supporting Information *
ABSTRACT: The induction time for the nucleation of hydrates can be significantly reduced by electronucleation, which consists of applying an electrical potential across the hydrate precursor solution. This study reveals that open-cell aluminum foam electrodes can reduce the electronucleation induction time by 150× when compared to nonfoam electrodes. Experiments with tetrahydrofuran hydrates show that aluminum foam electrodes trigger near-instantaneous nucleation (in only tens of seconds) at low voltages. Furthermore, this study suggests that two distinct interfacial mechanisms influence electronucleation, namely, electrolytic bubble generation and the formation of metal ion complex-based coordination compounds. These mechanisms (which depend on the electrode material and polarity) affect the induction time to vastly different extents. Coordination compound formation (verified via detection of metal ions in solution) exerts a much greater influence on electronucleation than the mechanistic effects associated with bubble generation. This work uncovers the benefits of using foams to promote electronucleation and shows that foams lead to more deterministic (as opposed to stochastic) nucleation when compared with nonfoam electrodes.
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INTRODUCTION Clathrate hydrates1,2 are water-based crystalline solids consisting of a guest molecule (methane, carbon dioxide, tetrahydrofuran, cyclopentane, etc.) trapped in a lattice of water molecules. Hydrate formation in laboratory conditions can be challenging due to the high pressure and low temperature environment required for synthesis. Another significant challenge underlying hydrate formation is the significant induction time before hydrates nucleate. Induction times can range from hours to days, especially in quiescent systems.3 This poses challenges for the development of applications,4,5 which require rapid formation of hydrates (e.g., desalination by forming a hydrate). The use of surfactants and mechanical agitation of the hydrate precursor solution are two common techniques to promote the nucleation of hydrates.6−9 However, both these techniques have limitations related to environmental issues, performance, and cost. Recently, the present group demonstrated the concept of electronucleation for rapid and controlled nucleation of hydrates.10 Experiments with tetrahydrofuran hydrate formation demonstrated a reduction in induction times by applying electrical potentials using cylindrical stainless steel (inert) electrodes across the precursor solution. The voltage-dependent induction time was reduced10 to a few minutes at high voltages (100 V). The present study reveals that the use of open-cell aluminum foam as the electronucleation electrode can reduce the induction time by more than 150× when compared to nonfoam (bare stainless steel) electrodes. In the past, the use of aluminum foams for hydrate formation has been suggested11,12 to enable rapid removal of the heat of hydrate © XXXX American Chemical Society
formation (due to the high thermal conductivity of the foam). This study shows that aluminum foams also accelerate the nucleation kinetics by 2 orders of magnitude as compared to inert, bare electrodes. This enhancement can be attributed to two distinct interfacial phenomena (electrolytic bubble generation, and formation of aluminum-based metal-ion complexes) at the electrode−liquid interface. Both these phenomena are strongly dependent on the material and polarity of the electrodes. A key f inding is that aluminum-foam-based electrodes trigger nearinstantaneous nucleation when used as the anode. Induction times of O(10 s) were observed at voltages as low as 20 V, which is a significant advancement from our previous findings10 (induction times of a few minutes at much higher voltages of 100 V). Interestingly, the use of foams also reduces scatter in the otherwise widespread nucleation time measurements, thus leading to a more deterministic nucleation when compared to nonfoam-based electronucleation. Overall, this study identif ies the electrochemistry-based mechanisms and uncovers the benef its of foam-based electronucleation.
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EXPERIMENTAL PROCEDURES
Electronucleation of tetrahydrofuran (THF) hydrates was studied in this work. It is noted that THF hydrates are commonly used as a model for methane hydrates,13−17 which are challenging to study since they require high-pressure conditions (>75 atm) to form. THF (C4H8O) forms structure II hydrates,18 from a THF−water mixture (stoichiometric molar ratio of THF:water is 1:17) at atmospheric pressure, and below 4.4 °C. In this work, there was an excess of THF Received: March 16, 2017 Revised: May 1, 2017 Published: May 22, 2017 A
DOI: 10.1021/acs.langmuir.7b00913 Langmuir XXXX, XXX, XXX−XXX
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conductivity of the solution (Figure 1c). It is noted that these methods have also been used by other researchers to infer the nucleation of THF hydrates18 and ice.19,21 Importantly, the magnitude of Joule heating is very low, and its influence is neglected. The maximum current in all these experiments was 86, 211, and 803 μA at 5, 10, and 20 V, respectively; this translates to less than 16 mW (at 20 V) of heat generation. Also, the temperature increase to 4 °C indicates hydrate formation and confirms that ice is not being formed (in which case the temperature spike would have been to 0 °C).
to prevent ice formation, and the ratio of THF to water was selected as 1:15. Figures 1a,b show a schematic depiction of the experimental setup. All experiments were conducted in a water/glycol-based cold bath.
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RESULTS Figure 2 shows the measured induction times as a function of the voltage for the baseline (nonfoam) case and the cases with
Figure 1. (a) Experimental setup, (b) stainless steel and aluminum foam electrodes inside the tube (right image shows the foam electrode), and (c) detection of nucleation by tracking the thermal signature and current flow in the hydrate precursor solution.
Figure 2. Voltage-dependent electronucleation induction times for the baseline (nonfoam, inert electrode) case and the cases where the aluminum foam was the cathode and anode. The numbers next to the data points indicate the average and standard deviation (in parentheses) in the measurements.
THF electronucleation was studied in glass tubes (inner diameter: 14 mm; length: 95 mm) fitted with a rubber stopper. The stopper also held the two electrodes and a thermocouple (Figure 1b). A T-type ungrounded thermocouple was used to detect electronucleation; the use of this type of thermocouple prevents the applied voltage from influencing temperature measurements. Open-cell aluminum foams with a porosity of 92% and a surface area-to-volume of 1720 m2/m3 were used in this study. A 6 mm × 8 mm × 50 mm sized foam plug was used as one of the electrodes as shown in Figure 1b. A stainless steel electrode (diameter: 1.6 mm) was used as the other electrode and can be considered inert when compared to the more electrochemically active aluminum electrode. The spacing between the electrodes and the thermocouple was approximately 5 mm. The electrodes were connected to a dc power supply. Additionally, baseline electronucleation experiments were conducted with two stainless steel electrodes, i.e., without any foam electrode. A single tube was used in every experimental run to avoid the possibility of nucleation in one tube influencing any other surrounding tubes in the cooling bath. Details of the cleaning steps prior to the experiments are provided in the Supporting Information. The tube contained 8.77 mL of THF hydrate precursor solution (water−THF mixture), which was agitated (to ensure complete mixing) and degassed to remove air bubbles (which can act as potential nucleation sites). The tube was then immersed in the cooling bath set at 5 °C. After the tube reached 5 °C, the bath temperature was lowered to −5 °C. Once the water−THF mixture supercooled to a steady temperature of −5 °C, an electrical voltage (5, 10, or 20 V dc) was applied. The induction time was measured starting from this point onward to the time when hydrate nucleation was detected. Electronucleation was detected by tracking the thermal signature of the solution, as detailed in our previous study.10 The heat released at the onset of nucleation (recalescence) instantaneously raises the temperature of the entire solution to ∼4 °C (Figure 1c). This also confirms that a THF hydrate is being formed and not ice, which would have otherwise led to a temperature spike to 0 °C. The second indicator10 of hydrate nucleation is a sudden decrease in the electrical
the aluminum foam electrode acting as the cathode and anode. Each data point is the average of more than five measurements. The baseline case (with stainless steel electrodes) shows voltage-dependent reduction in the induction time, in line with our previous study.10 The use of aluminum foam as the cathode (negative polarity electrode) significantly reduces the induction time, as evident from the 10× decrease at 20 V. This clearly highlights the benefits of foams, with the high surface area associated with the porous foams clearly aiding nucleation. In this work, the porosity of the aluminum foam resulted in a 17× enhancement in the surface area compared to the bare electrode. The induction time is further reduced dramatically by switching the polarity to make the foam electrode as the anode (positive polarity electrode). Figure 2 shows that the induction time is reduced by ∼40× (at 5 V) when compared to the same foam used as the cathode. The average induction times at 10 and 20 V, with the foam anode were only 43 and 20 s, respectively, which reflects a substantial acceleration in nucleation kinetics when compared with our previous work10 (nucleation time of 7 min at 100 V). Positively biased aluminum electrode can thus enable instantaneous nucleation, which can benefit the development of applications which need “hydrates on demand”. It is noted that no nucleation was observed in any experiment at 0 V even after 12 h. Overall, these results suggest that aluminum foams with the appropriate polarity can enable a 2 orders of magnitude reduction in induction time as compared to nonfoam inert electrodes. As an illustration, the induction time decreases by 150× at 5 V, when an inert stainless steel electrode is replaced with an aluminum foam electrode as the anode. An interesting observation from Figure 2 is that the spread in the measurements is significantly reduced in the foam B
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of the foam, and the presence of surface irregularities, provides a large number of nucleation sites for gas bubble generation, which explains the faster electronucleation as compared to the nonfoam electrode. At the anode (stainless steel) the hydroxyl ions are oxidized to generate oxygen (4OH− → O2↑ + 2H2O + 4e−). Furthermore, stoichiometric calculations indicate that less than 0.001% of the water is electrolyzed; this will not change the composition of the hydrate-forming mixture. Polarity-dependent nucleation can be explained by a different reaction occurring at the foam, when it is the anode. In this case, the oxidation of aluminum is favored22 over the oxidation of hydroxyl ions due to the high ionization tendency of aluminum (Al → Al3+ + 3e−). Al3+ ions therefore enter the solution and are surrounded by water molecules to form a hydroxo−aquo−aluminum coordination compound [Al(H2O)6]3+. Furthermore, OH− ions form bridges between the coordination compounds, leading to the synthesis of an octahedral polynuclear complex22 (Figure 3b). We hypothesize (similar to ref 22) that the resemblance of this structure to the lattice structure of the hydrate promotes hydrate nucleation. The bubble formation hypothesis was validated by high magnification visualization of bubble activity in the foam electrode during electronucleation. Figure 4 shows the
experiments, especially at higher voltages. The standard deviations in the induction time measurements for the nonfoam experiments is ∼60% of the mean value, for experiments at 10 and 20 V. The corresponding standard deviations with the use of foam electrodes (either as cathode and anode) are reduced to 13−25% of the mean value. This suggests that the use of foams can suppress the inherent stochastic nature of nucleation and transform nucleation to a more deterministic phenomenon. It is noted that data used in Figure 2 are tabulated in the Supporting Information. The influence of polarity is very remarkable, with the induction time reduced by factors of 40, 14, and 7 at 5, 10, and 20 V, respectively, by switching the foam polarity from negative to positive. This also suggests that multiple physical phenomena are likely at play. One electronucleation mechanism briefly mentioned in our previous study10 was bubble generation at the electrodes, resulting from hydrolysis reactions. These bubbles can act as nucleation sites. Furthermore, the convection associated with bubble growth and detachment can assist in triggering nucleation. Bubble generation on the foam electrode was indeed observed as detailed below. However, this mechanism alone cannot explain the polarity-dependent induction time. This study identifies and proves the existence of another mechanism, which affects nucleation more profoundly than bubble-related effects and is polarity dependent. This mechanism can be understood by examining the results of Hozumi et al.22 and Shichiri and Nagata,23 who conducted experimental studies to determine the influence of electrode material on the electric-field-induced freezing of pure water. Freezing was enhanced22 with aluminum electrodes as compared to more inert materials (platinum, gold). It was hypothesized22 that this enhancement is due to the formation of aluminum-based coordination compounds at the electrodes, the structure of which resembles the crystal structure of ice.22 A few other studies24,25 have also hypothesized the role of such metal-ion complexes in accelerating nucleation in water. The existence of a similar mechanism is analyzed in this work to explain the accelerated hydrate formation with aluminum foam as the anode. Both the above mechanisms (bubble generation, coordination compound formation) can be further understood by considering the chemical reactions taking place at the electrodes. For the case of the foam electrode as the cathode, water is reduced to hydroxyl ions and hydrogen gas is generated (Figure 3a), which accounts for the bubbles (4H2O + 4e− → 4OH− + 2H2↑) observed at the cathode. The high surface area
Figure 4. Aluminum foams acting as the (a) cathode, with leads to significant bubble generation, and (b) anode, where no bubble generation is observed.
aluminum foam electrode as the cathode and the anode in separate experiments. A video depicting the bubble activity is included in the Supporting Information. When the foam is the cathode (Figure 4a), significant bubble generation and departures are seen on the foam surface, as depicted in Figure 4a and the associated video. Mechanistic effects associated with bubble growth and detachment such as contact line motion, localized fluid convection, etc., can provide the activation energy to trigger nucleation. In contrast, there is negligible bubble generation observed when the foam is the anode (Figure 4b); this is clearly evident in the video (Supporting Information) accompanying Figure 4b. This indicates that an alternative electrochemical reaction (oxidation of aluminum to form coordination compounds) occurs at the foam anode and is responsible for nucleation promotion. While it is challenging to experimentally detect the formation of coordination compounds at the interface, this work successfully detected the presence of Al3+ ions in solution, which are the precursors to the Al-based coordination compounds. The current−time plot (Figure 1c) can be used to estimate the concentration of Al3+ ions in the present experiments by estimating the total charge transfer in the solution until the onset of nucleation. These calculations indicate the concentrations of Al3+ ions will be O(10−6 mol/L) at the onset of nucleation. The [Al(H2O)6]3+ concentrations from such low concentrations of Al3+ ions could be challenging to detect with conventional spectroscopic studies26−28 and was not attempted.
Figure 3. Schematic depiction of mechanisms underlying electronucleation. (a) Bubble-related effects when aluminum foam is the cathode. (b) Coordination compound formation-based nucleation when aluminum foam is the anode. C
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Higher thermal conductivity aids removal of the heat generated during hydrate formation. In this work, the decreased time for hydrate formation was quantified by measuring the phase change propagation time, which is the time taken since the onset of nucleation to convert the entire tube to a hydrate plug. This time can be inferred from the temperature−time curve in Figure 1c and is summarized for various cases in Table 1. First, it is seen that the propagation time for the −5 °C
In this work, a colorimetric indicator reaction was used to prove that Al3+ ions enter the solution when the foam is the anode. Subsequent solvation of these ions leads to the formation of [Al(H2O)6]3+ based coordination compounds. Pyrocatechol Violet (PV) is commonly used as a complexometric indicator dye to detect the presence of group III cations.29−31 As it chelates metals it forms a blue-violet-colored coordination compound. In this work, PV was used to detect Al3+ ions in solution to partly validate our hypothesis that aluminum ions leave the foam electrode (when it is the anode) to form coordination compounds, which accelerates the nucleation of hydrates. Figure 5 shows the aluminum foam electrode as the cathode and the anode in separate electronucleation experiments where
Table 1. Time Taken for Hydrates To Form in the Entire Tube (in minutes) with foam electrode
without foam electrode
−5 −10
5.1 1.9
7.5 4.8
experiments is reduced from 7.5 min in the absence of foams (nonfoam electrodes used) to 5.1 min with the foam (average of five experiments each with the foam as the cathode and anode). Importantly, it was seen that the foam polarity and the magnitude of the applied voltage did not measurably influence the propagation time. Repeating the experiments at −10 °C shows that the propagation time is reduced from 4.8 to 1.9 min upon using foams. The −10 °C experiment was carried out in the absence of voltages, since the additional supercooling ensures nucleation with low induction times. It is noted that that hydrate formation rates are determined by all the pathways available to reject the generated heat, and the present results apply only to this particular geometry. Nevertheless, it is clear that the heat transfer benefits and the electronucleation promotion associated with foams will assist in the synthesis of hydrates.
Figure 5. Bubble generation (a) is seen with the foam electrode as the cathode. When the foam electrode is the anode (b), aluminum ions in solution are detected via a color change (due to chelation), which indicates that aluminum-based coordination compounds are formed.
0.2 mM PV is dissolved in the solution. When the foam is the cathode (Figure 5a), no color change is observed; instead, there is bubble formation, which will also accelerate nucleation. However, when the foam is the anode (Figure 5b), the color of the solution changes to violet-blue as the PV chelates aluminum ions. This color change starts at the foam and can be seen clearly in a video available in the Supporting Information. The above experiments offer compelling evidence to attribute accelerated hydrate nucleation to the formation of aluminum-based coordination compound in the absence of bubbles. Furthermore, induction time measurements indicate that the coordination compound formation mechanism influences nucleation more strongly than bubble-related mechanistic effects.
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CONCLUSIONS In conclusion, this study reveals that positively biased aluminum foams can enable near-instantaneous low-voltage electronucleation. This study has shown up to a 150× decrease in induction time with foams as compared to nonfoam electrode electronucleation. Bubble-based mechanistic effects and electrochemistry-based mechanisms influence the nucleation kinetics. While this study utilized THF hydrates, similar benefits can be expected for other hydrate systems such as cyclopentane (hydrates form from two immiscible liquids) and methane (hydrates form from a water−gas mixture). This study suggests that foam-based electronucleation can promote rapid hydrate formation without requiring excessive supercooling, which has energy consumption reduction benefits.
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DISCUSSION It is important to note that metal foams also accelerate the rate at which the hydrate formation front progresses, in addition to promoting electronucleation. This can be attributed to the higher thermal conductivity of the aluminum foam−precursor solution network (12 W/(m K)), as opposed to the conductivity of the precursor solution alone (0.6 W/(m K)). The effective thermal conductivity of a metal foam (keffective) in a liquid solution can be estimated as32 ⎡ ksol ksol ⎤ ⎢ 2 + kAl − 2ϕ 1 − kAl ⎥ keffective = kAl ⎢ ⎥ ⎢ 2 + ksol + ϕ 1 − ksol ⎥ kAl kAl ⎦ ⎣ (1)
( (
bath temperature (°C)
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ASSOCIATED CONTENT
* Supporting Information S
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.langmuir.7b00913. Details of the cleaning processes and experimental data on induction times (used in Figure 2) (PDF) Movie (corresponding to Figure 4) showing polaritydependent bubble generation on aluminum foams (AVI) Movie (corresponding to Figure 5) showing evidence of coordination compound formation (via a color change of the precursor solution) when the foam electrode is the anode (AVI)
) )
where kAl is thermal conductivity of aluminum (205 W/(m K)), ksol is thermal conductivity of the THF/water solution (∼0.6 W/(m K)), and ϕ is the porosity of the foam (0.92). D
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(15) Liu, W.; Wang, S.; Yang, M.; Song, Y.; Wang, S.; Zhao, J. Investigation of the Induction Time for THF Hydrate Formation in Porous Media. J. J. Nat. Gas Sci. Eng. 2015, 24, 357−364. (16) Wilson, P. W.; Haymet, A. D. J. Hydrate Formation and ReFormation in Nucleating THF/water Mixtures Show No Evidence to Support a “Memory” Effect. Chem. Eng. J. 2010, 161, 146−150. (17) Tombari, E.; Presto, S.; Salvetti, G.; Johari, G. P. Heat Capacity of Tetrahydrofuran Clathrate Hydrate and of Its Components, and the Clathrate Formation from Supercooled Melt. J. Chem. Phys. 2006, 124, 154507−154506. (18) Dai, S.; Lee, J. Y.; Santamarina, J. C. Hydrate Nucleation in Quiescent and Dynamic Conditions. Fluid Phase Equilib. 2014, 378, 107−112. (19) Bauerecker, S.; Ulbig, P.; Buch, V.; Vrbka, L.; Jungwirth, P. Monitoring Ice Nucleation in Pure and Salty Water via High-Speed Imaging and Computer Simulations. J. Phys. Chem. C 2008, 112, 7631−7636. (20) Alizadeh, A.; Yamada, M.; Li, R.; Shang, W.; Otta, S.; Zhong, S.; Ge, L.; Dhinojwala, A.; Conway, K. R.; Bahadur, V.; et al. Dynamics of Ice Nucleation on Water Repellent Surfaces. Langmuir 2012, 28, 3180−3186. (21) Carpenter, K.; Bahadur, V. Electrofreezing of Water Droplets under Electrowetting Fields. Langmuir 2015, 31, 2243−2248. (22) Hozumi, T.; Saito, A.; Okawa, S.; Watanabe, K. Effects of electrode materials on freezing of supercooled water in electric freeze control. Int. J. Refrig. 2003, 26, 537−542. (23) Shichiri, T.; Nagata, T. Effect of Electric currents on the nucleation of ice crystals in the melt. J. Cryst. Growth 1981, 54, 207− 210. (24) Orlowska, M.; Havet, M.; Le-Bail, A. Controlled ice nucleation under high voltage DC Electrostatic field conditions. Food Res. Int. 2009, 42 (7), 879−884. (25) Wei, S.; Xiaobin, X.; Hong, Z.; Chuanxiang, X. Effect of dipole polarization of water molecules on ice formation under an electrostatic field. Cryobiology 2008, 56, 93−99. (26) Hay, M. B.; Myneni, S. C. Geometric and Electronic Structure of the Aqueous [Al(H2O)6]3+ Complex. J. Phys. Chem. A 2008, 112 (42), 10595−10603. (27) Hay, M. B.; Myneni, S. C. X-ray absorption spectroscopy of aqueous aluminum-organic complexes. J. Phys. Chem. A 2010, 114 (20), 6138−6148. (28) Rudolph, W. W.; Mason, R.; Pye, C. C. Aluminium (III) hydration in aqueous solution. A Raman spectroscopic investigation and an ab initio molecular orbital study of aluminium (III) water clusters. Phys. Chem. Chem. Phys. 2000, 2 (22), 5030−5040. (29) Narin, I.; Tuzen, M.; Soylak, M. Aluminium determination in environmental samples by graphite furnace atomic absorption spectrometry after solid phase extraction on Amberlite XAD-1180/ pyrocatechol violet chelating resin. Talanta 2004, 63, 411−418. (30) Marczenko, Z. Separation and Spectrophotometric Determination of Elements; Wiley: Chichester, 1986. (31) Narin, I.; Soylak, M.; Elci, L.; Dogan, M. Determination of trace metal ions by AAS in natural water samples after preconcentration of pyrocatechol violet complexes on an activated carbon column. Talanta 2000, 52, 1041−1046. (32) Reay, D.; Kew, P. Heat Pipes Theory, Design and Applications, 5th ed.; Butterworth-Heinemann: Oxford, UK, 2006.
AUTHOR INFORMATION
Corresponding Author
*(V.B.) E-mail
[email protected]. ORCID
Vaibhav Bahadur: 0000-0001-7442-7769 Author Contributions
A.S., P.V.A., and K.C. contributed equally to this work. K.C. and V.B. conceptualized this work. A.S., P.V.A., and K.C. conducted experiments. All authors were involved in manuscript preparation. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS The authors acknowledge American Chemical Society Petroleum Research Fund PRF 54706- DNI5, Welch Foundation Grant # F-1837, and National Science Foundation grants CBET- 1605789 and CBET-1653412 for supporting this work.
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REFERENCES
(1) Eslamimanesh, A.; Mohammadi, A. H.; Richon, D.; Naidoo, P.; Ramjugernath, D. Application of Gas Hydrate Formation in Separation Processes: A Review of Experimental Studies. J. Chem. Thermodyn. 2012, 46, 62−71. (2) Veluswamy, H. P.; Kumar, R.; Linga, P. Hydrogen Storage in Clathrate Hydrates: Current State of the Art and Future Directions. Appl. Energy 2014, 122, 112−132. (3) Sloan, E. D.; Koh, C. A. Clathrate Hydrates of Natural Gases, 3rd ed.; CRC Press: 2008; p 119. (4) Sum, A. K.; Koh, C. A.; Sloan, E. D. Clathrate Hydrates: From Laboratory Science to Engineering Practice. Ind. Eng. Chem. Res. 2009, 48 (16), 7457−7465. (5) Chatti, I.; Delahaye, A.; Fournaison, L.; Petitet, J. P. Benefits and Drawbacks of Clathrate Hydrates: A Review of Their Areas of Interest. Energy Convers. Manage. 2005, 46, 1333−1343. (6) Zhong, Y.; Rogers, R. E. Surfactant Effects on Gas Hydrate Formation. Chem. Eng. Sci. 2000, 55, 4175−4187. (7) Zhang, J. S.; Lee, S.; Lee, J. W. Kinetics of Methane Hydrate Formation from SDS Solution. Ind. Eng. Chem. Res. 2007, 46, 6353− 6359. (8) Ganji, H.; Manteghian, M.; Sadaghiani zadeh, K.; Omidkhah, M. R.; Rahimi Mofrad, H. Effect of Different Surfactants on Methane Hydrate Formation Rate, Stability and Storage Capacity. Fuel 2007, 86, 434−441. (9) Ando, N.; Kuwabara, Y.; Mori, Y. H. Surfactant Effects on Hydrate Formation in an Unstirred Gas/liquid System: An Experimental Study Using Methane and Micelle-Forming Surfactants. Chem. Eng. Sci. 2012, 73, 79−85. (10) Carpenter, K.; Bahadur, V. Electronucleation for rapid and controlled formation of hydrates. J. Phys. Chem. Lett. 2016, 7 (13), 2465−2469. (11) Yang, L.; Fan, S. S.; Wang, Y. H.; Lang, X. M.; Xie, D. L. Accelerated formation of methane hydrate in aluminum foam. Ind. Eng. Chem. Res. 2011, 50, 11563−11569. (12) Fan, S.; Yang, L.; Lang, X.; Wang, Y.; Xie, D. Kinetics and thermal analysis of methane hydrate formation in aluminum foam,. Chem. Eng. Sci. 2012, 82, 185−193. (13) Wilson, P. W.; Lester, D.; Haymet, a. D. J. Heterogeneous Nucleation of Clathrates from Supercooled Tetrahydrofuran (THF)/ water Mixtures, and the Effect of an Added Catalyst. Chem. Eng. Sci. 2005, 60, 2937−2941. (14) Zhang, J. S.; Lo, C.; Somasundaran, P.; Lu, S.; Couzis, A.; Lee, J. W. Adsorption of Sodium Dodecyl Sulfate at THF Hydrate/Liquid Interface. J. Phys. Chem. C 2008, 112, 12381−12385. E
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