Aqueous Brine Research Articles

Synthesis and Characterization of Magnetic Nanoparticles and its Study to Displace Oil from a Hele-Shaw Cell

Introduction:: Oil spill incidents caused by human activities can cause major habitat damage and pose serious threats to all living organisms living on and within sources of water and soil. Finding a solution for oil spills is necessary to protect ecosystems, the environment, and health. Nanotechnology seems to be an interesting tool in many applications, such as soil and water remediation and oil recovery. Nanoparticles are a good alternative since they are not as expensive as chemicals used to remove oil. Objective:: The prime purpose of this research work was the comparison of the additional displacement of sunflower oil from a single fracture using ferrofluids prepared with bare and novel covalent functionalized magnetic nanoparticles. Experiences were performed at constant nanoparticle concentration and variable flow rate and at constant flow rate and variable nanoparticle concentration. The novel ferrofluid stability and its recovery properties related to a low-cost process were explored. Methods:: Tests were carried out by image analysis. Stable ferrofluids were prepared using magnetic nanoparticles (MNPs) and novel covalent functionalized magnetic nanoparticles (MSMs). Their ability to displace the residual oil in a single fracture model previously invaded by an aqueous brine solution was tested. A flow channel of a single fracture by a typical transparent Hele-Shaw cell with 12% of its area covered by a random distribution of obstacles was modeled. Oil recovery was performed at three different flow rates: 0.36, 1.80, and 3.60 mL min-1, using relatively low ferrofluid concentrations (0.0125 wt%). Oil recovery was also carried out with MSM ferrofluid at a constant flow rate of 1.80 and 3.60 mL min-1 at different nanoparticle concentrations (0.00625, 0.0125, and 0.025 wt%). Results:: Ferrofluids prepared with MSMs were more effective for oil recovery than those prepared with bare nanoparticles due to their surfactant behavior for all flows studied here. A 7.86% extra percentage of oil was removed after brine flooding. Oil recovery using MSM ferrofluid at a constant flow rate of 1.80 and 3.60 mL min-1 increased linearly with nanoparticle concentration. Magnetic nanoparticles can be efficiently recovered and reused in at least three oil displacements for the fracture model used as covalent functionalization promotes ferrofluids' stability. Conclusion:: The characteristics of the MSM amphiphilic novel coating cause the nanoparticles to be attracted to both water and oil, enhancing oil displacement. These results indicate that this novel material, whose structure stability is related to the covalent bonding of organic coating, can be considered for remediation and oil recovery in fractured media

Overcoming passivation through improved mass transport in dense ionic fluids.

Deep Eutectic Solvents (DESs) have recently been shown to be part of a dense ionic fluid continuum between ionic liquids and concentrated aqueous brines. Charge transport was shown to be governed by fluidity, with no discontinuity between molar conductivity and fluidity irrespective of cation, charge density or ionic radius. By adjusting the activity of water and chloride ions, mass transport, speciation and reactivity can be altered. It has been shown that while brines provide a high chloride content at a lower viscosity than DESs, unlike DESs, brines are unable to prevent metal passivation due to their high water content. This results in the possibility to impart a level of selectivity towards metal dissolution (or passivation) when processing mixed metal materials. Forced convection can be used to avoid the issue of slow mass transport in viscous media, and the use of jets or targeted ultrasound are effective methods for overcoming this issue. High-powered ultrasound was applied to copper, cobalt, and aluminium electrodes undergoing anodic dissolution, and linear sweep voltammetry showed a linear current-voltage response at potentials anodic of the oxidation potential under sonication, with total charge passed being 5 to 134 times greater than under silent conditions. Application of ultrasound to silver and nickel electrodes displayed an initial linear current-voltage response, but the increased water content of the brines resulted in passivation. Mass transport throughout the bulk solution is governed by the forced convection imparted by the ultrasound and ionic species must only migrate across the electrical double layer. It is shown that the anodic dissolution of a range of metals classically expected to passivate, e.g. aluminium, can be significantly accelerated under insonation conditions.

Effect of Anionic, Cationic, and Non-Ionic Surfactants on the Structural Stability and Morphology of Perfluorinated Sulfonic Acid Membranes

Redox flow batteries (RFB) are a critical technology for stationary grid-scale energy storage, with potential usage with intermittent power sources, such as wind and solar. RFBs are attractive for long-duration energy storage because the anolyte and catholyte are stored separately external to the electrochemical reactor, which allows the RFBs to be modular and stationary. Separating the electrolytes and the electrochemical cell decouples energy and power densities, unlike batteries that store charge in the solid-state, such as Li-ion, Pb-acid, or Ni-Cd. A standard RFB chemistry is the all-vanadium redox flow battery (VRFB), which utilizes the four oxidation states of vanadium, with V2+, V3+, V4+, and V5+. Recently, new electrolytes are being studied in energy storage devices. Such as the first redox flow battery to utilize microemulsions as the electrolyte.Microemulsions are a breakthrough electrolyte for energy storage (BEES) that is emerging as an alternative to traditional RFB electrolytes because they produce thermodynamically stable, homogeneous solutions of polar and non-polar molecules. The stabilization of oil and water solutions allows microemulsion electrolytes to accommodate organic redox species with fast electron transfer rates that are not soluble in the aqueous phase while still offering the high conductivity of an aqueous salt electrolyte. Microemulsions consist of two immiscible phases stabilized by a surfactant, a non-polar "oil" phase, solubilizing the redox material, and the polar phase, which typically consists of an aqueous brine that provides charge balance and conductivity. Additionally, if the redox molecule was a non-polar liquid, it could serve as the entire oil phase, maximizing the energy density. An attractive property of a microemulsion electrolyte is that each component can be environmentally and biologically safe. For example, the aqueous phase only contains salt and water, and surfactants are found in many household, personal, and food products. Furthermore, some redox materials investigated in our lab are vitamins such as menadione (vitamin K3) and tocopherol (vitamin E).This talk describes the structural, mechanical, and morphological studies of surfactants' effects on perfluorinated sulfonic acid membranes. Small-angle X-ray scattering monitored the morphological changes as a function of surfactant concentration and soaking time, revealing how the surfactant penetrated and altered the polymer membrane. FTIR and NMR spectroscopy are also employed, providing insight into any polymer membrane degradation or dissolution. We demonstrate that surfactant choice is not only crucial to the stability of the microemulsion used as an electrolyte but can ultimately destroy the separator in a redox flow battery.This work was supported as part of the Breakthrough Electrolytes for Energy Storage and Systems (BEES2), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409.

(Invited) Sustainable Recycling of Metals from Solar Cells

The share of solar energy is increasing worldwide, leading to a widespread use of solar panels. Knowing that the 80 Mt of waste solar panels will be produced by 2050, sustainable processes must be designed in order to deal with the inevitable increase of waste solar cells in the coming years.The main advantage associated with recycling is to avoid the inevitable dispersion of hazardous materials in the environment occurring when the solar cells are landfilled. It also reduces the need for primary mineral resources and may reduce the supply risk for important components like silicon wafers, for which the production is concentrated in a few countries. The recycling process applied plays a major role to allow reducing the carbon footprint of solar cells, advocating in favour of sustainable practices for solar cells recycling.Mono-crystalline solar cells representing 90% of the market, it is therefore this kind of solar cells that are more likely to reach their end-of-life soon. Mono-crystalline solar cells are made of an aluminium frame surrounding the solar module. Underneath a glass layer, layers of ethylene vinyl acetate (EVA) encapsulate the solar cell. The solar cell in itself is made of a silicon wafer with aluminium and silver electrode as well as a silicon nitride anti-reflective coating. Recycling of the metals, particularly silver, is the main economic driver for solar cells recycling.Recycling mono-crystalline solar cells involves a mechanical removal of the aluminium frame and the junction box prior to removal of the glass and EVA layers. Different process were evaluated to get rid of EVA. Solvent-assisted dissolution allowed EVA dissolution but it requires the use of harmful solvents and often leads to breakage of the solar cell. Pyrolysis allows to recover the wafer intact while removing the glass and polymers layers. Provided that the thermal treatment is applied under an inert atmosphere, EVA decomposition leads to relatively non-toxic chemicals such as acetic acid. Recent developments include laser assisted would lead to efficient and straightforward removal of EVA.The removal of metals from the solar cells involves the use of harsh chemicals such as hydrofluoric acid for the removal of silicon nitride, nitric acid to solubilise silver and sodium hydroxide for the dissolution of aluminium. Recently, the use of aqueous brines was introduced to recover silver and aluminium from solar cells. A green and re-usable oxidising agent such as iron(III) chloride can be used to oxidise and dissolve silver, as evidenced in Figure 1, which shows a solar cells before (up) and after (down) etching, revealing the removal of the white silver lines.Using water as a solvent, silver dissolution is impossible due to the low chloride content. By increasing the chloride content, oxidation of silver and its dissolution becomes possible due to the formation of iron-chloride and silver-chloride complexes which have a different redox behaviour and a higher solubility. Overall, silver is completely dissolved in about 10 minutes without using any acids or harmful chemical. Silver can be easily recovered by precipitation or cementation, while the oxidising agent can be regenerated using oxygen from air or via electrolytic means. The objective of this presentation is to give an overview of the current recycling options and provide some guidance on the best and more sustainable practices for the complete recycling of solar cells. The choice is guided by techno-economic analysis and life cycle assessment as well as experimental demonstration of the recycling on real waste solar cells. Figure 1

Concentrated Ionic Fluids: Is There a Difference Between Chloride‐Based Brines and Deep Eutectic Solvents?

AbstractDeep Eutectic Solvents (DESs) have been lauded as novel solvents, but is there really a difference between them and concentrated aqueous brines? They provide a method of adjusting the activity of water and chloride ions which can affect mass transport, speciation and reactivity. This study proposes a continuum of properties across concentrated ionic fluids and uses metal processing as an example. Charge transport is shown to be governed by fluidity and there is no discontinuity between molar conductivity and fluidity irrespective of cation, charge density or ionic radius. Diffusion coefficients of iron(III) and copper(II) chloride in numerous concentrated ionic fluids show the same linear correlation between diffusion coefficient and fluidity. These oxidising agents were used to etch copper, silver and nickel and while the etching rate increased with fluidity for copper, etching of silver and nickel only occurred at high chloride and low water activity as passivation occurred when water activity increased. Overall, brines provide a high chloride content at a lower viscosity than DESs, but unlike DESs, brines are unable to prevent passivation due to their high water content. The results show how selective etching of mixed metal waste streams can be achieved by tuning chloride and water activity.

Concentrated Ionic Fluids: Is There a Difference Between Chloride-Based Brines and Deep Eutectic Solvents?

Deep Eutectic Solvents (DESs) have been lauded as novel solvents, but is there really a difference between them and concentrated aqueous brines? They provide a method of adjusting the activity of water and chloride ions which can affect mass transport, speciation and reactivity. This study proposes a continuum of properties across concentrated ionic fluids and uses metal processing as an example. Charge transport is shown to be governed by fluidity and there is no discontinuity between molar conductivity and fluidity irrespective of cation, charge density or ionic radius. Diffusion coefficients of iron(III) and copper(II) chloride in numerous concentrated ionic fluids show the same linear correlation between diffusion coefficient and fluidity. These oxidising agents were used to etch copper, silver and nickel and while the etching rate increased with fluidity for copper, etching of silver and nickel only occurred at high chloride and low water activity as passivation occurred when water activity increased. Overall, brines provide a high chloride content at a lower viscosity than DESs, but unlike DESs, brines are unable to prevent passivation due to their high water content. The results show how selective etching of mixed metal waste streams can be achieved by tuning chloride and water activity.

Catch and release: Gold adsorption and sorbent electrochemical regeneration

Wastewater generated from e-waste leaching is rich in precious metals including gold, silver and platinum. Conventional precipitation and solvent extraction are chemically intensive separations with concerning environmental externalities. Sorbents, in particular carbon nanotubes, have low chemical consumption, and have shown promise for gold adsorption due to their high specific surface area and chemical functionalization potential. However, regenerating sorbents used to adsorb Au is hazardous requiring strong acids. Herein, we delineate the effect of various functional groups on the sidewalls of multiwall carbon nanotubes (MWCNTs) on gold adsorption, and we introduced an acid-free electrochemical technique for Au elution from MWCNTs. Pristine MWCNTs (P-MWCNTs), carboxylic functionalised MWCNTs (COOH-MWCNTs) and amide functionalised MWCNTs (NH2-MWCNTs) were compared for their affinity for Au adsorption from acidic AuCl4−solutions mimicking acidic e-waste leachate. Au adsorption affinity onto MWCNTs followed the order of P-MWCNT > NH2-MWCNT > COOH-MWCNTs. Au elution from Au-saturated MWCNTs was subsequently achieved up to 65%, using acid-free electrochemical desorption in neutral aqueous brine. The Au electro-desorption was shown to have a direct relationship with both the applied current and the mass of the Au adsorbed on the MWCNTs. This study demonstrates enhanced adsorption-based preconcentration of gold and acid-free regeneration of sorbents.

Machine learning-based prediction of CO2 fugacity coefficients: Application to estimation of CO2 solubility in aqueous brines as a function of pressure, temperature, and salinity

Fugacity is a fundamental thermodynamical property of gas and gas mixtures to determine their behavior and dynamics in complex systems. Fugacity can be deduced experimentally from the measurements of volume as a function of pressure at constant temperature or calculated iteratively using analytical equations of states (EOS). Experimental measurement is time-consuming, and analytical models based on EOS are computationally demanding, especially when an approximate but quick estimation is desired. In this work, machine learning (ML) is employed as a viable alternative to analytical EOSs for quick and accurate approximation of CO2 fugacity coefficients. Five different ML algorithms are used to estimate the fugacity coefficients of pure CO2 as a function of pressure (≤ 2000 bar) and temperature (≤ 1000 °C). A combination of experimental and pseudo-experimental (obtained from an analytical EOS) data of CO2 fugacity coefficients is used to train, validate, and test the models. The best results were found using the Extreme Gradient Boosting algorithm, which showed a mean square error of only 0.0002 in the validation data and an average deviation of only 1.3% in the test data (pure prediction). To quantify the effectiveness of the machine learning techniques, results from the best-performing model are compared with two state-of-the-art analytical models. The ML model with significantly less computational complexity showed similar accuracy to the analytical models. The estimated fugacity data are then used to compute the CO2 solubility in aqueous NaCl solution of different concentrations, and a maximum deviation of only 3.2% from the experimental data is observed.

STUDY OF THE VARIABILITY OF RHEOLOGICAL PROPERTIES OF WATER-BASED BIOPOLYMER DISPERSIONS IN DRILLING FLUIDS

Link for citation: Lambin A.I., Averkina E.V. Study of the variability of rheological properties of water-based biopolymer dispersions in drilling fluids. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 91-97. In Rus. The relevance. Water-based biopolymer drilling fluids have become quite widespread in the technology of oil and gas well construction. Much attention is paid to the methods of regulating the physical and mechanical properties of biopolymer systems. In particular, rheological properties of solutions based on xanthan gum are of great practical interest. The effectiveness of the use of polymers is determined by the amount of the main reagent and modifying additives necessary to impart the required properties to the washing liquid. Biopolymer water drilling fluids based on xanthan gum have shown their effectiveness in many regions of the Russian Federation. However, the evaluation of the effectiveness of the solutions is difficult due to the differences in the saleable products of the producing companies in solubility, swelling and composition, which affects the optimized performance of the drilling mud. The main aim: consideration of the differences in aqueous solutions of a number of samples of xanthan gum in terms of power dependence: K-coefficient of consistency and n-degree of deviation from the Newtonian flow regime of the study. Objects: rheology of aqueous solutions of several xanthan samples, both purely aqueous and based on aqueous brines of potassium chloride (KCl) and sodium (NaCl). Methods: instrumental methods for determining the parameters of drilling fluids according to SS 33213-2014; the difference in the parameters of the power rheological dependence was determined by comparing its indicators after measuring the viscosity of solutions on a viscometer with direct indications. Results. The influence of a fixed concentration of NaCl and KCl salts on the considered indicators of the power model is shown. A generalized optimization indicator is proposed for solutions obeying a power-law rheological law. The calculated dependence of the accuracy of approximation of experimental data by a power model, which showed acceptable accuracy, is presented.

Lithium extraction from geothermal brine by granulated HTO titanium-based adsorbent with block-co-polymer poly (ethylene-co-vinyl alcohol) (EVAL) as binder

This study reports a novel highly selective H2TiO3 lithium-ion sieve (LIS) based adsorbent spheres using a block-co-polymer poly (ethylene-co-vinyl alcohol) (EVAL) as the binder for selective extraction of lithium from geothermal brine. Combination of the intrinsic hydrophobic/hydrophilic characters of EVAL satisfies the requirement for adsorbent’s robust mechanical strength and access by aqueous brine. Via adjustment of EVAL concentration and the pore former polyethylene glycol (PEG), porous structure as well as the pore connectivity of the spherical EVAL-HTO were well controlled. The adsorption equilibrium, kinetic characteristics, and cycle performance were investigated using a simulated brine with pH adjustment and the real Tibet geothermal brine. The equilibrium adsorption behavior of Li+ on EVAL-HTO showed Langmuir adsorption and the adsorption kinetics conformed to the pseudo-second-order kinetic model. Kinetic analysis using the intra-particular diffusion model confirmed the open porous structure in EVAL-HTO spheres. In real geothermal brine with no pH adjustment, the EVAL-HTO showed adsorption capacity of 11.8 mg/g, slightly below 13.5 mg/g in the simulated brine at pH = 12, but with more stable cycle performance and cost advantage. Excellent selectivity between Li+ and other contaminant ions, except Ca2+, indicated great potential to obtained purified lithium chemicals. Options to remove Ca2+ ions were proposed for future investigation. The results indicate great promise to use EVAL-HTO in lithium adsorption from real geothermal brine.

Scaling CO2–brine mixing in permeable media via analogue models

Supercritical ${\rm CO}_2$ injection and dissolution into deep brine aquifers allow its sequestration within geological formations. After injection, ${\rm CO}_{2}$ gas phase is buoyancy-driven over the denser aqueous brine, reaching an apparent gravitational stable distribution. However, ${\rm CO}_2$ dissolution in brine propels convection since the mixture is even denser than the underlying brine. This process still needs to be characterised comprehensively. Here, we investigate the irreversible mixing of dissolved ${\rm CO}_2$ in brine through laboratory-scale numerical experiments utilising the Hele-Shaw model (Letelier et al., J. Fluid Mech., vol. 864, 2019, pp. 746–767) and a fully miscible two-fluid system. In this scenario, mixing the less dense fluid – mimicking ${\rm CO}_{2}$ gas phase – with the heavier fluid – representing aqueous brine – catalyses cabbeling-powered convection. Our numerical simulations recover the laboratory results in porous media by Neufeld et al. (Geophys. Res. Lett., vol. 37, issue 22, 2010, L22404) and may explain the scaling law obtained by Backhaus et al. (Phys. Rev. Lett., vol. 106, issue 10, 2011, 104501) in Hele-Shaw cells. More remarkably, we show that the mass flux between the two analogue fluids, characterised by the Sherwood number $ {{Sh}}$ , obeys the universal scaling law $ {{Sh}}\sim {{Ra}}\, \vartheta _{scalar}$ , with $ {{Ra}}$ the Rayleigh number and $\vartheta _{scalar}$ the mean scalar dissipation rate. This paper sheds light on the fluid dynamics and solubility trapping in geological carbon sequestration.

Metal budget and origin of aqueous brines depositing deep-seated Zn-Pb mineralization linked to hydrocarbon reservoirs, North German Basin

The origin, evolution, and interplay of brine and hydrocarbon fluid systems play a crucial role in the formation of deep sediment-hosted base metal ore deposits. Here we investigate ratios of halogens, noble gases, stable C and S isotopes, and metal budgets of aqueous brines, which deposited deep-seated and near-surface hydrothermal Zn-Pb mineralization hosted by Zechstein carbonates in the Lower Saxony Basin (North German Basin), by studies of fluid inclusions in sphalerite and quartz. Major and trace element geochemistry and noble gas isotopic signatures of brine inclusions revealed that the ore-forming fluids were highly reactive and experienced prolonged interactions with host rocks in the constricted, over-pressured metal source regions and consequently evolved from near-neutral, oxidized brines towards more reduced, acidic high-salinity brines. Quartz-hosted halite-saturated fluid inclusions with Th <200°C contain Zn and Pb concentrations up to ca. 9400 μg g-1 and 5200 μg g-1, respectively, and indicate the efficiency of metal scavenging processes. The interactions with Westphalian coals and Corg-rich shales influenced the redox state as well as the trace and critical element budget of the sphalerite-hosted fluid inclusions, with enrichment in Ge, Pd, Sb, Tl, Bi, and Ag. The salinities of metalliferous fluids originated primarily from seawater evaporation, however in addition a significant halite-dissolution component is present in the southern part of the Lower Saxony Basin. High concentrations of radiogenic noble gases and potassium in the sphalerite-hosted fluid inclusions are ascribed to strong interactions with the Paleozoic siliciclastic sedimentary pile and crystalline basement rocks. Reflux of the strongly modified, sulfur-poor, Zn-Pb-bearing acidic brines, proceeded via re-activated structurally controlled pathways into sour gas or gas-saturated brine pools in the Zechstein Ca2 carbonate unit. Here, mixing of the ascending metal-rich brines with H2S derived from thermochemical sulfate reduction (TSR), resulted in the deposition of deep-seated Zn-Pb ores in the Lower Saxony Basin. The overall timing of the Zn-Pb ore formation can be constrained to the Upper Cretaceous basin inversion.

Polymetallic Sulfide–Quartz Vein System in the Koudiat Aïcha Massive Sulfide Deposit, Jebilet Massif, Morocco: Microanalytical and Fluid Inclusion Approaches

The Koudiat Aïcha Zn-Cu-Pb deposit (3–Mt ore @ 3 wt.% Zn, 1 wt.% Pb, 0.6 wt.% Cu) in the Jebilet massif (Morocco) comprises stratabound lenticular orebodies and crosscutting sulfide-bearing quartz ± carbonate veins in the lower Carboniferous Sarhlef volcano sedimentary succession. The veins are characterized by abundant pyrrhotite, sphalerite, subordinate chalcopyrite and galena and rare Ag and Au minerals. The stratabound massive sulfide ores are attributed to a “VMS” type, whereas the origin of the sulfide–quartz ± carbonate veins remains poorly understood. New mineralogical and microanalytical data (SEM, EPMA and LA-ICP-MS) combined with fluid inclusion results point to two-stage vein formation. The early stage involved C–H–O–N Variscan metamorphic fluids which percolated through fractures and shear zones and deposited pyrite at &gt;400 °C, followed by the formation of pyrrhotite and sphalerite (300 ± 20 °C) in quartz veins and in banded and breccia ores. The pyrrhotite–sphalerite mineralization was overprinted by aqueous brines (34 to 38 wt% eq. NaCl + CaCl2) that precipitated carbonate and Cu-Pb sulfides (±Ag-Au) at ~180–210 °C through mixing with low-salinity fluids during tectonic reworking of early-formed structures and in late extension fractures. The latter ore fluids were similar to widspread post-Variscan evaporitic brines that circulated in the Central Jebilet. Overlapping or successive pulses of different ore fluids, i.e., metamorphic fluids and basinal brines, led to metal enrichment in the quartz–carbonate veins compared to the massive sulfide ores. These results underscore that even a single deposit may record several distinct mineralizing styles, such that the ultimate metal endowment may be cumulative over multiple stages.

In Situ Produced Nanoparticles at the Oil-Water Interface for Conformance Control and Enhanced Oil Recovery.

Nanoparticle-assisted enhanced oil recovery (Nano-EOR) has attracted intensive interest in the laboratory as a promising oil recovery technology. However, the nanoparticles' stability and long-distance delivery of nanoparticles (NPs) in large-scale reservoirs are two main challenges. In this work, we developed a novel concept of in situ synthesizing NPs at the oil-water interface inside the reservoir for EOR instead of injecting presynthesized NPs from outside. The pore-scale flooding experiments show that EOR efficiencies for tertiary flooding were 6.3% without reaction (Case 3), 14.6% for slow reaction (Case 1), and 25.4% for relatively quick reaction (Case 4). Examination of the EOR mechanism shows that in situ produced SiO2 NPs in microchannels could alter the substrate wettability toward neutral wetting. Moreover, the produced NPs tended to assemble on the immiscible oil-water interface, forming a barrier toward interface deformation. As the reaction continued, excessive surface-modified NPs could also diffuse into aqueous brine and accumulate as a soft gel in the flowing path swept by brine. Collectively, these processes induced a "shut-off" effect and diverted displacing fluids to unswept areas, which consequently increased the sweep efficiency and improved the oil recovery efficiency. Auxiliary bulk-scale experiments also showed that the reaction-induced nanoparticle synthesis and assembly at an immiscible interface reduced the interfacial tension and generated an elastic oil-water interface.

Microemulsions As Emerging Electrolytes: The Correlation of Structure to Electrochemical Response

Microemulsions are a breakthrough electrolyte for energy storage (BEES) that is emerging as an alternative to traditional RFB electrolytes because of their ability to produce thermodynamically stable, homogeneous solutions of polar and non-polar molecules. The stabilization of oil and water solutions allows microemulsion electrolytes to accommodate organic redox species with fast electron transfer rates that are not soluble in the aqueous phase while still offering the high conductivity of an aqueous salt electrolyte. Microemulsion electrolytes consist of two immiscible phases stabilized by a surfactant, a non-polar phase, solubilizing the redox material—or the redox material can be the entire oil phase—and an aqueous brine phase. Moreover, each component can be environmentally and biologically safe. For example, the aqueous phase only consists of salt and water, the surfactant used in this study, polysorbate-20, is found in many cosmetics and food products, and some of the redox materials investigated in our lab are vitamins such as menadione (vitamin K3) and tocopherol (vitamin E).Microemulsions form many self-assembled bulk nanoscale structures, such as oil-in-water or water-in-oil droplets and bicontinuous. Furthermore, microemulsions exhibit ordering near surfaces that can be different from the bulk structure. Understanding the bulk and surface structures is critical to understanding a material's properties, such as conductivity and diffusion to an electrode surface. Understanding structural changes with composition variation and surface hydrophobicity provide a path to optimizing the balance between acceptable conductivity levels in the electrolyte and the high volume of an oil phase bearing the redox-active species in a µE. This optimization is critical to achieving high-performing electrochemical systems using µEs.This talk describes structural studies of microemulsions prepared from water, toluene, butanol, and polysorbate-20. Small-angle neutron scattering was used to monitor the development of the bicontinuous system as a function of the water-to-surfactant mass ratio on a constant oil-to-surfactant dilution line, revealing how the domain size, correlation length, amphiphilicity factor, and bending moduli change with composition. Kratky and Porod analyses are also employed, providing further structural detail of the scattering domains. We demonstrate that controlling the water-to-surfactant ratio with a constant oil-to-surfactant dilution affects the bicontinuous phase, reveals a sizeable compositional region with structural similarities, and provides insight into the correlation of structure to physical properties. Additionally, neutron reflectivity was used to probe the surface ordering of the microemulsions with hydrophilic and amphiphilic surfaces. Figure 1

Sulfur isotopes as biosignatures for Mars and Europa exploration

Sulfur (S) isotopes are used to trace metabolic pathways associated with biological S-cycling in past and present environments on Earth. These pathways (sulfate reduction, sulfur disproportionation and sulfide oxidation) can produce unique S isotope signals that provide insight into biogeochemical S-cycling. The S cycle is also relevant for extraterrestrial environments and processes. On early Mars, sulfur existed in different redox states and was involved in a large range of surface processes (e.g. volcanic, atmospheric, hydrothermal and aqueous brines). Sulfur compounds have also been detected on Europa's icy moon surface, with the S cycle implicated in Europa's surface and ocean geochemistry. Given the well-established utility of S isotopes in providing a record for past life on Earth, S isotopes are a valuable tool for identifying biosignatures on Mars and Europa. Here, we review S isotopes as a biosignature, in light of two recent advances in understanding the S cycle in both Mars and Europa: (1) the measurements of δ 34 S in situ at Gale Crater and quadruple S isotopes (QSI) in Martian meteorites; (2) the identification of a likely exogenous origin of sulfur on Europa's surface. We discuss important considerations for unravelling QSI biosignatures in Martian environments, considering high- and low-sulfur environments, atmospheric mass-independent fractionation of sulfur isotopes (S-MIF) signals and metabolic energy-limited niches. For Europa, we describe the potential for S isotopes to probe biogeochemistry, and identify key knowledge gaps to be addressed to unlock S isotopic tools for future life detection efforts. The resulting picture demonstrates how S isotopes will be a valuable tool for Mars sample return, and how future missions can focus on the search for environments where QSI signatures of microbial S-cycling processes have a greater chance of being preserved. For Europa, the first step will be to account for the S isotope composition of the various S pools, to recognize or rule out non-biologically mediated S isotope values, with a focus on experimental examination of potential S isotope signatures from exogenous sulfur sources. Thematic collection: This article is part of the Sulfur in the Earth system collection available at: https://www.lyellcollection.org/cc/sulfur-in-the-earth-system

CO2 zonal injection rate allocation and plume extent evaluation through wellbore temperature analysis

Temperature analysis during a pause in injection operations, known as warmback analysis, has been used in the petroleum industry for evaluating the injection conformance and estimating the location of the flooded front in applications, such as waterflooding oil reservoirs. In this work, methods are introduced to extend the application of temperature warmback analysis to estimate the zonal CO2 injection rate and zonal CO2 plume extent during geologic CO2 storage in a saline aquifer. First, novel analytical solutions are developed to model transient temperature in the aquifer during the injection and subsequent shut-in periods considering two-phase flow (gaseous CO2 and aqueous brine) conditions in the aquifer. The solution involves a discretization of the aquifer into regions; the energy and mass conservation equations for the regions are solved simultaneously considering appropriate boundary conditions at the interfaces. Two solutions techniques are presented: multi-region and three-region solutions. Inverse models are developed accordingly to evaluate the injection profile and estimate the extent of the plume front in the reservoir during the injection period. The multi-region solution results in an inversion approach that requires regression analysis. However, the three-region formulation results in a simple graphical technique for inverse modeling. The analytical solutions are validated against a thermally coupled reservoir simulation tool using different synthetic cases for CO2 injection in deep saline aquifers. The results of the developed solutions provide a good match with numerical results during forward and inverse modeling.

Annular corrosion risk analysis of gas injection in CO2 flooding and development of oil-based annulus protection fluid

Abstract To investigate the corrosion behavior of gas-injection well of CO 2 flooding and then to take measures to inhibit the corrosion of casing, firstly an HTHP autoclave and surface characterization technology are applied to analyzing the corrosion behavior of casing and then a new type of oil-based annulus protection fluid has been developed to avoid the casing corrosion issue. The results show that the casing in the simulated supercritical CO 2 -saturated aqueous brine phase (SC CO 2 -saturated aqueous phase) has severe uniform corrosion, while that in the simulated water-saturated supercritical CO 2 (SC CO 2 phase) has severe pitting corrosion. The temperature and CO 2 partial pressure can promote the water film adsorbed on the steel surface, further inducing the corrosion of casing. In order to prevent casing corrosion, an oil-based annulus protection fluid suitable for gas-injection well in CO 2 flooding is developed, and the preparation process of oil-based annulus protection fluid is proposed. The oil-based annulus protection fluid is composed of white oil and 1000 mg/L imidazoline inhibitor. The flash point of the oil-based annulus protection fluid is over 160 °C, the freezing point −23 °C, and the density 0.85 g/cm 3 . The corrosion inhibition rate is more than 80% when P110 steel is in SC CO 2 phase with oil-based annulus protection fluid, and it is more than 95% when P110 steel is in SC CO 2 -saturated aqueous phase. It proves that the newly developed oil-based annulus fluid can effectively solve the corrosion problem of P110 steel as casing in gas-injection well of CO 2 flooding. • Corrosion risk of casing in CO 2 flooding gas well is analyzed. • Preparation method of oil-based annulus protection fluid is established. • A novel oil-based annulus protection fluid for injected gas well in CO 2 flooding is developed.

Evaluation of percrystallization coupled with electrodialysis for zero liquid discharge in the pulping industry

We evaluated percrystallization at laboratory scale to determine its suitability as core technology for achieving Zero Liquid Discharge (ZLD) in a Kraft effluent desalination process. Compared with conventional evaporation/crystallization techniques, percrystallization allows to operate at room temperature and with barely pressurized fluids, using relatively unexpensive membranes and vacuum to allow evaporation of aqueous brine solutions. For further comprehension of the technology before experimentation, a computational fluid dynamics model was developed, showing how temperature affects the performance of percrystallization in terms of transmembrane flux. Additionally, we performed experiments with single and double salt solutions (NaCl and NaCl/Na2SO4) and concentrated industrial effluent from a Kraft pulp mill (brine from the effluent desalination with electrodialysis). Percrystallization of the concentrated industrial effluent was successfully achieved at laboratory scale, showing no signs of fouling on the membrane surface. However, high energy consumptions (above 3000 kWh/ton of evaporated water) were measured. Theoretical power consumptions of an optimized industrial percrystallization system were therefore computed. Percrystallization showed a more efficient performance compared with similar membrane systems, such as vacuum membrane distillation, but higher energy consumptions than conventional ZLD technologies (mechanical vapor compression), having an estimated energy consumption of around 110–150 kWh/ton of removed water, depending on the feed fluid temperature. Nevertheless, percrystallization could be suitable for ZLD applications where low-cost heating (e.g., solar) is available, since the vacuum energy demand is only 32–140 kWh/ton. Alternatively, it could be applied to low scale processes where the temperature of the solution must remain low (e.g., less than 40 °C).

Electrocatalysis of CO2 and CH4 Hydrates at Subzero Temperatures

So far electrocatalytic process in aqueous solution have been extensively studied as a function of the temperature in the range 0 and 99 °C but very little is known about electrocatalytic processes at temperatures below the freezing point. In electrochemistry at low temperatures, the reactions associated with water splitting might be suppressed due to the formation of ice-like structure at the interface, while the stabilization of other reaction species can be stabilized resulting in changes to the kinetics of the reactions studied.1-3 In addition, decreasing the temperature of water to subfreezing temperatures would significantly increase the solubility of some gases in water thus affecting the reaction rate and reaction mechanism of the electrochemical reactions. By taking advantage of the high solubility of the carbon monoxide and methane at low temperature, achievable in brines, we report the electrochemical conversion of these gases in aqueous media down to −40 °C. We will report the electrochemical conversion of CO2 at low temperatures and demonstrate, unexpectedly, that its reduction in these conditions follows an anti-Arrhenius kinetics electrochemical environment. We will also show that electrochemical oxidation of CH4 is feasible at subzero temperatures due to the 5-fold increase in the concentration of CH4 and the formation of in gas hydrate slurries. These findings open windows of investigation into electrocatalysis in brines below the freezing point of water.Gas hydrates or clathrates are a crystalline solid formed of water and gas. Clathrates looks and acts much like ice, but it contains large amounts of gas trapped within a crystal structure of water. Gas hydrates such as hydrates of hydrocarbons, sulfur dioxide (SO2) and carbon dioxide (CO2) have been reported but they are only used for academic purposes with just a very few examples which have reached technical application. However, gas hydrates might have play an important role in the origin of life, and the chemistry on gas hydrates is relevant in energy applications in particular for space exploration.We will show the electrochemical behavior of hydrogen and oxygen adsorption and desorption processes on different metal electrodes in aqueous brines at subfreezing temperatures. Finally, we will report the first electrochemical results of the CO2RR and the oxidation of CH4 in aqueous brines at subfreezing temperatures down to -40°C.4 Our results will be explained on the basis of the presence of ice-structure clathrates,5,6 solubility of the gases as a function of temperature, kinematic viscosity, mass transport and the changes in the pH of the solution.7,8 The understanding of the electrochemistry of gas hydrates at low temperature is paramount for the development of sustainable energy cycle based on CH4 and CO2 reversible fuel cells under severe environmental conditions. This will be critical to ensure the availability of key in situ resources sustaining future human exploration and colonization of other planets.