NaCl Brine Research Articles

Measurement of diffusion coefficients of hydrogen sulfide in water and brine using in-situ Raman spectroscopy

Diffusion coefficients of hydrogen sulfide in water and brine are critical in geology and chemical industries for hydrogen sulfide geological storage and hydrogen sulfide separation from natural gas. However, previous studies have mostly measured the diffusion coefficient of hydrogen sulfide in water at room temperature and normal pressure and the diffusion coefficient of hydrogen sulfide in brine had not been reported. In this study, ratio of the Raman signal intensity of the H-S bond of hydrogen sulfide to the HO bond of water, HRH2S/H2O, was used to measure the diffusion coefficients of hydrogen sulfide in water at 0.1–2 MPa and 273.1–373.1 K and in four brine solutions (0.62, 1, 2, and 3 mol•kg−1 NaCl) at 1 MPa and 273.1–373.1 K. Results showed that the diffusion coefficient of hydrogen sulfide in water increased with the increasing temperature and was insignificantly affected by the pressure, which follows the relationship derived from the Speedy–Angell power-law: D(cm2/s)=13.013×10−5[T/216.478−1]1.974, where T is in the temperature (K). In brine, the diffusion coefficient of hydrogen sulfide also increased with the temperature and was clearly inhibited by salinity, which can be described using the Ratcliff–Holdcroft model D(cm2/s)=13.013×10−5(T/216.478)1.974(1−0.0755Cs), where Cs is concentration of NaCl in brine (mol•kg−1).

Hydrolysis of imidazoline based corrosion inhibitor and effects on inhibition performance of X65 steel in CO2 saturated brine

The molecular characteristics of a TOFA/DETA based imidazoline inhibitor were evaluated by analysing the inhibitor protonation profile, the CMC and micelle size and the rate of acid-catalysed hydrolysis of the inhibitor to improve understanding of the corrosion inhibition performance of the main imidazoline component and its hydrolysis products. The ability of the TOFA/DETA imidazoline based corrosion inhibitor and its products of hydrolysis in retarding both uniform and localized corrosion were assessed and compared on wet-ground X65 carbon steel at 80 °C in CO2 saturated 3 wt % NaCl brines. The findings indicate that the imidazoline based inhibitor forms micellar solutions, with a characteristic micelle size of 18 ± 9 nm at the CMC (10 ± 1 ppm) in CO2 saturated 3 wt % NaCl brines, and that under such conditions (pH~4.1), the inhibitor is fully protonated which increases inhibitor solubility/dispersibility and enhances molecular adsorption of the positively charged imidazoline on the metal surface thereby improving inhibition performance. Hydrolysis of the imidazoline and amido-amine is acid-catalysed and the consumption of imidazoline follows a pseudo-first-order reaction mechanism with an activation energy of 72.0 ± 2.9 kJ mol-1. The study concludes that the pre-aged inhibitor has different effects on uniform and localized corrosion behavior of X65 carbon steel.

Optimization of an in-situ polymerized and crosslinked hydrogel formulation for lost circulation control

Lost circulation is a common problem during drilling and completion, and it contributes much to the nonproductive time of the operation. The Brazilian pre-salt is composed of highly heterogeneous carbonates and is highly susceptible to circulation loss. In this work, a removable, solid-free polymer gel formulation based on in-situ polymerization and gelation was proposed and optimized using design of experiments. The proposed gel contains acrylic acid (monomer), carboxymethylcellulose (thickener), ammonium persulfate (initiator), chromium (III) salt (crosslinking agent) and 240,000 NaCl brine as a solvent. The concentrations of these components, and the solution pH, were the variables considered in this study. The plateau modulus, maximum elastic modulus, gel stability, and gelation times were obtained and analyzed. The gelation time was obtained from oscillatory rheology time curves fitted by the Hill 5 model and from low-frequency nuclear magnetic resonance. Most of the studied gels presented elastic moduli from 1000 to 7000 Pa, close to and higher than the moduli of other gels for lost circulation. The gelation times ranged from 5 to 30 min, which could be improved by changing the initiator, protecting or inhibiting it. A pH of 9 led to faster gelation times, syneresis, and lower elastic moduli; therefore, pH values from 5 to 7 are ideal. Carboxymethylcellulose and the chromium salt increased slightly the gelation time, the elastic moduli, and the stability. Acrylic acid concentration controlled the overall elastic moduli, and higher concentrations led to shorter gelation times. Ammonium persulfate was able to both initiate the polymerization and also internally break the gel, depending on the concentration. Molecular explanations for these effects were provided. This proposed system is a promising candidate for lost circulation control for operations in the Brazilian pre-salt. Future steps involve studying the plugging and removable properties of the gels with optimized composition in high pressure and temperature settings. • A promising gel formulation for lost circulation control was proposed and optimized. • The pre-gel solution has low viscosity, but very high elasticity after gelation. • The gelation mechanism involves in-situ crosslinking and polymerization. • Rheological properties and gelation time can be modeled with R 2 ≥ 0.95. • Rheological properties match or surpass those from the literature.

Nrf2 Pathway Involvement in the Beneficial Skin Effects of Moderate Ionic Osmotic Stress—The Case of The Dead Sea Water

Objectives: Exposing skin to moderate ionic osmotic stress (MIOS) triggers several biochemical responses. The objective of this work is to reveal the mechanism triggered by MIOS on the skin surface. Furthermore, this work aims to study the involvement of the Nrf2 (nuclear factor erythroid-2-related factor 2) pathway, activated by MIOS, and its beneficial effect in protecting skin against stress via the stimulation of phase II enzymes. Methods: HaCaT cells and human skin organ culture were exposed to Dead Sea Water (DSW) as MIOS inducers and the induction of internal ROS elevation, Nrf2 translocation, mRNA gene expressions of the phase II enzymes, heme-oxygenase 1 (HO1), and Catalase (CAT) were determined. Results: Skin exposure to MIOS increases Nrf2 translocation to the nucleus, leading to increased levels of ROS, HO1, and CAT. Furthermore, exposing skin to MIOS promotes protection against UVB-related risks. This is demonstrated by attenuation of the expression of biomarkers, related to UVB-induced damage, Caspase-3, IL-8, and IL-1β. Conclusions: Skin exposure to MIOS leads to the activation of Nrf2 skin defense pathway and, therefore, could present beneficial advantages to human skin health, as demonstrated on human skin models. The beneficial effects of MIOS, induced by DSW are significantly superior to eq. NaCl brine, suggests that MIOS protection of skin against stress is partially related to specific mineral combinations.

Experimental investigation of GO-HPAM and SiO2-HPAM composite for cEOR: Rheology, interfacial tension reduction, and wettability alteration

The interest in designing and developing polymeric nanoparticles has grown in recent years. The inclusion of nanoparticles in polymer solutions enhances several properties, such as stability, rheological and shear characteristics, polymer adsorption, wettability alteration, and so on, leading to increased oil recovery. Graphene oxide (GO) nanosheets and Aerosil 300 Silica oxide (SiO2) are the superior nanoparticles because of their robust thermal and mechanical properties. However, a systematic study of the use of GO and SiO2 in hydrolyzed polyacrylamide (HPAM) has not been reported. The present research seeks to improve the stability of nanoparticles, the rheological characteristics of polymeric nanofluids, and to understand the functional interaction of nanoparticles in reducing interfacial tension and altering wettability. The nano polymer composites were characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. The samples were treated with NaCl (30,000 mg/L) and CaCl2 (1000 mg/L) brine solutions at 25 °C and 80 °C. The findings indicated that the addition of GO and SiO2 into HPAM significantly improves rheological properties, reduced IFT, and decreased contact angle. GO performs better than SiO2 in terms of better rheological properties and the reduction of IFT. However, the use of SiO2 in HPAM resulted in a lower contact angle in comparison to GO-HPAM nano-polymeric solution. The synergetic effect of GO and SiO2 with HPAM showed promising results under harsh reservoir conditions and hence can be considered as a good candidate for the application of chemical enhanced oil recovery.

Phyto-based sodium chloride hydrogel for highway winter maintenance of porous asphalt pavements

The need of the highway agencies to customize their winter maintenance operations on porous asphalt pavements prompted the authors to develop an innovative anti-icing technology based on the hot liquid spray application of a saline hydrogel. A bio-based (phyto-based) thermo-sensitive sodium chloride (NaCl) brine, that has the ability to form a gel simply by coming into contact with a very cold surface, was conceived. The increase in viscosity and the formation of a gel-like structure would make this anti-icing product able of filling the surface voids without permeating through the mixture (longer residual deicing effectiveness), while maintaining at the same time the pavement frictional resistance. In view of adopting sustainable winter maintenance strategies, this innovative blend was formulated by exploiting the thickening and gelling properties of wall-cell polysaccharides contained in seaweeds fibers. The mechanisms of gel formation were experimentally studied in laboratory, analyzing in detail the thermal and rheological properties of the salt hydrogel during the different phases of preparation, storage and application. On the basis of this characterization, a full-scale validation was carried out on an existing highway porous asphalt pavement. For this purpose, a tank truck prototype was equipped with a heating capacity tank and a customized specific spraying system.

Electro-kinetically tailored interfaces for chemical enhanced oil recovery in carbonates

SmartWater flooding through the injection of optimized chemistry water has lately become an attractive proposition for improved/enhanced oil recovery (IOR/EOR) in carbonate reservoirs. The wettability alteration towards water-wet conditions caused by favorable surface charge alteration is identified as the main mechanism responsible for oil recovery. In this experimental investigation, the impact of SmartWater/surfactant synergy on wettability alteration was thoroughly studied by measuring zeta-potentials at calcite/brine and crude oil/brine interfaces using electrophoresis technique. Different types of surfactants are considered including: anionic, amphoteric and non-ionic. Four different low salinity water recipes including SmartWater (10-times reduced high salinity water) as well as the high salinity water (HSW) were chosen for zeta potential measurements. The results showed that both anionic surfactants increased the magnitude of the negative zeta-potentials at the interfaces by almost same order of magnitude. The negative zeta-potentials were increased the most with anionic surfactants in the low salinity NaCl brine, from (−15 to −21 and up to −37 mV) at the calcite interface and from (−6 to −19 mV) at the oil interface. SmartWater showed relatively higher negative zeta-potentials for calcite when compared to low salinity Na2SO4 brine and HSW in the presence of anionic surfactant. These results indicate that both NaCl brine and SmartWater can synergistically combine with anionic surfactants for effective wettability alteration in carbonates. Amphoteric surfactant showed a negligible impact on electrical double layer (EDL) expansion and consequently the wettability alteration. The nonionic surfactant induced electrostatic repulsion forces at both calcite/brine by shifting the zeta potentials from (+5.9 to −6.3 mV) and crude oil/brine interface from (−0.2 to −4.7 mV) respectively in high salinity water. As a result, nonionic surfactant can be considered as the best chemical formulation to reduce interfacial tension and cause wettability alteration in conventional chemical flooding processes. The negligible impact of adding surfactant chemicals on the measured di-electric constant of different brines confirmed the robustness of zeta-potential values reported in this study. This work for the first time evaluated the synergistic effects of different brines including the SmartWater with surfactant chemicals by measuring zeta-potentials at calcite/brine and oil/brine interfaces. The optimally suited water recipes were identified to synergistically combine with these chemicals to enhance wettability alteration in carbonates. The new knowledge gained from this electro-kinetic study will provide practical guidance on how to design efficient chemical flooding processes for wettability alteration and enhanced oil recovery in carbonates.

The challenge in measuring low-permeability materials: a comparison of different approaches

Abstract. The German repository site selection procedure calls for a radioactive waste containment zone with a low-permeability host rock (kf<10-10 m s−1, StandAG §23, 5) and long-term sealing by barrier materials (EndlSiAnfV, 2020; ESK, 2019). The potential host rocks, clay and rock salt, as well as the considered barrier materials, bentonite and compacted crushed salt, show permeability in the range of kf∼10-16 m s−1 (K∼10-21 m2). These low values suggest that advective flow is as slow as diffusive mass flux. Measuring such low permeability with adequate accuracy challenges measurement setups and respective error evaluation. Methodologies. Several low-permeability measurements are carried out by transient tests, e.g. by monitoring controlled fluid pressure changes in: (1) pressure decay and (2) oscillating pulse tests. The first method (1) deviates permeability from the time needed to compensate pressure differences through the sample. The latter (2) monitors phase shift and amplitude attenuation of controlled pressure pulses passing through the sample. Any permeability measurement needs to be post-processed, e.g. for: (1) material-intrinsic controls (saturation state, storativity, the fluids' compressibility, etc.), (2) environmental controls (temperature, confining pressures, etc.) and (3) theoretical considerations (Klinkenberg correction, multi-phase wetting angles, etc.). Salts. A porosity-permeability relation was found down to K=10-19 m2 (e.g., Popp et al., 2007). Testing fluids were NaCl brine, oils, He and N2 as a fluid. As a matter of current research, a critical, low-permeability value might be associated with the so-called “percolation threshold” that defines the minimal requirements for an interconnected pore system (e.g., DAEF, 2016). Clays. A major challenge is the long duration of sample saturation (up to several months) and pressure equilibration (often days), as well as precise, temperature-compensated measuring and the determination of the samples' storativity (e.g., Winhausen et al., 2021). Testing fluids are commonly designed mixtures mimicking the rocks' pore waters. Geotechnical barrier materials. The permeability testing performed is similar to that of salt and clays mentioned above. However, both barrier materials, crushed salt and bentonite, have significant permeability early after emplacement. This is beneficial, as it allows the outflow of unwanted canister corrosion gases. Eventually, the permeability drops by orders of magnitude and the barriers become tight seals in the long-term. Here, identifying the gas entry/breakthrough pressure has been valuable (e.g., Rothfuchs et al., 2007). Figure 1 shows a preliminary sensitivity analysis as an example of pressure decay measurements. It suggests that the pressure equilibration term (c), and hence the test duration, is most sensitive to the calculation of low permeability. However, the large variation of (representative) material and environmental controls make permeability measurements complex. This workshop aims to encourage discussions on uncertainty and sensitivity of the influencing controls, such that it may lead to a “best-practice” guide for permeability measurements.

Temperature and Pressure Dependence of Salt-Brine Dihedral Angles in the Subsurface.

Elevated temperature and pressure in the earth's subsurface alters the permeability of salt formations, due to changing properties of the salt-brine interface. Molecular dynamics (MD) simulations are used to investigate the mechanisms of temperature and pressure dependence of liquid-solid interfacial tensions of NaCl, KCl, and NaCl-KCl brines in contact with (100) salt surfaces. Salt-brine dihedral angles vary between 55 and 76° across the temperature (300-450 K) and pressure range (0-150 MPa) evaluated. Temperature-dependent brine composition results in elevated dihedral angles of 65-80°, which falls above the reported salt percolation threshold of 60°. Mixed NaCl-KCl brine compositions increased this effect. Elevated temperatures excluded dissolved Na+ ions from the interface, causing the strong temperature dependence of the liquid-solid interfacial tension and the resulting dihedral angle. Therefore, at higher temperature, pressure, and brine concentrations Na-Cl systems may underpredict the dihedral angle. Higher dihedral angles in more realistic mixed brine systems maintain low permeability of salt formations due to changes in the structure and energetics of the salt-brine interface.

Raman spectroscopy of high salinity brines and ices

Raman spectroscopy is an ideal tool to analyze the geochemistry and mineralogy of heterogenous mixtures of solids, liquid, and gases in situ, while maintaining planetary protection protocols. Here we characterize saturated CaCl2, MgCl2, MgSO4, Na2SO4, NaCl, and NaClO4 brines, as well as ultrapure water, and mixed MgSO4-NaCl, MgSO4-NaClO4, Na2SO4-NaCl, Na2SO4-NaClO4, and NaCl-NaClO4 brines from 200 K to 295 K to determine how changes in temperature affect spectral signatures of planetary analogue brines. The resulting reference dataset can be used to interpret spectra from future samples analyzed in situ on planetary bodies. Sulfate and perchlorate brines produced clear, distinct peaks associated with each polyatomic anion. While chloride brines did not produce anion peaks, subtle changes were observed in the OH-stretching region, suggesting changes to the molecular water vibration states due to complexation. Solid-liquid phase transitions were clearly observed in each of the solutions using both 785 nm (red) and 532 nm (green) excitation lasers, particularly in the OH-stretching region between 3000 and 4000 cm−1 with the 532 nm laser. Differences observed in the spectra of frozen sulfate brines suggest that cooling rates may influence the hydration state and/or crystallinity of the solid magnesium and sodium- sulfate salts. These experiments and the resulting spectral library will allow future researchers to use Raman spectroscopy to look for in situ melting, freezing, evaporation, and deliquescence as well as identify the composition of high salinity brines and their frozen products in a range of planetary environments, including permafrost and recurring slope lineae on Mars, potential ice and salt-rich regolith on asteroids such as Ceres, and ice shells and possible seeps or geysers on icy moons and other bodies.

The Role of Chloride Concentration on the Pitting Kinetics of Aluminum

This work examines the role of chloride concentration on the polarization behavior and pitting susceptibility of aluminum in highly concentrated NaCl brines. NaCl-rich brines are typically present during marine atmospheric corrosion at elevated humidity levels, which include the range from 75 % RH up to 98 % RH, corresponding to 6 M (saturated) and 0.6 M NaCl respectively at 25 oC. Although aluminum pitting is well-studied at chloride solution concentrations below 2 M (> 90% RH), electrochemical insight of aluminum atmospheric corrosion occurring at higher chloride concentrations (> 2 M [Cl-]) is hindered by lack of data. To address this, anodic polarization experiments along with post-mortem microscopy were performed on high purity Al (> 99.9 wt%) in NaCl solutions ranging from 0.6 to 6 M. Results to date show that pitting potentials and pitting transition potentials are logarithmically proportional to chloride concentration within this range, extending the applicability of previously proposed semi-empirical models to higher concentrations.1,2 Measured repassivation potentials, however, deviated considerably from previously reported trends and predictions based on measurements at lower chloride concentrations. The role of pit morphology, IR drop and hydrogen evolution during anodic polarization will be addressed to rationalize these discrepancies.SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. References S.T. Pride, J.R. Scully, J.L. Hudson, Journal of the Electrochemical Society, 141, 3028 (1994).J.R. Galvele, Journal of the Electrochemical Society, 123, 464 (1976).

EFFECTS OF PARTICLES DISAGGREGATION UNDER ULTRASONIC-ASSISTED WATERFLOODING ON OIL RECOVERY

Ultrasonic waves have a wide variety of applications in a variety of fields. It is used in the oil and gas industry to remove near wellbore damage, and several studies have been conducted to examine its application with waterflooding. Additionally, ultrasonic waves are used in engineering to determine the stability of sediments through dispersion and disaggregation. This study aims to incorporate both the ultrasonic waterflooding aspect with the stability of the sediment by investigating the impact of sonication exposure duration on particle size and oil recovery under waterflooding. Six (6) coarse sand samples were used in the experiment to simulate the porous media found in a sand pack. A sieving test was conducted on each sand sample to obtain its Particle Size Distribution (PSD) curve prior and post sonication. Waterflooding was conducted using 3% NaCl brine as the wetting phase and decane (C10H22) as a non-wetting phase. Ultrasonic waves were applied continuously throughout the waterflooding durations (i.e., 15,30,45 minutes), and both temperature and decane recovery were recorded. The results show that ultrasonic results in minimal additional recovery less than 2%, and an increase in temperature of 2-8°C was observed. However, longer sonication results in higher particle disaggregation, which reduces permeability by15.50%-41.85% and can result in sand production. This study can be continued through investigation on the utilization of cyclic ultrasonic-assisted waterflooding as a technique that may aid in recovery without causing detrital effects to the reservoir sand layer.Keywords: permeability, stability, sonication, dispersion, size distribution

Time Evolution of Microbial Composition and Metabolic Profile for Biogenic Amines and Free Amino Acids in a Model Cucumber Fermentation System Brined with 0.5% to 5.0% Sodium Chloride

Salt concentrations in brine and temperature are the major environmental factors that affect activity of microorganisms and, thus may affect formation of biogenic amines (BAs) during the fermentation process. A model system to ferment cucumbers with low salt (0.5%, 1.5% or 5.0% NaCl) at two temperatures (11 or 23 °C) was used to study the ability of indigenous microbiota to produce biogenic amines and metabolize amino acid precursors. Colony counts for presumptive Enterococcus and Enterobacteriaceae increased by 4 and up to 2 log of CFU∙mL−1, respectively, and remained viable for more than 10 days. 16S rRNA sequencing showed that Lactobacillus and Enterobacter were dominant in fermented cucumbers with 0.5% and 1.5% salt concentrations after storage. The initial content of BAs in raw material of 25.44 ± 4.03 mg∙kg−1 fluctuated throughout experiment, but after 6 months there were no significant differences between tested variants. The most abundant BA was putrescine, that reached a maximum concentration of 158.02 ± 25.11 mg∙kg−1. The Biogenic Amines Index (BAI) calculated for all samples was significantly below that needed to induce undesirable effects upon consumption. The highest value was calculated for the 23 °C/5.0% NaCl brine variant after 192 h of fermentation (223.93 ± 54.40). Results presented in this work indicate that possibilities to control spontaneous fermentation by changing salt concentration and temperature to inhibit the formation of BAs are very limited.

Emulsions of glycerol in olefin: A critical evaluation for application in oil well drilling fluids

Drilling in ultra-deep waters presents a series of difficulties and specificities, related to well depth, water depth, high pressures and saline formations found in the pre-salt basins. In addition, there is still a need to use fluids that meet environmental legislation for cleaning and disposal of cuttings in the sea. In view of these requirements, the invert emulsion fluids, of brine in olefin, are promising and have been extensively used for this application. These fluids need to maintain their rheological properties throughout the drilling, also considering the temperature variation, in order to minimize the formation of hydrates, interaction with clay areas, interaction with saline zones and damages to the permeable rock. The hypothesis of this research is that the substitution of brine by glycerol in the drilling fluid can lead to the following advantages: (a) maintenance of rheological properties; (b) mitigation of interactions with clay and saline areas; (c) no formation of hydrates, due to absence of water in the fluid; and (d) introduction of a new economic effectiveness for glycerol waste disposal. For this, crude glycerol was used to replace saturated NaCl brine in the invert emulsion drilling fluid. The interaction with saline and clay-rich zones was investigated by evaluating the interaction of the dispersed phase and the continuous phase using clay and salt plugs. Among the main results, crude glycerol obtained as a by-product of biodiesel was compatible with commercial additives used in drilling fluids based on brine in olefin emulsions, demonstrating feasibility of immediate application in drilling fluids, in view of the maintenance of rheological properties, reduction of filtrate volume and lower reactivity with salt and clay areas. Thus, the article presents a new composition of drilling fluid for ultra-deep waters, with the potential to minimize damage to the rock formation, through the use of a waste from the biodiesel production industry, without the need of previous treatments.

Effect of wet-curing on physical properties and proteins of cured ham

AbstractConsuming enough protein is a very important part of a balanced and healthy diet. Complete proteins are those in which all essential amino acids are present. In meat products, like hams, many different reactions occur during ageing and storage. For example, the production of free amino acids or the production of biogenic amines is formed by decarboxylation. In this study, the presence of these amino acids and biogenic amines, as well as the quality properties of cured hams during curing and ageing, were investigated.The meat samples were immersed into 100 g L−1 NaCl brine. The curing took 20 days, followed by smoking and ageing for 35 days (12 °C, 75% RH). The wet-cured ham samples were analysed for changes in NaCl concentration (at 3 parts: surface, core, bottom layer). Moreover, color, water activity, denaturation temperature and enthalpy (Differential Scanning Calorimetry), free amino acids (FAAs) and biogenic amines (BAs) were also evaluated.

Salt frost attack on concrete: the combined effect of cryogenic suction and chloride binding on ice formation

Scaling of concrete due to salt frost attack is an important durability issue in moderate and cold climates. The actual damage mechanism is still not completely understood. Two recent damage theories—the glue spall theory and the cryogenic suction theory—offer plausible, but conflicting explanations for the salt frost scaling mechanism. The present study deals with the cryogenic suction theory, which assumes that freezing concrete can take up unfrozen brine from a partly frozen deicing solution during salt frost attack. According to the model hypothesis, the resulting saturation of the concrete surface layer intensifies the ice formation in this layer and causes salt frost scaling. In this study an experimental technique was developed that makes it possible to quantify to which extent brine uptake can increase ice formation in hardened cement paste (used as a model material for concrete). The experiments were carried out with low temperature differential scanning calorimetry, where specimens were subjected to freeze–thaw cycles while being in contact with NaCl brine. Results showed that the ice content in the specimens increased with subsequent freeze–thaw cycles due to the brine uptake at temperatures below 0 °C. The ability of the hardened cement paste to bind chlorides from the absorbed brine at the same time affected the freezing/melting behavior of the pore solution and the magnitude of the ice content.

Investigation of the interaction between nanoparticles, asphaltenes, and silica surfaces by real‐time quartz crystal microbalance with dissipation

AbstractThe effects of nanofluids as wettability alternators and inhibitors of asphaltene precipitation and formation damage were studied in this work. Silicate‐based nanoparticles with different chemical surfaces, named neutral (NN), basic (BN), and acidic (AN), dispersed in NaCl brine were tested to observe their interactions with n‐C7 asphaltenes and silica surfaces using the quartz crystal microbalance with dissipation (QCM‐D). The properties of nanoparticles were characterized using XRD, BET, TPD, and HRTEM. Heptol 70 asphaltenes, pre‐adsorbed/deposited on SiO2 sensors were used for studying the concentration effect of 10 nm‐sized BN‐based nanofluids, which exhibited a decreasing trend in frequency shift in the following order 1 > 10 > 25 mg/L. For toluene asphaltenes, the frequency shifts in BN nanofluids changed with the following order of concentration 100 > 150 > 50 > 25 mg/L. The effect of particle size on frequency shift, tested for toluene asphaltenes demonstrated the following order 10 > 99 > 45 > 20 nm BN. A cycle injection test between asphaltenes and a nanofluid solution was performed to evaluate the effect of the nanoparticles in a sequence injection. Wettability alteration was assessed before and after nanofluid injection using contact angle measurements, which resulted in a decrease after nanofluid injection. In addition, atomic force microscopy (AFM) measurements were performed on some of the samples to support the findings. The QSense data analysis software Q‐Tools was used to determine the thickness of the layer before and after the injection of nanofluids; the trend was similar to the change in frequency for all parameters. Finally, brine‐based nanofluids with 10 nm‐sized BN at 1 and 100 mg/L were more effective in treating the deposited asphaltenes in heptol 70 and toluene, respectively.

Dual-Functional Graphene Oxide-Based Photothermal Materials with Aligned Channels and Oleophobicity for Efficient Solar Steam Generation.

Desalination by solar steam generation (SSG) has emerged as one of the most efficient approaches to address the issue of global water shortage. In this work, novel graphene oxide (GO)-based solar steam generators (GO-SSGs) with aligned channels were prepared by directional freezing and simple carbonization of a hydrogel composed of GO and poly(vinyl alcohol) (PVA). Benefitting from their excellent light absorption (light absorption efficiency exceeds 94%), better thermal insulation (thermal conductivity, 0.259 W/(m K)), and suitable porous structure, which facilitates rapid water transportation, the GO-SSGs show superior SSG performance with a high solar energy conversion efficiency of up to 92% achieved under an irradiation of 1.0 kW/m2. Interestingly, uniquely aligned channels endow them with good salt-rejection performance; the solar energy conversion efficiency of GO-SSGs in 20 wt % NaCl, KCl, and MgCl2 brine can reach more than 85%. To improve their antifouling performance, a chemically hydrophilic and oleophobic modification was conducted, making it possible to run SSG even in oily wastewater; for instance, a solar energy conversion efficiency of 84% was obtained in an aqueous solution containing 10 wt % n-hexadecane. Compared with the existing photothermal materials, these materials show advantages of simple manufacture, high SSG efficiency, superior salt tolerance, and antifouling performance, which make them promising candidates as a kind of new high-performance photothermal materials for desalination even in oily wastewater, thus further expanding the scope of their practical SSG application.

Modification of GO-based pervaporation membranes to improve stability in oscillating temperature operation

Graphene oxide (GO)-based pervaporation membranes have great potential for desalination and lithium containing brine enrichment. However, they experienced critical challenges when used in aqueous solution and exposed to oscillating temperatures due to swelling and microdefects. In this work, the GO-based membranes were fabricated by the filtration of GO suspension with sulfonate-containing diamine molecules on porous substrates, then dip-coated with chitosan and polyvinyl alcohol (PVA). The resultant GO-based membranes demonstrated 99.99% salt rejection during pervaporation using NaCl or lithium-containing concentrated inland brine with humic acid as the feed solution under oscillating temperature. The intercalation of diamine molecules inside the GO nanochannels was able to increase water flux by 20% while the coated chitosan/PVA layer reduced structural defects and undesired scaling/fouling on the membrane surface resulting in minimal reduction of water flux (16%) over 72 h of oscillating temperature pervaporation. Moreover, the membrane exhibited good stability after chemical cleaning. The proposed GO-based membranes provided significant performance sustainability in concentrated inland brine and oscillating feed temperature condition.

Fly Ash–Ca(OH)2 Reactivity in Hypersaline NaCl and CaCl2 Brines

The disposal of highly concentrated brines from coal power generation can be effectively accomplished by physical solidification and chemical stabilization (S&S) processes that utilize fly ashes as a reactant. Herein, pozzolanic fly ashes are typically combined with calcium-based additives to achieve S&S. While the reactions of fly ash–(cement)–water systems have been extensively studied, the reactivity of fly ashes in hypersaline brines (ionic strength, Im > 1 mol/L) is comparatively less understood. Therefore, the interactions of a Class C (Ca-rich) fly ash and a Class F (Ca-poor) fly ash were examined in the presence of Ca(OH)2, and their thermodynamic phase equilibria were modeled on contact with NaCl or CaCl2 brines for 0 ≤ Im ≤ 7.5 mol/L. At low ionic strengths (<0.3 mol/L), reactivity and stable phase assemblages remain effectively unaltered. However, at high(er) ionic strengths (>0.5 mol/L), the phase assemblage shows a particular abundance of Cl-AFm compounds (i.e., Kuzel’s and Friedel’s salts). Although formation of Kuzel’s and Friedel’s salts enhances the Class F fly ash reactions in both NaCl and CaCl2 brines, NaCl brines compromise Class C fly ash reactivity substantially, while CaCl2 results in the reactivity remaining essentially unchanged. Thermodynamic modeling that accounts for the fractional and noncongruent dissolution of the fly ashes indicates that their differences in reaction behavior are provoked by differences in the prevalent pore solution pH, which affects phase stability. The outcomes offer new insights for matching fly ashes, Ca additives, and brines, and accounting for and controlling fly ash–brine interactions as relevant to optimizing physical solidification and chemical stabilization applications.