High Salinity Conditions Research Articles

Electrocatalytic degradation of octadecylamine and 4-dodecylmorpholine by the Ti/SnO2-Sb/β-PbO2 anode at high salinity conditions: Activity and mechanism insights

Increased levels of octadecylamine (ODA) and 4-dodecylmorpholine (DMP) in the aqueous, primarily utilized as flotation agents in the worldwide production of potash fertilizer, imperil the stability of ecosystems and the downstream production of high-end chemicals. Nevertheless, there is a dearth of exhaustive studies pertaining to the elimination of ODA and DMP. Herein, the Ti/SnO2-Sb/β-PbO2 anode was fabricated by a thermal decomposition-electrodeposition technique for the electrocatalytic degradation of ODA and DMP. The degradation efficiency of ODA and DMP can achieve complete degradation, reaching 100%, after treatment periods of 10 min and 120 min, respectively. Meanwhile, the TOC removal efficiency of ODA and DMP is up to 85% and 61% at 30 min and 120 min, respectively. In particular, sulphate exhibits inhibitory degradation activity of ODA and DMP in comparison to chloride salt. The recycling and accelerated lifetime tests indicate excellent stability and recyclability of the Ti/SnO2-Sb/β-PbO2 electrode. The mechanism of electrocatalytic degradation involves indirect electrochemical oxidation mediated by free radicals. The primary reactive species responsible for the degradation of DMP and ODA, as determined through scavenger quenching experiments and ESR, are ·OH and Cl·. The degradation of the ODA and DMP commences with the elimination of N element, leading to the formation of the NO3-. The carbon chain subsequently undergoes the breakdown. The degradation pathways of ODA and DMP were also proposed based on the GC–MS and H-NMR analyses, respectively. Moreover, the Ti/SnO2-Sb/β-PbO2 anode performed excellently in the removal of ODA and DMP in real samples, TOC removal from ODA and DMP in natural samples was 56% and 52%, respectively, within 180 min. This study provides the first exploration of electrocatalytic degradation mechanisms and pathways of ODA and DMP based on the Ti/SnO2-Sb/β-PbO2 anode.

Probing the surface forces between air bubbles and bitumen via direct force Measurements: Effects of aqueous chemistry

The surface interactions of air bubbles and other components (e.g., particles, oil droplets) significantly influence the operation efficiency of a variety of engineering processes such as oily water treatment, bitumen extraction and flotation. Herein, the surface interactions of air bubbles with two types of Athabasca bitumen samples in aqueous solutions of varying pH, salinity, type of cations and in the presence of surfactants have been systematically characterized using a bubble probe atomic force microscope (AFM) technique. AFM imaging has revealed that exposure to high concentrations of NaCl and CaCl2 solutions or alkaline environments causes roughening of the bitumen surfaces. The results of surface force measurements demonstrate that the interaction and attachment behaviors between bubbles and bitumen are significantly affected by ionic strength, solution pH, and the presence of surfactants. The experimental force measurement results could be accurately described by a theoretical model that incorporates Reynolds lubrication theory and augmented Young-Laplace equation, with the inclusion of disjoining pressure. In low-salinity conditions, the bubble-bitumen interaction is dominated by electric double layer (EDL) repulsion, which prevents surface attachment. This effect is more pronounced at elevated pH conditions. In high-salinity solutions, however, the EDL interactions are significantly reduced, and the hydrophobic interaction becomes the dominant factor, overcoming the van der Waals repulsion and leading to the attachment of bubbles to bitumen surfaces. Raising aqueous pH weakens the bubble-bitumen hydrophobic interaction, whereas the introduction of calcium ions strengthens this interaction, resulting in enhanced surface attachment. Interestingly, even in high-salinity conditions, the presence of a small number of surfactants can inhibit bubble-bitumen contact, mainly caused by reduced hydrophobic attraction and increased steric repulsion. This work provides valuable nanoscale insights into how bubbles and bitumen interact in intricate aqueous environments, and the results show practical implications for controlling similar interfacial phenomena in various engineering processes.

Anaerobic biodegradation of azo dye reactive black 5 by a novel strain Shewanella sp. SR1: Pathway and mechanisms

The efficiency of microbial populations in degrading refractory pollutants and the impact of adverse environmental factors often presents challenges for the biological treatment of azo dyes. In this study, the genome analysis and azo dye Reactive Black 5 (RB5) degrading capability of a newly isolated strain, Shewanella sp. SR1, were investigated. By analyzing the genome, functional genes involved in dye degradation and mechanisms for adaptation to low-temperature and high-salinity conditions were identified in SR1. The addition of co-substrates, such as glucose and yeast extract, significantly enhanced RB5 decolorization efficiency, reaching up to 87.6%. Notably, SR1 demonstrated remarkable robustness towards a wide range of NaCl concentrations (1–30 g/L) and temperatures (10–30 °C), maintaining efficient decolorization and high biomass concentration. The metabolic pathways of RB5 degradation were deduced based on the metabolites and genes detected in the genome, in which the azo bond was first cleaved by FMN-dependent NADH-azoreductase and NAD(P)H-flavin reductase, followed by deamination, desulfonation, and hydroxylation mediated by various oxidoreductases. Importantly, the degradation metabolites exhibited reduced toxicity, as revealed by toxicity analysis. These findings highlighted the great potential of Shewanella sp. SR1 for bioremediation of wastewaters contaminated with azo dyes.

Activation of PMS degradation of chlorotriazine herbicides (atrazine and simazine) by MIL101-derived Fe/Co@C under high salinity conditions

In this work, a carbon-based catalyst Fe/Co@C with MOF as a self-sacrificing template was prepared by high-temperature roasting of FeCo-MIL101, which was applied to activate PMS for the degradation of chlorotriazine herbicides (ATZ and SIM) showing excellent performance. Characterization analysis revealed that Fe/Co@C possesses a certain graphene structure and has a saturation magnetization rate of 0.87 emu/g, which can be separated from the solution easily and quickly. The degradation of ATZ and SIM was enhanced by introducing chloride ions into the system, and 100 mmol/L Cl- could lead to the complete removal of ATZ and SIM in 6 min, while improving the interfacial electron transfer of Fe/Co@C/PMS. In combination with quenching experiments, ESR test results and DFT calculations, two important roles of chlorine radicals in the reaction are proposed: (1) direct electron transfer and (2) indirect promotion of 1O2 generation through the production of HOCl. In addition, the testing of the influencing factors of the catalyst in the system (catalyst dosing, PMS dosing, pH, temperature), the testing of coexisting anions in the aqueous matrix, and the reusability all showed satisfactory performance. Finally, the degradation mechanisms of ATZ and SIM were proposed in combination with GC–MS determination of contaminant intermediates and analysis of their toxicity.

Effects of salinity on life history traits and fatty acid-binding proteins in the marine rotifer, Brachionus plicatilis

We present a comprehensive analysis of the impact of increased salinity on Brachionus plicatilis, focusing on growth, reproduction, behavior, and fatty acid-binding protein (FABP) gene expression. We discovered delays in maturation and potential disruptions in the reproductive process under conditions of high salinity. Experiments demonstrated that while the total number of B. plicatilis offspring remained unchanged across different salinity levels, the peak daily offspring count was delayed, and the pace of reproduction was slower at higher salinity. However, the pre-reproductive and reproductive periods at 35 practical saline units were extended, contributing to longer timeframes to produce all offspring, but the post-reproductive period was shortened, thus balancing the overall lifespan across different salinity levels. Furthermore, we noted that high salinity impedes the growth of B. plicatilis and causes alterations in swimming behavior. Our findings also demonstrated five pairs of FABPs within the three Brachionus species (B. plicatilis, B. rotundiformis, and B. koreanus) with distinctive sequences. Phylogenetic analysis revealed that Brachionus FABPs diverged before the speciation of the three species and were found outside the vertebrate FABP group. The results contribute to our understanding of the impact of high salinity on B. plicatilis and the evolutionary positioning of FABPs in these species, while also highlighting the need for further research into specific FABP differentiation and expression patterns in Brachionus species.

Effect of salinity on genes involved in the stress response in mangrove soils.

Mangroves are a challenging ecosystem for the microorganisms that inhabit them, considering they are subjected to stressful conditions such as high and fluctuating salinity. Metagenomic analysis of mangrove soils under contrasting salinity conditions was performed at the mouth of the Ranchera River to the Caribbean Sea in La Guajira, Colombia, using shotgun sequencing and the Illumina Hiseq 2500 platform. Functional gene analysis demonstrated that salinity could influence the abundance of microbial genes involved in osmoprotectant transport, DNA repair, heat shock proteins (HSP), and Quorum Sensing, among others. In total, 135 genes were discovered to be linked to 12 pathways. Thirty-four genes out of 10 pathways had statistical differences for a p-value and FDR < 0.05. UvrA and uvrB (nucleotide excision repair), groEL (HSP), and secA (bacterial secretion system) genes were the most abundant and were enriched by high salinity. The results of this study showed the prevalence of diverse genetic mechanisms that bacteria use as a response to survive in the challenging mangrove, as well as the presence of various genes that are recruited in order to maintain bacterial homeostasis under conditions of high salinity.

Interactive effects of salinity, temperature and food web configuration on performance and harmfulness of the raphidophyte Heterosigma akashiwo

The cosmopolitan raphidophyte Heterosigma akashiwo commonly forms harmful algal blooms (HABs) in diverse estuaries discharging into Algoa Bay, South Africa, potentially leading to hypoxia, fish kills and a decline in key primary consumers. Despite the high environmental variability in these estuaries, little is known about how abiotic factors such as temperature and salinity constrain bloom formation and harmfulness of H. akashiwo. The present study therefore investigates growth, competition, and grazing interactions of H. akashiwo in laboratory experiments in response to two naturally relevant levels of salinity (15, 30) and temperature (16, 22°C), respectively. Experiments were set up with the naturally co-occurring dinoflagellate competitor Heterocapsa rotundata and two estuarine microzooplankton consumers, i.e., nauplii of the copepod Acartia tonsa and the rotifer Brachionus plicatilis. In monoculture, H. akashiwo growth was promoted at high temperature – low salinity conditions, while H. rotundata thrived under low temperature – high salinity conditions. In polyculture, H. akashiwo dominated at high temperature irrespective of the salinity regime, while at low temperature, it only dominated at low salinity and was suppressed by H. rotundata at high salinity. Grazing assays revealed highly negative effects of H. akashiwo on copepod nauplii survival and growth as well as mucus-induced immobilization, especially at high temperatures in combination with low salinity, while the estuarine adapted rotifers showed highest mortalities at the higher salinity level. The presence of H. rotundata significantly alleviated the harmful effects of H. akashiwo on both grazers, and the selectively feeding copepod nauplii actively avoided H. akashiwo when non-harmful prey was present. Overall, this study demonstrates that population dynamics and harmful effects of H. akashiwo are interactively determined by both abiotic conditions and food web configuration, implying competitor and consumer specific tolerances to the abiotic environment and their susceptibility to the harmful alga H. akashiwo.

A Novel Amphoteric Ion-Modified, Styrene-Based Nano-Microsphere and Its Application in Drilling Fluid.

With the gradual depletion of shallow oil and gas, deep oil and gas has become the focus of development. However, deep formations generally face the challenge of high-temperature and high-salinity, and drilling fluid agents are prone to failure, leading to drilling fluid intrusion into the formation that can cause serious drilling accidents such as well bore collapse. For this, a styrene-based nano-microsphere (SSD) modified with amphoteric ions was developed, with a particle size of 228 nm which could resist temperatures up to 200 °C and sodium chloride (NaCl) up to saturation. SSD has significant salt-responsive properties and its aqueous dispersion becomes transparent with increasing salinity. The SSD provided superior plugging performance in solutions containing NaCl, with a core plugging efficiency of 95.2%, and it was significantly better than the anion-modified microspheres. In addition, in drilling fluids under high temperature and high-salinity conditions, the SSD promotes particle gradation of drilling fluids and improves the zeta potential through its own plugging and synergistic effect with clay, which significantly improves the comprehensive performance of drilling fluids, such as stability, rheological performance, and filtration reduction performance. The development of SSD provides a new idea for research of high-temperature and high-salinity-resistant drilling fluid agents.

Ion fluxes Involved in the Adaptation of the Estuarine Diatom Coscinodiscus centralis Ehrenberg to Salinity Stress.

Although estuarine diatoms have a wide range of salt tolerance, they are often severely stressed by elevated salt concentrations. It remains poorly understood how estuarine diatoms maintain ionic homeostasis under high-salinity conditions. Using a scanning ion-selective electrode technique, this study determined the fluxes of H+, Na+, and K+ involved in the acclimatization of the estuarine diatom Coscinodiscus centralis Ehrenberg after an elevation in salinity from 15 psu to 35 psu. The C. centralis cells exhibited marked H+ effluxes after a transient treatment (TT, 30 min) and short-term treatment (ST, 24 h). However, a drastic shift of H+ efflux toward an influx was induced in the long-term treatment (LT, 10 days). The Na+ flux under TT, ST, and LT salinity conditions was found to accelerate the Na+ efflux. More pronounced effects were observed under the ST and LT salinity conditions compared to the TT salinity condition. The K+ influx showed a significant increase under the LT salinity condition. However, the salinity-induced Na+/H+ exchange in the estuarine diatom was inhibited by amiloride and sodium orthovanadate. These results indicate that the Na+ extrusion in salt-stressed cells is mainly the result of an active Na+/H+ antiport across the plasma membrane. The pattern of ion fluxes under the TT and ST salinity conditions were different from those under the LT salinity conditions, suggesting an incomplete regulation of the acclimation process in the estuarine diatom under short-term salinity stress.

Salinity and cultivar effects on alfalfa forage yield and nutritive value in a Mediterranean climate

AbstractBackgroundSoil and water salinity are increasing problems worldwide, causing significantly reduced crop yields. Alfalfa (Medicago sativa L.) is often listed as salt‐sensitive, but field testing of improved cultivars is limited. Forage systems and improved high‐quality alfalfa varieties are needed to enable crop production under high salinity (HS) conditions.MethodsThe objective of this study was to measure the yield and quality response of alfalfa to high saline conditions in the field and to document the relative saline tolerance of its varieties. HS irrigation water (electrical conductivity of water, or ECw 8.0–11.0 dS m−1) was applied to 33 nondormant alfalfa cultivars and were compared with low salinity (LS) treatments (ECw 0.5–1.2 dS m−1) over 4 years in a Mediterranean environment on a clay loam soil utilizing a split‐plot design. Crops were harvested seven to eight times per year, and the forage quality was measured on selected harvests utilizing near‐infrared spectroscopy.ResultsThe average yield loss due to HS treatment was 23.9% compared with LS treatment, but yields averaged 23.4 Mg ha−1 under HS over the 3 full years of production. This level of production is considered to be economically viable in this region. Differences in salinity tolerance between lines were identified in the field; individual cultivars lost 5%–35% of their LS yield when grown under HS conditions. Forage quality was significantly improved under HS versus LS conditions, but improvements were negatively correlated with biomass yield (R2 &gt; 0.81), similar to responses observed in drought‐stressed alfalfa.ConclusionsThese yield results confirm greenhouse studies, indicating that alfalfa is highly salt tolerant once established in the field, with potential for further improvement with tolerant cultivars. Salinity tolerance should be chosen based on total biomass yield as well as on the salinity tolerance index (HS yield relative to LS yield). Agronomic practices to mitigate salinity and sodicity are critical, along with improved cultivars.

Efficient degradation of tetracycline with N-rGO/CuO catalysts under high salinity condition via persulfate activation dominated by non-radical pathways

The degradation of organic pollutants under high-salt conditions is significant for the resource utilization and environmental remediation. In this work, nitrogen-doped graphene supported copper oxide (N-rGO/CuO, NGC) was synthesized to activate persulfate (PS) for tetracycline (TC) degradation. The TC removal rate reached 97% within 90 min and the catalyst showed high resistance to saline ions. Dual catalytic effects of N and Cu sites on NGC significantly improved the PS activation and the TC oxidation by dominated non-radical reactions involving 1O2 and electron transfer. The dopped N provided more active sites for PS activation and promoted the generation of 1O2. Besides, the CuO loaded on nitrogen-doped graphene enhanced the adsorption of PS and reinforced the oxidative degradation of TC by accelerating electron transfer. Moreover, the successful COD removal from real high salinity wastewater demonstrated that PS activation on NGC is a promising method for treating organic pollutants under high-salt environment.

Biochemical Basis of Abiotic Stress Tolerance in Native Isolates of &lt;i&gt;Beauveria bassiana&lt;/i&gt; (Balsamo) Vuillemin from Kerala

A study on the screening of Beauveria bassiana (Balsamo) Vuillemin native isolates for abiotic stress tolerance was carried out at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, Thrissur, Kerala during 2019-2023. The growth and biochemical parameters of the three native isolates of B. bassiana (BTL1: OP271760, BTL2: OP290199 and PKDE: OP292066) were studied under different abiotic stress conditions viz., temperature, water stress, acidity and salinity. The results revealed that the highest temperature tolerance (40° C) was displayed by the B. bassiana isolate PKDE. It also survived at high water stress (45% polyethylene glycol), acidic (pH2) and saline (1.5 M) conditions. The analysis of biochemical parameters in stress tolerant isolate revealed that the greatest levels of trehalose (2.033± 0.025, 2.043± 0.006 mg/ min/ g of mycelia), catalase (0.0072± 0.007, 0.0032± 0.003 EU/ min/ mg protein) and peroxidase (0.0602± 0.005, 0.0175± 0.017 EU/ min/ mg tissue weight) were observed after exposure to high temperature and water stress, respectively. This shows that exposure to abioticstress and biochemical parameters are closely related and can be used as determinants for evaluating the potential of biocontrol agents.

LEAF PIGMENT AND TOTAL CARBOHYDRATE CONTENT AT EARLY STAGES OF HERITIERA FOMES BUCH. SEEDLINGS GROWN AT THREE SALINE ZONES OF THE SUNDARBANS, BANGLADESH

The experiment was conducted to find the leaf pigments and carbohydrate content in Heritiera fomes at different growth stages exposed to different salinity levels in the Sundarbans areas, Bangladesh. Three leaf pigments, viz., chlorophyll a, chlorophyll b, and carotenoid, total chlorophyll, and total carbohydrate content of Heritiera fomes Buch. Ham seedlings were determined in the leaves grown in the oligohaline, mesohaline, and polyhalite zones at early (6 and 9 months) and survival ages (30 months) following standard methods. Leaves from seedlings at the age of 30 months (survival aged) show relatively high leaf pigments than that of the 6 and 9-month-old seedlings grown in the three saline zones. Total chlorophyll content in leaves was found low in the oligohaline zone at the early and survival ages, but higher in the polyhalite zone at the early ages, and higher in the mesohaline zone at the survival age. Chlorophyll b was relatively higher than chlorophyll a. Leaves of 30 months seedlings showed relatively higher chlorophyll a than chlorophyll b at the polyhalite zone, but higher chlorophyll b was noted at the mesohaline zone. The highest content of total carbohydrates was observed in the shoots of 6, 9, and 30 months ages H. fomes seedlings in the polyhalite zone, while the lowest was in the mesohaline zone. At the same age periods in the mesohaline zone, the roots of the H. fomes seedlings showed relatively higher carbohydrate content and lower at the 30 months seedlings in the all saline zones. Chlorophyll a was found to be more sensitive than chlorophyll b and carotenoid at different salinity levels tested. Higher carbohydrate content was discovered as an additional mechanism to prevent salt toxicity at early ages of high saline conditions (polyline zone).

Combined effects of excess boron and salinity on the growth and ionic imbalance of lavandin (Lavandula × intermedia) plant

Generally, moderate to high salinity conditions and excess boron (B) occur together as limiting factors for plant growth in the soils of arid and semiarid regions. To determine the combined effect of excessive boron, salinity stress, or both, five different levels of B (0, 0.3, 0.6, 1.2, and 1.8 mM) and 80 mM sodium chloride (NaCl) were applied to lavandin plants grown in a greenhouse. The results showed that under nonsaline conditions, biomass production in shoots and roots and photosynthetic pigment contents (chlorophyll (Chl) a, b, and Chl a + b) decreased with exceptionally high B applications compared to the control. Moreover, the bioconcentration (BCF) of B (in shoots and roots), potassium (K) concentrations (in roots), K/sodium (Na) and calcium (Ca)/Na ratios (in shoots), and Ca/B ratios (in shoots and roots) decreased for all B applications compared to the control. In contrast, all B applications caused a remarkable increase in the carotenoid (Car)/Chl ratio, B concentrations (in shoots and roots), translocation (TF) of B, and net B accumulation compared to the control. In addition, under nonsaline conditions, concentrations of K (in shoots), Ca (in shoots and roots), and K/Na and Ca/Na ratios (in roots) were significantly increased by B applications compared with the control. Under saline conditions, significant decreases in Chl b, Chl a + b, BCF of B (in shoots and roots), and Ca/B ratio (in shoots) were observed in all B applications compared to the control. However, under saline conditions, B application caused significant increases in the Car/Chl ratio, TF of B, net B accumulation, and concentrations of B (in shoots and roots), K (in shoots), Ca, and Na (in shoots and roots) compared to the control. It was concluded that although it is not seen in the growth parameters, NaCl application could effectively alleviate the harmful effects of B toxicity in lavandin plants. Under saline conditions, notable decreases in the mean B concentration in shoots could be strong evidence for this hypothesis.

Physiological and transcriptomic analysis of salt tolerant Glaux maritima grown under high saline condition.

Land salinization considerably limits crop production. Biological improvement of saline and alkaline land is an important way to achieve efficient land use. It is crucial to study the salt tolerance of halophyte resources in order to explore and improve plant resources through biological improvement. Glaux maritima is a mesophyte halophyte with strong salt tolerance. In this study, we conducted research on the salt tolerance mechanism of G. maritima through phenotypic, physiological, and transcriptomic aspects. The results indicate that leaf cross-sections revealed that G. maritima has a salt gland tissue composed of stalk, collecting, and secretory cells, which are trapped in epidermal cells. At the physiological level, the maximum salt tolerance threshold of G. maritima leaves was 600 mM/L. At this concentration, proline content, relative conductivity, and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activities were maximum. At the transcriptional level, transcriptome data of three experimental groups (N0: 0 mM/L, N3: 600 mM/L, and N4: 800 mM/L) were analyzed, and six essential genes related to proline synthesis and five essential genes related to SOD and CAT enzyme activities were identified. Two genes involved in CAT enzyme activity were also found to play an important role in the MAPK signaling pathway. Trend analysis revealed that the MAPK signaling regulation (37 differentially expressed genes (DEGs)), phytohormone regulation (48 DEGs), glutathione metabolism (8 DEGs), flavonoid and flavonoid biosynthesis (2DEGs), and flavonoid biosynthesis (24 DEGs) pathways played important roles in regulating the salt tolerance of G. maritima. These findings provide valuable information for further studies on the functional characteristics of G. maritima in response to abiotic stress and may contribute to salt resistance breeding of fodder crops for cultivation in saline alkali land.

Insight into the effect of rice-straw ash on enhancing the anaerobic digestion performance of high salinity organic wastewater

Anaerobic digestion is an economic method for treating high salinity organic wastewater (HSOW), but performance enhancement is needed because of the inhibitory effect of high salinity. In this study, rice-straw ash (RSA) was applied to alleviate the inhibitory effect during HSOW anaerobic digestion. The results showed that, when the NaCl content increased from 0% to 3.0%, the methane production decreased by 87.35%, and the TOC removal rate decreased to 34.12%. As a K+ and alkalinity source, RSA addition enhanced the anaerobic digestion performance, and the optimal dosage was 0.88 g/L. Under this dosage, the methane production increased by 221.60%, and TOC removal rate reached 66.42% at 3.0% salinity. The addition of RSA increased the proportion of living cells in the high salinity environment, and enhanced the activity of key enzymes and electron transfer efficiency in the anaerobic digestion process. The addition of RSA with a dosage of 0.88 g/L promoted the accumulation of acetoclastic methanogen Methanothrix. The abundance of substrate transporters, ion transporters and electron transfer related functional genes were enriched, which might be key for promoting HSOW anaerobic digestion performance. The results also showed that RSA addition played an important role in maintaining the stability of the anaerobic digestion system, and it could be a potential strategy for enhancing the anaerobic digestion performance under high salinity conditions.

A switchable ionic diode membrane enabled by sub-3 nm covalent organic framework channels

Various efforts have been made to mimic the regulatory properties of biological channels that exist in cell membranes of living organisms. Such ion channels are able to tune electric signals in response to changes in surrounding environments (e.g., pH or ions). Here, we report the design and fabrication of a novel pH-switchable ionic diode membrane (IDM), TFP-EB COF@PET, composed of a thin layer of sub-3 nm covalent organic framework (COF) channels and a polyethylene terephthalate (PET) membrane having conical nanochannels with tip size of 20–40 nm. The designed IDM is found to exhibit ion current rectification (ICR) over a wide range of electrolyte concentrations, attributable to its structural and charge asymmetries. Interestingly, the TFP-EB COF@PET can exhibit pH-switchable ion transport behaviors even though the surface charge natures of TFP-EB COF and PET channels remain unchanged. The mechanisms for the pH-switchable ICR properties are proposed to explain the inversion phenomenon. This work highlights the pH-switchable ionic transport properties of the sub-3 nm-scale COF-based IDM, as well as its potential for long-term operation under high salinity conditions.

Demulsification of crude oil emulsions using a three-branched betaine type ionic liquid and its demulsification mechanism

In this work, a three-branched betaine type ionic liquid (TESA) with elevated interfacial activity was synthesized to separate water from crude oil emulsions at low temperature. The chemical structure, demulsification performance, and demulsification mechanism of TESA was investigated. The bottle tests exhibited that the dehydration efficiency was 100% with 150 mg/L of TESA for 40 min at 50 °C. TESA was effective in acidic, alkaline, and high salinity conditions. The dehydration efficiency of TESA was more than 95.63% with a wide pH range of 3–11. Furthermore, the dehydration efficiency was 100% with 50000 mg/L of salinity for 20 min at 50 °C. Encouragingly, the dehydration efficiency of TESA was better than that of commercial demulsifiers and reported work. The excellent dehydration efficiency of TESA was ascribed to the elevated interfacial activity, amphipathy, and strong interaction with asphaltenes. As a result, TESA improved the substitution of asphaltenes and considerably reduced interfacial tension, resulting in an unstable interfacial film and leading to demulsification. It indicated that TESA was an effective demulsifier, which promised application in the oil industry.

Representative Elementary Volume Estimation and Neural Network-Based Prediction of Change Rates of Dense Non-Aqueous Phase Liquid Saturation and Dense Non-Aqueous Phase Liquid–Water Interfacial Area in Porous Media

Investigation of the change rate for contaminant parameters is important to characterize dense non-aqueous phase liquid (DNAPL) transport and distribution in groundwater systems. In this study, four experiments of perchloroethylene (PCE) migration are conducted in two-dimensional (2D) sandboxes to characterize change rates of PCE saturation (So) and PCE–water interfacial area (AOW) under different conditions of salinity, surface active agent, and heterogeneity. Associated representative elementary volume (REV) of the change rate of So (So rate) and change rate of AOW (AOW rate) is derived over the long-term transport process through light transmission techniques. REV of So rate (SR-REV) and REV of AOW rate (AR-REV) are estimated based on the relative gradient error (εgi). Regression analysis is applied to investigate the regularity, and a model based on a back-propagation (BP) neural network is built to simulate and predict the frequencies of SR-REV and AR-REV. Experimental results indicated the salinity, surface active agent, and heterogeneity are important factors that affect the So rate, AOW rate, SR-REV, and AR-REV of the PCE plume in porous media. The first moment of the PCE plume along the vertical direction is decreased under conditions of high salinity, surface active agent, and heterogeneity, while these factors have different effects on the second moment of the PCE plume. Compared with the salinity and surface active agent, heterogeneity has the greatest effect on the GTP, the distributions of the So rate and AOW rate along the depth, and dM, dI. For SR-REV, the standard deviation is increased by the salinity, surface active agent, and heterogeneity. Simultaneously, the salinity and heterogeneity lead to lower values of the mean value of SR-REV, while the surface active agent increases the mean value of SR-REV. However, the mean and standard deviation of AR-REV have no apparent difference under different experimental conditions. These findings reveal the complexity of PCE transport and scale effect in the groundwater system, which have important significance in improving our understanding of DNAPL transport regularity and promoting associated prediction.

Desorption behaviour of polymers on sepiolite surfaces under high-temperature and high-salinity conditions

AbstractPolymers maintain colloidal stability by adsorbing onto the surface of sepiolite particles, and changes in temperature and salinity can affect this process. We chose three typical polymers to investigate their interactions with sepiolite under high-salinity (15 wt.% NaCl) conditions at &gt;180°C. Sepiolite samples were characterized using infrared testing, X-ray diffraction testing, contact angle testing, thermogravimetric testing, filtration loss testing and rheological testing. The experimental results showed that the desorption of the polymers under high-temperature and high-salinity conditions reduces the stability and filtration control of the suspension significantly. Adding polymers to sepiolite suspensions can maintain good stability even after thermal ageing at 240°C. In terms of drilling fluid regulation, sepiolite can play a role in regulating rheological properties, and the interactions between various polymers and sepiolite can be utilized to maintain the stable colloidal state of the drilling fluid. Studying the adsorption behaviour of various types of polymers on the surface of sepiolite under high-temperature and high-salinity conditions has important implications for the design and selection of sepiolite drilling fluid treatment agents.