Weak Alkali Research Articles

Study on Microscopic Oil Displacement Mechanism of Alkaline-Surfactant-Polymer Ternary Flooding.

Alkali-surfactant-polymer (ASP) flooding is one of the most effective and promising ways to enhance oil recovery (EOR). The synergistic effect between alkali, surfactant, and polymer can respectively promote emulsification performance, reduce interfacial tension, and improve bulk phase viscosity, thus effectively improving flooding efficiency. However, the displacement mechanism of ASP flooding and the contribution of different components to the oil displacement effect still need further discussion. In this study, five groups of chemical slugs were injected into the fracture model after water flooding to characterize the displacement effect of weak alkali, surfactant, polymer, and their binary/ternary combinations on residual oil. Additionally, the dominant mechanism of the ASP flooding system to improve the recovery was studied. The results showed that EOR can be improved through interfacial reaction, low oil/water interfacial tension (IFT), and increased viscosity. In particular, the synergistic effect of ASP includes sweep and oil washing. As for sweep, the swept volume is expanded by the interfacial reaction between the alkali and the acidic components in Daqing crude oil, and the polymer increases the viscosity of the system. As for oil washing, the surfactant generated by the alkali cooperates with surfactants to reduce the IFT to an ultra-low level, which promotes the formation and migration of oil-in-water emulsions and increases the efficiency of oil washing. Overall, ASP can not only activate discontinuous oil ganglia in the pores within the water flooding range, but also emulsify, decompose, and migrate the continuous residual oil in the expanded range outside the water flooding. The EOR of ASP is 38.0% higher than that of water flooding. Therefore, the ASP system is a new ternary composite flooding technology with low cost, technical feasibility, and broad application prospects.

A coumarin-hemicyanine fluorescent probe for simultaneous detection and discrimination of biothiols, HSO3− and S2-

Biomercaptan, bisulfite (HSO3−) and hydrogen sulfide (H2S) are involved in many physiological and pathological processes in the human body. Therefore, it is of great significance to develop a fluorescent probe that can simultaneously detect and distinguish biological mercaptans from HSO3− and S2−. The probe CDI-1 was synthesized by combining coumarin with hemicyanine. The maximum absorption wavelength of the probe is at 609 nm. After adding Cys/Hcy and GSH, the probe shows varying degrees of blue shift, which can be used to distinguish Cys/Hcy and GSH. After it reacts with Cys/Hcy, the fluorescence intensity of the solution increases about twice, while it increases three times after it reacts with GSH. This phenomenon can also be used to distinguish Cys/Hcy from GSH. The probe CDI-1 can react with Cys completely within 30 min, with Hcy or GSH completely within 80 min, and with HSO3− and S2− quickly within 20 min. The study on the effect of pH on the fluorescence performance of CDI-1 shows that the probe is suitable for detecting biological mercaptan or HSO3−, S2− in weak acid to weak alkali environments. The selectivity study showed that the probe CDI-1 had high specificity for biological mercaptan, HSO3− and S2−. This provides a new and simple method for simultaneous detection of biological mercaptan, HSO3− and S2− ions.

Alkaline-resistant covalent organic framework membranes for selective hydroxide ion separation

Alkali holds a pivotal role in the chemical industry, however, the substantial discharge of alkaline wastewater causes a severe waste of resources and environmental pollution. Conventional polymer membranes have ether bonded backbones and form randomly assembled nanochannels, suffering from a weak alkali resistance and a low hydroxide ion selectivity. Covalent organic frameworks (COFs), known for their robust framework structure, highly ordered channels, and tunable channel chemistry, have been considered as the competent candidate for alkaline-resistant membranes for selective hydroxide ion separation. Herein, we fabricate a β-ketoenamine COF (TpTAPB) membrane with a high alkaline resistance via the interfacial growth strategy. After post-sulfonation, the negatively charged channels of sulfonated TpTAPB membrane allows OH- with smaller size and lower charges to pass through while repulsing WO42- ions, achieving a selectivity of OH-/WO42- up to ∼ 60 and surpassing commercial and most reported polymeric membranes. This work expands the application scope of COF membranes in selective alkali separation.

Preparation and Characterization of Responsive Cellulose-Based Gel Microspheres for Enhanced Oil Recovery.

As an important means to enhance oil recovery, ternary composite flooding (ASP flooding for short) technology has achieved remarkable results in Daqing Oilfield. Alkalis, surfactants and polymers are mixed in specific proportions and injected into the reservoir to give full play to the synergistic effect of each component, which can effectively enhance the fluidity of crude oil and greatly improve the oil recovery. At present, the technology for further improving oil recovery after ternary composite flooding is not mature and belongs to the stage of technical exploration. The presence of alkaline substances significantly alters the reservoir's physical properties and causes considerable corrosion to the equipment used in its development. This is detrimental to both the environment and production. Therefore, it is necessary to develop green displacement control agents. In the reservoir environment post-ASP flooding, 2-(methylamino)ethyl methacrylate and glycidyl methacrylate were chosen as monomers to synthesize a polymer responsive to alkali, and then grafted with cellulose nanocrystals to form microspheres of alkali-resistant swelling hydrogel. Cellulose nanocrystals (CNCs) modified with functional groups and other materials were utilized to fabricate hydrogel microspheres. The product's structure was characterized and validated using Fourier transform infrared spectroscopy and X-ray diffraction. The infrared spectrum revealed characteristic absorption peaks of CNCs at 1165 cm-1, 1577 cm-1, 1746 cm-1, and 3342 cm-1. The diffraction spectrum corroborated the findings of the infrared analysis, indicating that the functional modification occurred on the CNC surface. After evaluating the swelling and erosion resistance of the hydrogel microspheres under various alkaline conditions, the optimal particle size for compatibility with the target reservoir was determined to be 6 μm. The potential of cellulose-based gel microspheres to enhance oil recovery was assessed through the evaluation of Zeta potential and laboratory physical simulations of oil displacement. The study revealed that the absolute value of the Zeta potential for gel microspheres exceeds 30 in an alkaline environment with pH values ranging from 7 to 14, exhibiting a phenomenon where stronger alkalinity correlates with a greater absolute value of Zeta potential. The dispersion stability spans from good to excellent. The laboratory oil displacement simulation experiment was conducted using a cellulose-based gel microsphere system following weak alkali ASP flooding within the pH value range from 7 to 10. The experimental interventions yielded recovery rates of 2.98%, 3.20%, 3.31%, and 3.38%, respectively. The study indicates that cellulose-based gel microspheres exhibit good adaptability in alkaline reservoirs. This research offers a theoretical foundation and experimental approaches to enhance oil recovery techniques post-ASP flooding.

Straw Biochar and Graphite Oxide Enhanced External Pressure Ultrafiltration for Leaded Wastewater Treatment.

In order to solve the problem of the low treatment efficiency of wastewater containing heavy metals in mining areas, straw biochar and graphene oxide enhanced external pressure ultrafiltration (SGU) was used to treat wastewater containing high concentrations of Pb2+. The operation parameters such as pH and temperature were optimized, and the removal efficiency of CODCr, NH3-N, turbidity and Pb2+ via SGU, straw biochar ultrafiltration (SU), ultrafiltration (UF), and conventional treatment (CT) were systematically investigated. The results showed that the pH and temperature of polluted water were 4.8-5.2 and 21-30 °C, respectively, the average removal rates of CODCr, NH3-N, turbidity and Pb2+ by SGU reached 91%, 97%, 98% and 95%, respectively, and the removal effect was better than that of other processes. In addition, under the backwash conditions of clean water, weak acid, and weak alkali, the membrane flux recovered 65%, 88%, and 89% of the new membrane, respectively. This study provides scientific and theoretical support for the advanced treatment of polluted water in mining areas.

Degradation of sodium dodecylbenzene sulfonate (SDBS) and high efficiency treatment of real grey water by TiO2-loaded stainless steel mesh under VUV irradiation

Reusing treated greywater indoors in buildings is an advanced strategy to increase the utilization of limited water resources, but currently there is a lack of feasible technologies for efficiently purifying greywater indoors. In this study, we construct the heterogeneous TiO2-stainless steel mesh (SSM) interface with photocatalytic degradation of sodium dodecylbenzene sulfonate (SDBS) by under vacuum ultraviolet (VUV) irradiation. At the initial SDBS of 10 mg/L, the degradation rates of SDBS with UV/TiO2-SSM and VUV/TiO2-SSM process were 53 % and 74 % respectively within 50 min. The results of specific scavengers experiments and EPR analysis revealed that the ·OH, h+ and direct photolysis contributed to SDBS degradation and mineralization. The degradation rate of SDBS in VUV/TiO2-SSM process was higher at weak acid or weak alkali conditions, while the performance of UV/TiO2-SSM process was better at alkaline conditions. Both Cl− and HCO3− could inhibit SDBS degradation, while SO42− slightly promoted the degradation. Active oxygen species mainly degrade SDBS in two ways: by attacking the α carbon, β carbon, or branched chain carbon on the alkane chain; or by attacking the adjacent carbon on the alkane chain, resulting in the formation of three branch forms of products. The toxicity of the intermediate products shows a decreasing or stable trend. The experiment shows that UV or VUV photocatalytic TiO2-SSM has a good prospect of removing anionic surfactant in the real greywater. This study provides strategies for the development and design of indoor water reuse technologies and devices in buildings.

Molybdenum iron carbide-copper hybrid as efficient electrooxidation catalyst for oxygen evolution reaction and synthesis of cinnamaldehyde/benzalacetone

Oxygen evolution reaction (OER) is the efficiency limiting half-reaction in water electrolysis for green hydrogen production due to the 4-electron multistep process with sluggish kinetics. The electrooxidation of thermodynamically more favorable organics accompanied by CC coupling is a promising way to synthesize value-added chemicals instead of OER. Efficient catalyst is of paramount importance to fulfill such a goal. Herein, a molybdenum iron carbide-copper hybrid (Mo2C-FeCu) was designed as anodic catalyst, which demonstrated decent OER catalytic capability with low overpotential of 238 mV at response current density of 10 mA cm−2 and fine stability. More importantly, the Mo2C-FeCu enabled electrooxidation assisted aldol condensation of phenylcarbinol with α-H containing alcohol/ketone in weak alkali electrolyte to selective synthesize cinnamaldehyde/benzalacetone at reduced potential. The hydroxyl and superoxide intermediate radicals generated at high potential are deemed to be responsible for the electrooxidation of phenylcarbinol and aldol condensation reactions to afford cinnamaldehyde/benzalacetone. The current work showcases an electrochemical-chemical combined CC coupling reaction to prepare organic chemicals, we believe more widespread organics can be synthesized by tailored electrochemical reactions.

A low-friction and high-stability hydrophilic PVP/PEG coated TPU for interventional catheter applications

Vascular interventional catheters are generally made of hydrophobic polymers, which may lead to vascular injury, poor lubrication and other consequences due to friction with vascular wall or stent in the process of intervention. In this study, the PDA-PVP/PEG composite coating was prepared based on common TPU catheter material to improve its hydrophilic lubrication behavior. Firstly, the oxidative self-polymerization of dopamine (PDA) was initiated and deposited on the surface of TPU in a weak alkali environment, and then the PVP/PEG coating was prepared by UV curing with PDA as the intermediate adhesion layer. The composite coating was optimized step by step by lubricating material system, process parameters, molecular weight, and concentration. Compared with the blank control group, the water contact angle decreased from 91.3° to about 28.3°, and the friction coefficient decreased from 0.4 to about 0.03, and the composite coating was not damaged after 30 min of reciprocating sliding. The results of cytotoxicity grade Level 1 and hemolysis rate less than 5 % also proved that the composite coating showed good cytotoxicity and blood compatibility. In summary, the PDA-PVP/PEG hydrophilic lubricating composite coating revealed excellent comprehensive properties.

A Systematical Review of the Largest Alkali-Surfactant-Polymer Flood Project in the World: From Laboratory to Pilots and Field Application

Summary This paper presents a systematical review of the largest alkali-surfactant-polymer (ASP) flood project in the world, applied to the largest oil field in China. First, reservoir and fluid characteristics are highlighted. Next, project history is summarized, including laboratory studies, pilot tests, industrial-scale tests, and fieldwide application. Third, typical ASP flooding performance and reservoir management measures from more than 30 years’ experience are presented. In addition, performances of ASP flood and polymer flood in the same field, which is also the largest project in the world, are compared. The Lamadian-Saertu-Xingshugang (La-Sa-Xing) Field in the Daqing Field Complex (including the La-Sa-Xing Field and three smaller satellite fields) is the largest oil field in China. The Upper Cretaceous Saertu-Putaohua-Gaotaizi reservoir has an average porosity of 25% and average permeability of 610 md. The reservoir consists of more than 100 flow units with an average gross and net thickness of 1,377 ft and 394 ft, respectively, and is characterized by significant heterogeneity, both vertically and laterally. The reservoir lies at a depth of 2,566–2,585 ft true vertical depth (TVD), with original reservoir pressure of 1,534–1,740 psi and a reservoir temperature of 113–122°F. Crude oil has an API gravity of 33° and a viscosity of 9 cp at reservoir conditions. The discussed ASP flood project mainly targets high-quality reservoir sands. The field was brought on-stream in 1960 with immediate waterflood. Crossflow and water breakthrough became common issues during water injection, calling for a suitable enhanced oil recovery (EOR) method. The Saertu-Putaohua-Gaotaizi reservoir features favorable conditions for ASP flood, such as temperature, viscosity, permeability, and formation water salinity (7000 mg/L). In addition, the heterogeneous reservoir (permeability variation coefficient of 0.6–0.8) is suitable for ASP flood. ASP flood was studied in the laboratory from 1987 to 1993, followed by five small-scale pilots from 1994 to 1999, all being successful with incremental recoveries of ~20% stock tank oil initially in place (STOIIP). As a result, industrial-scale tests were conducted from 2000 to 2007, resulting in substantial improvement in production from ~4,000 BOPD to greater than 19,000 BOPD. Encouraged by those successes, the ASP project was expanded to fieldwide since December 2007, which is the largest ASP flood project in the industry worldwide. By 2021, daily oil production by ASP flood had reached 96,000 BOPD through 4,825 producers and 4,825 injectors. The actual average incremental recovery factor is 20% over waterflood and 8–10% over polymer flood, resulting in ultimate recovery factor of >60%. Zonal injection and profile modification are effective measures to further improve sweeping efficiency. Scaling is the major challenge during the operation of ASP flood, which is mitigated or remediated by adopting weak alkali ASP, progressive cavity pumps (PCP), scale inhibitor treatment, and fracturing stimulation on damaged wells. As of 2022, oil production by ASP flood is still ongoing at 88,635 BOPD, accounting for 39.9% of total field production. The world’s largest ASP flood project in the La-Sa-Xing Field proved the fieldwide applicability of ASP flood, both technically and economically. The effective reservoir management measures and lessons learned from more than 30 years’ experience provide valuable experiences for large-scale ASP flood projects in the industry.

Study on the Alkali-Free Three-Component Flooding System in the Daqing Oilfield.

ASP flooding is an important method to further improve oil recovery by a large margin. At present, it has entered the stage of industrial application, but there are still problems of scaling in the injection production system and high production maintenance costs. Based on the industrialized mature technology of weak alkali ASP flooding, sodium chloride is used to replace sodium carbonate, and the alkali-free three-component flooding (TC) system in the Daqing Oilfield is developed by mixing with petroleum sulfonate and partially hydrolyzed polyacrylamide. Based on the experiments of viscosity increasing, interface performance, stability, adsorption, and oil displacement effect, the differences between the alkali-free TC system and the weak alkali ASP system are compared and analyzed. The laboratory research results show that both systems are basically the same in terms of viscosity, viscoelasticity, shear resistance, interfacial activity, stability, and flowability. Due to the lack of alkaline water, the adsorption, emulsification, and oil displacement performance of the alkali-free TC system is slightly lower than that of the weak alkali ASP system. The recovery factor of core flooding can be increased by 27.31% over water flooding, which is 2.56 percentage points lower than that of the weak alkali ASP system. On the premise of the same 1% EOR effect, the agent cost of the alkali-free system is 17.02% lower than that of the alkali ASP system. This article innovatively verifies the feasibility of using NaCl instead of Na2CO3 and explains the mechanism of significantly improving oil recovery in composite systems under alkali-free conditions from the ion level. However, the emulsification effect of the alkali-free TC system is relatively weak. The next step of research would be to consider adding an E-surfactant to enhance the emulsification performance of the composite system. By improving the system composition, technical references are provided for the efficient development of other terrestrial sandstone oilfields.

Fabrication of Eco-Friendly Hydrolyzed Ethylene-Maleic Anhydride Copolymer-Avermectin Nanoemulsion with High Stability, Adhesion Property, pH, and Temperature-Responsive Releasing Behaviors.

In this study, novel amphiphilic polymer emulsifiers for avermectin (Avm) were synthesized facilely via the hydrolysis of ethylene-maleic anhydride copolymer (EMA) with different agents, and their structures were confirmed by various techniques. Then, water-based Avm-nanoemulsions were fabricated with the emulsifiers via phase inversion emulsification process, and superior emulsifier was selected via the emulsification effects. Using the superior emulsifier, an optimal Avm-nanoemulsion (defined as Avm@HEMA) with satisfying particle size of 156.8 ± 4.9 nm, encapsulation efficiency (EE) of 69.72 ± 4.01% and drug loading capacity (DLC) of 54.93 ± 1.12% was constructed based on response surface methodology (RSM). Owing to the emulsifier, the Avm@HEMA showed a series of advantages, including high stability, ultraviolet resistance, low surface tension, good spreading and high affinity to different leaves. Additionally, compared to pure Avm and Avm-emulsifiable concentrate (Avm-EC), Avm@HEMA displayed a controlled releasing feature. The encapsulated Avm was released quite slowly at normal conditions (pH 7.0, 25 °C or 15 °C) but could be released at an accelerated rate in weak acid (pH 5.5) or weak alkali (pH 8.5) media or at high temperature (40 °C). The drug releasing profiles of Avm@HEMA fit the Korsmeyer-Peppas model quite well at pH 7.0 and 25 °C (controlled by Fickian diffusion) and at pH 7.0 and 10 °C (controlled by non-Fickian diffusion), while it fits the logistic model under other conditions (pH 5.5 and 25 °C, pH 8.5 and 25 °C, pH 7.0 and 40 °C).

Role of interfacial flexibility in emulsifying ability of coconut protein isolate remodeled by pulsed light coupled with weak alkali cycling treatment

The interfacial flexibility of proteins is a crucial factor that affects their functional properties. In this study, we investigated the role of interfacial flexibility in the emulsifying ability of coconut protein isolate (CPI) treated by pulsed light coupled with weak alkali cycling (pH 7 → 9 → 7). After treatment, the structure of CPI was unfolded and re-folded, which resulted in the exposure of hydrophobic groups and the formation of smaller aggregates, with the change of secondary structure. Additionally, the S–S bond content increased while the free –SH content decreased. The interfacial flexibility of CPI-based samples at the oil-water interface was evaluated by dissipative quartz crystal microbalance and interfacial dilatational rheology. Compared to CPI, PCPI-9 (CPI treated by pulsed light coupled with pH 9 cycling) possessed a greater viscoelastic modulus and a smaller relaxation time. Meanwhile, the anti-perturbation ability was better than CPI. Then, microstructure, centrifugal stability and emulsifying properties of the O/W emulsions stabilized by CPI-based samples were measured. The results showed that emulsion stabilized by PCPI-9 had significant advantages in long-term stability. The emulsification stability (ESI) increased by 25.45 times compared to CPI. In conclusion, moderate pulsed light coupled with weak alkali cycling treatment could improve the emulsifying ability of CPI by remodeling its structure to change the interfacial flexibility. These results could provide an in-depth insight into the relationship between interfacial flexibility and emulsifying properties of coconut protein isolate.

Reservoir Sensitivity Analysis of Tight Sandstone and Its Controlling Factors: A Case Study from Chang 4+5 to Chang 6 Reservoirs in N 212 Well Block of Nanniwan Oilfield, Ordos Basin

Reservoir sensitivity can lead to the physical or chemical reactions to block the pore throat. It is helpful for reducing the damage on tight sandstone reservoir to study the reservoir sensitivity and its controlling factors. This paper mainly focuses on the tight sandstone of the Chang 4+5 and Chang 6 reservoirs of the Yanchang Formation in the Nanniwan Oilfield, Ordos Basin. The reservoir sensitivity characteristics were evaluated through the core sensitivity experiment after the petrological and petrophysical analysis and pore structure study. The influencing factors on tight sandstone reservoir sensitivity were discussed from several aspects, such as clay mineral composition, porosity, permeability, and pore structure. The results show that the rock type of the Chang 4+5 and Chang 6 reservoirs in the N 212 well block of the Nanniwan Oilfield is mainly arkose, with the mean porosity of 11.2% and 8.45% and the mean permeability of 0.35 × 10 − 3 μm2 and 0.44 × 10 − 3 μm2, respectively. The clay mineral components mainly include chlorite and illite/smectite. Both the two reservoirs are characterized by moderate to weak velocity sensitivity, moderate to weak water sensitivity, moderate to strong salt sensitivity, weak acid sensitivity, and moderate to weak alkali sensitivity. In specific, the Chang 4+5 reservoir is stronger in velocity and salt sensitivities, while it is weaker in water, acid, and alkali sensitivities than those of the Chang 6. The major controlling factors on reservoir sensitivity are clay mineral component, petrophysical property, and pore structure. Among these, the velocity sensitivity displays the positive correlation with pore structure, porosity, and permeability. The water sensitivity will become strong with the increase of the volume content of illite/smectite, but weak with the getting better of pore structure. The acid sensitivity is positively correlated with the volume content of chlorite but is negatively correlated with pore structure. With the getting better of pore structure, the salt sensitivity and alkali sensitivity will become strong and weak, respectively. The research results can be as the guidance for the tight sandstone reservoir protection in the study area and the adjustment and optimization of the regional reservoir development scheme.

Superhydrophobic soot as a mechanically robust, heat insulating and anti-corrosion protective coating for concrete surfaces

An artful strategy for protecting the concrete structures from cracking, flacking and corrosion is to make them non-wettable. Nonetheless, many hydrophobic modifiers are incompatible with the cement, hamper its hydration, possess weak alkali resistance and environmental toxicity, hence, retarding the adaptability of water-repellent chemicals in building materials. In this research, we propose a possible innovative solution to the aforementioned hurdles by drop-casting silicone-turpentine blend on pre-cured concrete and depositing rapeseed oil soot to convert the surface into superhydrophobic. The as-prepared silicone-soot composite inhibits the absorption of water and corrosive ions, thermally isolates the pristine concrete and withstands mechanical wear caused by abrasion, heavy rainfall, dynamic impact of sulfuric acid droplets and adhesion tape. Our invention is time-efficient, scalable and inexpensive, revealing opportunities for facile synthesis of durable superhydrophobic concrete on a large scale for aiding the construction of industrial facilities.

Co-Extraction of Flaxseed Protein and Polysaccharide with a High Emulsifying and Foaming Property: Enrichment through the Sequence Extraction Approach

A new focus with respect to the extraction of plant protein is that ingredient enrichment should target functionality instead of pursuing purity. Herein, the sequence aqueous extraction method was used to co-enrich five protein-polysaccharide natural fractions from flaxseed meal, and their composition, structure, and functional properties were investigated. The total recovery rate of flaxseed protein obtained by the sequence extraction approach was more than 80%, which was far higher than the existing reports. The defatted flaxseed meal was soaked by deionized water to obtain fraction 1 (supernatant), and the residue was further treated to get fraction 2 (supernatant) and 3 (precipitate) through weak alkali solubilization. Part of the fraction 2 was taken out, followed by adjusting its pH to 4.2. After centrifuging, the albumin-rich supernatant and precipitate with protein content of 73.05% were gained and labeled as fraction 4 and fraction 5. The solubility of fraction 2 and 4 exceeded 90%, and the foaming ability and stability of fraction 5 were 12.76 times and 9.89 times higher than commercial flaxseed protein, respectively. The emulsifying properties of fractions 1, 2, and 5 were all greater than that of commercial sodium caseinate, implying that these fractions could be utilized as high-efficiency emulsifiers. Cryo-SEM results showed that polysaccharides in fractions were beneficial to the formation of network structure and induced the formation of tighter and smoother interfacial layers, which could prevent emulsion flocculation, disproportionation, and coalescence. This study provides a reference to promote the high-value utilization of flaxseed meals.

Study on formation damage mechanism of carbonate reservoir in Shunbei No.2 area of northwest oil field

A series of experiments were carried out to evaluate and analyze the damage mechanism of carbonate reservoir in Shunbei No.2 Area, Xinjiang, China. According to the analysis of reservoir lithology and physical properties, combined with reservoir fluid characteristics and environmental characteristics, the potential factors of formation core damage were analyzed. The potential damage of reservoir is as follows: solid phase particle intrusion blockage, stress sensitivity and strong water lock damage. The effect of pressure time on permeability was eliminated by fracture stability correction. Fracture stability correction was used to evaluate core sensitivity. There is no velocity sensitive damage in the reservoir core, but weak water sensitive and salt sensitive damage, moderate and weak alkali sensitive damage and strong stress sensitive damage.

Improvement in alkali‐resistance of basalt fiber‐reinforced polymer by Ti3C2TX (MXene) modified matrix

AbstractFiber‐reinforced polymer (FRP) is a kind of potential construction material due to its low density and strong mechanical properties, but its weak alkali stability impedes its widespread use. MXene nanosheets' two‐dimensional (2D) property makes them an attractive contender as a nanofiller for polymer‐based composites. Here, a basalt fiber‐reinforced polymer (BFRP) laminate with a matrix modified with MXene nanosheets was made using a vacuum‐assisted resin‐transfer molding (VaRTM) process. The flexural strength (530.1 MPa) and flexural modulus (26.7 GPa) of the M0.5/BFRP composite were superior to those of the BFRP laminate, increasing by 39.4% and 4.6%, respectively. According to DMA examination, the MXene/BFRP composite exhibited increased crosslinking density, which could improve stability as well as aid in energy dissipation. As anticipated, the BFRP composites enhanced with MXene nanosheets demonstrated exceptional long‐term stability in a hostile alkali environment. After being submerged in alkali solution at 40°C for 60 days, the M0.5/BFRP's flexural strength reached 398.0 MPa, exceeding that of pristine BFRP that had not been submerged in alkali solution. This study gives an insight into the effect of MXene Ti3C2TX nanosheets modified resin on the durability of BFRP in strong alkali environment.

Ultrasound coupled with weak alkali cycling-induced exchange of free sulfhydryl-disulfide bond for remodeling interfacial flexibility of flaxseed protein isolates

The limitation of plant protein adsorbed on the oil/water interface is more rigid than milk protein. Herein, the interfacial rigidity or flexibility of flaxseed protein isolate (FPI) was regulated by ultrasound coupled with weak alkali cycling (pH 7 → 10→7) treatment. The interfacial properties of FPI during the treatment were investigated by interfacial rheology, Lissajous plots, cryo-SEM, and Langmuir-Blodgett films combined AFM tests. Compared with FPI, UFPI-10 (FPI treated by ultrasound coupled with pH 10 cycling) possessed higher emulsification stability (ESI∼308.20 min), increasing by 1.74 times. Three stages of emulsifying property enhancement were obtained. First, FPI aggregates had more disulfide bond (-S-S-). After treated by ultrasound coupled with weak alkali cycling, the protein underwent a deaggregation-reassembly process, resulting in the breakage of -S-S- and the exposure of internal sulfhydryl group (-SH) as well as hydrophobic group on the protein surface. These induced the significant improve of -SH and surface hydrophobicity (H0) as well as the decrease of particle size and -S-S- (P < 0.05). Second, the above altered structural properties endowed protein faster adsorption rate onto the interface. The -SH on the surface of adsorbed proteins could convert to -S-S-, leading to form an interfacial flexible layer with high viscoelastic modulus and mechanical behavior. Third, this tight and solid-like interfacial film affirmed by the cryo-SEM and interfacial dilatational rheological results could protect emulsion droplet against flocculation, coalescence, and disproportionation, thus contributing to good emulsification stability. We conformed that the exchange between -S-S- and -SH played an important role in regulating the interfacial flexibility.

Modelling the effect of pH and H2S on the germination of F. graminearum spores under different temperature conditions

Fusarium graminearum (F. graminearum) is a vital pathogen of Fusarium head blight (FHB). Hydrogen sulfide (H2S), which can be induced by stress in plants as a fungal inhibitor, affects the germination of spores through the detection of environmental factors such as temperature and pH. Based on mathematical models, F. graminearum was treated with different temperatures, pH, and H2S concentration to investigate spore germination events. This paper considered the synergistic effects of temperature and pH on spores in order to determine the optimal germination environment. Under these circumstances, the inhibition of spore germination with different concentrations of H2S was quantified. The results suggested that the germination time negatively correlates with the germinating rate. An increase in temperature altered the weak alkali preference of F. graminearum spores. At 28 °C, spores were more sensitive to the changes in pH. H2S gas could delay the germinating process significantly, however the required H2S concentration varied with environmental changes. This paper provides a perspective on the synergistic effect of temperature and pH on spore germination and contributes to determining the concentration of H2S as a management of FHB.

Convenient sorption of uranium by Amidoxime-functionalized mesoporous silica with magnetic core from aqueous solution

The use of inexpensive and biocompatible sorbents for effective removal of uranium from water environment is still an open challenge for many researchers. Herein, the magnetic amidoxime-functionalized mesoporous silica (MMS-AO) has been prepared by a combination of soft template method and co-condensation method in weak alkali oil/water phase. A feature of MMS-AO is core–shell configuration with Fe3O4 service as core, which makes the material easy to be recovered by an external magnetic field after sorption. Various characterization techniques of SEM, TEM, N2 sorption–desorption, FT-IR, TGA, Zeta potential and VSM were applied to evaluate MMS-AO. Batch sorption experiments confirmed that there were some good behavior to U(VI) removal on MMS-AO from aqueous including sorption capacity, selectivity and reusability. The experimental data fitted well to Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum sorption amount at 298 K and pH 5.50 was 236.70 mg·g−1 and the dynamic equilibrium can be reached in 90 min. The sorption process is spontaneous and endothermic via thermodynamic study. The analysis of XPS provided three insights on mechanism based on the chelation of U(VI) with amidoxime groups.