Study on the Effect of Cations on the Surface Energy of Nano-SiO2 Particles for Oil/Gas Exploration and Development Based on the Density Functional Theory.

Although nano SiO2 exhibits excellent application potential in the field of oil and gas exploration and development, such as drilling fluid, enhanced oil/gas recovery, etc., it is prone to agglomeration and loses its effectiveness due to the action of cations in saline environments of oil and gas reservoirs. Therefore, it is crucial to study the mechanism of the change in energy between nano SiO2 and cations for its industrial application. In this paper, the effect of cations (Na+, K+, Ca2+, and Mg2+) on the surface energy of nano SiO2 particles is investigated from the perspective of molecular motion and electronic change by density functional theory. The results are as follows: Due to the electrostatic interactions, cations can migrate towards the surface of nano SiO2 particles. During the migration process, monovalent cations are almost unaffected by water molecules, and they can be directly adsorbed on the surface by nano SiO2 particles. However, when divalent cations migrate from a distance to the surface of nano SiO2 particles, they can combine with water molecules to create an energy barrier, which can prevent them from moving forward. When divalent cations break through the energy barrier, the electronic kinetic energy between them and nano SiO2 particles changes more strongly, and the electrons carried by them are more likely to break through the edge of the atomic nucleus and undergo charge exchange with nano SiO2 particles. The change in interaction energy is more intense, which can further disrupt the configuration stability of nano SiO2. The interaction energy between cations and nano SiO2 particles mainly comes from electrostatic energy, followed by Van der Waals energy. From the degree of influence of four cations on nano SiO2 particles, the order from small to large is as follows: K+ < Na+ < Mg2+ < Ca2+. The research results can provide a theoretical understanding of the interaction between nano SiO2 particles and cations during the application of nano SiO2 in the field of oil and gas exploration and development.

Realizing Scalable Nano-SiO2-Aerogel-Reinforced Composite Polymer Electrolytes with High Ionic Conductivity via Rheology-Tuning UV Polymerization.

Polymer electrolytes for lithium metal batteries have aroused widespread interest because of their flexibility and excellent processability. However, the low ambient ionic conductivity and conventional fabrication process hinder their large-scale application. Herein, a novel polyethylene-oxide-based composite polymer electrolyte is designed and fabricated by introducing nano-SiO2 aerogel as an inorganic filler. The Lewis acid-base interaction between SiO2 and anions from Li salts facilitates the dissociation of Li+. Moreover, the SiO2 interacts with ether oxygen (EO) groups, which weakens the interaction between Li+ and EO groups. This synergistic effect produces more free Li+ in the electrolyte. Additionally, the facile rheology-tuning UV polymerization method achieves continuous coating and has potential for scalable fabrication. The composite polymer electrolyte exhibits high ambient ionic conductivity (0.68 mS cm-1) and mechanical properties (e.g., the elastic modulus of 150 MPa). Stable lithium plating/stripping for 1400 h in Li//Li symmetrical cells at 0.1 mA cm-2 is achieved. Furthermore, LiFePO4//Li full cells deliver superior discharge capacity (153 mAh g-1 at 0.5 C) and cycling stability (with a retention rate of 92.3% at 0.5 C after 250 cycles) at ambient temperature. This work provides a promising strategy for polymer-based lithium metal batteries.

Characterization and preliminary safety evaluation of nano-SiO2 isolated from instant coffee.

The physiological and toxicological evaluation of nano-silicon dioxide (nano-SiO2) particles in food is important for ensuring food safety. In this study, nano-SiO2 particles isolated from five brands of instant coffee, were structurally characterized using transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential analyses. Their toxicity was assessed by measuring cell viability, membrane integrity, and reactive oxygen species (ROS) levels in model gastrointestinal cells (GES-1 and Caco-2). Additionally, mortality, deformity rate, heart rate and death of whole zebra fish embryos were measured. The five types of nano-SiO2 samples comprised amorphous particles with a purity of approximately 99%, which met the food additive standard. Considering that the original particle size ranged from 10 to 50 nm, the samples were classified as nano-SiO2 food additives. Nano-SiO2 did not significantly impact the activity of GES-1 or Caco-2 cells, and no significant cell membrane damage was observed (Caco-2 cells exhibited mild micro damage); however, a slight increase in intracellular RPS levels was detected. Moreover, nano-SiO2 was found to cause head deformity, pericardial edema, yolk sac edema and tail bending. Collectively, the results show that nano-SiO2 time- and dose-dependently affects GES-1 and Caco-2 cell viability, as well as the mortality, heart rate, and abnormality rate of zebra fish embryos. Specifically, a high concentration (≥ 200 µg/mL) and long exposure time (≥ 48 h) of food additive nano-SiO2 affected GES-1, Caco-2 cells, and the gastrointestinal tract in zebra fish embryos.

Experimental Study on Damage Identification of Nano-SiO2 Concrete Filled GFRP Tube Column Using Piezoceramic Transducers.

This paper proposes a new approach to damage detection of nano-SiO2 concrete-filled glass fiber reinforced polymer (GFRP) tube column using piezoceramic transducers. Stress waves are emitted and received by a pair of piezoceramic transducers embedded in the concrete-filled GFRP tube, and the energy and damage indices at different levels of loading in the tube are obtained by wavelet packet to evaluate the damage degree of GFRP tube nano-SiO2 concrete column. Through the experimental studies, the effects of different nano-SiO2 contents, concrete grades, and superplasticizer on the damage were analyzed to gain load-displacement curves, load-energy index curves, and load-damage index curves. The results show that the wave method can be adopted to monitor the damage of GFRP tube nano-SiO2 concrete column. The specimens with 3% nano-SiO2 content have the smallest energy change rate, indicating that adding 3% nano-SiO2 content into concrete can effectively delay the development of damage. After the addition of superplasticizer, with the increase in the strength grade of concrete, the cracks in the specimen tend to develop slowly, and therefore the specimens have a stronger resistance to damage. The damage of the specimens with the nano-SiO2 content of 1% appeared the latest, while the damage without the nano-SiO2 specimen appeared the fastest. The experimental results show that this method can better monitor the damage of the Nano-SiO2 concrete in the glass fiber reinforced polymer (GFRP) tube.

Effect of Silicon Nitride/Oxide on the Structure and the Thermal Conductivity of CoSi Nanocomposites.

In this work, the fabrication of nanocomposites with silicon nitride/oxide into the thermoelectric matrix of cobalt silicide is presented. The different concentrations of nano-Si3N4 were intentionally introduced by mechanical grinding while it was found that the nanocomposites also included SiO2 phase at micro- as well as at nano-scale. The structural and morphological modifications of the materials were studied by powder X-ray Diffraction, Scanning Electron Microscopy and Transmission Electron Microscopy. The nanocomposites were studied in terms of Hall Effect, Seebeck coefficient, electrical and thermal conductivity. Emphasis is given on the lattice thermal conductivity that was analyzed based on Effective Medium Theory and the contribution of each phase is taken into account.

Combined exposure to nano-silica and lead induced potentiation of oxidative stress and DNA damage in human lung epithelial cells.

Growing evidence has confirmed that exposure to ambient particulate matters (PM) is associated with increased morbidity and mortality of cardiovascular and pulmonary diseases. Ambient PM is a complex mixture of particles and air pollutants. Harmful effects of PM are specifically associated with ultrafine particles (UFPs) that can adsorb high concentrations of toxic air pollutants and are easily inhaled into the lungs. However, combined effects of UFPs and air pollutants on human health remain unclear. In the present study, we elucidated the combined toxicity of silica nanoparticles (nano-SiO2), a typical UFP, and lead acetate (Pb), a typical air pollutant. Lung adenocarcinoma A549 cells were exposed to nano-SiO2 and Pb alone or their combination, and their combined toxicity was investigated by focusing on cellular oxidative stress and DNA damage. Factorial analyses were performed to determine the potential interactions between nano-SiO2 and Pb. Our results showed that exposure of A549 cells to a modest cytotoxic concentration of Pb alone induced oxidative stress, as evidenced by elevated reactive oxygen species generation and lipid peroxidation, and reduced glutathione content and superoxide dismutase and glutathione peroxidase activities. In addition, exposure of A549 cells to Pb alone induced DNA damage, as evaluated by alkaline comet assay. Exposure of A549 cells to non-cytotoxic concentration of nano-SiO2 did not induce cellular oxidative stress and DNA damage. However, exposure to the combination of nano-SiO2 and Pb potentiated oxidative stress and DNA damage in A549 cells. Factorial analyses indicated that the potentiation of combined toxicity of nano-SiO2 and Pb was induced by additive or synergistic interactions.

Creep and Shrinkage Properties of Nano-SiO2-Modified Recycled Aggregate Concrete.

The poor performance of recycled concrete aggregate (RCA) leads to greater creep in recycled aggregate concrete (RAC) compared to natural aggregate concrete (NAC). To enhance the quality of RCA, this paper utilizes a 2% concentration of a nano-SiO2 (NS) solution for pre-soaking RCA. This study aims to replace natural aggregate (NA) with NS-modified recycled aggregate (SRCA) and investigate the creep and shrinkage properties of NS-modified recycled aggregate concrete (SRAC) at various SRCA replacement rates. Subsequently, the creep and shrinkage strains of NAC, SRAC, and RAC are simulated using the finite element method. Finally, a comparative analysis is conducted with the predicted creep and shrinkage strains from CEB-FIP, ACI, B3, and GL2000 models. The experimental results indicate that the creep and shrinkage deformation of SRAC increases with the SRCA replacement rate. Compared to NAC, the creep and shrinkage deformation of SRAC at replacement rates of 30%, 50%, 70%, and 100% increased by 2%, 7%, 13%, and 30%, respectively. However, when 100% of the natural aggregate is replaced with SRCA, the creep and shrinkage deformation decreases by 7% compared to RAC. Moreover, the CEB-FIP and ACI models can predict the creep and shrinkage deformation of concrete reasonably well.

Simultaneous stabilization of particulate and bioavailable arsenic in soils from the realgar mining area by polyacrylamide, nano-SiO2, and ferrihydrite composite materials.

Arsenic (As) contamination in realgar mining areas poses a severe environmental and health risk, highlighting the critical need for effective strategies to manage As migration, particularly in its particulate and bioavailable states. Soil erosion and water leaching serve as significant pathways for spreading As, emphasizing the imperative to curtail its mobility. In the present study, we proposed an effective strategy that combines the utilization of polyacrylamide (PAM), nano-SiO2 (NS), and ferrihydrite (Fh) to elevate the stability of As in soils from a realgar mining area. The results show that this composite material demonstrates the capability to concurrently regulate soil erosion and mitigate the leaching of bioavailable As. The combination of the three materials in the proportion of 0.5 % PAM +0.1 % NS + 1.0 % Fh can reduce the soil particulate and bioavailable As content by 99.11 % and 93.98 %, respectively. The unconfined compressive strength of the soil can be increased by about 30 % under this condition. The SEM analyses show that the addition of PAM and NS can significantly enhance the aggregation of soil particles and then reduce the soil erosion rate. These findings highlight the significant potential of the proposed approach in mitigating As contamination in soil within mining environments. The approach offers a sustainable and comprehensive solution to address the transport of heavy metal contaminants in both particulate and bioavailable states in mining areas.

Self-Healing Properties of Water Tree with Microcapsule/Cross-Linked Polyethylene Composite Material Based on Three-Layer Core-Shell Structure.

To overcome the degradation of insulating properties caused by the water tree aging of cross-linked polyethylene (XLPE), a self-repairing material for XLPE based on a microcapsule system is proposed. Three-layer shell nucleus microcapsules/XLPE composites with different microcapsule doping content are prepared. The water tree aging experiments are carried out using the water-needle electrode method to analyze the ability of microcapsules to repair the damaged areas of water trees. The results show that, compared with the XLPE material without microcapsules, the electrical properties of composites decline significantly when the doping concentration of three-layer shell nucleus microcapsules is large. When the doping concentration is 1.0 wt%, the microcapsule/XLPE composite breakdown strength has no noticeable change, and the dielectric loss factor does not change significantly, the space charge density decreases, and the space charge properties have been improved considerably. When the water tree branch develops to the position where the microcapsules are located, the microcapsules will rupture and release their internal repair materials and catalysts and react with water to produce an organic silicone resin to fill the water tree cavity, which can achieve an excellent self-healing effect. In addition, the nano-SiO2 on the surface microcapsules can make the microcapsules and matrix better integrated, which avoids the microcapsule accumulation that tends to occur when incorporating microcapsules, thus improving the repair rate.

A Critical Review Examining the Characteristics of Modified Concretes with Different Nanomaterials.

The movement of the construction industry towards sustainable development has drawn attention to the revision of concrete. In addition to reducing pollution, the use of nano-materials should lead to the provision of higher quality concrete in terms of regulatory items (workability, resistance characteristics, durability characteristics, microstructure). The present study investigates 15 key characteristics of concrete modified with nano-CaCO3, nano-clay, nano-TiO2, and nano-SiO2. The results of the study showed that nanomaterials significantly have a positive effect on the hydration mechanism and the production of more C-S-H gel. The evaluation of resistance characteristics also indicates the promising results of these valuable materials. The durability characteristics of nano-containing concrete showed significant improvement despite high dispersion. Concrete in coastal areas (such as bridges or platforms), concrete exposed to radiation (such as hospitals), concrete exposed to impact load (such as nuclear power plants), and concrete containing recycled aggregate (such as bricks, tiles, ceramics) can be effectively improved by using nanomaterials. It is hoped that the current review paper can provide an effective image and idea for future applied studies by other researchers.

Cyclic Behavior and Stress-Strain Model of Nano-SiO2-Modified Recycled Aggregate Concrete.

Recycled aggregate concrete (RAC) possesses different mechanical properties than ordinary concrete because of inherent faults in recycled aggregates (RAs), such as the old interfacial transition zone (ITZ). However, the application of nano-SiO2 presents an effective methodology to enhance the quality of RA. In this study, nano-SiO2-modified recycled aggregate (SRA) was used to replace natural aggregate (NA), and the stress-strain relationships and cyclic behavior of nano-SiO2-modified recycled aggregate concrete (SRAC) with different SRA replacement rates were investigated. After evaluating the skeleton curve of SRAC specimens, the existing constitutive models were compared. Additionally, the study also proposed a stress-strain model designed to predict the mechanical behavior of concrete in relation to the SRA replacement rate. The results show that compared with RAC, the axial compressive strength of SRAC specimens showed increases of 40.27%, 29.21%, 26.55%, 16.37%, and 8.41% at specific SRA replacement rates of 0%, 30%, 50%, 70%, and 100%, respectively. Moreover, the study found that the Guo model's calculated results can accurately predict the skeleton curves of SRAC specimens.

Preparation and characterization of polyvinyl alcohol (PVA)-glycerol composite films incorporating nanosilica from municipal solid waste incinerator bottom ash.

This study investigates the fabrication of a composite film composed of polyvinyl alcohol (PVA) and glycerol, incorporating nanosilica derived from municipal solid waste incinerator bottom ash (BA). The nanosilica is blended with a PVA film-forming solution containing glycerol as a plasticizer. The composite films are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Additionally, thermogravimetric analysis (TGA) is conducted to evaluate the thermal properties, while the mechanical properties are assessed in terms of tensile strength (TS) and elongation at break (EAB). The results indicate that the presence of silica nanoparticles reduces transparency and increases film thickness in the presence of glycerol. Notably, the film containing 1% silica demonstrates a significant enhancement in tensile strength, exhibiting a 50% increase compared to the film without silica. However, higher silica loadings lead to a deterioration in mechanical properties due to silica agglomeration within the polymer matrix. As expected, the presence of silica in the films slightly elevates the degradation temperature.

In Vivo Toxicity of Oral Administrated Nano-SiO2: Can Food Additives Increase Apoptosis?

Nano-silicon dioxide (nano-SiO2) has a great deal of application in food packaging, as antibacterial food additives, and in drug delivery systems but this nanoparticle, despite its wide range of utilizations, can generate destructive effects on organs such as the liver, kidney, and lungs. This study is aimed at investigating the toxicological effects of nano-SiO2 through apoptotic factors. For this purpose, 40 female rats in 4 groups (n = 10) received 300, 600, and 900 mg/kg/day of nano-SiO2 at 20-30 nm size orally for 20 days. Relative expression of Caspase3, Bcl-2, and BAX genes in kidney and liver was evaluated in real time-PCR. The results indicated the overexpression of BAX and Caspase3 genes in the liver and kidney in groups receiving 300 and 900 mg/kg/day of nano-SiO2. Bcl-2 gene was up-regulated in the liver and kidney at 600 mg/kg/day compared to the control group. Overexpression of the Bcl-2 gene in the kidney in 300 and 900 mg/kg/day recipient groups was observed (P ≤ 0.05). Histopathological examination demonstrated 600 mg/kg/day hyperemia in the kidney and lungs. In addition, at 900 mg/kg/day were distinguished scattered necrosis and hyperemia in the liver. The rate of epithelialization in the lungs increased. The nano-SiO2 at 300 and 900 mg/kg/day can induce more cytotoxicity in the liver and lung after oral exposure. However, cytotoxicity of nano-SiO2 at 600 mg/kg/day in the kidney and lung was noticed. Hence, the using of nano-SiO2 as an additive and food packaging should be more considered due to their deleterious effects.

Experimental Study on the Curing Mechanism of Red Mud-Based Stabilized Soil Co-Modified by Nano-SiO2 and Gypsum.

In order to effectively utilize red mud and reduce its occupation of land resources, as well as its impact on the environment, experiments were conducted to develop stabilized soil materials using nano-SiO2 synergistically modified red mud and to investigate the curing mechanism of stabilized soil. The unconfined compressive strength, microscopic morphology, and curing mechanism of the red mud-based stabilized soil materials with different amounts of modified materials were investigated. The test results show that after 7 days of curing, the unconfined compressive strength of red mud-based stabilized soil meets the compressive strength requirement of road base material when nano-SiO2, gypsum, and cement are synergistically modified. In such cases, the soil structure has the lowest fracture rate and the best structural compactness when the amount of nano-SiO2 is 1%. It is found that the needle-like and columnar calcium alumina in the modified red mud-based stabilized soil increases, and the binding energy of hydration product ions in the modified material is improved. The chemical curing mechanism of modified red mud-based stabilized soil includes hydration reaction, pozzolanic reaction, promotion effect of nano-SiO2, and enhancement effect of gypsum. On this base, a model of the early start hydration process of red mud-based stabilized soil promoted by nano-SiO2 is established.

Enhancement of Hydration Activity and Microstructure Analysis of γ-C2S.

This paper investigated the combined effect of chemical activators and nano-SiO2 on the hydration reaction and the microstructure of γ-C2S. The hydration reaction of γ-C2S slurry activated with chemical activators (NaHCO3, NaOH, K2CO3, and KOH at 1 mol/L) was enhanced by 1% nano-SiO2. The hydrate reaction rate was determined by isothermal calorimetry, and the hydrated samples were characterized by XRD, TGA/DTG, SEM-EDS, and 29Si MAS/NMR. The results revealed a substantial enhancement in the hydration activity of γ-C2S due to the presence of the alkaline activator. Furthermore, nano-SiO2 did not alter the composition of γ-C2S hydration products, instead providing nucleation sites for the growth of hydration products. Incorporating nano-SiO2 promoted the formation of C-(R)-S-H gel with a low calcium-to-silica ratio and increased its polymerization levels, resulting in more favorable structures. Among all the activators used in this study, potassium salts had a better activation effect than sodium salts. After 28 days of curing, the degree of hydration reaction in the KC+Si group was 48% and about 37% for the NHC+Si group. Whereas, the KH+Si and NH+Si groups only reached approximately 20% after the same hydration duration.

Modified nano-SiO2/PU hydrophobic composite film prepared through in-situ coupling by KH550 for oil-water separation.

In this study, hydrophobic polymer composite films based on polyurethane (PU) were prepared for oil-water separation. Hydrophilic fumed silica (nano-SiO2) was introduced as reinforcing filler, and silane coupling agent (KH550) was used to crosslink PU with nano-SiO2 in situ for enhancing the nano-SiO2 dispersion in the films. The microscopic morphology, crystalline structure, and hydrophobic properties of the films were characterized by using scanning electron microscopy, X-ray diffraction, FTIR spectroscopy, water contact angle, and water absorption tests. The results showed that the hydrophobicity of the nano-SiO2/PU composite films increased with the addition of nano-SiO2. KH550 not only significantly promoted the crosslink action between PU and nano-SiO2 but also enhanced the dispersion of nano-SiO2 in the composite films. Moreover, the pore structure of the prepared films was changed with the addition of nano-SiO2 and KH550, which greatly improved the hydrophobicity. The test results for oil-water separation performance showed that the prepared composite films can efficiently separate the oil from oil-water mixtures with good repeatability.

Analysis of the Synergistic Effect on the Strength Characteristics of Modified Red Mud-Based Stabilized Soil.

Based on the existing research results, this research team developed roadbed stabilized soil materials using nano-SiO2 synergistically modified red mud in order to study whether the strength of the stabilized soil materials meets the strength requirements of the roadbed materials, and at the same time, analyze its strength characteristics to make the feasibility of it being used as a roadbed material clear. Through different combination schemes, the effects of different nano-SiO2 and cement contents on the strength of the stabilized materials were explored. The test results show the following: In the synergistic modification of nano-SiO2 and cement, nano-SiO2 can significantly improve the early unconfined compressive strength of red mud-based stabilized soil. In the synergistic modification of nano-SiO2, gypsum, and cement, the 7 d unconfined compressive strength of red mud-based stabilized soil is greater than 2 MPa, which meets the strength requirements of road base materials and shows the superiority of synergism. The nominal stress-strain curves are divided into five stages: compressed and compacted stage, elastic deformation stage, plastic deformation stage, damage deformation stage, and residual deformation stage. The macroscopic compressive damage pattern of the specimens shows that the modified red mud-based stabilized soil mostly exhibits brittle damage. Tests have shown that the strength of modified terracotta-based stabilized soil meets the requirements of roadbed strength.

Influence of Nano-SiO2 Content on Cement Paste and the Interfacial Transition Zone.

Nano-SiO2 (NS) is widely used in cement-based materials due to its excellent physical properties. To study the influence of NS content on a cement paste and the interfacial transition zone (ITZ), cement paste samples containing nano content ranging from 0 to 2% (by weight of cement) were prepared, and digital image correlation (DIC) technology was applied to test the mechanical properties. Finally, the optimal NS content was obtained with statistical analysis. The mini-slump cone test showed that, with the help of superplasticizer and ultrasonic treatment, the flowability decreased continuously, as the NS content increased. The DIC experimental results showed that NS could effectively improve the mechanical properties of the cement paste and the ITZ. Specifically, at the content level of 1%, the elastic modulus of cement paste and ITZ was 20.95 GPa and 3.20 GPa, respectively. When compared to that without nanomaterials, the increased amplitude was 73.50% and 90.50%, respectively. However, with the further increase in NS content, the mechanical properties decreased, which was mainly caused by the agglomeration of nanomaterials. Additionally, the NS content did not exhibit a significant effect on the thickness of the ITZ, and its value was maintained at 76.91-91.38 µm. SEM confirmed that NS would enhance the microstructure of both cement paste and ITZ.

Local Electrochemical Corrosion of 6061 Aluminum Alloy with Nano-SiO2/MAO Composite Coating.

To improve the corrosion resistance of 6061 Al in electric vehicle battery packs, a composite coating of nano-SiO2/Micro-Arc oxidation (MAO) ceramic structure was prepared on its surface. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves (PDP) were used to evaluate the corrosion resistance of the specimens after 7 days immersion in a 3.5% NaCl solution. The corrosion resistance of the prefabricated coatings was measured via local electrochemical impedance spectroscopy (LEIS). Confocal microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize the microstructure and phase composition of the specimens. An energy dispersive spectrometer (EDS) was used to detect the elemental composition of the surface of the specimen. The results showed that the specimen with nano-SiO2/MAO composite coating had the least amount of micropores and superior corrosion resistance. The global electrochemical impedance of nano-SiO2/MAO composite coating was 1.1 times higher than that of the MAO coating and 8.4 times higher than that of the 6061 Al. When the coating was defective, the local electrochemical impedance of the nano-SiO2/MAO composite coating was still two times higher than that of the MAO coating. In the presence of scratches, the nano-SiO2/MAO composite coating still showed high corrosion resistance. The collapse corrosion mechanism of the nano-SiO2/MAO composite coating was proposed.

Investigation of Polymer Gel Reinforced by Oxygen Scavengers and Nano-SiO2 for Flue Gas Flooding Reservoir.

Polymer gel plugging is an effective technique for gas mobility control in flue gas flooding reservoirs. However, the performance of polymer gels is extremely susceptible to the injected flue gas. A reinforced chromium acetate/partially hydrolyzed polyacrylamide (HPAM) gel, using thiourea as the oxygen scavenger and nano-SiO2 as the stabilizer, was formulated. The related properties were evaluated systematically, including gelation time, gel strength, and long-term stability. The results indicated that the degradation of polymers was effectively suppressed by oxygen scavengers and nano-SiO2. The gel strength would be increased by 40% and the gel kept desirable stability after aging for 180 days at elevated flue gas pressures. Dynamic light scattering (DLS) analysis and Cryo-scanning electron microscopy (Cryo-SEM) revealed that nano-SiO2 was adsorbed on polymer chains by hydrogen bonding, which improved the homogeneity of gel structure and thus enhanced the gel strength. Besides, the compression resistance of gels was studied by creep and creep recovery tests. The failure stress of gel with the addition of thiourea and nanoparticles could reach up to 35 Pa. The gel retained a robust structure despite extensive deformation. Moreover, the flow experiment indicated that the plugging rate of reinforced gel still maintained up to 93% after flue gas flooding. It is concluded that the reinforced gel is applicable for flue gas flooding reservoirs.