Sheet Surface Research Articles

Direct Z-Scheme CoFe2O4-Loaded g-C3N4 Photocatalyst with High Degradation Efficiency of Methylene Blue under Visible-Light Irradiation

Magnetically recyclable direct Z-scheme CoFe2O4-loaded g-C3N4 photocatalyst material was fabricated using a facile hydrothermal technique and subsequently characterized by XRD, VSM, PL, FT-IR, EDX, DRS, SEM, and BET techniques. The characterization results confirmed that nanoparticles of CoFe2O4 are loaded on the surface of g-C3N4 sheets. The optical band gap of g-C3N4 has been decreased from 2.65 eV to 1.30 eV by means of the loading of CoFe2O4 nanoparticles onto the nanosheets of g-C3N4. This has enhanced the separation process of electron-hole. Under visible light irradiation, the photocatalytic activity of the developed direct Z-scheme CoFe2O4-loaded g-C3N4 photocatalyst was evaluated for the photodegradation of methylene blue (MB); during this process the MB decomposed by up to 98.86% in 140 min. Meanwhile, under the same irradiation and time conditions, the g-C3N4 and CoFe2O4 themselves degraded MB up to 74.92% and 51.53%, respectively. The direct Z-scheme CoFe2O4-loaded g-C3N4 material was recovered from the solution after the photocatalytic activity using an external magnet and studied to determine its stability. It was shown that the photoactivity did not change significantly after five consecutive cycles.

Surface Plasmon Resonance Induced Photocatalysis in 2D/2D Graphene/g-C3N4 Heterostructure for Enhanced Degradation of Amine-Based Pharmaceuticals under Solar Light Illumination

Pharmaceuticals, especially amine-based pharmaceuticals, such as nizatidine and ranitidine, contaminate water and resist water treatment. Here, different amounts of graphene sheets are coupled with g-C3N4 nanosheets (wt% ratio of 0.5, 1, 3 and 5 wt% of graphene) to verify the effect of surface plasmon resonance introduced to the g-C3N4 material. The synthesized materials were systematically examined by advanced analytical techniques. The prepared photocatalysts were used for the degradation of amine-based pharmaceuticals (nizatidine and ranitidine). The results show that by introducing only 3 wt% graphene to g-C3N4, the absorption ability in the visible and near-infrared regions dramatically enhanced. The absorption in the visible range was 50 times higher when compared to the pure sample. These absorption features suggest that the surfaces of the carbon nitride sheet are covered by the graphene nanosheet, which would effectively apply the LSPR properties for catalytic determinations. The enhancement in visible light absorption in the composite was confirmed by PL analysis, which showed greater inhibition of the electron-hole recombination process. The XRD showed a decrease in the (002) plan due to the presence of graphene, which prevents further stacking of carbon nitride layers. Accordingly, the Gr/g-C3N4 composite samples exhibited an enhancement in the photocatalytic performance, specifically for the 5% Gr/g-C3N4 sample, and close to 85% degradation was achieved within 20 min under solar irradiation. Therefore, applying the Gr/g-C3N4 for the degradation of a pharmaceutical can be taken into consideration as an alternative method for the removal of such pollutants during the water treatment process. This enhancement can be attributed to surface plasmon resonance-induced photocatalysis in a 2D/2D graphene/g-C3N4 heterostructure.

A facile synthesis of sub-10 nm Ni2P/g-C3N4 photocatalytic composite with ohmic contact for clean H2-energy generation under visible light irradiation

It is very attractive to find a cheap and efficient cocatalyst for enhancing the H2 generation of graphitic carbon nitride (CN) under visible light. To achieve that, we proposed a novel two-step method to deposit sub-10 nm metallic Ni2P particles on the surface of CN sheets for a maximized interfacial contact. Characteristic results confirmed the establishment of ohmic heterojunction upon Ni2P-modification of CN, which deemed to be an effective measure to alleviate photo-charges recombination. In addition to facilitating spatial separation of charges, Ni2P could also enhance the optical properties of CN while reducing its impedance for interfacial electron shuttling. Better still, the P-end of Ni2P is highly electronegative, offering desirable H+-capturing capability for enhanced H2 generation. These give rise to an improved H2 production of Ni2P/CN composite, optimally at 645.3 μmol g−1·h−1 as compared to immeasurable H2 yielded by the pristine CN. Such photocatalytic performance is even comparable to the Pt-modified CN photocatalyst (640.6 μmol g−1·h−1). In recyclability test, a notable activity suppression of 33.17% was recorded after four reaction cycles. This can be ascribed to the pronounced photo-corrosion of the Ni2P cocatalyst during photoreaction. Nonetheless, a remarkably high H2 generation (1328.6 μmol g−1 in 3 h) was still attained at 4th cycle. This justifies the effectiveness of our synthesized Ni2P cocatalyst in enhancing H2 generation of CN under visible light irradiation.

Enhanced Photocatalytic Degradation of Emerging Contaminants Using Ti3C2Tx MXene-Supported CdS Quantum Dots.

The synthesis of efficient and stable catalysts for photocatalytic reactions is still a challenge. In this study, a new photocatalyst composed of two-dimensional titanium carbide (Ti3C2Tx) and CdS quantum dots (QDs) was fabricated, in which CdS QDs were intimately anchored on the Ti3C2Tx sheet surface. Due to the specific interface characteristics of CdS QDs/Ti3C2Tx, Ti3C2Tx can considerably facilitate the generation of photogenerated charge carriers, their separation, and their transfer from CdS. As expected, the obtained CdS QDs/Ti3C2Tx exhibit outstanding photocatalytic performance for carbamazepine (CBZ) degradation. Moreover, the quenching experiments demonstrated that superoxide radicals (•O2-), H2O2, 1O2, and •OH are the reactive species involved in CBZ degradation, while •O2- made a major contribution. In addition, the sunlight-driven CdS QDs/Ti3C2Tx photocatalytic system is widely suitable for the elimination of different emerging pollutants in various water matrices, suggesting its potential practical environmental applications.

Stabilization of lysozyme in aqueous dispersion of graphene oxide sheets

This study examines the effect of surface oxygen groups upon ability of graphene oxide (GO) sheets in suppressing the fibrillation of lysozyme (LYZ). Graphite was oxidized using 6 and 8 wt equivalents of KMnO4, and as produced sheets were abbreviated as GO-06 and GO-08, respectively. Particulate characteristics of sheets were characterized by light scattering and electron microscopic techniques, and their interaction with LYZ was analysed by circular dichroism (CD) spectroscopy. After ascertaining acid-driven conversion of LYZ to fibrillary form, we have shown that the fibrillation of dispersed protein can be prevented by adding GO sheets. Inhibitory effect could be attributed to binding of LYZ over the sheets via noncovalent forces. A comparison between GO-06 and GO-08 samples showed superior binding affinity of the latter. Higher aqueous dispersibility and density of oxygenated groups in GO-08 sheets would have facilitated the adsorption of protein molecules, thus making them unavailable for aggregation. Pre-treatment of GO sheets with Pluronic 103 (P103, a nonionic triblock copolymer), caused reduction in the adsorption of LYZ. P103 aggregates would have rendered the sheet surface unavailable for the adsorption of LYZ. Based on these observations, we conclude that fibrillation of LYZ can be prevented in association with graphene oxide sheets.

MXene/chitosan/lignosulfonate (MCL) nanocomposite for simultaneous removal of Co(II), Cr(VI), Cu(II), Ni(II) and Pb(II) heavy metals from wastewater

In this work, a novel Ti3C2T x MXene/chitosan/lignosulfonate adsorbent (MCL), was prepared via a facile decoration of Ti3C2T x MXene sheets with chitosan/lignosulfonate nanospheres as a renewable and biodegradable additive that can improve the biocompatibility and aqueous stability of MXenes. Chitosan/lignosulfonate nanospheres were stabilized on the surface of MXne sheets, endowing them with a variety of surface functionalities, high specific surface area, and antioxidant characteristics. The competitive adsorption of multi-metal systems revealed that MCL had a preferential adsorption affinity toward various heavy metal ions; the MCL removal efficiency for the quinary-metal ions adsorption followed a trend of Pb(II) > Cr(VI) ≈ Cu(II) > Ni(II) ≈ Co(II) in neutral pH conditions. A moderate reduction was observed for Cu(II) and Cr(VI) ions. For all metals, the kinetics data fitted well with the pseudo-second-order model, and the adsorption equilibrium was best described by the Langmuir model. The adsorption mechanism is suggested to be a synergic combination of electrostatic interaction, surface complexation, and ion exchange. The findings of this study provide a new approach for eco-friendly MXene surface modification and give a general pattern of metal pollutants interactions during adsorption.

S-scheme heterojunction CeO2/TiO2 modified by reduced graphene oxide (rGO) as charge transfer route for integrated photothermal catalytic oxidation of Hg0

This study explored the photothermal catalytic oxidation of Hg0 by using S-scheme heterojunction CeO2/TiO2 modified by reduced graphene oxide (rGO) at 100-200 °C. The surface properties of self-prepared photothermal catalysts were characterized by BET, SEM, TEM, EDS, XRD, Raman, UV–Vis, XPS, EPR, and UPS. The crystal structure of TiO2 was mainly anatase and the nano-sized CeO2/TiO2 was uniformly distributed on the surface of the rGO sheet. The oxidation efficiency of Hg0 decreased with reaction temperature in the order of Ƞ100 °C = Ƞ150 °C > Ƞ200 °C, implying that the oxidation of Hg0 was controlled by mass transfer governed by adsorption instead of photothermal catalytic reaction. Both photo- and thermos-catalytic reaction mechanisms were involved in the oxidation of Hg0 at 100–200 °C. Moreover, rGO-modified CeO2/TiO2 could tolerate multi-pollutants (SO2 and NO) except for 100 ppm NO, which slightly reduced the oxidation efficiency of Hg0.

Features of radiothermal study of ice in the microwave range

The subject of the study is ice formations, which are formed as a result of the release of groundwater to the surface of ice sheets or soil. These formations cause significant damage in human economic activity. The work investigated natural ice located on fresh ice cover, as well as artificial ice formations on the ground. The glaciers located in the Transbaikal region near the city of Chita were investigated. The power of thermal radiation of these objects in the microwave range was determined at wavelengths of 2.3 cm and 0.88 cm. The power of thermal radiation in the microwave range was determined using radiometric receivers at wavelengths of 0.88 cm and 2.3 cm mounted on a car or on a fixed support. Cores of ice removed from the ice were studied to determine the layer-by-layer distribution of ice mineralization. A model of a plane-layered non-isothermal medium was used to calculate the thermal radiation of ice. The possibility of registering ice formations by radiothermal radiation of these objects in the microwave range is shown. If there is a layer of water on the ice, the radio brightness temperature will be significantly lower than the object on the surface of which there is no water mass. By the value of the radio brightness temperature in the microwave range for several ranges, as a result of which it is possible to indirectly estimate the thickness of ice formations. At the same time, it is necessary to take into account the variations in the radiofrequency temperature of the medium depending on its thickness due to the interference of radiothermal radiation of a plane-layered medium.

Study on microstructure and mechanical properties of RSW joints of 7075T-6 containing Sc

Currently, resistance spot welding (RSW) is a common welding method used in automobile and other industries, and 7000 series aluminum (Al) alloys have become a very common industrial material because of their high strength and easy machinability. Scandium (Sc) is often used for alloy strengthening; however, there are few studies on the RSW joints of aluminum alloys containing scandium. Here, 7075-T6 alloys containing a small amount of scandium were obtained to investigate the joint of resistance spot weldability. The simulation shows that the effective contact area between the aluminum sheet surface is about 19.5%, which is an important factor in nucleation. It was found that the average grain size of the nugget decreased from 51.51 ± 5.74 to 8.15 ± 1.09 μm when scandium was added from 0 to 0.4 wt%, which is mainly due to Al3Sc particles acting as a heterogeneous nucleus in the melt. The test results show that the tensile shear strength of welded joints with 0.4 wt% scandium addition is 29.2% higher than that of the joints without scandium because of grain refinement strengthening.

Sustainable synthesis of cellulose-derived magnetic iron oxide/sulfonated graphene oxide-like material from corncob for conversion of hemicellulose to furfural

Developing a method to convert biomass sources into valuable products has always been a matter of great interest to many researchers. In this work, a cellulose-derived magnetic iron oxide/sulfonated graphene oxide-like (Cel-MSGO) material was synthesized from corncob by sulfonation and hydrothermal processing, in order to catalyze the conversion of hemicellulose to furfural. Characteristics of the as-synthesizedCel-MSGO were investigated using modern analytical methods. Scanning electron microscopy revealed that Fe3O4particles were attached to the surface of sheets structurally similar to sulfonated graphene oxide. The sheet-like structure of the obtained Cel-MSGO was also observed from high-resolution transmission electron microscopy as similar to that of graphene oxide. The Cel-MSGO material was investigated for its ability to convert hemicellulose of corncob into furfural through the following factors: reaction temperature, reaction time, amount of catalyst, and solvent ratio H2O:γ-valerolactone (H2O:GVL). The Cel-MSGO material showed excellent catalysis with a furfural yield of 55.05%, xylose conversion of 97.80%, and furfural selectivity of 57.20% under reaction conditions of 190°C, a reaction time of 150 min, and a catalyst amount of 10 wt% in a solvent system consisting 80:20 H2O:GVL (v/v). Furthermore, the catalyst showed good reusability after6 cycles. This study opens a new application direction in utilizing biomass to synthesize high-value products, contributing to reducing environmental pollution and solving the situation of exhausted renewable raw materials.

Effect of oxidation on mechanical properties and surface condition of heat-resistance titanium alloy VT41

The present article dedicated to influence of oxygen affected zone of VT41 heat-resistant titanium alloy's samples. The samples were made of 023 mm rods and 1 mm thick sheets and processed by short term heat treatment at 300 - 900°C in atmosphere furnace. Mechanical properties of samples were measured at room temperature by straining (rods) and bending (sheets) Surface of fractured samples were studied by means of ТЕМ. The results of the present work gave an opportunity to match the temper colors of the samples with the temperature of heat-treatment, mechanical properties and the depth of fragile oxygen affected zone. The dependencies of relative strain and reduction area versus heat-treatment temperatures were determined. It was defined that a critical changing of plasticity's characteristics appears at heattreatment temperature above 500°C. The appearance of bright temper colors leads to enlarging of dispersion of ultimate stress and critical bending angle. When temperature of annealing goes up to 800°C the bending angle of sheet-samples decrease significantly at room temperature. As accurate measuring of the depth of oxygen affected zone and thickness of Ti02 layer by means of optical metallography and fractography at low temperatures is seriously complicated than one could qualify a depth of oxygen affected zone on the spot by determining an annealing colors. The appearance of bright yellow annealing colors with metal shining didn't bring any critical changes of mechanical properties.

Bioinspired Sandwich Structure in Composite Panels

The phenomenon of separation into constituent layers connecting the core and laminate of a composite sandwich complex is a vital complication that leads to early failure of such material. The direction of the sandwich construction's exfoliation rigidity is increased between interlaminar low fiber augmentation. The bioinspired technique of hybrid material layers was used on an aluminium face sheet with an interlayer composition of PET foam core and glass fabric of a material that appears to have greater potential as a flimsy substitute for materials currently used in automotive, aeronautical, and marine applications. This examination seeks to develop the making of such material along the retardation in fibre supplements. Fibre bridging has been recognized as an important appliance in the progress of this operating procedure. Consequently, this method points to promoting the event of fibre bridging by differing aggregates, including the mass and extent of augmented fibres and the quantity of epoxy resin applied. A few advancements were made to the production methods, and though the outcomes for the resisting ability of specimens were found to be indecisive, it was found that the layer separation hardness had even improved. This was confirmed through the operation of scanning electron microscopy and also predicted the mechanically peeled material surfaces which identified the adhesive strength variations with respect to the face sheet surface modified with the sand blasting process. The analysis also revealed the need for further research into optimizing the attachment between aluminium sheet and pet foam and glass fabric based hybrid sandwich panels.

Research on the Durability and Reliability of Industrial Layered Coatings on Metal Substrate Due to Abrasive Wear

This paper discusses the issue of evaluating the durability and reliability of organic coatings applied on the outer surfaces of roofing sheets. Two sheets, i.e., ZA200 and S220GD, were selected as research objects. Metal surfaces of these sheets are protected with multilayer organic coatings to protect them against weather conditions, assembly, and operational damages. The durability of these coatings was tested by evaluating their resistance to tribological wear using the ball-on-disc method. The testing was conducted in reversible gear according to a sinuous trajectory at a 3 Hz frequency. The test load was 5 N. When the coating was scratched, the metallic counter sample touched the metallic surface of the roofing sheet, which indicated a significant drop in electrical resistance. It is assumed that the number of performed cycles specifies the durability of the coating. Weibull analysis was applied to examine the findings. The reliability of the tested coatings was evaluated. The tests have confirmed that the structure of the coating is essential for the durability and reliability of products. The research and analysis included in this paper present important findings.

Synthesis of RGO/γ-Fe2O3 nanocomposite for the removal of heavy metals from aqueous solutions

Abstract Reduced graphene oxide/maghemite (RGO/γ-Fe2O3) material was successfully synthesized by combining the modified Hummers method with co-precipitation (RGO 10 wt.%). γ-Fe2O3 nanoparticles with a particle size of ∼14.8 nm were distributed on the surface of RGO sheets. Results of Brunauer–Emmett–Teller analysis showed that RGO/γ-Fe2O3 had a mesoporous structure and a narrow capillary size distribution curve at about 13 nm. The specific surface area of the RGO/γ-Fe2O3 was 168 m2·g−1. The RGO/γ-Fe2O3 nanocomposite was used to adsorb arsenic As(V) and a mixture of heavy metals (As(V), Cr(VI), Pb(II), and Fe(III)) in water. The maximum adsorption efficiency of As(V) reached 98.9% after 45 min with an adsorption capacity of 5.93 mg·g−1, higher than the simultaneous adsorption of the four metal ions. Competitive adsorption decreased in the order As(V), Cr(VI), Pb(II), and Fe(III). Therefore, RGO/γ-Fe2O3 could be used as an effective adsorbent to remove heavy metals from aqueous solutions.

Reinforcing interlaminar interface of carbon fiber reinforced metal laminates by graphene

Fiber metal laminas (FMLs) are disadvantaged by weak interlaminar strength limiting their application where dynamic loads are expected. In this study, graphene platelets (GnPs) were employed to strengthen the interlaminar interface in carbon fiber (CF) metal laminates. GnPs within range of 0–1 wt% were added into epoxy resin via ultrasonication. GnPs-based FML samples were prepared by wet lay-up method and tested under flexural loading, short beam shear and single lap shear. The reinforcing mechanism and failure modes were investigated. The results show that 0.5 wt% of GnPs increases the flexural strength and interlaminar shear strength by 39.7% and 53.2%, respectively. In addition, molecular dynamics (MD) simulations concluded that the addition of low content of GnPs increases the elastic modulus of the matrix and improves the resin adsorption on the surface of carbon fiber and Al sheets. The results from both the experimental and MD simulation indicate that adding GnPs can effectively improve the interlaminar mechanical properties of FMLs. In principle, the research method in this paper can be applied to the study of FMLs with other nanomaterials.

Synthesis of zeolitic imidazolate framework‐8 modified graphene oxide composite and its application for lead removal

AbstractBACKGROUNDThe removal of lead ions (Pb2+) from industrial wastewater can be achieved using adsorption technology. Composites of zeolitic imidazolate framework‐8 (ZIF‐8) and graphene oxide (GO) were prepared via room temperature synthesis (RTS) using RO water as the solvent and by mixing GO with separated parts of ZIF‐8 precursors before its combination. Three weight percentages of GO, 10wt%, 30wt% and 50wt%, were used to synthesize ZGH10, ZGH30 and ZGH50 to determine optimum preparation and application conditions.ResultsZGH30 showed the most outstanding performance as an adsorbent for Pb2+ removal from aqueous solution. As captured by field emission scanning electron microscopy image, ZGH30 showed an adequate amount of ZIF‐8 grown on all surfaces of thr GO sheet, with an appropriate exposure of GO sheet layers for further Pb2+ interaction. The Pb2+ adsorption test revealed that ZGH30 obtained the optimum operating values between pH 5 and 6, using 10 mg dosage and it could remove ≤97% of 100 mg L−1 Pb2+. Additionally, ZGH30 achieved the most rapid equilibrium time within 10 min, similar to ZGH50, as compared to their individual components, ZIF‐8 (240 min) and GO (300 min). The mechanism of Pb2+ adsorption fitted well with a Langmuir isotherm and pseudo‐second‐order kinetic model. The theoretical maximum adsorption capacities obtained through Langmuir isotherm were 200, 454.55, 476.19, 555.56 and 454.55 mg g−1, for GO, ZH, ZGH10, ZGH30 and ZGH50, respectively.ConclusionsTherefore, ZGH30 hybrid successfully unleashed its potential as the adsorbent for wastewater treatment technology with improved performance after modification. © 2023 Society of Chemical Industry (SCI).

Gradient Recrystallization Behavior of a Moderate Warm-Rolled Non-Oriented Fe-6.5wt%Si Alloy

In Fe-Si alloy systems, the Fe-6.5wt%Si alloy shows low iron core losses and near-zero magnetostriction, thus having great potential for high-frequency applications. In this study, an Fe-6.5wt%Si alloy hot band was subjected to a moderate warm rolling with a thickness reduction of 40%, and then annealed at different temperatures. The recrystallization behavior was investigated using the EBSD technique. After the moderate warm rolling, the initial gradient structure of the hot band is inherited, leading to gradient recrystallization behaviors during the further annealing process. The sheet surface first densely nucleates and forms strong <110>//ND and {221}<114> textures. However, the <110>//ND and {221}<114> grains have fewer high-mobility and high-energy (20–45°) boundaries than the other oriented matrix grains, leading to insufficient growth advantages. In the center region, the recrystallization is slow, but the nuclei usually have larger sizes. The inheritance of the <001>//ND (θ-fiber) texture from the initial hot band appears. Some θ-fiber grains, which have easy-magnetized <001> axes lying in the sheet plane, preferentially nucleate in the strong α-fiber textured matrices and form a strong θ-fiber recrystallization texture in the center region.

Macroscale Superlubricity with Ultralow Wear and Ultrashort Running-In Period (∼1 s) through Phytic Acid-Based Complex Green Liquid Lubricants.

Liquid superlubricity has attracted much attention, due to its ability to significantly reduce friction on the macroscale. However, the severe wear caused by the long running-in period is still one of the bottlenecks restricting the practical application of liquid superlubricating materials. In this work, the obtained polyethylene glycol-phytic acid (PEG-PA) composite liquid lubricants showed outstanding superlubricating properties (μ ≈ 0.006) for Si3N4/glass friction pairs with an ultrashort running-in period (∼1 s) under high Hertzian contact pressure of ∼758 MPa. More importantly, even after up to 12 h (∼700 m of travel), only about 100 nm deep wear scars were found on the surface of the glass sheet (wear rate = 2.51× 10-9 mm3 N-1 m-1). From the molecular point of view, the water molecules anchored between the two friction pairs have extremely low shear force during the friction process, and the strong hydrogen bond interaction between PEG and PA greatly improves the bearing capacity of the lubricant. This work addresses the challenge of liquid superlubricant simultaneously exhibiting low shear force and high load-carrying capacity and makes it possible to obtain liquid superlubrication performance with an extremely short running-in time.

Low-Cost Production of Fe3O4/C Nanocomposite Anodes Derived from Banana Stem Waste Recycling for Sustainable Lithium-Ion Batteries

The development of lithium-ion batteries (LIBs) has become an important aspect of advanced technologies. Although LIBS have already outperformed other secondary batteries, they still require improvement in various aspects. Most crucially, graphite, the commercial anode, has a lower capacity than emerging materials. The goal of this research is to develop carbon-based materials from sustainable sources. Banana stem waste was employed as a precursor because of its xylem structure and large surface area. In addition, catalytic graphitization of biomass yields both graphitic carbon and metal oxides, which can be converted into higher-capacity Fe3O4/C nanocomposites. The nanocomposites consist of nanoparticles distributed on the surface of the carbon sheet. It was found that Fe3O4/C nanocomposites not only achieved a superior specific capacity (405.6 mAh/g at 0.1 A/g), but also had good stability in long-term cycling (1000 cycles). Interestingly, they had a significantly greater capacity than graphite at a high current density (2 A/g), 172.8 mAh/g compared to 63.9 mAh/g. For these reasons, the simple preparation approach, with its environmental friendliness and low cost, can be employed to produce Fe3O4/C nanocomposites with good electrochemical properties. Thus, this approach may be applicable to varied biomasses. These newly developed Fe3O4/C nanocomposites derived from banana waste recycling were found to be suitable to be used as anodes for sustainable LIBs.

Investigation of silica nanoparticles grafted with sulphonated polymer for enhanced oil recovery at high temperature and high salt

AbstractNano‐fluids' application for enhanced oil recovery (EOR) has attracted noticeable attention and formed a new research area in recent years. Currently, the greatest challenge in this area is to formulate stable nano‐fluids for oil reservoirs with high temperatures and salinity. To overcome the limitations of its application in high‐temperature drilling, polymer‐coated nanoparticles (SiO2‐PAMPS NPs) were prepared via solution polymerization of 2‐acrylamide‐2‐methyl‐1‐propane sulphonic acid (AMPS) from the surface of aminopropyl‐functionalized silica nanoparticles. The SiO2‐PAMPS NPs were characterized by Fourier‐transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dynamic light scattering (DLS). The results indicated that the AMPS was successfully grafted onto the surface of silica nanoparticles, and the average diameter of SiO2‐PAMPS NPs was about 16 nm. The nano‐fluids showed noticeable stability in American Petroleum Institute (API) brine (2 wt.% CaCl2 and 8 wt.% NaCl) at 90°C beyond 46 days. When amphipathic nanoparticles were introduced to brine at 90°C, the potential of the nano‐fluids in recovering oil was evaluated by investigating the interfacial tension with kerosene oil and the oil contact angle in the nano‐fluids. The contact angle of the glass sheet surface before treatment was about 144°, while after SiO2‐PAMPS NPs treatment for 72 h, it became about 92°. Meanwhile, the nano‐fluids showed an excellent enhancing emulsibility property, which plays a vital role in promoting the development of EOR in high‐temperature and high‐salt environments.