Synthesis and Mechanistic Investigation of an Amphiphilic Polymer in Enhancing Extra-Heavy Oil Recovery via Viscosity Reduction.

When applied to extra-heavy oil, conventional polymer surfactants exhibit poor efficacy in reducing viscosity and have limited adaptability. In this work, a novel amphiphilic polymer named PAADB was prepared by incorporating 2-acryloylamino-2-methyl-1-propanesulfonic acid (AMPS), benzyldimethyl [2-[(1-oxoallyl) zoxy] propyl] ammonium chloride (DML), and poly(ethylene glycol) methyl ether acrylate (BEM) into the main chain of acrylamide through free radical polymerization. PAADB exhibited outstanding interfacial activity, water-phase thickening ability, and emulsifying performance. The critical micelle concentration of PAADB was approximately 2500 mg/L, with a viscosity of 84.69 mPa·s at 50 °C. Additionally, interfacial tension experienced a notable decrease from 46.53 to 14.56 mN/m. At an optimal concentration of 4000 mg/L, PAADB reduced the viscosity of extra-heavy oil by over 92% across various temperatures and by more than 93% for different types of extra-heavy oil. PAADB demonstrated excellent emulsification ability and emulsion stability, effectively dispersing crude oil to create water-in-oil droplets measuring 35.33 µm in size. Meanwhile, molecular dynamics simulations further unveiled the viscosity reduction mechanism of PAADB. The hydrophilic groups within PAADB molecules are regularly distributed on the water interface, while the hydrophobic groups infiltrate the oil molecules to form a stable interfacial film. PAADB and asphaltene spontaneously form a sandwich structure, reducing intermolecular forces and disrupting the interlayer structure of asphaltene molecules. In general, this novel amphiphilic polymer demonstrates broad applicability and potential in extra-heavy oil recovery, providing valuable insights for the development of new heavy oil viscosity reducers (HOVRs).

Molecular Dynamics Simulation of the Effects of Complex Surfactants on Oil-Water Interaction and Aggregation Characteristics at the Interface.

In response to the problem of complex interaction between oil and water in the oil-water interface, especially heavy oil and water, this study investigated the effects of complex surfactants on the interaction of two phases and their aggregation characteristics by molecular dynamics simulation. The results showed that increasing the content of sodium lauryl polyether carboxylate (AEC-9Na) was beneficial to the coordination between it and alkyl glycoside (APG-10), improved the interfacial activity, and enhanced the interfacial stability of the composite system, and the best effect was achieved when AEC-9Na:APG-10 = 8:2. The thickness of the oil and water film on the oil-water interface was irregular. When the concentration of AEC-9Na was lower than that of APG-10, the total thickness of the interfacial film (ttotal) first increased. When the content of AEC-9Na is higher, a large number of sodium ions were adsorbed near the -COO- group of AEC-9Na, which will polarize out of the hydration layer structure and attract water molecules from the second hydration layer on the heavy oil surface to the first hydration layer through electrostatic interaction. Then, the thickness of the interface film was compressed, and the interface film was reduced. When the ratio increased to 10:0, the oil and water phase competed to adsorb surfactant molecules, and the headgroup tended to lay on the interface. Moreover, the hydrophilicity of the surfactant layer was weakened, and the thickness of the water film decreased. The distribution of surfactant was looser than 8:2, the light components of heavy oil molecules (saturated and aromatic hydrocarbons) entered the gap between surfactants in large quantities, and the hydrophobic tail chain tended to be laid on the oil-water interface. The oleophilicity of the surfactant layer increased, and the thickness of the oil film remarkably increased, so the total thickness of the interface film increased again.

Insights into High-Performance and Selective Elimination of Cationic Dye from Multicomponent Systems by Using Fe-Based Metal-Organic Frameworks.

Metal-organic frameworks (MOFs), especially Fe-MOFs, have shown prospective application in eliminating organic dyes from wastewater due to their well-developed pores, water stability, easy preparation, and economy. Herein, we synthesized four types of Fe-MOFs (such as MIL-88A, MIL-88B, MIL-100, and MIL-101) using the hydrothermal method. The products were analyzed with several methods. By comparing the adsorption effect of those four types of Fe-MOFs on three kinds of dyes, it has been shown that MIL-100 owns the best adsorption efficiency on cationic organic dyes methylene blue (MB) and Rhodamine B (RhB) in 180 min, while all MOFs have slight removal capacity on methyl orange (MO). MIL-100, as an adsorbent, was studied under various research conditions, and the maximum removal efficiencies to MB, RhB, and MO were found to be up to 97.36%, 88.75%, and 13.00%, respectively. Furthermore, cationic dye MB's removal by MIL-100 was fitted with a pseudo-second-order model and Langmuir isotherm model (Qm = 411.041 mg/g) by adsorption kinetics and isotherms research, and MIL-100 could rapidly and selectively divide MB from a binary complex aqueous solution of MB and MO. The as-fabricated MIL-100 also exhibited excellent recyclability after four adsorption-desorption recycles and can be treated as a potential substance with high removal efficiency of cationic organic dye-containing industrial effluents.

An efficient supramolecular adsorbent for co-adsorption of dyes and metal ions from wastewater and its application in self-healing materials.

Herein, a novel type of two-component supramolecular adsorbent, 2-OA, was developed based on non-covalent interactions using tetrazolyl derivative with octadecylamine (OA) and fully characterized using a number of structural and spectral techniques. The self-assembled 2-OA gels displayed remarkable stimuli-responsiveness as well as shape-persistent and self-healing properties. In addition, it was found that the adsorbent 2-OA was able to remove dyes (10 kinds of cationic and anionic dyes) and metal ions (Cu2+ and Fe2+) simultaneously from wastewater owing to synergistic electrostatic attraction, hydrogen-bonding, and hydrophobic and coordination interactions. It also exhibited excellent co-adsorption capability to dye mixtures and binary mixtures of dyes and metal ions. In particular, the dye/metal-loaded adsorbents could be obtained easily from the aqueous phase, and recycling of the adsorbents could thus be achieved. These results suggest that the supramolecular gel 2-OA not only has great potential application in wastewater treatment but also provides a strategy for the development of intriguing self-healing materials.

A microvolume molecularly imprinted polymer modified fiber-optic evanescent wave sensor for bisphenol A determination.

A fiber-optic evanescent wave sensor for bisphenol A (BPA) determination based on a molecularly imprinted polymer (MIP)-modified fiber column was developed. MIP film immobilized with BPA was synthesized on the fiber column, and the sensor was then constructed by inserting the optical fiber prepared into a transparent capillary. A microchannel (about 2.0 µL) formed between the fiber and the capillary acted as a flow cell. BPA can be selectively adsorbed online by the MIP film and excited to produce fluorescence by the evanescent wave produced on the fiber core surface. The conditions for BPA enrichment, elution, and fluorescence detection are discussed in detail. The analytical measurements were made at 276 nm/306 nm (λ(ex)/λ(em)), and linearity of 3 × 10(-9)-5 × 10(-6) g mL(-1) BPA, a limit of detection of 1.7 × 10(-9) g mL(-1) BPA (3σ), and a relative standard deviation of 2.4% (n = 5) were obtained. The sensor selectivity and MIP binding measurement were also evaluated. The results indicated that the selectivity and sensitivity of the proposed fiber-optic sensor could be greatly improved by using MIP as a recognition and enrichment element. Further, by modification of the sensing and detection elements on the optical fiber, the proposed sensor showed the advantages of easy fabrication and low cost. The novel sensor configuration provided a platform for monitoring other species by simply changing the light source and sensing elements. The sensor presented has been successfully applied to determine BPA released from plastic products treated at different temperatures.

Application of Low-Salinity Waterflooding in Heavy Oil Sandstone Reservoir: Oil Recovery Efficiency and Mechanistic Study.

Low-salinity water injection (LSWI) is a recently emerged and promising technique to enhance oil recovery. In addition, it is attractive due to its relatively low-cost, environmental friendliness, and sustainability. However, the underlying mechanisms remain unclear, and very limited research has been conducted on heavy oil. To verify the feasibility of injecting a low-salinity aquifer water (LSAW) to improve the oil recovery of our target offshore heavy oil reservoir, first, a series of experiments on the core scale, including coreflooding and spontaneous imbibition experiments, were carried out. Furthermore, atomic force microscopy (AFM), contact angle, zeta potential measurement, as well as disjoining pressure calculations based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory were carried out to explore the underlying governing mechanism at the microscopic scale. The secondary oil recovery factors of the coreflood tests are 67.11, 70.55, and 77.18% for seawater (SW), produced water (PW), and LSAW, respectively. The additional oil recoveries by LSAW when injected in tertiary modes are 6.38% after SW injection and 5.68% after PW injection. These results indicate that compared with SW and PW which have high brine salinity, the low-salinity brine from the subsurface aquifer (LSAW) can improve oil recovery in both secondary and tertiary modes. In addition, the oil recovery factors from the spontaneous imbibition tests (27.52% by LSAW, 17.32% by PW, and 14.00% by SW) and the insignificant variation of IFTs among the three brines lead to the anticipation that the LSAW can alter the rock to a more water-wet condition compared with SW and PW, thereby giving rise to a higher oil recovery factor in the coreflooding tests. By using AFM imaging and contact angle tests, we proved that the polar asphaltene could desorb from the rock surface and consequently reduce the water contact angle substantially when subjected to low-salinity brine. Furthermore, the zeta potential and the disjoining pressure results indicate that a more repulsive force was developed between oil and the rock under the low-salinity environment, which thereby promotes asphaltene desorption and consequent wettability alteration. Our work has paved the way to apply LSWI to the offshore heavy oil sandstone reservoir.

An integrated micro-volume fiber-optic sensor for oxygen determination in exhaled breath based on iridium(III) complexes immobilized in fluorinated xerogels.

A novel integrated fiber-optic sensor with micro detection volume is developed and evaluated for O(2) determination on a breath-by-breath basis in human health monitoring applications. The sensing element was fabricated by dip-coating an uncladded optical fiber with [Ir(piq)(2)(acac)]-doped hybrid fluorinated ORMOSIL (organically modified silicate) film, which was prepared from 3,3,3-trifluoropropyltrimethoxysilane (TFP-TriMOS) and n-propyltrimethoxysilane (n-propyl-TriMOS). The sensor was then constructed by inserting the prepared optical fiber into a transparent capillary. A microchannel formed between the optical fiber and the capillary inner wall acted as a flow cell for the sample flowing through. The evanescent wave (EW) field produced on the fiber core surface can excite the O(2)-sensitive fluorophores of [Ir(piq)(2)(acac)] to produce emission fluorescence. O(2) can be sensed by its quenching effect on the emission fluorescence intensity. Spectroscopic properties have been characterized by FTIR and fluorescence measurements. Stern-Volmer and Demas models were both employed to analyse the sensor sensitivity, which is 13.0 with the LOD = 0.009% (3σ) and the response time is about 1 s. By integrating the sensing and detection elements on the optical fiber, the novel configuration showed advantages of easy fabrication and low cost. Parameters of sensitivity, response time, repeatability, humidity effect and temperature effect were discussed in detail. The proposed sensor showed potential for practical in-breath O(2) analysis application due to its advantages of easy fabrication, low cost, fast response, excellent hydrophobicity, negligible temperature interference and suitable sensitivity.

The Effect of Shear on the Properties of an Associated Polymer Solution for Oil Displacement.

Polymer flooding is one of the techniques used to enhance oil recovery from depleted hydrocarbon reservoirs. Although this technology is popular for this application, the shearing effect in the injection process causes poor performance, which is an obstacle to meeting the needs of the formation. An experimental evaluation of the rheological properties, viscoelasticity, hydrodynamic size, static adsorption, and seepage characteristics of the associated polymer solution before and after shearing was conducted to determine the influence of shearing on the polymer solution. The results show that the effect of shear on the polymer was irreversible, and the properties of the polymer solution damaged by shear were attenuated. After the critical associating concentration, the associated polymer can recover its solution properties through hydrophobic association, which can improve the shear resistance of the polymer solution and make its own rheological law and reduce the viscoelastic change. Although the hydrodynamic size, viscoelasticity, and adsorption capacity of the polymer solution after shear failure decreased, strong flow resistance during porous media seepage and mobility control was achieved. Improving the shear resistance of the polymer solution by increasing the intermolecular force is proposed to develop new polymer systems for subsequent oil displacement.

Active site regulated Z-scheme MIL-101(Fe)/Bi2WO6/Fe(III) with the synergy of hydrogen peroxide and visible-light-driven photo-Fenton degradation of organic contaminants.

Water pollution control is one of the major challenges currently faced. With the development of photocatalytic technology, an increasing number of new and efficient catalysts have been developed, but most of the catalysts have limited light capture ability and catalytic degradation efficiency. Therefore, in this work, hydrogen peroxide was further introduced to establish a photo-Fenton system to improve the photocatalytic effect by constructing a Z-scheme, and the degradation ability of the catalyst was maximized. Moreover, we successfully adhered bismuth tungstate nanosheets onto the surface of a MIL-101(Fe) framework and changed the number of active sites with iron ions of different doping amounts. We found that the number of active sites in the photo-Fenton system does not increase linearly, but increases and decreases regularly, which is similar to the change in band structure after doping. In addition, the results of the radical scavenger experiment and electron paramagnetic resonance (EPR) revealed that both hydroxide radical (˙OH) and superoxide radical (˙O2-) participated in methylene blue (MB) degradation, of which ˙OH was the main active species for pollutant degradation. Based on high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, the possible degradation pathways were proposed. We believed that this work will provide insights into the heterojunction photo-Fenton system.

Experimental Investigation of Supercritical CO2-Rock-Water Interactions in a Tight Formation with the Pore Scale during CO2-EOR and Sequestration.

In recent years, gas injection, especially CO2 injection, has been acknowledged as a promising approach for enhanced oil recovery (EOR) and CO2 capture and storage (CCS), especially for tight reservoirs. However, when CO2 is injected into the oil reservoirs, it can disturb the equilibrium of the system and lead to chemical reactions between CO2, formation water, and reservoir rocks. The reactions will alter some geochemical and physicochemical characteristics of the target reservoirs. However, the reactions still lack quantitative characterization at the pore scale, especially under reservoir conditions. Herein, we conducted an experimental study of the interactions between CO2, brine, and rocks in the Mahu oilfield at 20 MPa and 70 °C. The low-field nuclear magnetic resonance (LF-NMR) measurements showed that the incremental amplitude for tight cores of CO2-rock-water tests was larger than that for CO2-rock tests, and the amplitude alteration presented significant differences corresponding to different types of minerals and pores. Furthermore, the interplanar spacing of the core samples was increased with the increase of reaction time in the CO2-rock experiments but still lower than that in CO2-rock-water tests. This research demonstrated evident changes in the geochemistry in tight reservoirs caused by CO2, brine, and rock reactions. The results of this study may provide a significant reference for the exploration of similar reservoirs in the field of CO2-EOR and CO2 sequestration.

Flow injection small-volume fiber-optic pH sensor based on evanescent wave excitation and fluorescence determination.

A small-volume fiber-optic pH sensor (FOEWS) based on evanescent wave excitation is developed and evaluated. The sensor is simply fabricated by inserting a decladded optical fiber into a transparent capillary tube. A microchannel between the optical fiber and the capillary inner wall was formed and acted as flow cell for solution flowing through. The pH-sensitive fluorophore of fluorescein can be excited by the evanescent wave field produced on the fiber core surface to produce emission fluorescence. pH value was then sensed by its enhancing effect on the emission fluorescence intensity. The response range of the sensor is from pH 2.09 to pH 8.85 and the linear range is from pH 3.25 to 8.85. The proposed sensor has a small detection volume of 2.5 µL and a short response time of 8 s. It has been applied to measure pH values of real water samples and was in good agreement with the results obtained by commercial pH meter.

Adsorption Characteristics of Polymer Solutions on Media Surfaces and Their Main Influencing Factors.

In practical applications, the chemical and physical adsorption of a polymer solution greatly affects its action mode and effect. Understanding the adsorption mechanism and its influencing factors can help to optimize the application mode and ensure application efficiency. Three types of polymer solutions-partially hydrolyzed polyacrylamide (HPAM), hydrophobically associating polymer (AP-P4), and dendrimer hydrophobically associating polymer (DHAP), which are viscoelastic liquids-were used as sorbates to study their adsorption by a sorbent such as quartz sand. The effects of the solution concentration, contact time, particle size of quartz sand, solid-liquid ratio, and fluid movement on the adsorption capacity of the polymer solutions were examined. The results showed that HPAM presents a typical Langmuir monolayer adsorption characteristic, and its adsorption capacity (per unit area) is 1.17-1.62 µg/cm2. The association enhances the interactions of the AP-P4 and DHAP solutions, and they present multilayer characteristics of first-order chemical adsorption and secondary physical molecule adsorption. Moreover, the dendrite structure further increases the adsorption thickness of DHAP. Hence, the adsorption thicknesses of AP-P4 and DHAP are four and six times that of HPAM, respectively. The adsorption of the three polymers is consistent with the influence of fluid motion and decreases with increasing fluid velocity. However, the larger the thickness of the adsorption layer, the clearer the influence of the flow, and the higher the decrease in adsorption capacity. Optimizing the injection rate is an effective method to control the applications of a polymer in porous media.

The seepage flow characteristics of hydrophobically associated polymers with different aggregation behaviours in porous media.

The polymer solution for oil displacement is subjected to strong shear action in practical application, and this action will affect its percolation characteristics in porous media. The effects of mechanical shearing on the solution properties and seepage characteristics of modified hydrophobically associated polymers and dendrimers with two different aggregation behaviours were studied. The results showed that mechanical shearing did not affect hydrophobic microzones. Polymers can re-associate to restore part of the network structure, thereby improving shear resistance (dendritic hydrophobically associating polymers > hydrophobically modified partially hydrolysed polyacrylamide). Polymers with 'cluster' aggregation behaviour enhanced solution performance, enabling them to establish higher resistance coefficient (RF) and residual resistance factor (RRF) in porous media but also bringing about injection difficulties. Increasing the injection rate would increase the injection pressure, but the established RF and RRF showed a downward trend. Mechanical shear pretreatment effectively improved the injectability of the polymer. To achieve polymer injection and flow control, pre-shearing polymer solution and low-speed injection can be used in field applications.

Synthesis and Solution Properties of a Novel Hyperbranched Polymer Based on Chitosan for Enhanced Oil Recovery.

A new type of chitosan-modified hyperbranched polymer (named HPDACS) was synthesized through the free-radical polymerization of surface-modified chitosan with acrylic acid (AA) and acrylamide (AM) to achieve an enhanced oil recovery. The optimal polymerization conditions of HPDACS were explored and its structure was characterized by Fourier-transform infrared spectroscopy, hydrogen nuclear magnetic resonance, and environmental scanning electron microscopy. The solution properties of HPDACS in ultrapure water and simulated brine were deeply studied and then compared with those of partially hydrolyzed polyacrylamide (HPAM) and a dendritic polymer named HPDA. The experimental results showed that HPDACS has a good thickening ability, temperature resistance, and salt resistance. Its viscosity retention rate exceeded 79.49% after 90 days of aging, thus meeting the performance requirements of polymer flooding. After mechanical shearing, the viscosity retention rates of HPDACS in ultrapure water and simulated brine were higher than those of HPAM and HPDA, indicating its excellent shear resistance and good viscoelasticity. Following a 95% water cut after preliminary water flooding, 0.3 pore volume (PV) and 1500 mg/L HPDACS solution flooding and extended water flooding could further increase the oil recovery by 19.20%, which was higher than that by HPAM at 10.65% and HPDA at 13.72%. This finding indicates that HPDACS has great potential for oil displacement.

Triple Phase Inversion of Emulsions Stabilized by Amphiphilic Graphene Oxide and Cationic Surfactants.

Amphiphilic graphene oxide (A-GO) with grafted octylamine was prepared via a one-step method of N,N'-dicyclohexylcarbodiimide coupling and epoxide ring opening at a mild temperature of 40 °C. The phase of oil-water emulsion stabilized by the complexes of A-GO and the cetyltrimethyl ammonium bromide (CTAB) surfactant could invert three times by adding CTAB or A-GO. This process was called triple phase inversion, which was a function of the concentration of A-GO or CTAB surfactants. The conductivity and zeta potential measurements confirmed that CTAB could influence the carboxyl ionization of A-GO. In addition, the turbidity of the A-GO and CTAB mixed dispersion system revealed that the appearance and disappearance of precipitation occurred when CTAB or A-GO concentration was increased. Meanwhile, the emulsion prepared by mixing the dispersion with an equal volume of xylene at a fixed CTAB concentration also showed triple phase inversion as the A-GO concentration varied. Results indicated that the stability of the emulsion and the size of the emulsion droplets had a certain correlation during the phase inversion process, which varied with the concentration of CTAB or A-GO.

Photocatalytic Activity Investigation of α-Zirconium Phosphate Nanoparticles Compositing with C3N4 under Ultraviolet Light.

In order to further develop efficient ultraviolet light-driven photocatalysts for environmental application, α-zirconium phosphate (α-ZrP) and carbon nitride (C3N4) were synthesized, respectively. Then, C3N4-ZrP compositing nanomaterials were prepared by compositing α-ZrP nanocrystals and C3N4 with different mass ratios. C3N4-ZrP compositing nanomaterials were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results illustrated that α-ZrP and C3N4 were successfully composited, and the polarization of the compositing nanomaterials was reduced compared with raw materials. The photocatalytic performances of C3N4-ZrP compositing nanomaterials with different mass ratios were studied by photodegradation of RhB under ultraviolet irradiation. All of the degradation rates of the C3N4-ZrP compositing nanomaterials system were achieved more than 90% after 18 min. When the mass ratio of C3N4-ZrP compositing nanomaterials is 2:1, the degradation efficiency achieved 99.95%, which is more efficient than other tested mass ratios. The result indicated the possibility of utilizing C3N4-ZrP compositing nanomaterials for environmental pollutants degradation.

Experimental Investigation of Hydrophobically Modified α-ZrP Nanosheets for Enhancing Oil Recovery in Low-Permeability Sandstone Cores.

Highly crystalline α-zirconium phosphate (α-ZrP) nanoparticles were synthesized and exfoliated into nanosheets, and then the hydrophilic nanosheets were modified into hydrophobic nanosheets with octadecyltrichlorosilane (OTS). Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were applied to confirm the morphology and chemical structure of the nanosheets. Contact angle measurement was conducted to explore the wettability alteration of the hydrophobically modified α-ZrP nanosheets, and the result showed that the wettability of the core was changed into hydrophobicity. When ZrP-OTS nanosheets were injected during water-flooding, a Pickering emulsion will be formed. The droplet diameters and viscosities of the Pickering emulsions were measured. The hydrophobically modified α-ZrP nanosheets were applied in low-permeability sandstone cores and various concentrations were tested. The injectivity of the hydrophobically modified α-ZrP nanosheets was also studied and the result indicated that the nanosheets exhibit good injectivity. The mechanisms for enhancing oil recovery by utilizing hydrophobic α-ZrP nanosheets were analyzed: forming Pickering emulsions and increasing the viscosity of the displacing phase. Forming emulsions and increasing the viscosity of the flooding phase can enhance the microdisplacement efficiency, while good injectivity can also enhance the macrodisplacement efficiency. The result indicated the possibility of using hydrophobically modified α-ZrP nanosheets for enhancing oil recovery in a low-permeability reservoir.

Preparation and application of melamine cross-linked poly ammonium as shale inhibitor.

In this paper, a series of poly ammonium shale inhibitors were prepared from diethylamine, epichlorohydrin, and melamine (DEM) and their inhibition to shale were evaluated by bentonite linear expansion test, anti-swelling experiments, and mud ball experiments. Additionally, other properties of drilling fluid treated by poly ammonium were evaluated. Anti-swelling results showed that anti-swelling rate of DEM-8 reaches up to 97.8% when its concentration reaches to 0.8%. Mud ball experiment and drilling fluid evaluation showed DEM-8 has strong inhibitive capability to bentonite hydration swelling and controlling the particle size of bentonite in a large scale. The inhibition mechanism of DEM-8 was studied by thermogravimetric analysis and scanning electron microscope. The results demonstrate that DEM-8 can be adsorbed on clay surface through electrostatic interaction and hydrogen bonds by an anchoring effect and a hydrophobic effect.

The ultralow interfacial tensions between crude oils and gemini surfactant solutions.

In this paper, the interfacial tension between crude oil and solution of cationic gemini surfactant has been studied. It is found that the interfacial tension between crude oil and water is closely related to the nature of a gemini surfactant and oil; meanwhile, in the case without additives, some gemini surfactants or mixtures of some gemini surfactants can reduce the interfacial tension between crude oil and water to an ultralow value.

Self-healing supramolecular heterometallic gels based on the synergistic effect of the constituent metal ions.

Supramolecular heterometallic gels with synergistic properties were prepared for the first time using ligand with Co(2+) and Ni(2+), and their macroscopic self-healing has been achieved by improving the unfavorable viscoelasticity of each monometallic gel.