An Experimental Study on Alkaline/Surfactant/Polymer Flooding Systems Using Natural Mixed Carboxylate

Orthogonal-test-design method has been used to determine the optimal formula by phase behavior and interfacial tension studies, respectively. The effect of each component of two alkaline/surfactant/polymer flooding systems on interfacial tension is discussed, in which a low-price natural mixed carboxylate (SDC) is used as the major surfactant. The results indicate that the optimal composition is SDC (0.5%), alkaline NaHCO3/Na2CO3 with mass ratio of 1 (1.0%), and hydrolyzed polyacrylamide(0.1%). In the coreflood experiment, their oil recovery is increased by about 25.2% and 26.8% original oil in place, respectively.

Effect of nonionic surfactants in release media on accelerated in-vitro release profile of sirolimus eluting stents with biodegradable polymeric coating

It is a well-known fact that sirolimus(SRL) undergoes degradation process via hydrolysis in aqueous media, leading to incorrect assessment of drug amount and thus release characteristics of formulations.The main objective of the present study was to evaluate the effect of nonionic surfactants in media on invitro release profiles for sirolimus eluting stents(SES) coated with biodegradable polymeric matrix.Phosphate buffer and acetate buffer incorporating nonionic surfactants with varying concentrations were examined for adequate solubility and stability(by RP-HPLC). Good sink condition was achieved in phosphate buffer(at pH 4.0) with 1.0% Tween 20, 1.0% Brij 35% and 0.5% Brij 58. Hydrodynamic size(by DLS) and the micelle-water partition coefficient(P) with standard free energy of solubilization(ΔGs°) of drug were evaluated to get some understanding about the solubilization phenomena. About 80% of drug release during the period of 48 h was achieved in optimized drug release media which was 1.0% Tween20 in phosphate buffer pH 4.0. The obtained accelerated SRL release profile in optimized medium correlated well with the real time in-vitro release in phosphate buffer(pH 7.4). Surface morphology changes(by SEM), changes in gravimetric weights and molecular weight change(by GPC) were examined before and after drug release to understand the drug release mechanism which explains that the polymer did not undergo degradation during the drug release.

Effects of pore structure on surfactant/polymer floodingbased enhanced oil recovery in conglomerate reservoirs

To understand the displacement characteristics and remaining oil displacement process by the surfactant/polymer(SP) flooding in cores with different pore structures, the effects of pore structure on the enhanced oil recovery of SP flooding was investigated at the pore, core and field scales through conducting experiments on natural core samples with three typical types of pore structures. First, the in-situ nuclear magnetic resonance core flooding test was carried out to capture the remaining oil variation features in the water flooding and SP flooding through these three types of cores. Subsequently, at the core scale, displacement characteristics and performances of water flooding and SP flooding in these three types of cores were evaluated based on the full-size core flooding tests. Finally, at the field scale, production characteristics of SP flooding in the bimodal sandstone reservoir and multimodal conglomerate reservoir were compared using the actual field production data. The results show: as the pore structure gets more and more complex, the water flooding performance gets poorer, but the incremental recovery factor by SP flooding gets higher;the SP flooding can enhance the producing degree of oil in 1-3 μm pores in the unimodal and bimodal core samples, while it produces largely oil in medium and large pores more than 3 μm in pore radius in the multimodal core sample. The core flooding test using full-size core sample demonstrates that the injection of SP solution can significantly raise up the displacement pressure of the multimodal core sample, and greatly enhance recovery factor by emulsifying the remaining oil and enlarging swept volume. Compared with the sandstone reservoir, the multimodal conglomerate reservoir is more prone to channeling. With proper profile control treatments to efficiently enlarge the microscopic and macroscopic swept volumes, SP flooding in the conglomerate reservoir can contribute to lower water cuts and longer effective durations.

Electrochemical Performance of Nickel Hydroxide/Activated Carbon Supercapacitors Using a Modified Polyvinyl Alcohol Based Alkaline Polymer Electrolyte

Polyvinyl alcohol （PVA）-sodium polyacrylate （PAAS）-KOH-H2O alkaline polymer electrolyte film with high ionic conductivity was prepared by a solution-casting method. Polymer Ni（OH）2/activated carbon （AC） hybrid supercapacitors with different electrode active material mass ratios （positive to negative） were fabricated using this alkaline polymer electrolyte, nickel hydroxide positive electrodes, and AC negative electrodes. Galvanostatic charge/ discharge and electrochemical impedance spectroscopy （EIS） methods were used to study the electrochemical performance of the capacitors, such as charge/discharge specific capacitance, rate charge/discharge ability, and charge/discharge cyclic stability. Experimental results showed that with the decreasing of active material mass ratio m（Ni（OH）2）/m（AC）, the charge/discharge specific capacitance increases, but the rate charge/discharge ability and the charge/discharge cyclic stability decrease.

The effect of betaine surfactants on the association behavior of associating polymer

The interfacial properties and rheological behavior of surfactant/polymer complex systems were measured to investigate the association behavior of the associating polymer.Compared with the pure surfactant solution,there are two inflection points in the surface tension curve for the surfactant/polymer complex systems.The two inflection points are dependent on the surfactant type and polymer concentration.The effect of surfactant on the rheological behavior of polymer can be divided into two aspects.First,the addition of short-chain betaine surfactant is detrimental to the viscosity of polymer solution due to the electrostatic shielding effect.Second,long-chain betaine surfactant also reduces the viscosity of polymer solutions at low concentrations.However,when the concentration of the long-chain betaine surfactant is relatively high,the long-chain betaine surfactant could form worm-like micelles that promote the intermolecular association and thus increase the number of associating junctions,thereby resulting in the augmentation of viscosity.So it is necessary to apply the long-chain betaine surfactant to build the polymer/surfactant flooding system.The interaction model between surfactant and polymer is proposed,which is different from the traditional‘Three-Region Model’.

Stabilization of nickel nanoparticle suspensions with the aid of polymer and surfactant: static bottle tests and dynamic micromodel flow tests

Nickel nanoparticles can work as catalyst for the aquathermolysis reactions between water and heavy oil.A homogeneous and stable suspension is needed to carry the nickel nanoparticles into deeper reservoirs.This study conducts a detailed investigation on how to achieve stabilized nickel nanoparticle suspensions with the use of surfactant and polymer.To stabilize the nickel nanoparticle suspension,three surfactants including sodium dodecyl sulfate,cationic surfactant cetyltrimethylammonium bromide and polyoxyalkalene amine derivative(Hypermer) along with xanthan gum polymer were introduced into the nickel nanoparticle suspension.Static stability tests and zeta potential measurements were conducted to determine the polymer/surfactant recipes yielding the most stable nickel nanoparticle suspensions.Dynamic micromodel flow tests were also conducted on three suspensions to reveal how the nickel nanoparticles would travel and distribute in porous media.Test results showed that when the injection was initiated,most nickel nanoparticles were able to pass through the gaps between the sand grains and produced in the outlet of the micromodel;only a small number of the nickel nanoparticles were attached to the grain surface.A higher nickel concentration in the suspension may lead to agglomeration of nickel nanoparticles in porous media,while a lower concentration can mitigate this agglomeration.Moreover,clusters tended to form when the nickel nanoparticle suspension carried an electrical charge opposite to that of the porous media.Follow-up waterflood was initiated after the nanofluid injection.It was found that the waterflood could not flush away the nanoparticles that were remaining in the micromodel.

Influence of Surfactant-polymer Complexes on Crystallization and Aggregation of CaCO_3

Hollow calcium carbonate（CaCO3） microspheres with different morphologies were synthesized via the precipitation reaction of calcium chloride with sodium carbonate in the presence of different surfactant-polymer complexes.The selected anionic surfactants were sodium dodecyl sulfonate（SDS） and sodium dodecyl benzenesulfonate（SDBS）,respectively.The selected water-soluble polymers were polyacrylic acid（PAA） and polyvinyl pyrrolidone（PVP）.In this work,SDS-PVP ＂pearl-necklace model＂ micellar complex was formed via hydrophobic effectiveness between SDS and PVP and it served as the spherical template to generate spherical CaCO3 aggregates with hollow microspheres composed of about 500 nm irregular shaped particles.SDS-PAA complexes and SDBS-PAA complexes formed ＂core-shell model＂ aggregates with calcium ions serving as the medium to link the anionic surfactant and the polymer.SDS-PAA ＂core-shell model＂ aggregates would act as templates for hollow CaCO3 microspheres consisting of 30―50nm irregular shaped crystallites.SDBS-PAA ＂core-shell model＂ aggregates served as the spherical aggregate templates to generate spherical CaCO3 aggregates consisted of many small spherical particles which had grown together.All the obtained CaCO3 hollow microspheres are calcite particles.This research may provide new insight into the control of morphologies of hollow CaCO3 microspheres in the presence of surfactantpolymer complexes.

Surfactants as Inhibitors for Alkaline Corrosion of Aluminium

Inhibition of aluminium corrosion in NaOH solution by anionic surfactant as sodium (lauryl)sulphate, cationic surfactant as cetyl trimethyl ammonium bromide and non ionic surfactant asTriton-X 100 has been studied using weight-loss and hydrogen evolution methods. It is foundthat the inhibition efficiency depends on the type of SAS as well as its concentration. The orderof increasing inhibition is as followsSLS < Triton - X 100 < CTABThermodynamic parameters are calculated.

XPS Study on Water-Soluble Polymer Surfactant Film

By means of changing the detection angle, the molecular conformation of a new type of polymer surfactant, acrylamide-poly(oxyethykene alkyl ether)acrylate-anionic monomer random copolymer, was studied by x-ray photoelectron spectroscopy(XPS) in detail.

Rheological behavior of alkali-surfactant-polymer/oil emulsion in porous media

Based on deep analysis of ASP/oil emulsions flow behavior characteristic,a mathematical description of non-Newtonian emulsion was developed,and variation of rheological behaviors along the percolation flow direction was given.The effects of emulsions rheological behavior on oil recovery were quantity researched by a 2-D positive rhythm profile geological model.The result shows that the high viscosity and reduction of water phase permeability by emulsification can improve low-middle layer flow rate and enhance sweep efficiency,and the enhancement degree is related with emulsification degree.The study result can be used as reference for scheme design and production performance forecast during ASP flooding.

A SURFACTANT-ASSISTED APPROACH FOR PREPARING COLLOIDAL AZO POLYMER SPHERES WITH NARROW SIZE DISTRIBUTION

A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered

The Research of Complex System Property between Thermosensitive Polymer and Surfactant

In this paper, the rigid structural thermosensitive polymer （made in lab） of NBS （N-butyl styrene）, N, N-DEAM （diethyl acrylamide） and AM （acrylamide） was prepared. The influence of viscosity for copolymer solution under different reaction conditions such as temperatures and inorganic salt （monovalent salt and divalent salt） was analyzed. The experiment studies the combination of polymer situation and three different types of surfactants under certain conditions of the room temperature （25℃） and the formation temperature （76℃）. At last, the influence of the surfactant kinds and concentration on the viscosity of the polymer solution are studied. The results show that： The copolymer solution, the apparent viscosity of which decreases with the increasement of temperature, but its viscosity has suddenly increased and thereafter dropped in the transition temperature. So the temperature sensitive effect ofcopolymer is very significantly. When the concentration of inorganic salt and surfactant can be controlled in certain extent, the copolymer solution, the effect increases with the increasement of the concentration, but the viscosity of which decreases with the increasement of shear rate. Shear rate can be controlled in certain extent, shearing stability properties of the copolymer solution are proved.

Study on Optimization of Polymer Enhanced Foam Formulation System

Taking the pilot test area of polymer enhanced foam flooding in Y oilfield as the prototype, a numerical core model was established, and the polymer enhanced foam formulation system was optimized by analyzing the resistance factor and the change rule of oil recovery of different formulation systems. Research shows that the higher the polymer concentration, the greater the resistance factor, and the more obvious the sealing effect formed in the formation. The concentration of surfactant has a greater impact on the resistance factor. With the increase of surfactant concentration, the resistance factor increases significantly, and the plugging effect of foam agent on core is significantly enhanced. With the increase of gas-liquid ratio, the resistance factor first increases and then decreases. When the gas-liquid ratio is 1:1, the resistance is the largest, and the foam agent has the strongest plugging effect on the core. The optimal formula system of polymer enhanced foam flooding in Y oilfield is: polymer concentration is 1200 mg/L, surfactant concentration is 0.25 wt%, gas-liquid ratio is 1:1.

Long-lifespan aqueous alkaline and acidic batteries enabled by redox conjugated covalent organic polymer anodes

Herein,we introduce a redox conjugated covalent organic polymer(p-HATN,HATN=hexaazatrinaphthylene)anode bearing HATN species for long-lifespan aqueous alkaline and acidic batteries.The p-HATN features intriguing superhydrophilicity and unique wide pH adaptability,while the conjugated network and amorphous cross-linked structure further endow p-HATN with improved electron transport,facile ion diffusion and superior acid-alkali tolerability.As a result,p-HATN exhibits fast surface-controlled redox activity and superior stability for K^(+)and H^(+)ions storage with remarkable capacity retentions in three-electrode cells(88%capacity retention in 13 M KOH over 30000 cycles;nearly 100%capacity retention in 0.5 M H_(2)SO_(4)over 54000 cycles).Moreover,the assembled p-HATN//Ni(OH)_(2)cell with 13 M KOH and p-HATN//PbO_(2)cell with 0.5 M H_(2)SO_(4)also achieve ca-pacity retentions of 83%retention over 55000 cycles and 92%over 15000 cycles,respectively,outperforming most similar systems.This work sheds light on the rational design of advanced polymer anodes for long-lifespan alkaline and acidic batteries.

Research on Influence Factors of Surfactivity of Polyester Polyether Block Copolymer

Polyester polyether block copolymer （PPBC） was synthesized by ester-exchange and polycondensation reactions using dimethyl terephthalate （DMT）, ethylene glycol （EG） and polyethylene glycol （PEG） as monomer. The effects of PEG molecular weight, mol ratio of DMT to PEG （nDMT/nPEG）, temperature and time of polycondensation reaction and vacuum degree in the reaction system on the surface tension and critical micelle concentration （CMC） of PPBC aqueous solution were studied. It was found that both the molecular weight and the concentration of PEG can affect PPBC＇s surface activity obviously, and the optimum synthesis condition of PPBC used as surfactant is as follows： PEG molecular weight is 1 500, tool ratio of DMT to PEG is 3, temperature and time of polycondensation reaction is 260℃ × 1 h, vacuum degree of condensation reaction is 0.03-0.05 MPa. It was proved by surface tension measurement of PPBC aqueous solution that the PPBC synthesized in this condition is a good surfactant with excellent surfactivity.

EFFECTS OF NH_4Cl ON THE INTERACTION BETWEEN POLY(ETHYLENE OXIDE) AND IONIC SURFACTANTS IN AQUEOUS SOLUTIONS

The interaction of poly(ethylene oxide)(PEO)with the ionic surfactants,sodium dodecylsulfate(SDS)and cetyltrimethylammonium chloride(CTAC)respectively,in aqueous solutions containing a certain concentration of NH_4Cl, is studied by the viscosity measurement.It has been found that the ion-dipole interaction between PEO and ionic surfactants is changed considerably by the organic salt.For anionic suffactant of SDS,the addition of NH_4Cl into solution strengthens the interaction between PEO and the headgroup o...

Ni(OH)_2-Ni/C for hydrogen oxidation reaction in alkaline media

The development of the hydrogen electrode is vital for the application of alkaline polymer electrolyte fuel cells(APEFCs).In this study,a series of Ni(OH)_2 decorated Ni/C catalysts(Ni(OH)_2-Ni/C) were prepared by a three-step electrochemical treatment of Ni/C.The existence of Ni(OH)_2 was demonstrated by X-ray photoelectron spectroscopy(XPS),and the surface molar ratio of Ni(OH)_2/Ni of the samples was estimated via an electrochemical method.The HOR catalytic activity of the catalysts was evaluated by a rotation disk electrode(RDE) method,and a "volcano plot" was established between the HOR exchange current(j0) and the surface molar ratio of Ni(OH)_2/Ni.On top of the "volcano",the surface molar ratio of Ni(OH)_2/Ni is1.1:1,the j0 of which was 6.8 times of that of Ni/C.The stability of the samples toward HOR was evaluated to be good.Our study added a systematic experimental evidence to the HOR research,showing that the HOR catalytic activity of Ni can be deliberately controlled via decoration of Ni(OH)_2,which may help understanding the HOR mechanism on Ni.

A review of fluid displacement mechanisms in surfactant-based chemical enhanced oil recovery processes:Analyses of key influencing factors

Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes,change the wettability of rock to a more water-wet system and emulsify the oil to displace it in subsurface porous media.Furthermore,these phenomena can reduce the capillary pressure and enhance spontaneous imbibition.The key factors affecting such immiscible displacement process are temperature,salinity and p H of the fluids,surfactant concentration and adsorption.Therefore,before any surfactant flooding process is applied,extensive studies of fluid-fluid and rock-fluid interactions are needed.The use of other chemicals along with surfactants in chemical enhanced oil recovery(c EOR)processes have been widely considered to exploit the synergy of individual chemicals and complement the weakness arises from each of them during immiscible displacement of fluids in porous media.Therefore,such combinations of chemicals lead to alkaline-surfactant(AS),surfactantpolymer(SP),alkaline-surfactant-polymer(ASP),and nanoparticle-surfactant(NS)flooding processes,among others.In this review study,we categorised the role and displacement mechanisms of surfactants and discussed the key factors to be considered for analysing the fluid displacement in porous media.

Double-layer Modifi cation of Water-based Aluminum with SiO2 and Polyacrylic Acid by Solgel Process and in situ Polymerization

A double-layer aluminum consisting of an aluminum core and a shellof SiO2 and polyacrylic acid was synthesized.This modified aluminum was used to improve the corrosion resistance and dispersive property of aluminum in waterborne media.TEM,FTIR,XPS,and EDX determination showed that PAA and SiO2 were coated on the surface of aluminum.Evolved hydrogen detection showed that the corrosion resistance of composite particle had been markedly improved.Maximum corrosion inhibition efficiency of SiO2 coated aluminum（SiO2@Al）was 95.1% while that of double-layer coated aluminum（PAA/SiO2@Al）was 98.8%.Meanwhile,polyacrylic acid layer improved the agglomeration of aluminum significantly.According to the dispersibility test,the particle size of 50% volume fraction [d（0.5）] of aluminum,SiO2@Aland PAA/SiO2@Alwere 42,53,and 34 μm,respectively.