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As the amount of oilfield produced water (PW) keeps going up, highly efficient flotation agent is needed. In this paper, a series of surfactants (abbreviated as Q-PTEA-Cn) derived from polytriethanolamine were synthesized. Their surface activities and flotation performance were evaluated. The result showed that the Q-PTEA-Cns can effectively reduce the surface tension of water and interface tension of crude oil/water. The Q-PTEA-C12-1 had the best flotation performance and the rational flotation condition was recommended as follows: Q-PTEA-C12-1 dosage 100 mg/L, gas flow 3 L/min, and flotation time 20 minutes. At this condition, the oil removal efficiency of two commonly used flotation agents (FL-1 and FL-2) and Q-PTEA-C12-1 were 62.3%, 69.1%, and 83.6%, respectively. The flotation kinetic of Q-PTEA-C12-1 can be described by Maruyama's flotation model, which presented that there was adsorption of oil droplet adsorbed surfactant onto bubble. Floatation mechanism study confirmed that the Q-PTEA-C12-1 can absorb onto the oil droplet and showed that the Q-PTEA-C12-1 can enhance the bubble–drop attachment efficiency and the stability of bubble–drop agglomerates. [ABSTRACT FROM AUTHOR]

A novel demulsifier (noted as PSADP) having high molecular weight and branch structure was prepared via one-pot synthesis by using two PEO-PPO demulsifiers (SP-1 and DMEA-1), acrylic acid (AA), and pentaerythritol tetraacrylate (PET4A) as materials. The demulsification experiments showed that PSADP can achieve high water removal and clear separated water at the same time. Optimal preparation condition of PSADP was elected by orthogonal test. In addition, the study of partition coefficient and interfacial dilational moduli showed that the best PSADP had best capacity to displace the natural active agents and destroy the interface. [ABSTRACT FROM AUTHOR]

An acrylic emulsion-type inverse demulsifier (named as PMEMA latex) was prepared by using methyl methacrylate (MMA), ethyl acrylate (EA), methacrylic acid (MAA), and acrylamide (AM) as monomers. The effects of reaction conditions toward the copolymerization results were investigated by evaluating various evaluation parameters, including conversion, molecular weight, and diameter. In addition, the interfacial properties of PMEMA latex were investigated to study its demulsification mechanism about treating the O/W emulsion. [ABSTRACT FROM AUTHOR]

Coacervate behavior of polyelectrolyte complexes has been studied by many papers. Few studies have focused on the coacervate behavior of amphoteric polymer. In this study, amphoteric copolymer of diallyldimethylammonium chloride (DM) and sodium styrenesulfonate (SS) (the copolymer was noted as DMS) was synthesized with the mole content of SS to DM ranged from 0 to 10%. Firstly, DMS was characterized by static light scattering, FTIR, 1H-NMR, TGA and DSC. Then, its phase and coacervate behaviors were studied. Turbidity was utilized as an indicator for the coacervate formation. It was found that when the SS content was more than 4 mol%, DMS coacervate would be formed in deionized water at a certain concentration. Temperature and pH have no effect on the formation of DMS coacervate. Meanwhile, salts has a great influence on the DMS coacervation. Unlike the results of the other polyelectrolyte complexes, Na2SO4, Na2HPO4, NaCOOCH3, sodium citrate and NaI cannot prevent the DMS coacervate formation. However, the addition of NaCl, NaNO3, NaBr and NaSCN can prevent the coacervate formation. The influence cannot be described by Hofmeister-like behavior. Results of surface tension and fluorescence spectrum presented that the driving forces to formation of DMS coacervate are the electrostatic interaction and the intermolecular hydrophobic interaction. [ABSTRACT FROM AUTHOR]

In this work, a novel magnetic demulsifier was synthesized by a facile way within one step. The propyleneoxide-ethyleneoxide block polyether, one of the most frequently used demulsifier in petroleum industry, was endowed with the magnetism by reacting with iron (III) acetylacetonate. The as-prepared magnetic demulsifier was characterized by transmission electron microscopy (TEM), superconducting quantum interference device (SQUID), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The magnetic demulsifier showed excellent demulsification performance for water in crude oil emulsion. The demulsification process was revealed by using confocal microscope. Besides, the used magnetic demulsifier could be readily recycled by magnetic separation and solvent washing, and it presented excellent demulsification performance within 3 cycles. The findings in this work might provide a facile approach to prepare varieties of magnetic demulsifiers. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has gathered widespread interest within the scientific community due to its unique properties. Understanding the adsorption behaviors of GO at the oil–water interface has become increasingly important both in terms of fundamental science and applications of GO in emulsions. In the present work, the adsorption dynamics of GO sheets at the toluene/water interface were explored by using pendant drop tensiometry to trace the evolution of oil/water interfacial tensions. A shift from diffusion-controlled to kinetic controlled feature was observed during the aging of the interface, indicating the irreversible adsorption of GO to the interface. Assembly of GO at oil/water interfaces in the presence of surfactants were discussed. Robust large-area films could be prepared by taking advantage of the assembly of GO at the oil/water interface in the presence of cetyltrimethylammonium bromide and octane phenol polyoxyethylene-10. Corresponding interaction mechanisms were discussed. Ultimately, the acquired insights on the interfacial adsorption and the interfacial assembly behavior of GO sheets were combined to reveal the demulsification performance of GO for different emulsions. The findings in the present study are crucial for fully understanding the interfacial activity of GO in emulsions and might provide a facile way to prepare large-area graphene oxide thin films. [ABSTRACT FROM AUTHOR]

In this study, several magnetic flocculants were synthesized by using polyether flocculants. The properties of the as-prepared products were characterized by performing a series of analysis. Further, oily wastewater treatment experiments were performed, and the effects of ultrasonic time, temperature, size of products, and type of polyether on the treatment efficiency were investigated. It was revealed that temperature played a major role, and more than 4 min of ultrasonic time was needed to achieve greater than 80% of oil removal. The magnetic flocculants having smaller size displayed better flocculation performance. Both magnetic flocculants with linear polyether coating and branch polyether coating had good flocculation performance. [ABSTRACT FROM AUTHOR]

Compound poly(methylmethacrylate (MMA)-acrylic acid (AA)-ethyl acrylate (EA))/Fe 3 O 4 superparamagnetic nanoparticles were synthesized successfully by emulsion polymerization and solvothermal reaction methods. The nanoparticles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD) and thermogravimetry analysis (TGA). P(MMA-AA-EA)/Fe 3 O 4 nanoparticles exhibited superparamagnetic properties with a saturation magnetization value of 20 emu/g. The selective adsorption behaviors of nanoparticles toward dyes were investigated and the function of electronic interaction during the adsorption process was also discussed. [ABSTRACT FROM AUTHOR]

Oil-in-water emulsion is an innovate manner by which heavy crude oil can be transported from producing sites to transforming sites through pipelines. The effect of emulsifier on the interfacial properties and demulsification performance of demulsifier for heavy crude oil–in-water emulsion has been studied by many researchers. However, the influence of asphaltene in heavy crude oil on the interfacial properties of demulsifier has not been investigated yet. In this article, the influence of asphaltene concentration of two typical demulsifiers (straight-chained SP-1 and branch-chained AE-1) was systematically studied in terms of absorption thermodynamics, absorption kinetics, and coalescence kinetics. The results revealed that the demulsifier adsorption was aΔScontrolled spontaneous process. The absolute value ofΔGof SP-1 adsorption was found to decrease with asphaltene concentration, whilst the asphaltene concentration had no significant influence on that of AE-1. With the increase of asphaltene concentration, the demulsifiers’ adsorption rates increased, but the reorganization rates on the interface decreased. Coalescence speed of asphaltene droplet decreased with asphaltene concentration in spite of demulsifier type. Additionally, AE-1 had higher absolute value ofΔG, adsorption speed, and coalescence speed than that of SP-1 at the same condition. [ABSTRACT FROM PUBLISHER]

The treatment of produced liquid from polymer flooding is a significant problem in the oil field industry. Produced liquid from polymer flooding studied in this paper was composed of W/O emulsion and wastewater containing the residual polymer. Alkyltrimethylammonium halides (C12TAB, C14TAB, C16TAB, and C18TAB) and dialkyl-dimethylammonium halides (DC12TAB, DC16TAB, DC18TAB) were used both as the demulsifier for the W/O emulsion and as the flocculant for the wastewater. The demulsification tests showed that C16TAB is the best performing demulsifier for the W/O emulsion of these cationic surfactants and its water removal can reach 91% at the dosage of 150 ppm. The results of interfacial tension and interfacial dilational modulus showed that C16TAB had a rapid migration of surface-active agents to the water/oil interface and can lower the film strength significantly at the same time. Therefore, the C16TAB can have the best demulsification performance. In addition, C14TAB and C16TAB exhibited much better flocculation performance than the other surfactants. After the treatment with C14TAB and C16TAB, the oil content in wastewater decreased significantly to the 30 ppm because C14TAB and C16TAB can move to the oil/water interface and destroy the stability of the oil droplet in wastewater easily, which can be confirmed by the results of zeta potential. [ABSTRACT FROM PUBLISHER]

A novel cationic-nonionic bifunctional polymerizable surfactant (PEP) was prepared by the quaternarization of poly (ethylene oxide-propylene oxide) block polymers (PEO-PPO) having terminal tertiary amine group with chloropropene. Polymeric surfactant (PAM-g-PEP) was prepared by the copolymerization of acrylamide and PEP in water and the product was confirmed by FTIR. PAM-g-PEP has exhibit excellent surface and interfacial activity and its surface tension and interfacial tension at cmc are 40.13 mN/m and 11.69 mN/m, respectively. The influence of temperature on the micellar behavior of the PAM-g-PEP in water was studied by the dynamic laser scatting (DLS) and ultraviolet spectroscope. The results showed that PAM-g-PEP in water is thermo-associative. In diluted PAM-g-PEP solution, the Rhof the polymeric surfactant increases with the temperature due to the interpolymeric aggregations are formed. In the case of concentrated PAM-g-PEP solution, the light transmittance of PAM-g-PEP aqueous solution decreases with the increasing temperature, which is may be caused by the increase of the number of the interpolymeric PEP chain aggregates. [ABSTRACT FROM PUBLISHER]

The heavy oil activator is one kind of amphiphilic polymers used for oil displacement and its potential application in the field of enhanced heavy oil recovery has attracted much attention in offshore oilfield in China. Before the large-scale application, the study of the effect of heavy oil activator on the treatment of produced fluid is meaningful. In this paper, the influences of two activators (P1 and P2, P1 had the polyether and alkyl chain mixed hydrophobic group, while the hydrophobic monomer in P2 only had the alkyl chain hydrophobic group) on the stability and treatment of W/O and O/W emulsions were investigated, respectively. Both P1 and P2 were helpful for the W/O emulsion demulsification, while the influence of P1 was less than that of P2. On the other hand, both P1 and P2 were not beneficial for the O/W treatment, while the influence of P1 was greater than that of P2. In addition, the interfacial behavior of the activators was systematically studied by means of surface/interfacial tensiometer, dual-polarization interferometry test and optical tweezers to explain the corresponding influences. [ABSTRACT FROM AUTHOR]

The primary objective of this work was to prepare star copolymers of acrylamide and N,N-dimethyl-N-vinylnonadecan-1-aminium chloride(C18DMAAC) and to investigate the dilute solution behavior of these star hydrophobically modified acrylamide (SHMPAM) copolymers with different C18DMAAC content. The SHMPAMs were prepared using photopolymerization. For the different polymer solutions, the relationship between specific viscosity and polymer concentration obeyed the Rabin's relation well, which means that the conformations of these polymer chains were nearly spherical in dilute solution. The data of these dilute solutions were fitted by four different equations. The results showed that Schulz-Blaschke(S-B) and Fedors equations more accuratly described the dilute solution properties of these kinds of copolymers. The intrinsic viscosities calculated by different equations were different from each other, which is different from the results found for linear HMPAM. The equivalent hydrodynamic volume (voluminosity VE) of these star copolymer solutions can not calculated by the regular method because the relationship between Y (Y = (ηr0.5-1)/C (1.35ηr0.5-0.1), ηr is relative viscosity and C is polymer concentration) and polymer concentration was abnormal. [ABSTRACT FROM AUTHOR]

Water-soluble thioxanthone-terminated poly(ethylene imine) (PEI 600, PEI 1800, PEI 3000 and PEI 10000; 600, 1800, 3000 and 10000 are the weight-average molecular weights of the above PEIs, respectively). Macrophotoinitiators were synthesized by introducing a certain amount of thioxanthone (TX) moieties into the periphery of PEI, and the products were confirmed by 1H-NMR, FT-IR, and elemental analysis. Star polyacrylamides (PAMs) were prepared using the obtained macrophotoinitiator as a core via photopolymerization. The effect of the molecular weight of the macrophotoinitiator on photoinitiation efficiency of the resulting polymers was investigated. The result shows that the choice of the macrophotoimitator has no influence on the rate of polymerization. In addition, three plots of characteristic properties with the star polymer were studied to confirm the existence of arms in the resulting star PAM. [ABSTRACT FROM AUTHOR]

The viscosity behavior of the dilute aqueous solutions of hydrophobically modified acrylamide copolymer (HMPAM) and poly(N-isopropylacrylamide) (PNIPAM) was investigated. A negative deviation of reduced viscosity of HMPAM + PNIPAM from the theoretical values was observed. Both a conventional viscometry method and a method using an aqueous solution of one polymer as the solvent for the other polymer were used to clarify the mechanism behind the observed viscosity behavior. With the conventional method, the theoretical predictions obtained by the Δb (or α) criterion are contradictory to the experimental results and cannot be applied to describe the interaction between HMPAM and PNIPAM, where Δb is the difference of experimental interspecific interaction coefficient bm and theoretical bm,i and α is the difference of experimental Huggins coefficient km and theoretical km,i. The change of Δ[η]/[η]i suggests that there is only an attractive interaction between HMPAM and PNIPAM, where Δ[η] is the difference of experimental intrinsic viscosity [η]m and theoretical [η]i. Results from the method using an aqueous solution of one polymer as the solvent for the other polymer confirmed the attractive interaction between HMPAM and PNIPAM and indicated that the attachment of the PNIPAM molecules to the hydrophobic groups in HMPAM can disrupt both the initial intra- and intermolecular associations between HMPAM chains simultaneously. The disruption of the original intramolecular association of HMPAM leads to an increase in the intrinsic viscosity [η], while the disruption of the original intermolecular association of HMPAM yields a negative deviation of the reduced viscosity. [ABSTRACT FROM AUTHOR]

Polymer brushes are special structures that can be described as polymer chains tethered to another polymer chain or to the surface of planar, cylindrical, or spherical matrix. Tremendous potential applications of polymer brushes have been explored such as in drug delivery, antifouling coating, and enhance oil recovery (EOR). Herein, combining the "grafting to" and "grafting from" techniques, we present a facile and scalable method to obtain spherical polymer brushes utilizing a rational designed difunctional ligand. The difunctional ligand allows for the generation of polymer colloidal core along with the growth of polymer chains in situ at the surface simultaneously. By this strategy, a well-defined spherical polymer brushes with core–shell morphology were formed in a high yield (95%). Benefiting from the difunctional ligand, the usage of emulsifier for emulsion polymerization was adequately reduced. Furthermore, the obtained polymer brushes exhibit excellent surface and interfacial activity. Oil–water interfacial tension reduced approximately 9 mN/m at extremely low concentration (1.0 ppm). Meanwhile, the obtained polymer brushes can stabilize O/W emulsion more effectively than the unmodified counterparts. Additionally, the swelling behavior of the well-defined polymer brushes could be well controlled by cross-link degree. This strategy will provide a new avenue for scalable synthesis of polymer brush–based functional materials for industrial applications. [ABSTRACT FROM AUTHOR]

• Identical bands were observed in the fingerprint region of different infrared spectra. • Chemical shifts of XPS spectra of N1s, O1s and Al2p after adsorption were explained. • DFT calculations were carried out to illustrate the coordination adsorption. One of the main challenges in cleaning crude oil-contaminated soil is the unknown adsorption mechanism between residual oil and soil. Herein, infrared spectrometer (IR) is used to detect the existence of dibutylphthalate (DBP) and pelargonamide on montmorillonite (MMT) surface. In addition, after the adsorption of DBP and pelargonamide on MMT, the bands in fingerprint region of the two IR spectra are almost identical, indicating coordination bonds were formed on the surface of MMT. X-ray photoelectron spectroscopy (XPS) is employed to detect the chemical environment of N, O and Al. The reverse migration of Al2p spectrum and forward migration of N1s and O1s spectra indicate the coordination adsorption of carbonyl and amine groups on MMT surface. Then, density functional theory (DFT) calculations are applied to make a further explanation of the bonding mechanisms of DBP and pelargonamide onto MMT surfaces. The result shows that there are two types of aluminum on the surface of MMT acting as Lewis acid sites in coordination adsorption, namely Al3+/Si4+ isomorphic substitutions and Al3+ adsorbed on MMT by means of electrostatic adsorption. Meanwhile, the oxygenium on the surface of MMT acts as Brønsted bases in hydrogen bonding adsorption. [ABSTRACT FROM AUTHOR]

Gum-based materials were prepared by the condensation reaction between salicylhydrazine and aldehydes guar gum for capturing heavy metal ions from aqueous solution. • Hydrazine-Functionalized Guar-gum material was prepared for capturing Ni2+, Cr3+ and Co2+ from aqueous solution. • The adsorption isotherms may follow the Langmuir model, indicating a monolayer coverage adsorption mechanism. • Maximum adsorption capacity for Ni2+, Cr3+ and Co2+ were 1272.4 mg g-1, 748.86 mg g-1 and 521.81 mg g-1, remarkably. • Adsorption mechanism has been demonstrated through 1H NMR titration experiments of model molecular and metal ions. • Recyclability studies confirmed that the GG-SH could be used repeatedly for the adsorption-desorption of ions. This research demonstrates the capability of guar-gum modified with salicylhydrazine to remove Ni2+, Co2+ and Cr3+ from aqueous solution. Structural characterization showed that aldehydes guar gum was grafted with salicylhydrazine with morphology. The as-prepared nanocomposite had a large surface area and hydrophobicity, which ensured its good sorption ability and convenience of separation. The sorption equilibrium data were well fitted to the Langmuir model, and uniquely high adsorption capacities for nickel, chromium and cobalt, which are 1272.4 mg•g−1, 748.86 mg•g−1 and 521.81 mg•g−1, remarkably, were achieved. The thermodynamic parameters for the sorption were also determined, and ΔG and ΔH values indicate exothermic behavior. Adsorption mechanism of capturing cation with GG-SH has been demonstrated through 1H NMR titration experiments of model molecular and metal ions. The features make this carbohydrate-based material suitable in water purification and separation treatment. [ABSTRACT FROM AUTHOR]

Polyacrylate crude oil demulsifier is one of the hot topics in the research and development of demulsifier at present, there is a lack of systematic comparative study on performance and properties of polyether and polyacrylate crude oil demulsifier. In this paper, the demulsification performance and microscopic demulsification process of the two demulsifiers, namely polyacrylate P(MA-DBC) and polyether P199–59 are discussed. The demulsification performance of polyether P199–59 was superior to that of polyacrylate P(MA-DBC). The study of the microscopic process of demulsification established that for P199–59, the diffusion rate was faster, the saturated adsorption capacity was higher, the ability to destroy the oil-water interface film was stronger and the probability of water droplets collision coalescence was higher; therefore, it can achieve faster dehydration speed and higher dehydration rate than that of P(MA-DBC). The results of this comparative study are meaningful for improving the demulsification performance of polyacrylate demulsifier. [ABSTRACT FROM AUTHOR]

Previous studies have found that ionic surfactant micelles can induce depletion forces between oil droplets, whereas the depletion forces induced by nonionic surfactant micelles cannot be measured. Nonionic surfactants are usually mixed with ionic surfactants to induce depletion forces. Here, we report that mixing of nonionic polymer micelles and inorganic salt is also an effective method for inducing depletion between oil droplets. Optical tweezers are used to measure the interaction forces between oil droplets in the aqueous solution of polyoxyethylene–polyoxypropylene–polyoxyethylene nonionic polymer. Without salts, there is no depletion force between oil droplets regardless of whether the concentration of polymer is above or below the critical micelle concentration (CMC). This result is consistent with literature that the oil drops adsorbed by the nonionic polymers were stable against coalescence. However, the depletion force between oil droplets generates when NaCl is added, and the concentration of Pluronic F127 is above or equal to the CMC. This suggests that salts can enhance the depletion force induced by nonionic polymer micelles. These findings have significant implications for the stability of emulsions in the food, oilfield, and medicine industries. [ABSTRACT FROM AUTHOR]

Functional Fe3O4 nanoparticle (Fe3O4 NP) is one of the most attractive candidates in the demulsification field because of its outstanding recycling ability, low cytotoxicity, and good biocompatibility. However, the lack of research on their interfacial properties greatly inhibits further development in the industrial demulsification process. The main aim of this work is to explore interfacial properties of functional Fe3O4 NPs from their intrinsic natures, namely morphologies and structures. Three Fe3O4 NPs with different morphologies, including triangle-shaped Fe3O4 NPs (TF NPs), octahedron-shaped Fe3O4 NPs (OF NPs) and truncated octahedron-shaped Fe3O4 NPs (TOF NPs), were prepared by using the solvothermal reaction. Their demulsification capacities of water-in-cyclohexane (W/C) emulsion were evaluated and the TOF NPs had best performance. The demulsification process including diffusion, adsorption and phase separation stages of these Fe3O4 NPs were investigated in detail by interfacial experiments and mathematical models for explain the demulsification result. The diffusion coefficient was calculated at both the early and late stages of the demulsification process, along with their adsorption energy and the elastic modulus of oil-water interfaces. TOF NPs had the largest diffusion coefficient of 1.777 × 10−6 and 2.443 × 10−6 m2/s at the early and late stages, respectively. The W/C interface adsorption energy of TOF NPs were much lower than that of the others and the elastic modulus of W/C interface reduced by TOF NPs was also more effective than that by the others. [ABSTRACT FROM AUTHOR]

Highlights • A guar-gum based material GG-GH was synthesized and characterized. • A rapid uptake of dyes was observed and the equilibrium is achieved in 0.5 h. • The adsorption isotherms may follow the Langmuir model, indicating a monolayer coverage adsorption mechanism. • Maximum adsorption capacity for MB, RhB, MeO and BrB were 1522.2 mg·g−1, 1359.96 mg·g−1, 868.83 mg·g−1 and 904.7 mg·g−1, respectively. • Recyclability studies confirmed that the GG-GH could be used repeatedly for the adsorption-desorption of dyes. Abstract The galacylhydrazine modified guar gum (GG-GH) was prepared through oxidation and condensation. GG-GH demonstrated highly efficient removing performance for organic dyes in large volume of water sample solutions, a rapid uptake of dyes was observed and the equilibrium is achieved in 0.5 h. The maximum adsorption capacity for MB, RhB, MeO and BrB were 1522.2 mg g−1, 1359.96 mg g−1, 868.83 mg g−1and 904.7 mg g−1 at room temperature according to the Langmuir adsorption isotherm(R2 > 0.977). The removal percentage still remains high(>95%) after ten filtration-regeneration cycles, suggesting GG-GH is an excellent gum-based materials for the water treatment with high recyclability and long life. [ABSTRACT FROM AUTHOR]

The thermochemical cleaning method was used to treat the oily sludge produced from Daqing oilfield. Cleaning agents were screened innovatively by using interfacial tension (IFT) method. The mixture of sodium carbonate, fatty alcohol ethoxylate (AEO-9), and rhamnolipid with a ratio of 5:1:0.5 was found that had the lowest IFT. They were selected as the cleaning agents and when their mass fraction was 2 wt%, cleaning agents aqeous solution/sludge ratio was 3:1, cleaning time was 40 min and cleaning temperature was 50 °C, the oil content contained by solids after cleaning was reduced to less than 1 wt %, meeting the environmental protection requirement in China. In addition, the simulated adsorption experiment and the characterization of residue on the cleaned solids were done to provide insight into the cleaning process. The results revealed that the oil adsorbed onto the solids (clinoptilolite) mainly by the multilayer physisorption, most of them can be easily removed by the emulsification of cleaning agents, and the residue is mainly asphaltene. [ABSTRACT FROM AUTHOR]

In this work, a colorimetric methodology was developed for free chlorine determination by constructing a fiber-optic sensor (FOS) which was designed by using a small LED as light source and two silica fibers as light transmission elements. Then the FOS was integrated with the sequential injection lab-on-valve (SI-LOV) manifold to fabricate a FOS-SI-LOV system for free chlorine detection. The colorimetric determination was based on the reaction between N , N -diethyl- p -phenylenediamine (DPD) reagent and free chlorine, which would produce a chromophore showing maximum absorbance at 511 and 551 nm and detected by a micro spectrometer detector. By choosing a green LED with emission wavelength at 520 nm as light source, the chlorine concentration could be simply evaluated according to Beer's law. The developed FOS-SI-LOV system showed improved performances of wide linear range (10–400 μg L −1 ), low detection limit (3.5 μg L −1 , 3σ), fast analysis (6.85 s) and excellent repeatability (0.0083 RSD, n=8) for chlorine determination. The proposed FOS-SI-LOV system has been applied to on-line and real-time chlorine determination in different water samples with excellent selectivity. Furthermore, this FOS-SI-LOV methodology provided a colorimetric and fluorescence detection platform for other hazardous species monitoring in water environment based on Beer's law and Stern-Volmer relationship, respectively. [ABSTRACT FROM AUTHOR]

Oil-based drilling cuttings (OBDC) are hazardous waste, oil removal treatment must be done before they are re-utilized. Winsor I microemulsion (composed by microemulsion phase and remaining phase) cleaning is one of oil removal methods. However, there are many surfactants in the Winsor I microemulsion, which result in high cleaning cost and high possibility of surfactant contamination. In this paper, hydrophilic deep eutectic solvent (DES) and mineral oil were used to replace the microemulsion phase and remaining phase in Winsor I microemulsion, respectively, and a low-cost and surfactant-free cleaning agent was formed. The recommended DES was the mixture of choline chloride, methanol, and water with a molar ratio of 1:2.5:3, and the best cleaning agent was the mixture of DES and mineral oil with a mass ratio of 3:1. The recommended cleaning process was that added the OBDC into cleaning agent with a mass ratio of solid to liquid of 1:3, and stirred at room temperature for 100 min. At this condition, the oil content of OBDC reduced from 14.57 wt% to 1.34 wt%. In addition, the cleaning mechanism was discussed. The DES has low surface tension and good wetting property, which is similar with the microemulsion. [ABSTRACT FROM AUTHOR]

Hierarchically engineered asymmetric ceramic membrane is successfully fabricated, and special wettability is endowed to the membrane by introducing superhydrophilic and underwater superoleophobic silica nanoparticles through dip-coating technology onto the active separation layer. Effect of reaction temperature on the wettability of the silica nanoparticles is discussed. It has been found that the hydrophilicity of the silica increases with increasing the temperature and superhydrophilicity can be obtained when the temperature reaches to 60 °C. Underwater oil contact measurements are performed using a series of oils and it turns out the as-prepared material bear excellent oil repellency towards various oil droplets. Separation performance of the membrane for oily wastewater treatment was investigated. It has been revealed that the as-prepared membrane can successfully separate the oil contaminated wastewater within one step under a small applied pressure (0.1 MPa) with oil rejection coefficient R >99.95%, indicating an extremely high separation efficiency. [ABSTRACT FROM AUTHOR]

With the large-scale development of shale gas, oil-based drilling fluids have found widespread application. However, a significant challenge arises in removing small harmful solids of oil-based drilling fluids after multiple uses. Investigating the stable mechanism of harmful solids in nonpolar solvents is crucial for their removal. Here, kaolin is chosen as the harmful solid phase. Various surfactants sodium bis(2-ethylhexyl) sulfosuccinate (AOT), sorbitan monooleate (Span 80), sorbitan trioleate (Span 85), cetyltrimethylammonium bromide (CTAB), oleic acid (OA), and stearic acid (SA) are used as dispersants to explore the dispersibility and stability mechanisms of kaolin in the oil phase. Results reveal that the Span 80 and Span 85 exhibit the best dispersibility and rheological performance for kaolin, followed by AOT, while SA shows the poorest dispersibility and rheological performance. Except for SA and CTAB, the other dispersants significantly improve the wettability of kaolin particles. X-ray diffraction (XRD) results indicate that all dispersants adsorb on the surface of kaolin. FT-IR and XPS confirm that nonionic surfactants Span 80 and Span 85 adsorb on the surface of kaolin through hydrogen bonding. Strong Zeta potential on the particle surface suggests that Span 80 and Span 85 stabilize the kaolin system through electrostatic repulsion mechanisms. • Harmful solids on the nanometer or micron scale in waste oil-based drilling fluids are difficult to remove. • The reuse of waste oil-based drilling fluids can reduce environmental pollution and the economic cost of drilling. • The stabilization mechanism of harmful solids is of guiding significance for their removal. • The stable dispersion mechanism of solid particles by different dispersants was investigated. [ABSTRACT FROM AUTHOR]

Generally, the emulsion of AM/AA-Na/AMPS-Na aqueous solution and kerosene was prepared by direct emulsification in which the surfactant mixture was initially placed in the oil phase and then the water phase was added. Transitional phase inversion (TPI) emulsification has been widely used for preparation of ultrafine emulsions, but there is no report about the P(AM/AA-Na/AMPS-Na) nanoemulsion obtained by polymerization of TPI emulsion. In this article, first, the emulsions of AM/AA-Na/AMPS-Na aqueous solution and kerosene were prepared by four different methods, then, the properties of different emulsions and the corresponding results of polymerization were compared. The P(AM/AA-Na/AMPS-Na) nanoemulsion was obtained by the polymerization of TPI emulsion. Compared to the P(AM/AA-Na/AMPS-Na) emulsion obtained by direct emulsification, the P(AM/AA-Na/AMPS-Na) nanoemulsion obtained by the polymerization of TPI emulsion has higher molecular weight and better freeze–thaw stability and thermal stability. [ABSTRACT FROM AUTHOR]

Polymer systems containing dynamic covalent bonds have great application potential in the field of enhanced oil recovery. In this paper a series of polyboric acid compounds were synthesized by using polyamine and formylbenzeneboronic acid as raw materials, and then a binary composite system containing dynamic borate ester bonds was formed by mixing guar gum with the polyboric acid compound. The effects of the polyboric acid compound structure, composite system concentration, temperature, inorganic salt concentration and pH on the apparent viscosity and rheological properties of the composite system solution were investigated. The results showed that the higher the content of boric acid groups in the polyboric acid compound, the greater the solution viscosity of the composite system. The apparent viscosity of the guar gum solution increased from 350 mPa.s to 1854 mPa.s at room temperature, the highest value obtained, when the guar gum was mixed with a polyboric acid compound formed by the reaction of polyethyleneimine (PEI) and 2-formylphenylboric acid (2-FPBA) at a molar ratio of 1:4.5. Temperature and pH had a great influence on the apparent viscosity of the composite system, whereas NaCl addition had little effect on the apparent viscosity of the composite system. In addition, the rheological test results showed that the composite system had good shear resistance and structural elasticity, which meets the basic requirements of a polymer flooding agent used for enhanced oil recovery. [ABSTRACT FROM AUTHOR]

Three new surfactant macromonomers (SMM) with different ethylene oxide (EO)/propylene oxide (PO) ratios (for SMM1, SMM2, and SMM3, the EO/PO ratios were 1:0.5, 1:0.9, and 1:1.25, respectively) were synthesized by the reaction between PEO-PPO di-block polymers having terminal tertiary amine groups and chloropropene. Graft copolymers of acrylamide and SMM (PAM-g-SMM) were prepared with different SMMs and grafting densities in water, and the products were confirmed by FTIR and elemental analysis. Owing to the strong hydrophobicity of the graft, the PAM-g-SMM3 was not water soluble. However, PAM-g-SMM1 and PAM-g-SMM2 aqueous solutions had good surface activity and their surface tensions were 44.26 and 37.63 mN/m at a concentration of 1000 mg/L, respectively. In general, in diluted graft PAM solutions, the copolymer predominantly formed intrapolymeric associates. The PAM-g-SMM2 was both thermo-associative and salt-associative in dilute solution. For PAM-g-SMM2, when the temperature and salt concentration increased, interpolymeric aggregations were formed. [ABSTRACT FROM PUBLISHER]

Highlights: [•] In dilute solution, SDS molecules adsorb at the surface as isotropic layer. [•] In higher concentration, SDS aggregate to form hemimicelles and the HMC is 1mM. [•] Competitive formation of micelles and hemimicelles leads to adsorption behaviors. [•] The adsorption of SDS at C18 surface obeys two-step process. [•] A four-stage adsorption model of SDS at C18 surface was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zwitterionic surfactant-octadecane oil interaction was studied by real-time interferometry experiment and MD simulation. • Slow-limiting step of arrangement was revealed by 4-step dynamics analysis with k 3 (a r r) < k 1 (d i f) , k 2 (a d s) , k 4 (a g g) . • Interaction stability and strength were indicated to be HSB-16 > HSB-12 with E H S B 16 - o i l < E H S B 12 - o i l by MDS calculation. • Interaction process is explained by molecular-orientation and force-dominance mechanism model. • This work constructs interfacial analysis platform and reveals intermolecular interaction/mechanism at oil–water interface. In this work, the interaction performances at octadecane oil–water interface were investigated for zwitterionic surfactants of dodecyl dimethyl hydroxypropyl sulfobetaine (HSB-12) and hexadecyl dimethyl hydroxypropyl sulfobetaine (HSB-16) from both experimental and simulation insights. For macroscopic experiment, optical interferometry methodology was developed to real-time measure the interfacial interaction process and obtain the quantitative interfacial thickness and mass results. The four-step dynamic process (diffusion, adsorption, arrangement and aggregation) was characterized by kinetic analysis, indicating arrangement process as slow-limiting step. The rate of the four step process (diffusion rate k 1 (d i f) , adsorption rate k 2 (a d s) , arrangement rate k 3 (a r r) , and aggregation rate k 4 (a g g)) is represented as k 3 (a r r) < k 1 (d i f) , k 2 (a d s) , k 4 (a g g) . The Langmuir model was characterized by thermodynamic analysis, deducing the aggregation spontaneity of HSB-16 > HSB-12. The free energy of the aggregation stages of HSB-16 and HSB-12 was expressed as Δ G a g g (H S B 16) = - 3.95 kJ/mol < Δ G a g g (H S B 12) = - 3.13 kJ/mol. For microscopic simulation, the interaction configurations and interaction energies were obtained through molecular dynamics simulation (MDS) calculation. The interaction stability and interaction strength were indicated to be HSB-16 > HSB-12. The interaction mechanism was explained by proposing molecular-orientation model below critical micelle concentration (CMC) and layer-interaction model above CMC. The different mechanisms were attributed to electronic attraction between surfactant molecules and hydrophobic interaction between surfactant and oil molecules. This work successfully constructs the interfacial platform for oil–water interface analysis, which not only elucidate the surfactant-oil intermolecular interactions but also provide mechanism understanding from macroscopic and microscopic scales. [ABSTRACT FROM AUTHOR]

[Display omitted] • HMPAMs containing different types of amphiphilic monomers were prepared. • DPI was used to study the interaction between HMPAM and crude oil. • The interaction between HMPAM and oil depends on the amphiphilic monomer type. Hydrophobically modified polyacrylamide (HMPAM) is one of most used amphiphilic polymers for polymer flooding in oilfield. The interaction between HMPAM and crude oil is key to the oil displacement efficiency of HMPAM. However, due to the lack of experimental research method, there is little research on this aspect. In this work, HMPAMs containing different types of amphiphilic monomers were prepared, their interactions with crude oil were studied by dual polarization interferometry (DPI) for the first time, and their adsorption conformations on the surface of crude oil were discussed. The DPI results directly shown that the influence of amphiphilic monomer type on the interaction strength was as follows: nonionic type > cationic type ≈ anionic type. This order was consistent with the adsorption capacity of amphiphilic monomer on the surface of crude oil, indicating that the interaction strength between HMPAM and crude oil mainly depended on the type of amphiphilic monomers. In addition, the DPI results indirectly shown that the effect of amphiphilic monomer type on the HMPAM molecular coiled conformation on the surface of crude oil was also determined by the adsorption capacity of amphiphilic monomer. The research results of this paper can provide useful information for the amphiphilic monomer selection from the perspective of improving oil displacement efficiency of HMPAM. [ABSTRACT FROM AUTHOR]

When cationic polymers are used as flotation agent in oil field to treat oily wastewater, viscous flocs are inevitably produced, which severely affect the oilfield production. In this paper, polypropylene glycol monomethyl ether (MPPG) was used to graft‐modify poly N‐(3‐dimethylaminopropyl) methacrylamide (PDPM). Five types of copolymers (PPG‐g‐PDPM‐X) with different theoretical grafting degrees of PPG (20 %, 40 %, 60 %, 80 %, 100 %) were prepared. Chemical structures and surface activities of these copolymers were investigated. The flotation performances of the synthesized PPG‐g‐PDPM‐X and PDPM were evaluated and compared. It was found that PPG‐g‐PDPM‐3 showed high oil removal efficiency and the stickiness of its flocs was significantly lower than that of PDPM flocs. Factors that can affect the flotation performance of PPG‐g‐PDPM‐X were also studied. The results showed that both the interfacial activity and the conformation of PPG‐G‐PDPM‐3 in water changed as the rising temperature and the increasing pH, resulting in a decrease in the oil removal rate. The oil removal rate of PPG‐g‐PDPM‐3 increased with the increasing dosage, gas flow rate and flotation time. The recommended flotation conditions for PPG‐g‐PDPM‐3 were as follows: 100 mg/L dosage at room temperature, 1.5 L/min gas flow and 15 min flotation time. The oil removal rate at this condition was 87.33 %. This paper provides a solution to solve the viscous flocs issue when cationic copolymers are used as the flotation agent. Meanwhile, the PPG‐g‐PDPM‐3 is expected to have more interesting applications because it is temperature sensitive and pH sensitive. [ABSTRACT FROM AUTHOR]

It was shown that methacrylic acid-ethyl acrylate copolymer (P(EA-MAA)) emulsion has a good reverse demulsification performance for treatment of water produced in oilfields. Its polymerization mechanism, kinetics and demulsification mechanism are important for its application and scale-up production. Therefore, they were studied in the research described in this paper. It was found that the demulsification mechanism of P(EA-MAA) was related to the ion compositions of the produced water and the conformation change of P(EA-MAA) when it was dissolved in the produced water. The distributions of monomer and surfactant before the polymerization were investigated and we found that there were both homogeneous nucleation and micellar nucleation during the first stage of emulsion polymerization. The relationships among the polymerization rate (Rp), monomer concentration ([M]), initiator concentration ([I]) and surfactant concentration ([S]) were studied. The emulsion copolymerization kinetic equation was Rp∝[M]0.64 [I]0.68 [S]0.41, which is related with the nucleation mechanism of the polymerization mechanism. In addition, the activation energy was 34.50 kJ/mol. [ABSTRACT FROM AUTHOR]

A new thermothickening aqueous system was presented based on mixtures of hydrophobically-modified acrylamide copolymer (HMPAM), poly(N-isopropylacryl-amide) (PNIPAM) and sodium dodecyl benzene sulfonate (SDBS). Unique in the thermothickening system, a maximum viscosity and the temperature (Tmax) when reaching such viscocity change independently, reflects the presence of intermolecular interactions. The Tmax of the new system suggests that its thermothickening behavior is correlated to the cloud point temperature (Tc) of PNIPAM, which can be easily adjusted to desired values by the addition of SDBS. The experimental data also indicate that the temperature between the rheological transition temperature (Tt) and Tmax in HMPAM+PNIPAM+SDBS is within the range of 35-65°C, and the thermothickening behavior originates from the reinforcement of the association network between HMPAM, PNIPAM and SDBS. Consequently, the viscosity over the corresponding thermosensitive range upon cooling is higher than that upon heating. [ABSTRACT FROM AUTHOR]

Chemical demulsification is the most effective, common and the cheapest method to break crude oil emulsion during oil extraction. The chemical demulsification process is related with the natural emulsifier displacement by demulsifier. In this article, a single droplet in situ displacement method was employed to evaluate demulsifier displace capacity and the experimental device was built. This device determines the displacement capacity of demulsifier by measuring the oil-water interfacial tension, demulsifier concentration and saturated adsorption amount of demulsifier. Displacement capacities of four commercially available polyether demulsifiers and the relationship between demulsifier displacement capacity and demulsification performance were investigated. The results showed that the demulsifier displacement capacity was not affected by natural emulsifier type (asphaltene, resin, or mixture of asphaltene) and was related to the demulsifier type, concentration, and temperature. Demulsifier displacement capacity increased with demulsifier concentration and temperature. However, only when the asphaltene concentration of was over 6.78 wt%, the demulsification increased with demulsifier displacement capacity. [ABSTRACT FROM AUTHOR]

The zwitterionic monomer, 1-(2-hydroxypropyl-sulfo)-acrylamide ethyl- N , N -dimethyl ammonium chloride (MeSA) was copolymerised with acrylamide (AM), acrylic acid (AA), and a hydrophobic monomer N , N -diallyl oleamide (DNDA) to obtain the zwitterionic hydrophobic association polymer AM/AA/DNDA/MeSA. The structure of the hydrophobic association polymer was characterised by 1H NMR, FT-IR, and intrinsic viscosity studies. The self-assembly system of the polymer and the surfactant Tween-40 was then formed, and the rheological properties and adsorptive performance of the self-assembly system were investigated. The result showed that the polymer–surfactant self-assembly system had good properties such as thickening, temperature resistance, salt resistance, and shear resistance. It is shown that the thermal thickening phenomenon, which allows the system to be used as a good petrochemical product in a high-temperature environment, provides a vital research foundation for the future application of this kind of self-assembly system. A self-assembly system was synthesised by a zwitterionic hydrophobic association polymer (AM/AA/DNDA/MeSA) and Tween-40. Under the synergistic effect of hydrogen bonding and hydrophobic association, the self-assembly system has salt resistance, shear resistance, and thermal thickening properties. [ABSTRACT FROM AUTHOR]

• The performance of W/O crude oil emulsion demulsifier was affected by HMPAM in water. • HMPAM had an effect on the demulsifier conformation on the W/O interface. • HMPAM reduce the demulsifier rearrangement rate during water droplets coalesce. Hydrophobically modified polyacrylamide (HMPAM) is one of the commonly used polymers for polymer flooding. Because it is water soluble, there are many reports on the impact of HMPAM on the stability and treatment of produced water (it is O/W emulsion), but few reports on its influence on the demulsification of W/O crude oil emulsion. In this paper, firstly, three types of HMPAM containing cationic, anionic, and nonionic hydrophobic monomers (abbreviated as P(AM-AANa-N)Cn, P(AM-AANA-S)Cn, and P(AM-AANA-O)Cn, respectively) were synthesized; Then, demulsification experiments and interface behavior experiments (including dynamic interfacial tension, dilatational rheology and dynamic coalescence time measurement) were conducted to investigate the influence of HMPAM on the demulsification performance of a W/O heavy oil emulsion demulsifier D1. The demulsification results showed that HMPAM reduced the dehydration speed of D1, the type of hydrophobic monomer and the length of hydrophobic chain in HMPAM can affect the final water separated of D1. P(AM-AANa-S)Cn, P(AM-AANa-N)Cn with long hydrophobic chain, and P(AM-AANa-O)Cn with short hydrophobic chains had the negative effect on performance of D1. The results of dynamic interfacial tension experiments indirectly showed that HMPAM had the influence on the D1′s conformation and speed of rearrangement at the W/O interface during the water droplet coalescence process, thereby affecting the reduction of elastic modulus (G ′) of W/O interface and the coalescence rate of water droplets. When there was HMPAM in water, the coalescence time of water droplets increased, resulting in the decrease of dehydration rate. At the meantime, HMPAM had an impact on the lg (G 1 ′ / G demulsifier ′) / lg G 1 ′ , thereby affecting the final water separated of D1. [ABSTRACT FROM AUTHOR]

In this paper, a series of hydrophobically modified polyacrylamide (HMPAM) containing different types of hydrophobic monomer were synthesized. Their effects on the performance of a typical flocculant DA, which was used in air floatation cyclone and is a copolymer of tertiary amine monomer and polymerizable polyether, were investigated. The experimental results showed that low concentration (≤200 mg/L) of HMPAM improved the oil removal performance of DA, and high concentration of HMPAM greatly reduced the oil removal performance of DA. It was proposed that the electrostatic attraction between HMPAM and DA had both the positive and negative effects on performance of DA, and which one dominated was influenced by HMPAM concentration. This propose was confirmed by the results of dynamic light scattering and zeta potential. In addition, we found that the negative effect decreased with the increasing hydrophobic monomer chain. The results of this study can provide a guidance for the synthesis and selection of HMPAM from the perspective of produced water treatment. [Display omitted] • HMPAM had electrostatic attraction with DA in produced water. • Low concentration (≤200 mg/L) of HMPAM improved the oil removal performance of DA. • The effect of long chain hydrophobic monomer on DA's performance was small. [ABSTRACT FROM AUTHOR]

Polymer microspheres offer fascinating prospects on oil recovery due to their distinctive swelling performance and deformation ability. However, because of the influence of emulsifiers in the product, the present polymer microspheres synthesized by traditional polymerization methods can greatly reduce the effect of oil displacement. "Water-in-water" (W/W) emulsion, an emulsion by using water phase as solvent and water-soluble macromolecular polymer as dispersant, can avoid contamination of oil phase and emulsifier. Composed of nano-SiO 2 and polymer, the organic-inorganic microsphere possessed remarkably dispersity, elasticity, swelling performance, deformation ability and migration ability. To verify the validity of the products, many tests were carried out, such as Field emission scanning electron microscope (SEM), FT-IR spectra, thermogravimetry (TGA), Energy-dispersive Xray Spectroscopy (EDS), contact Angle and dynamic light scattering (DLS), etc. Dependent on excellent swelling performance and elasticity, the microsphere promised its great potentials for plugging. Particularly, based on its feature of size changing with temperature, it must have great attraction and application value in temperature-controlled size of organic-inorganic microsphere. Unlabelled Image • Organic-inorganic microsphere was prepared by environmentally friendly strategy. • The microspheres PDS-SiO 2 had excellent swelling properties. • Good elasticity and temperature-controlled size ability allow microspheres to express high plugging rate. [ABSTRACT FROM AUTHOR]

The surface modification of calcite has been widely used to improve the compatibility of calcite with non-polar solutions, but this method is complex, time-consuming and uneconomical. Thus, we propose to use dispersants for improving the compatibility of calcite with non-polar solutions and systematically study the dispersion effect and mechanism of various dispersants. Anionic bis (2-ethylhexyl) sulfosuccinate sodium (AOT), non-ionic sorbitol monooleate sodium (Span 80) and sorbitol trioleate (Span 85), cationic cetyltrimethylammonium bromide (CTAB), oleic acid (OA) and stearic acid (SA), are used to change the surface properties of calcite in nonpolar solutions. The results of sedimentation and rheology showed that the anionic dispersant AOT had the best dispersion performance and efficiency. All dispersants, except CTAB, can significantly improve the wettability of particle surface, and the calcite adsorbed AOT has the best hydrophobicity. XRD results showed that all dispersants were adsorbed on the surface of calcite. FT-IR and XPS confirmed that AOT adsorbed on the particle surface through the coordination between AOT and Ca2+. Zeta potential shows that the calcite system with anionic AOT has the highest surface charges, indicating that the strong electrostatic interaction is one reason of the stabilization of calcite particles. This work has guiding implications for the selection of dispersants to improve the compatibility of calcite with non-polar solvents. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Produced fluid from polymer flooding is a complicated mixture of water/crude oil emulsion and crude oil/water emulsion. During the treatment of produced fluid, both demulsifier and reverse demulsifier are added into the oil water separator and the function of reverse demulsifier is to reduce the oil content in crude oil/water emulsion for relieving the load of oily wastewater treatment. In this paper, a novel reverse demulsifier was prepared by copolymerization of block polyether macromonomer (PEP-65) and diallyldimethylammonium chloride (DM). Its synthesis condition was optimized by using three indexes including product stability, the effect on dehydration of water/crude oil emulsion and oil removal of crude oil/water emulsion. The best copolymer of PEP-65 and DM (PDMP) had no negative effect on the dehydration of water/crude oil emulsion and had a more than three times of oil removal of crude oil/water emulsion than that of commercial reverse demulsifier. In addition, measurement of partition coefficient, interfacial tension, interfacial dilational modulus and dual polarization interferometry (DPI) test were carried out for investigating the reverse demulsification properties of PDMP. We found that PDMP had better interface activity, higher interface adsorption mass and lower interfacial dilational modulus than that of commercial reverse demulsifier. Highlights • A novel reverse demulsifier was prepared by copolymerization of PEP-65 and DM. • PDMP had no negative effect on demulsifier and can decrease OiW efficiently. • PDMP had higher interface adsorption mass and lower interface film strength than that of PDM. [ABSTRACT FROM AUTHOR]

Abstract Heavy oil sludge usually exists in the form of stable W/O emulsion, in which the water droplets were stabilized by natural surfactants and small solid particles. The oil recovery from the oil sludge is valuable, but the demulsification by using regular demulsifiers could be hindered by the solids. Therefore, the solid separation is important for oil recovery. In this paper, firstly, properties of heavy oil sludge produced from the Liaohe Oilfield were analyzed. Then, a multistage chemical treatment was proposed and chemicals were screened for solid separation. Limonene, sodium sulphate solution, (dioctadecyl dimethyl ammonium bromide + citric acid) were chosen for different purposes at different stages, respectively. At last, the rational separation conditions were investigated. After the treatment, the solid content in oil decreased from 18.57% to be 0.9% by mass. In addition, the mixture of recovered oil and fresh crude oil can be dehydrated easily by using regular demulsifiers. Highlights • Solid in the heavy oil sludge was characterized, including its size, shape, and component. • Chemical agents for solid separation were designed and screened. • Solid separation condition was optimized. [ABSTRACT FROM AUTHOR]

Highlights • A microfiltration membrane was decorated by mixture of PEG and tannic acid. • The decorated membrane had fast dye removal performance. • The molecular weight of PEG had significant effect on the dye removal. Abstract A polyether sulfone (PES) microfiltration membrane was decorated by the deposition of mixture of polyethylene glycol (PEG) and tannic acid (TA). It was used as an adsorbent for the removal of Rhodamine B (RhB) from water and had a high removal ratio (>98.9%) at high flux up to 4777 L/(m2⋅h) in dynamic test. The mixture of PEG and TA formed a stable suspension but it transformed to a viscous mixture during permeating the narrow channel of membrane, which resulted in high dispersion of the TA within the membrane and good dye adsorption. The turbulence and high driving force in the dynamic test ensured good contact of dye and the adsorbent, which led to good dye removal, while in stationary adsorption test it had only moderate dye adsorption. Molecular dynamics study revealed the molecular weight of PEG had an effect on the aggregation morphology of PEG and TA, as well as the exposure of TA on the surface, leading to different removal performance. Our study provided a simple and quick method to prepare adsorbent for the fast removal of dye from water. [ABSTRACT FROM AUTHOR]

Usually, the treatment of oil sludge produced from polymer flooding (OSPPF) in offshore oilfield needs transport and incineration. It is time‐consuming and high‐economic cost. In this paper, firstly, the OSPPF in an offshore oilfield was analyzed by IR, SEM, EDS, and XRD and its formation mechanism was discussed. Then, chemical degradation was proposed according to the formation mechanism. Mixture of H2O2 and diethylene triamine pentacetic acid (DTPA) was chosen for the chemical degradation of OSPPF. The effects of different factors on degradation rate were studied and the national condition was obtained as follows: 3 g OSPPF, 3 g kerosene, and 9 g aqueous solutions containing 5 wt% H2O2+ DTPA (H2O2:DTPA was 1:1) were mixed at 65°C for 12 hour. After the degradation, the oil in the OSPPF can be recovered and polymer gel in the OSPPF can be destroyed completely. This chemical degradation is a good choice for treatment of OSPPF in situ. In this paper, the composition and causation of OSPPF produced from one offshore oilfield was analyzed firstly and then it was treated by chemical degradation. The chemical degradation is a good choice for in situ treatment of OSPPF for the offshore oilfield. To our knowledge, this is the first study for treatment of OSPPF produced from offshore oilfield in situ by chemical degradation. [ABSTRACT FROM AUTHOR]

In this work, the adsorption performance of tween surfactant (tween 20, tween 60 and tween 80) on asphaltene surface was investigated by both experimental and calculation methods. For experimental investigation, dual polarization interferometry (DPI) technique was utilized for in-situ measuring the adsorption mass and thickness on natural asphaltene surface. The thermodynamics Langmuir fittings indicated the mono-layer of free molecular, semi-micelle and whole-micelle adsorption for low, middle and high surfactant concentrations, respectively. The kinetic normalization corrections indicated the maximum adsorption rate at 1/2 CMC with semi-micelle form for three surfactants. For calculation insight, molecular dynamics simulation (MDS) was used for analyzing the peak intensity and interaction energy between surfactant molecular and model asphaltene of C5Pe. The RDF fitting revealed the interaction positions from 4.37 Å to 8.69 Å and the COMPASS force field showed the interaction energies from − 45.41 to − 36.34 Kcal/mol for three different surfactant-asphaltene pairs. Combined with experimental and calculation results, this work reveals the interaction forms and interaction processes between surfactant and asphaltene. Based on the mechanism analysis, tween 20 was revealed to show the most excellent interaction performance with asphaltene and can be used as potential flooding reagent for enhanced oil recovery. The results indicated that the proposed method can provide a deep insight into the interfacial behavior of surfactants at oil surface, which is of great significance in oilfield chemical development and enhanced oil recovery. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, the technique of dual polarization interferometry (DPI) was applied to establish a new method to monitor the real-time evolution of oil/water interface in the presence of sodium dodecyl benzene sulfonate (SDBS) at molecular level. A three-stage model of adsorption-desorption-detachment had been proposed and was systematically discussed upon the addition of different SDBS concentrations based on the variation of the interfacial mass with time. The results demonstrated two patterns of adsorption morphology at the oil/water interface, SDBS mono-molecules and SDBS hemi-micelles at SDBS concentrations below and above cmc respectively according to the relaxation time obtained by theoretical model and the reaction order calculated by integral method in the analysis of adsorbed dynamics. The capability of oil detachment with the aid of SDBS as well as the properties of the outlet fluid were investigated under two patterns of adsorption morphologies, which showed different effects of oil detachment with the aid of SDBS molecules. The speed of oil detachment and the fluorescence intensity of the outlet fluid during the detachment process indicated the fact that the oil detachment capability was significantly promoted by the morphology of the absorbed hemi-micelles. The findings in the present study are crucial for fully understanding the interfacial behavior of surfactants applied in oil/water interface, which is of great significance in enhanced oil recovery and pollution industry. [ABSTRACT FROM AUTHOR]

In this work, a miniaturized optical sensor was developed for fluoride determination in tea samples to evaluate their specific risks of fluorosis for public health based on evanescent-wave interaction. The sensor design was integrated on the optical fiber by utilizing the evanescent wave produced on the fiber surface to react with sensing reagents. According to the absorption change at 575 nm, fluoride could be determined by colorimetric method and evaluated by Beer's law. With improved performances of small detection volume (1.2 μL), fast analysis (0.41 min), wide linear range (0.01–1.4 mg L −1 ), low detection limit (3.5 μg L −1 , 3σ) and excellent repeatability (2.34%), the sensor has been applied to fluoride determination in six different tea samples. Conventional spectrophotometry and ion chromatography were employed to validate the sensor's accuracy and potential application. Furthermore, this sensor fabrication provided a miniaturized colorimetric detection platform for other hazardous species monitoring based on evanescent wave interaction. [ABSTRACT FROM AUTHOR]

Chlorine is a powerful oxidizing agent extensively used in water disinfection and blanching processes. Too low or too high chlorine concentration in water supplies would cause hazards for water usage. In this work, a miniaturized microfluidic evanescent-wave sensor was developed for colorimetric determination of free chlorine in water. A microfluidic channel with narrow d c (50 μm) was constructed to act as both flow cell and detection cell in this sensor. When light propagated by total internal reflection (TIR) in the fiber core, evanescent wave produced on the fiber surface could interact with the DPD reagents and produce absorption change. The free chlorine could be determinated by colorimetric method and evaluated by absobance according to Beer’s law. This miniaturized sensor showed improved performances of small detection volume (1.2 μL), fast analysis (4.42 s), low detection limit (1.5 ppb) and excellent repeatability (1.59%) for chlorine determination. The sensor was applied to chlorine determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and iodometry, showing agreement and validating the sensor’s potential applications. Meanwhile, the fabrication of this sensor provides a miniaturized and portable detection platform for other hazardous species monitoring by simple modular design. [ABSTRACT FROM AUTHOR]