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CeO2 was synthesized by the co-precipitation method on the Cu mesh substrate and modified the surface of CeO2@Cu mesh by stearic acid (SA). The superhydrophobic behavior was ascribed to the combination of hierarchical micro-nanostructure of CeO2 and the hydrophobic alkyl groups from SA. The SA-CeO2@Cu mesh had antiacid and base stability and excellent durability as well as high separation efficiency. The separation efficiency can be up to 98.0% after separating 30 times.

In order to reduce the frequency of marine environmental pollution accidents, marine oil-water separation numerical simulation method is developed. The oil-water separation hydrocyclone is used for emergency treatment to deal with the marine surface oil pollution, and the oil-water separation optimal control parameter calculation method based on the mathematical model of the flow field is used to simulate the oil-water separation performance of the device. The simulation results show that when the split ratio is 4.1%, the inlet pressure is 0.15MPa, the overflow pipe diameter is 3 mm, the oil droplet size is 101, and the large vertebral angle is 27, the hydrocyclone has good separation performance. Under these conditions, this method can be used as a reference method for dealing with oil spills in the ocean and has certain application value.

Design and fabrication of smart materials with reversible wettability for oil-water separation have attracted worldwide attention due to the increasingly serious water pollution problem. In this study, a rough oxide coating with micro/nanoscale structures is developed on the 304 stainless steel mesh (SSM) by laser ablation. The smart surface with ethanol immersion and natural drying treatments shows the wetting conversion between underwater superoleophobicity and superhydrophobicity. Based on the wettability transition behavior, both light and heavy oil-water mixtures can be separated with the high separation efficiency. Moreover, after being exposed to various corrosive solutions and high temperatures, the smart surface still shows prominent environmental stability. Switchable surface with excellent properties should be an optimal choice to solve the environmental conditions that need to be addressed urgently.

Stratified flow is a common occurrence for various internal flow based industrial multiphase flow patterns. This involves fully or partially well-defined interface which continuously evolve with space and time. Hence stratified flow analysis essentially involves proper interface capturing approach. The present work focuses on the numerical analysis of oil-water stratified pattern using the Coupled level set and volume of fluid method (CLSVOF) in ANSYS Fluent in a two-dimensional channel. The work involves predicting the effect of density ratio, kinematic viscosity and surface tension coefficient on the mixture velocity and total pressure changes. At outset, the final conclusions may be gainfully employed in oil transportation pipeline, chemical industries and in pipeline flow control administration, etc.

High-performance functional materials capable of simultaneously separating oil from water and removing water-soluble contaminants are critically demanded for wastewater treatment but remain highly challenging. Wood, a naturally occurring porous material composed of numerous open microchannels along the growth direction, may serve as a desirable scaffold for the development of efficient filtration materials for water treatment. Herein, by in situ deposition of silver nanoparticles (Ag NPs) within the channels of balsa wood, we developed dual-functional Ag/wood filters for simultaneous oil/water separation and organic dye removal from water in a one-step process. Owing to their superhydrophilicity and underwater superoleophobicity, the as-prepared Ag/wood filters can selectively separate water from oil with a high efficiency (∼99%). Moreover, benefiting from the catalytic activity of Ag NPs anchored to the surface of the wood channels, the Ag/wood filters effectively removed methylene blue (MB) from water during the oil/water separation process; the MB removal efficiency was highly dependent on the thickness of the wood filters. Specifically, the gravity-driven separation using a 6 mm-thick Ag/wood filter showed a high MB degradation efficiency of 94.03% and a water flux of 2600 L·m–2·h–1. The proposed wood-based filtration material features renewable, inexpensive raw materials, facile processing, and scale-up potential. Such dual-functional Ag/wood filters capable of rapid and efficient removal of insoluble oils and soluble pollutants from water in a one-step process offer a promising solution for wastewater treatment.

The influence of density of amino groups, nanoparticles dimension and pH on the interaction between end-functionalized polymers and nanoparticles was extensively investigated in this study. PS–NH2 and H2N–PS–NH2 were prepared using reversible addition–fragmentation chain transfer polymerization and atom transfer radical polymerization. Zero-dimensional carbon dots with sulfonate groups, one-dimensional cellulose nanocrystals with sulfate groups and two-dimensional graphene with sulfonate groups in the aqueous phase were added into the toluene phase containing the aminated PS. The results indicate that aminated PS exhibited the strongest interfacial activity after compounding with sulfonated nanoparticles at a pH of 3. PS ended with two amino groups performed better in reducing the water/toluene interfacial tension than PS ended with only one amino group. The dimension of sulfonated nanoparticles also contributed significantly to the reduction in the water/toluene interfacial tension. The minimal interfacial tension was 4.49 mN/m after compounding PS–NH2 with sulfonated zero-dimensional carbon dots.

Velocity is an important parameter for fluid flow characteristics in profile logging. Particle tracking velocimetry (PTV) technology is often used to study the flow characteristics of oil wells with low flow velocity and high water cut, and the key to PTV technology is particle matching. The existing particle matching algorithms of PTV technology do not meet the matching demands of oil drops in the oil phase velocity measurement of oil-water two-phase flow with low velocity and high water cut. To raise the particle matching precision, we improved the particle matching algorithm from the oriented FAST and the rotated BRIEF (ORB) feature description and the random sample consensus (RANSAC) algorithm. The simulation and experiment were carried out. Simulation results show that the improved algorithm not only increases the number of matching points but also reduces the computation. The experiment shows that the improved algorithm in this paper not only reduces the computation of the feature description process, reaching half of the computation amount of the original algorithm, but also increases the number of matching results, thus improving the measurement accuracy of oil phase velocity. Compared with the SIFT algorithm and the ORB algorithm, the improved algorithm has the largest number of matching point pairs. And the variation coefficient of this algorithm is 0.039, which indicates that the algorithm is stable. The mean error of oil phase velocity measurement of the improved algorithm is 1.20 %, and the maximum error is 6.16 %, which is much lower than the maximum error of PTV, which is 25.89 %. The improved algorithm overcomes the high computation cost of the SIFT algorithm and achieves the precision of the SIFT algorithm. Therefore, this study contributes to the improvement of the measurement accuracy of oil phase velocity and provides reliable production logging data for oilfield.

Electrowetting has drawn significant interest because of the potential applications of displays, lab-on-a-chip microfluidic devices, electro-optical switches, and so forth. However, electrowetting display (EWD) is monostable, which needs extra continuous voltage supply to keep contracting the oil. This paper is concerned with the simulation of two-phase liquid flow in three-dimensional EWD pixels with two electrodes (E1 and E2) demonstrating bistability, where power is only needed to move the oil droplet between two stable states. The effects of E1 geometry, E2 geometry, and E2 pulse characteristics on the dynamics of the oil droplet motion have been analyzed. Also, predictions of the transient states in four stages of the reversible bistable operation process have been carried out by employing the finite element method, in qualitative agreement with our experimental results of the monostable EWD and the existing literature. We seek to shed more light on the fundamental two-phase liquid flow in three-dimensional pixels exhibiting bistability for low power EWD and guide optimizing the electrodes to the perfect patterns with the aid of rigorous modeling.

A novel ultralight superhydrophobic-superoleophilic hybrid Carbon Nanotubes (CNTs) film with double-layer structures is fabricated by using vacuum filtration method. The CNTs film can separate various surfactant-stabilized water-in-oil emulsions with a separation efficiency higher than 99.3%. Moreover, the hybrid films can be regenerated through a simple and rapid combustion process within 2 s. In addition, the CNTs film still retains good hydrophobic properties under the conditions of physical abrasion, and strong acidic and alkaline solutions, which shows the excellent durability. The hybrid CNTs film is ultralight, stable, and easily stored and reused. The outstanding features of the obtained CNTs films we present here may find many important applications in various fields like oil purification and wastewater treatment.

Reusing wastewater from oil-related industries is becoming increasingly important, especially in water-stressed oil-producing countries. Before oily wastewater can be discharged or reused, it must be properly treated, e.g., by membrane-based processes like ultrafiltration. A major issue of the applied membranes is their high fouling propensity. This paper reports on mitigating fouling inside ready-to-use ultrafiltration hollow-fiber modules used in a polishing step in oil/water separation. For this purpose, in-situ polyzwitterionic hydrogel coating was applied. The membrane performance was tested with oil nano-emulsions using a mini-plant system. The main factors influencing fouling were systematically investigated using statistical design of experiments.

A model of multi-stage formation of Visean oil deposits in Solikamsk depression in condition of stabilization of ancient oil-water contacts is provided. When reservoir rocks stay in condition of oil-water zones for extended periods of time, oxidizing processes actively develop, as result of which oil saturated reservoirs undergo non-reversible changes in rock wettability. After inflow of new portions of hydrocarbons and formation of modern oil-water contact residual products of oil oxidation are formed as solid bitumen. Cases of absence of reservoir bitumenosity in ranges of ancient oil-water contacts are explained by active fluid exchange in reservoirs. It is established that high specific resistance values in terrigenous reservoirs of Visean deposits in Solikamsk depression, exceeding 600 Ohm*m, are related to their hydrophobization in conditions of ancient oil-water contacts. Electrical laterlog results are compared with evaluation of rock wettability based on X-ray core tomography and microscopic analysis of thin sections. For Visean high-ohmic reservoirs of Shershnevskoe deposit statistically significant excess of rock porosity comparing to standard geophysical section is established. For ranges with resistivity < 120 Ohm*m porosity distribution maximum is observed within 12–16 %. In high-ohmic section for resistivity from 200 to 600 Ohm*m maximal porosity frequency is observed within 16–18 %; for resistivity > 600 Ohm*m – at porosity over 18 %. In average, excess porosity in high-ohmic section is over 3 %, which is probably due to predominance of reservoir deconsolidation (dissolution) processes over their cementation at levels of ancient oil-water contacts. For Visean operational objects of Shershnevskoe deposit geological model is built on basis of resistivity data, separating zones (volumes) of different wettability type reservoir development. In general, the established zones of development of hydrophilic and hydrophobic reservoirs are of regular spatial arrangement. Geological models built with regard to rock wettability may be used to optimize reservoir management technologies at oil operational objects.

Although artificial superhydrophobic materials have extensive and significant applications in antifouling, self-cleaning, anti-icing, fluid transport, oil/water separation, and so forth, the poor robustness of these surfaces has always been a bottleneck for their development in practical industrial applications. Here, we report a facile, economical, efficient, and versatile strategy to prepare environmentally friendly, mechanically robust, and transparent superhydrophobic surfaces by combining adhesive and hydrophobic paint, which is applicable for both hard and soft substrates. The coated substrates exhibit excellent superhydrophobic property and ultralow adhesion with water (contact angle ≈ 160° and sliding angle

The effects of different concentration of flaxseed gum (FG) (0.1–0.5%, w/w) on the stability of soybean oil emulsion were studied by particle size, rheological properties, creaming stability and nuclear magnetic resonance (NMR). Results showed that emulsion particle size decreased significantly with the increase in FG concentration. Rheological measurements showed FG exhibited thickening and gelling properties. Viscosity, storage modulus, and loss modulus increased accordingly with the increase in FG concentrations, and emulsions with 0.5% FG looked like a viscoelastic solid. Emulsions with a higher FG concentration exhibited better creaming stability and structure. With the increase of FG concentration, the 1H and 13C NMR spectra line widths in high field also increased, which confirms that the interaction between FG and oil molecules is enhanced. These results show that FG can substitute for other emulsifiers or stabilizers in emulsions, and is beneficial to the stability of emulsions.

Today emulsion preparation is receiving a lot of scientific attention, since emulsions are playing an essential role in many of the big industries, such as food, pharmaceutical or cosmetic industry. One of the most promising techniques for emulsion preparation is ultrasound emulsification. The purpose of this study is to expand the knowledge on the ultrasonically assisted emulsification model, that has not been amended since 1978. The model explains that oil-in-water emulsion formation is a two-step process. Firstly, the surface of the oil phase is disturbed and separated by the acoustic waves. Secondly, cavitation implosions further disrupt and disperse oil drops. We have used a high-speed camera to closely observe oil-in-water emulsion formation. The images show, that the ultrasound emulsification process is profoundly more complex. While the first and the last step of emulsion formation are the same as believed until now, additional intermediate stages of water-in-oil and even oil-in-water-in-oil occur.

Summary In this study, an investigation of sand transport in heavy-oil/water multiphase flow is performed. The study is conducted in three multiphase-flow pipeline-test facilities with internal diameters (IDs) of 1, 1, and 3 in. The pipeline orientations relative to the horizontal in the facilities are 0, +30, and 0°, respectively. Oil viscosity of 3.5 and 10.0 Pa·s with sand volume fractions from 0.010 to 0.100 vol% were used in the study. The effects of oil viscosity, upward inclination, sand volume fraction, pipe ID, and water cut on the sand-transport mechanism in pipelines are investigated. In the horizontal test section, flow patterns—namely, dispersed flow (DF), plug flow (PF), plug flow with moving sand bed (PFM), and plug flow with stationary sand bed (PFS)—were identified through flow visualization. In addition to the aforementioned, two flow patterns—stratified wavy flow with moving sand bed (SWM) and stratified wavy flow with dunes (SWD)—were observed in the inclined pipeline orientation. The pressure gradient measured decreased with a decrease in water cut until a minimum value was reached. Beyond the minimum pressure gradient, further reduction in water cut led to an increase in pressure gradient. The sand minimum transport condition (MTC) in the oil/water/sand test was largely the same for the 1-in. 30° upward inclined and the 1-in. horizontal test section. In contrast, that of the 3-in. horizontal test section was considerably higher. An improved MTC predictive correlation is proposed for multiphase heavy-oil/water/sand flow. The proposed correlation outperforms the existing models when tested on the heavy-oil/water/sand data set.

The increasing amount of oily wastewater discharges caused major challenges for current environmental issues, such as oil-water purification and separation [1-6]. Thus, the development of new functional materials for the efficient treatment of oil-water is imperative [7-11]. This paper reviewed the recently developed oil-water separation technologies, which were based on novel functional nanomaterials, and presented representative works in detail. Finally, the challenges and future research directions of this area were briefly discussed.

The introduction of the self-healing function into superhydrophobic surfaces has recently raised increasing attention because it can renew the feature of the surface iteratively to a large extent to extend the service life span of the surface in practical applications. However, it still faces a great challenge on how to achieve this unique surface with a tunable self-healing function via an easy and effective way. Here, we propose a general, yet easily implemented strategy to endow a diversity of commercial substrates with self-healable superhydrophobic surfaces mainly relying on the collective use of the polydopamine (PDA) chemistry with a hydrophobic silane-octadecyltrimethoxysilane (ODTMS). Upon applying ultrasonication for 30 min to an alkaline aqueous solution comprising dopamine hydrochloride (DA) and ODTMS, ODTMS disperses into the aqueous phase as microdroplets, while DA polymerizes into PDA exclusively onto the micro-sized oil droplets, forming capsules with nanoroughness. In the presence of substrates, PDA also anchors these composite capsules onto substrates, resulting in hierarchical surfaces. ODTMS is detected abundantly on the hierarchical surfaces, leading to superhydrophobic surfaces. Remarkably, this superhydrophobicity is self-restorable at room temperature (e.g., days) once it is deteriorated by the air plasma or extremely acid/alkali treatment, and this self-restoration can be significantly accelerated via the heating (2 h) or rubbing (5 min) treatment. Generally, heating and rubbing are the valid ways to induce self-healing, which is speculated to accelerate the migration of hidden ODTMS from the capsules to the surfaces because of the minimization of the global surface-free energy. Benefiting from the self-healing superhydrophobicity, we devise oil/water separation using various surface-modified commercial fabrics, which exhibit a prolonged life span in applications and may further facilitate other usage in environmental remediation and water purification.

The paper presents the results of a study concerned with the hydrodynamics of an annular downward multiphase flow of gas and two mutually non-mixing liquids through a vertical pipe with a diameter of 12.5 mm. The air, oil and water were used as working media in this study with changes in superficial velocities in the ranges of jg = 0.34–52.5 m/s for air, jo = 0.000165–0.75 m/s for oil, and jw = 0.02–2.5 m/s for water, respectively. The oil density and viscosity were varied within the ranges of ρo = 859–881 kg/m3 and ηo = 29–2190 mPas, respectively. The research involved the identification of multiphase flow patterns and determination of the void fraction of the individual phases. New flow patterns have been identified and described for the gravitational flow conditions of a two-phase water–oil liquid and a three-phase air–water–oil flow. New flow regime maps and equations for the calculation of air, oil and water void fractions have been developed. A good conformity between the calculated and measured values of void fraction were obtained. The map for the oil–water–air three-phase flow is valid for the following conditions: j3P = 0.35–53.4 m/s (velocity of three-phase mixture) and oil in liquid concentration βo* = 0.48–94% (oil in liquid concentration). In the case of a downward annular oil–water two-phase flow, this map is valid for liquid mixture velocity jl = 0.052–2.14 m/s and βo* = 0.48–94%.

We report a robust and continuous oil/water separation with nanostructured glass microfiber (GMF) membranes modified by oxygen plasma treatment and self-assembled monolayer coating with vertical polymerization. The modified GMF membrane had a nanostructured surface and showed excellent superhydrophobicity. With an appropriate membrane thickness, a high water intrusion pressure (−1 m−2) and high oil purity (> 99%). Under simulated industrial conditions, the modified GMF membrane exhibited robust chemical stability against strong acidic/alkaline solutions and corrosive environments. The proposed superhydrophobic composite coating technique is simple, low cost, environmentally friendly, and suitable for the mass production of scalable three-dimensional surfaces. Moreover, its stability and customizable functionality offers considerable potential for a wide range of novel applications.

Air and water pollution pose an enormous threat to human health and ecosystems. In particular, particulate matter (PM) and oily wastewater can cause serious environmental and health concerns. Thus, controlling PM and oily wastewater has been a great challenge. Various techniques have been reported to effectively remove PM particles and purify oily wastewater. In this article, we provide a review of the recent advancements in air filtration and oil/water separation using two- and three-dimensional (2D and 3D) bulk materials. Our review covers the advantages, characteristics, limitations, and challenges of air filters and oil/water separators using 2D and 3D bulk materials. In each section, we present representative works in detail and describe the concepts, backgrounds, employed materials, fabrication methods, and characteristics of 2D and 3D bulk material-based air filters and oil/water separators. Finally, the challenges, technical problems, and future research directions are briefly discussed for each section.

Produced water (PW) is a by-product of oil and gas operations, and its production is foreseen to increase in the upcoming years. Such an increase is justified by various entities through their projection of the expected increase in the demand of oil and gas. The treatment of produced water is a significantly growing challenge for the oil and gas industry that requires serious attention. The first part of this review will present the underlying issue of produced water and relevant practices. With adsorption being defined as the least expensive treatment method, the second part will introduce general adsorption principals. The third part will describe the recent applications of adsorption for the treatment of PW with more focus of categorizing the adsorbents as natural and non-natural adsorbents. The main aim of this review is to shed light on the recent research related to PW treatment using adsorption. This is performed to highlight the shortcomings in PW adsorption research and recommend research pathways that can help in developing the field further.

Discharging accumulated bilge water from the ship is very important in order to maintain its stability and safety. However, the bilge water that contains contaminants, including waste oils and oily wastes, must be treated prior discharging to the sea. The International Convention for the Prevention of Pollution from Ships (MARPOL) has set strict oil discharge limit in order to minimize sea pollution. Thus, an efficient oil–water separator must be installed to separate the oil from the bilge water. This chapter introduces and discusses the working mechanisms, as well as advantages and disadvantages of the available oil–water separation techniques for bilge water treatment, which include gravitational, centrifugation, flotation, coagulation and flocculation, biological processes as well as absorption and adsorption.

International audience; We argue against the structural interpretation given in the paper doi.org/10.1016/j.carbpol.2020.116843 that the primary structure of gum Arabic species is a disk-like nanoparticle. We show that both our and Isobe et al.’s SAXS data are comparable, which demonstrates we have investigated the same type of gum Arabic. However, we also show that two-dimensional models, as first proposed by Renard, Sanchez and coworkers, fail to fit SAXS curves adequately. We have rather proposed a three-dimensional multi-scale porous structure, consistently with the three well defined correlation distances that are observed in the SAXS curves. We also briefly argue against the loosely covered schematisation of the oil/water interface chosen by the authors, which is unrealistic when discussing emulsion metastability.

The targeted separation of oil/water mixtures is a rapidly growing field of research, mainly due to contaminated water becoming an increasingly important environmental issue. Superhydrophobic materials are highly suited to this application, however, growing efforts are being devoted to developing applicable technologies within a range of research communities. The optimal technical solution is one that combines a high separation efficiency with a straightforward fabrication procedure at a low cost. In this report, micronized polyethylene powder has been utilized as a low-cost hydrophobic material to manufacture easy-to-fabricate filters. The effect of heating and solvent addition on the water repellence behaviour has been investigated, according to which the optimum fabrication conditions were determined. The filters show high water repellence (WCA = 154&deg, ) and efficient oil/water separation (~99%). The filters are designed to provide a readily achievable approach for the separation of oils (hydrophobic solvents) from water in a range of potential applications.

The search for lower cost materials that reduce pressure drop in fluid transport systems in oil and gas industries to conserve pumping energy is of paramount importance. Polymers are known to reduce pressure drop in pipeline oil-water flows in a process referred to as drag reduction (DR). The effect of partially hydrolysed polyacrylamide, polyethylene oxide, aloe vera mucilage and their mixtures as drag reducing polymers (DRPs) on pressure gradient (pressure drop; Δp) in pipeline oil-water flows was studied. The experiment was carried out in flow rig with 0.02-m diameter straight unplasticised polyvinylchloride (uPVC) pipe, two centrifugal pumps, control valves and two storage tanks. Tap water (ρ = 997 Kg/m3 and µ = 0.89 cP) and diesel (ρ = 832 Kg/m3 and µ = 1.66 cP) were used as the test fluid at ambient condition. The polymer mixture total concentration (MTC) of 30 and 400 ppm at different mixing proportion, mixture Reynolds number (Remix) and oil input volume were investigated. The results show increase in pressure gradient with increase in oil input volume in both single-phase water flow and oil-water flow before adding drag reducing polymers (DRPs). But Δp decreased after adding DRPs with increase in Reynolds number (Re) or Remix and decrease in the oil-phase Re, vice versa. The results further showed higher reduction in pressure drop by the polymer mixture than in each of the polymer used at the same conditions. The rigidness of the biopolymer was improved by adding synthetic polymers which result to increase in DR efficiency.The search for lower cost materials that reduce pressure drop in fluid transport systems in oil and gas industries to conserve pumping energy is of paramount importance. Polymers are known to reduce pressure drop in pipeline oil-water flows in a process referred to as drag reduction (DR). The effect of partially hydrolysed polyacrylamide, polyethylene oxide, aloe vera mucilage and their mixtures as drag reducing polymers (DRPs) on pressure gradient (pressure drop; Δp) in pipeline oil-water flows was studied. The experiment was carried out in flow rig with 0.02-m diameter straight unplasticised polyvinylchloride (uPVC) pipe, two centrifugal pumps, control valves and two storage tanks. Tap water (ρ = 997 Kg/m3 and µ = 0.89 cP) and diesel (ρ = 832 Kg/m3 and µ = 1.66 cP) were used as the test fluid at ambient condition. The polymer mixture total concentration (MTC) of 30 and 400 ppm at different mixing proportion, mixture Reynolds number (Remix) and oil input volume were investigated. The results show increase in pressure gradient with increase in oil input volume in both single-phase water flow and oil-water flow before adding drag reducing polymers (DRPs). But Δp decreased after adding DRPs with increase in Reynolds number (Re) or Remix and decrease in the oil-phase Re, vice versa. The results further showed higher reduction in pressure drop by the polymer mixture than in each of the polymer used at the same conditions. The rigidness of the biopolymer was improved by adding synthetic polymers which result to increase in DR efficiency.

Nanoparticle (NP)–surfactants formed by the self-assembly of NPs and end-functionalized polymers at the hydrophilic/hydrophobic interface have a wide range of applications in many fields. In this study, the influence of density of amino groups, NPs dimension and pH on the interaction between end-functionalized polymers and NPs were extensively investigated. Single amino-terminated polystyrene (PS-NH2, Mw ≈ 0.6k, 2.5k, 3.5k, 3.9k) and diamino-terminated polystyrene (H2N-PS-NH2, Mw ≈ 1.1k, 2.8k) were prepared using reversible addition–fragmentation chain transfer polymerization and atom transfer radical polymerization. NPs with different dimensions (zero-dimensional carbon dots with sulfonate groups, one-dimensional cellulose nanocrystals with sulfate groups and two-dimensional graphene with sulfonate groups) in the aqueous phase were added into the toluene phase containing the aminated PS. The influence of pH and the molecular weight of amino-terminated PS on the interfacial tension between two phases were investigated. The results indicate that aminated PS exhibited the strongest interfacial activity after compounding with sulfonated NPs at a pH of 3. Terminating PS with amino groups on both ends leads to better performance in in reducing the water/toluene interfacial tension than modifying the molecular structure of PS on a single end. The dimension of sulfonated NPs also contributed significantly to the reduction of the water/toluene interfacial tension. The minimal interfacial tension was 4.49 mN/m after compounding PS-NH2 with sulfonated zero-dimensional carbon dots. Molecular dynamics simulation on the evolution of the water/toluene interface in the presence of sulfonated carbon dots and H2N-PS-NH2 revealed that these opposite charged substances moved towards the interface in an extreme short time and orderly assembled in a thermodynamic equilibrium.

The relative permeability of oil-water two-phase flow is an important parameter in fractured petroleum reservoirs. It is widely accepted that the sum of relative permeabilities is less than 1. In this study, a series of experiments have been conducted on six rectangular fractures for oil-water two-phase flows. Analytical investigations of the effects of flow rate, aspect ratio, and fracture size on the relative permeability of oil-water two-phase are analysed. Basic fluid flow equations are combined to develop a new analytical model for water-oil two-phase flow in a horizontal fracture. The simulation results predicted by this model are in good agreement with the experimental data. The relative permeability is a function of flow ratio, viscosity ratio, aspect ratio and saturation. It increases as aspect ratio increases if the fracture depths are the same, while it decreases as aspect ratio increases if the fracture widths are identical. Both experiment and model indicate that the sum of relative permeabilities of oil and water is greater than 1 in some cases, different from the accepted view.

Drilling fluids are complex mixtures of natural and synthetic chemical compounds used to cool and lubricate the drill bit, clean the wellbore, carry drilled cuttings to the surface, control formation pressure, and improve the function of the drill string and tools in the hole. The two main types of drilling fluids are water-based and oil-based drilling fluids, where the oil-based also include synthetic-based drilling fluids. Many rheological properties of drilling fluids are key parameters that must be controlled during design and operations. The base fluid properties are constructed by the interaction of the emulsified water droplets in combination with organophilic clay particles. The rheological properties resulted from this combination, along with the particle size distribution of weight materials are vital in controlling the physical stability of the microstructure in the drilling fluid. A weak fluid microstructure induces settling and sagging of weight material particles. The presence of sag has relatively often been the cause for gas kicks and oil-based drilling fluids are known to be more vulnerable for sag than water-based drilling fluids. Hence, the shear-dependent viscosity and elasticity of drilling fluids are central properties for the engineers to control the stability of weight material particles in suspension. In this study, we examined the stability of typical oil-based drilling fluids made for North Sea oilfield drilling application with oil-water-ratios (OWR) of 80/20 and 60/40. The structural character of the fluid samples was analyzed both at rest and dynamic conditions via flow and viscosity curves, amplitude sweep, frequency sweep, and time-dependent oscillatory sweep tests using a rheometer with a measuring system applying a grooved bob at atmospheric conditions. A high precision density meter was used to measure the density of the drilling fluid samples before and after each test. The measurement criteria used to rank the fluids stability include the yield stress as measured from flow curves and oscillatory tests, flow transition index, mechanical storage stability index, and dynamic sag index. We observed that between the two drilling fluids, the sample with OWR = 60/40 showed a stable dispersion with stronger network structure as evidenced by higher yield stress and flow transition index values, while the mechanical storage stability index and dynamic sag index recorded lower values. The results of this study enable drilling fluid engineers to design realistic oil-based drilling fluids with stable microstructure to mitigate settling and sagging of weight material particles for North Sea drilling operation.

The coalescence between crude oil droplets is a major factor influencing the efficiency of most produced water treatment processes. As the droplets grow bigger in size, it is easier to remove them from the continuous water phase, which will improve the quality of produced water and help meet increasingly stricter environmental and process regulations. Here, we investigate the coalescence process of crude oil drops in water with the use of previously reported microfluidic tools. It was shown that the composition of both oil and water phases heavily impacts the merging between droplets, both outcome (final droplet size distribution) and the kinetics of the phenomena (coalescence time). In the droplet aging experiments, the coalescence was always most extensive for the droplets with the shortest aging time, while the coalescence typically decreased with increasing droplet size distribution; however, this was oil-specific. Overall, the results underline the importance of crude oil and produced water chemistries during the water treatment process.

Dual-superlyophobic membranes that exhibit underwater superoleophobicity and underoil superhydrophobicity concurrently have gained considerable attention for oil/water separation. To effectively treat oily wastewater, consistent efforts have been made to develop fast and simple methodologies with low cost, environmentally friendly materials. Here, the dual-superlyophobic membranes are obtained based on one-step tailored growth of mussel-inspired polydopamine (PDA) nanoparticles on the surfaces of biomass membranes. The results demonstrate that the universal adhesion of PDA allows the modification of biomass fibers of different surface hydrophobicity. The oxidation polymerization of dopamine leads to the rapid growth of PDA nanostructures, which form stable coatings of high roughness instead of homogeneous conformal coatings generated in the conventional synthesis of PDA. The amphiphilic nature of PDA and the rough surfaces imparted by the PDA nanostructures collectively lead to dual-superlyophobic properties. Membranes of the coated biomass fibers prewetted by either water or oil become impermeable to the counterpart liquids, giving rise to efficient oil–water separation in a broad spectrum of mixtures. In particular, the membranes derived from cotton or kapok fibers show oil/water separation efficiencies of above 99.98%, fluxes ranging from 4000 to 22 200 L m−2 h−1, and robust performance for regeneration and repeated uses.

Geological reserves of oil-water transition zone (OWTZ) in low-permeability reservoirs have been considered as uneconomical resources because of high water cut and low abundance. Though the OWTZ may account for 30 %–50% of a reservoir, it has not been paid more attentions yet. The average oil saturation of the OWTZ is about 35%, which is equal to that of a reservoir after water flooding. Currently, CO2 flooding is an effective technique for residual oil recovery after water flooding, which could reduce the residual oil saturation greatly. Therefore, it is of significance for the EOR of the low-permeability reservoir if the CO2 flooding could be successfully applied in the OWTZ. In this study, a method based on a long core to simulate distribution of oil saturation in OWTZs is set up in the laboratory using bidirectional saturation. In order to investigate CO2 flooding characteristics in OWTZs, experiments are carried out on 3 sets of initial oil saturation, and the recoverable reserves of the OWTZ and its contribution to the EOR are calculated based on the WJ reservoir in the Jilin Oilfield, China. Keywords: Oil-water transition zone, Initial oil saturation, CO2 flooding, Laboratory simulation, CT scanning

Nowadays, its urgent need to develop and fabricate efficient, low cost, eco-friendly, oil-water separation methodologies especially for variety of polluted water in the environments. To deals with serious oil spills and industrial organic pollutants, here in we have developed a highly efficient oil-water separation methodology by using waste material such as expanded polyethylene (EPE) polymeric foam which is most commonly used for packaging as a shock absorber and most abundantly available in the surroundings as waste. Oil-water separation setup was fabricated by using waste EPE polymeric foam without any pre-treatment. By simply scratching, special properties (wettability performance) such as hydrophobicity, leophilicity, and low water adhesion was imparted to the EPE polymeric foam. The different types of oil-water mixture used for the study and separation were achieved almost up to 78%. The oil absorption efficiency of the EPE polymeric foam was within range of 0.491–0.788 g/g. In addition to efficient oil-water separation, the modified EPE polymeric foam exhibited fast and continuous oil-water separation solely by gravity. The easy operation, chemical durability, and efficiency of the waste EPE polymeric foam give it high potential for use in industrial and consumer applications for large scale oil-water separation. Keywords: Waste, Packaging foam, Oil-water separation, Removal, Wastewater, Environmental remediation

In this work an equivalent single-phase flow model is proposed based on the oil-water two-phase flow equation with saturation-dependent parameters such as equivalent viscosity and equivalent formation volume factor. The equivalent viscosity is calculated from the oil-water relative permeability curves and oil-water viscosity. The equivalent formation volume factor is obtained by the fractional flow of the water phase. In the equivalent single-phase flow model, the equivalent viscosity and phase saturation are interdependent when the relative permeability curves are known. Four numerical experiments based on PEBI grids show that equivalent single-phase flow has a good agreement with the oil-water two-phase flow, which shows that the equivalent single-phase flow model can be used to interpret oil-water two-phase pressure data measured in the wellbore during the buildup period. Because numerical solution of single-phase flow model is several times faster than that of the two-phase flow model, whether the new model interprets the pressure data directly or offers good initial values for the true oil-water two-phase pressure data interpretation, it will obviously improve the efficiency of the interpretation of oil-water pressure data and decrease the burden of engineers.

Superhydrophobic surfaces have great potential for application in self-cleaning and oil/water separation. However, the large-scale practical applications of superhydrophobic coating surfaces are impeded by many factors, such as complicated fabrication processes, the use of fluorinated reagents and noxious organic solvents and poor mechanical stability. Herein, we describe the successful preparation of a fluorine-free multifunctional coating without noxious organic solvents that was brushed, dipped or sprayed onto glass slides and stainless-steel meshes as substrates. The obtained multifunctional superhydrophobic and superoleophilic surfaces (MSHOs) demonstrated self-cleaning abilities even when contaminated with or immersed in oil. The superhydrophobic surfaces were robust and maintained their water repellency after being scratched with a knife or abraded with sandpaper for 50 cycles. In addition, stainless-steel meshes sprayed with the coating quickly separated various oil/water mixtures with a high separation efficiency (>93%). Furthermore, the coated mesh maintained a high separation efficiency above 95% over 20 cycles of separation. This simple and effective strategy will inspire the large-scale fabrication of multifunctional surfaces for practical applications in self-cleaning and oil/water separation.

For decades, oil and water separation has remained a challenge. Not only oil spills but also industrial oily wastewaters are threatening our environment. Over the years, oil-water separation methods have been developed, however, there are still considerable hurdles to overcome to provide a low cost and efficient process able to treat a large amount of liquid. In this work, we suggest a continuous, simultaneous and effective oil-water separation method based on the antagonistic functionalization of meshes using atmospheric pressure cold plasmas. Using this robust plasma method, superhydrophobic/underwater-superoleophilic or superhydrophilic/underwater-superoleophobic functionalized meshes are obtained. Antagonistically functionalized meshes can simultaneously separate oil and water and show continuous separation flow rates of water (900 L m

Numerous irregular flow structures exist in the complicated multiphase flow and result in lots of disparate spatial dynamical flow behaviors. The vertical oil-water slug flow continually attracts plenty of research interests on account of its significant importance. Based on the spatial transient flow information acquired through our designed double-layer distributed-sector conductance sensor, we construct multilayer modality-based network to encode the intricate spatial flow behavior. Particularly, we calculate the PageRank versatility and multilayer weighted clustering coefficient to quantitatively explore the inferred multilayer modality-based networks. Our analysis allows characterizing the complicated evolution of oil-water slug flow, from the opening formation of oil slugs, to the succedent inter-collision and coalescence among oil slugs, and then to the dispersed oil bubbles. These properties render our developed method particularly powerful for mining the essential flow features from the multilayer sensor measurements.

This work investigates the coalescence of water droplets settled on a water–oil interface in the presence of microparticles and surfactant. The successive stages of the coalescence process, including interstitial film formation, drainage, rupture, and retraction, are analyzed in detail. This leads us to distinguish between contrasted situations depending on the nature of the surfactant and its affinity with the microparticles. Hydrophilic particles have been previously shown to promote coalescence by means of a bridging mechanism. In that case, coalescence is a deterministic process that lasts the time required for the drainage to make the film thickness equal to the size of the particles. However, the present study shows how surfactants can totally change the effect of the particles upon coalescence. When surfactant both stabilizes the water–oil interface and adsorbs onto the particles, the bridging mechanism is inhibited and the coalescence becomes a random process. Since molecular forces between facing film interfaces are not attractive, thermal fluctuations are required to initiate the formation of a hole in the adsorbed surfactant layer. Provided the surfactant concentration in the bulk is large enough to ensure that the interfaces are close to saturation, the coalescence is delayed by a stochastic time interval and the drop coalescence becomes a Poisson process. These results shed a new light on the mechanisms of droplet coalescence in complex industrial applications where surfactant and particles are present, either purposely added or present as uncontrolled contaminants.

In this study, the reliability and quality of flow rate and water holdup measurements of oil-water flow in different pipe inclinations and diameters were investigated. The identified sources of errors in the measurement of flow rate were repeatability, accuracy of the flow meter, resolution of the measuring cylinder and instability of the regulating valves. The identified sources of errors in the measurement of water holdup were repeatability, resolution of the measuring cylinder and flow rate. The results showed that the relative uncertainty in the measurement of the oil-water flow rate was ±1.71 % while the relative uncertainty in the measurement of the water holdups was ±10.3 % at 0.5 m/s mixture velocity and 0.5 input water fraction in horizontal 30.6-mm ID pipe. It was also found that the flow meter accuracy made the largest contribution (about 50 %) while the resolution of the measuring cylinder made the least contribution (3 %) to the combined uncertainty in the flow rate measurement. In the case of the combined uncertainty in the water holdup measurement, the largest contribution came from the flow rate while the least contribution came from the resolution of the measuring cylinder in all the different pipe inclinations and diameters. Keywords: Oil-water flow; Flow rates; Water holdups; Standard uncertainty, Combined standard uncertainty; Expanded uncertainty

The regulatory effluent oil limit which is the allowable quantity of hydrocarbons in industrial and stormwater effluents varies from one country to another. Several authors have suggested the need to improve the design methods of conventional oil–water separators because current design methods do not address the quality of effluents produced despite the fact that the conventional oil-water separator is the predominant wastewater treatment facility in developing countries. Regulatory effluent oil limit and oil separation efficiency are not design parameters of the current standard design methods for conventional oil-water separators but there is pressure from environmental regulatory agencies on companies over compliance with regulatory effluent oil limit for industrial wastewaters. This research work conducted a survey on the oil content of the wastewater effluents of some functional conventional oil-water separators in the Niger Delta, Nigeria. Sequel to the outcome of the survey, this work invented novel design methods for conventional oil-water separators titled: novel design approach, innovative design approach and alternative design approach through mathematical modeling. The novel design methods apply the concept of design volume, novel sizing data and novel mathematical models to design conventional oil-water separators that conform to American Petroleum Institute (API) design criteria for conventional oil-water separators; taking into account oil separation efficiency and the regulatory effluent oil limit of a country to establish the technical basis for the periodic evaluation of separator performance and evaluation of compliance with the environmental regulation. The conventional oil-water separators designed with the novel design methods conformed to API design criteria and their dimensions are similar to dimensions of separators designed with the City of Tacoma design approach (a certified design approach), thus validating the novel design methods for the design of conventional oil-water separators. The novel design methods have global applicability. They can be applied in every country.

There is an increasing need to accurately predict the behaviour of fluid in the different flow geometry as applicable in the industries. The prediction of drag reduction phenomenon observed during the two-phase oil-water flow with drag reducing polymers in horizontal pipes was investigated. The Power law model was adopted in this study to empirically correlate the data acquired from our earlier experimental works in a 12-mm ID and 20-mm ID pipes. The model accurately predicts the drag reduction across the horizontal pipes. The agreement between the predicted and experimental drag reductions was better in the 12-mm ID pipe than in the 20-mm ID pipe. More work and data is needed to enhance the predictive accuracy of applicable models. Keywords: Drag reduction; polymers; horizontal pipes, oil-water flow, modelling

In this paper, we present a facile and efficient strategy for the fabrication of magnetic, durable, and superhydrophobic cotton for oil/water separation. The superhydrophobic cotton functionalized with Fe3O4 magnetic nanoparticles was prepared via the in situ coprecipitation of Fe2+/Fe3+ ions under ammonia solution on cotton fabrics using polyvinylpyrrolidone (PVP) as a coupling agent and hydrophobic treatment with tridecafluorooctyl triethoxysilane (FAS) in sequence. The as-prepared cotton demonstrated excellent superhydrophobicity with a water contact angle of 155.6&deg, &plusmn, 1.2&deg, and good magnetic responsiveness. Under the control of the external magnetic field, the cotton fabrics could be easily controlled to absorb the oil from water as oil absorbents, showing high oil/water separation efficiency, even in hot water. Moreover, the cotton demonstrated remarkable mechanical durable properties, being strongly friction-resistant against sandpaper and finger wipe, while maintaining its water repellency. This study developed a novel and efficient strategy for the construction of magnetic, durable, and superhydrophobic biomass-based adsorbent for oil/water separation, which can be easily scaled up for practical oil absorption.

Four different surface morphologies, including needle-like, bamboo leaf-like, pine needle-like, and peony flower-like structures, were prepared on Cu mesh surface, and the existence of these different surface morphologies were due to the formation of Cu(OH)2 or CuO microstructures by controlling the oxidation time and oxidation temperature of the chemical reaction. These freshly prepared Cu meshes all exhibit superhydrophilic-superoleophilic after dried with a hair dryer. They all have excellent separation efficiency, and the separation efficiency for oil-remove (~96%) is higher than that of water-remove (~94%). Interestingly, these meshes with four different surface morphologies can transform from superhydrophilic-superoleophilic to superhydrophobic-superoleophilic just after storage in air for >20 days without any further chemical modification. This is because oxygen adsorption on the mesh surface contributes to air trapped into the microstructures. These superhydrophobic-superoleophilic copper meshes have good durability. According to the investigation of separation efficiency of the superhydrophobic-superoleophilic mesh, we find that the separation efficiency for oil-remove of the superhydrophobic-superoleophilic mesh (~99%) is higher than that of the superhydrophilic-superoleophilic mesh (~96%).

To improve the production effect of oil-water transitional zone in thin-shallow extra heavy oil reservoirs of Chunfeng Oilfield in western marginal area of the Junggar Basin, microbial enhanced oil recovery was studied taking the P6-P48 well of the oil-water transitional zone as an example. In the early stage of steam stimulation, the P6-P48 well was shut-in due to high water cut caused by edge water incursion, and analysis showed that its reservoir conditions are suitable for microbial cold production technology. According to the P6-P48 well oil sample composition, the study screened indigenous microbe strain of bacillus XJ2-1, aeruginosa XJ3-1, Dietz's bacteria Z4M8-2, inoculating microbes strain of bacillus SLG5B10-17, nutrient solution, and activator; and designed microbial injection scheme according to near borehole zones treatment radius. In September 2014, 865 m3 of microbial bacterial liquid, nutrient solution and activator was injected and the well was shut in for 166 d of reaction time. The well-hole was opened to produce in March 15, 2015, and has produced 405 d until April 30, 2016, producing oil 3 464 t. The 50 °C degassing crude oil viscosity was decreased by 58% after microbial enhanced oil recovery, and the injected live bacteria was found in produced fluid, with more quantity, indicating that the injected bacteria are adaptive and has reproduced in formation condition. Compared with 16 adjacent wells of steam soaking, microbial enhanced oil recovery has long valid period and better economic benefit. Microbial enhanced oil recovery also got good results in the P6-P49 and P6-P47 wells. Key words: oil-water transitional zone, extra heavy oil reservoir, microbial enhanced oil recovery, economic benefit, Chunfeng oilfield, Junggar Basin

Gum Arabic “GA” is an organic adhesive produced from a tree called named Acacia Senegal. The gum has a wide range of industrial uses, especially in areas of feeds, textiles, and pharmaceuticals. It is used as emulsifier and serves mostly as stabilizer in both cosmetic and food products which contains oil water interface. GA sample was collected, formulated and prepared into various concentrations ranging from 20%w/v to 85%w/v. The quality and applicability of well characterized materials are directly related to their physical and chemical properties. From the physiochemical analysis, the result revealed that all the samples were slightly acidic (pH ranging from 4.81-6.41). This range is in good agreement with reported pH values for gum arabic and other Acacia gums by several authors. . The binding strength increases as the number of days increases for example in sample F (50%w/v) gum Arabic concentration increases from 1.5 in the 1st day to 1.97 in the 28th day. The samples prepared are denser than water which indicates that the density increases as the percentage concentration of the samples increases and the relative density of the gum solution is independent on time. The binding strength of sample G (75%w/v) gum concentration compared well to that of polyvinyl acetate (PVA). International Journal of Environment Vol. 5 (1) 2016, pp: 67-78

Oil wastewater and spilled oil have caused serious environmental pollution and damage to public health in the past few years. Therefore, considerable efforts are being made to develop sorbent materials that are able to separate oil from water with high selectivity and sorption capacity. However most of them exhibit low reusability, with low volume absorption capacity and poor mechanical properties. Moreover, their synthesis is time-consuming, complex and expensive, limiting their practical application in the case of an emergency. Here we propose an innovative approach for the fabrication of porous PDMS starting from an inverse water-in-silicone procedure able to selectively collect oil from water in a few seconds. The synthesis is dramatically faster than previous approaches, permitting the fabrication of the material in a few minutes independent of the dimensions of the sponges. The porous material possessed a higher volume sorption capacity with respect to other materials already proposed for oil sorption from water and excellent mechanical and reusability properties. This innovative, fast and simple approach can be successful in the case of an emergency, such as an oil spill accident, permitting in situ fabrication of porous absorbents.

Massive oily water produced in oil and gas industry is a catastrophe to the oil and water sources on the earth. Ceramic membrane separation is a promising approach to obtain clean water and oil fuel from oily water to mitigate this catastrophe. In this research, a low cost and biocompatible material, hydroxyapatite (HAP), is innovatively explored as bioceramic membranes for oily water separation. HAP powder was firstly synthesized by chemical precipitation and solid-state exchange methods, respectively. The powder was then fabricated into membranes with various geometries such as circular pellet, dense tube, and porous hollow fiber by different methods. The preparation, property, and oil-water separation performance of HAP hollow fiber membranes were studied in details. The HAP content, particle size, the viscosity of HAP suspension and sintering temperature of HAP hollow fibers all influenced the pore size, structure and oil-water separation performance of resultant HAP membranes.

Porous monolithic advanced functional materials based on supported ionic liquid-like phase (SILLP) systems were used for the preparation of oleophilic and hydrophobic cylindrical membranes and successfully tested as eco-friendly and safe systems for oil/water separation and for the continuous integration of catalytic and separation processes in an aqueous-organic biphasic reaction system.

This thesis includes my four-year researches on the fabrication of tunable twodimensional (2D) metasurfaces by assembling shape-controlled nanoparticles at the oilwater interface. Our aim is to break the limited planar structure and achieve the high tunability of macroscopic superstructures. In Chapter 1, we summarize recent studies on the fabrication of 2D structures, self-assembly method, parameters influencing assembled structure and the application of plasmonic structure. In Chapter 2, we report a new chemical strategy of controlling surface distribution to achieve tunable metasurfaces with non-planar nanocube orientations, creating novel lattice-dependent field localization patterns. In Chapter 3, we further utilize solvent-tunable molecular-level polymer conformation changes to achieve ‘multiple metacrystals using one nanoparticle with one chemical functionality’. This method breaks the limitation of changing surface chemistry by replacing surface ligands. In Chapter 4, we study the shape-mediated structure transformation and establish a phase diagram of polyhedral particles to indicate the relationship between vertex truncation, surface functionalization, interfacial position and superstructure. In the above works, we study the interfacial behavior by understanding the interaction between particle surface and two liquid phase. In Chapter 5, we study the particle-particle interaction to achieve the control over assembled structure by using two surface ligands with similar bulk wettability. ​Doctor of Philosophy (SPMS)