Demulsification Behavior, Characteristics, and Performance of Surfactant Stabilized Oil-in-Water Emulsion under Bidirectional Pulsed Electric Field

As a novel electric demulsification method,bidirectional pulsed electric field(BPEF)was employed to demulsify the surfactant stabilized oil-in-water(SSO/W)emulsion for oil/water separation in this work.The demulsification behavior,characteristics,and stages under BPEF were explored.It was discovered that BPEF drove SSO/W emulsion to move and form vortexes,during which the oil droplets aggregated and accumulated to generate an oil droplet layer(ODL).ODL subsequently transformed into a continuous oil layer(COL)leading to the demulsification and separation of SSO/W emulsion.The conversion rate of ODL to COL was defined and used to evaluate the demulsification process and reflect the coalescence ability and transformation efficiency of dispersed oil droplets into COL.Furthermore,the effects of BPEF voltage,frequency,duty cycle,ratio of pulse output time,and surfactant type and content on the demulsification performance were examined.The optimal values of BPEF parameters for demulsification operation were 400 V,25 Hz,50%,and 4:1.O/W emulsion containing anionic surfactant was apt to be demulsified by BPEF,nonionic surfactant took the second place and cationic surfactant was the most difficult.A high surfactant content was not conducive to the BPEF demulsification.This work is anticipated to provide useful guidance for oil/water separation and oil recovery from actual emulsified oily wastewater by BPEF.

Study on an improved rotating microchannel separator in the intensification for demulsification and separation process

An improved rotating microchannel(IRM) separator was further explored in the intensification for demulsification and separation process. Oil-in-water(O/W) emulsion system of 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507)–water without emulsifier was employed to evaluate the performance of the new equipment. In this experiment, the influence on demulsification separation process was explored by changing the geometrical structure and channel height of the microchannel and combining the liquid–liquid two-phase flow pattern, and the correlation general graph between demulsification efficiency and dimensionless parameters was established. The total demulsification effect of the IRM and the separation capacity of the clear organic phase recovered from demulsification are significantly improved. In addition, the liquid–liquid two-phase flow pattern of the clear organic phase after demulsification and the remaining emulsion in the IRM are observed and recorded by high-speed photography. The separation ability of organic phase from the upper outlet can be significantly improved when the total demulsification rate of IRM is up to 90%. There are 3 types and 6 kinds of flow patterns observed. The results demonstrated that the suitable demulsification performance is obtained when the liquid–liquid two-phase inside the IRM is in a parallel pattern. Finally, the relation map between total demulsification efficiency and the universal flow is drawn, which provides a basis for the accurate control of the IRM device.

Demulsification of Emulsion Liquid Membrane by Wetting Coalescence Materials

Demulsification of emulsified water-in-oil droplets was worked out with the employment of wetting coalescence materials. Demulsification is carried out in conventional stirred-column and packed-column. Among the four kinds of natural fibers and two kinds of inorganic materials tested, natural fiber A, originated from wood shavings was found to give the best performance of demulsification. The demulsification efficiency can exceed 96.5% when demulsification conditions are optimized. The packed-column showed much better performance both in terms of demulsification efficiency and repeated use of the recovered oil phase for extracting cadmium in simulated wastewater. Operating variables governing the demulsification efficiency were investigated.

Mechanism of Coalescence Demulsification with Microfiltra- tion Membrane

A study on the membrane coalescence demulsification was carried out with four working systems of water/n-butyl alcohol, water/n-octanol, water/30% TBP(in kerosene) and water/kerosene. The membranes made of polytetrafluoroethylene (PTFE) with 1.0μm pore size were used. The results indicated that the excellent demulsification efficiency for emulsions with various oil contents was obtained. A conductivity probe was used to study the demulsification mechanism. An electrode probe was designed and used to determine the oil content near the membrane surface. The obtained data showed that the oil content in the permeated stream was much higher than that in the feed emulsion. A physical mechanism to explain the membrane demulsification was put forward.

Demulsification of Water in oil Emulsion by Using Porous Glass Membrane

The hydrophilic porous glass membranes were used to demulsify water in oil emulsion, liquid membrane and demulsification efficiency can reach more than 96 percent. Effects of pore size of the membrane, transmembrane pressure and volumetric ratio of oil phase to internal aqueous phase in the emulsion on demulsification were investigated. Correspondingly, effect of transmembrane pressure on permeation flux of the droplets was also studied.

Demulsification with simultaneous water purification by coupling filtration and enhanced oil droplet coalescence at anode interface in an electrochemical reactor

With the increasing demand of recycling disposal of industrial wastewater,oil-in-water(O/W)emulsion has been paid much attention in recent years owing to its high oil con-tent.However,due to the presence of surfactant and salt,the emulsion was usually stable with complex physicochemical interfacial properties leading to increased processing diffi-culty.Herein,a novel flow-through electrode-based demulsification reactor(FEDR)was well designed for the treatment of saline O/W emulsion.In contrast to 53.7%for electrical demul-sification only and 80.3%for filtration only,the COD removal efficiency increased to 92.8%under FEDR system.Moreover,the pore size of electrode and the applied voltage were two key factors that governed the FEDR demulsification performance.By observing the mor-phology of oil droplets deposited layer after different operation conditions and the behavior of oil droplets at the electrode surface under different voltage conditions,the mechanism was proposed that the oil droplets first accumulated on the surface of flow-through elec-trode by sieving effect,subsequently the gathered oil droplets could further coalesce with the promoting effect of the anode,leading to a high-performing demulsification.This study offers an attractive option of using flow-through electrode to accomplish the oil recovery with simultaneous water purification.

Recent advances in switchable surfactants for heavy oil production:A review

Surfactants are extensively employed in the cold production of heavy oil.However,producing heavy oil emulsions using conventional surfactants poses a challenge to spontaneous demulsification,necessitating the addition of demulsifiers for oil-water separation.This inevitably increases the exploitation cost and environmental pollution risk.Switchable surfactants have garnered much attention due to their dual capabilities of underground heavy oil emulsification and surface demulsification.This study focuses on the fundamental working principles and classification of novel switchable surfactants for oil displacement developed in recent years.It offers a comprehensive overview of the latest advances in the applications of switchable surfactants in the fields of enhanced oil recovery(EOR),oil sand washing,and oil-water separation.Furthermore,it highlights the existing challenges and future development directions of switchable surfactants for heavy oil recovery.

Coupling magnetic particles with flocculants to enhance demulsification and separation of waste cutting emulsion for engineering applications

Magnetic particles were coupled with a flocculant to enhance the demulsification and separation of waste cutting emulsions.The optimal magnetic particle size and critical magnetic field conditions were investigated to achieve large-scale engineering application of magnetic demulsification separation for waste cutting emulsion treatment.The micro-scale magnetic particles were found to show comparable effects to nano-scale magnetic particles on enhancing the demulsification and separation of cutting emulsions,which are beneficial for broadening the selectivity of low-cost magnetic particles.The critical magnetic separation region was determined to be an area 40 mm from the magnetic field source.Compared to the flocculant demulsification,the magnetic demulsification separation exhibited a significant advantage in accelerating flocs-water separation by decreasing the separation time of flocs from 180-240 min to less than 15 min,compressing the flocs by reducing the floc volume ratio from 60%-90%to lower than 20%,and showing excellent adaptability to the variable properties of waste cutting emulsions.Coupled with the design of the magnetic disk separator,continuous demulsification separation of the waste cutting emulsion was achieved at 1.0 t/hr for at least 10 hr to obtain clear effluent with 81%chemical oxygen demand removal and 89%turbidity reduction.This study demonstrates the feasibility of applying magnetic demulsification separation to large-scale continuous treatment of waste emulsion.Moreover,it addresses the flocs-water separation problems that occur in practical flocculant demulsification engineering applications.

Formation,stabilization and chemical demulsification of crude oil-in-water emulsions:A review

The crude oil recovery process is frequently associated with the formation of stable emulsions due to factors such as turbulent flow in pipelines and the presence of surface-active substances that naturally occur in crude oil.These emulsions are undesirable for the petroleum industry because their destruction/treatment adds to the overall production cost and causes the loss of valuable amounts of crude oil.Therefore,it is essential,for economic and environmental reasons,to optimize the crude oil demulsification process.The effective treatment of crude oil emulsions requires understanding of the process and factors leading to their formation and stabilization.In this sense,suitable treatment methods and possible preventive measures to avoid their formation can be employed.The present study reviews recent oilfield emulsion types and the factors responsible for their formation and stabilization.The different demulsification techniques employed were then extensively examined.Demulsification tech-niques include mechanical,thermal,electrical,and chemical methods with different demulsification mechanisms affected by many factors such as emulsions type and properties,demulsifiers characteris-tics,presence of solids stabilized emulsions,etc.The demulsification efficiency depends on the operating parameters of the process,the economics involved,and the environmental impact,which are the main factors considered in selecting a suitable demulsification technique.Future research on the demulsifi-cation of crude oil emulsions should focus on real crude oil emulsions studies at a pilot scale level,the effect of aging on crude oil emulsions,the combination of multiple demulsification techniques and their synergistic effects,and the use of natural,ecofriendly demulsifiers.

Demulsification-induced Fast Solidification: a Novel Strategy for Preparation of Polymer Encapsulations

Encapsulations are being increasingly investigated in both academic research and industrial manufacturing and applied in numerous fields,such as phase change materials and smart materials.In this paper,a novel strategy of demulsification-induced fast solidification(DIFS)was proposed for the rapid fabrication(within 1 s)of polymer encapsulations via immersion of demulsifier particles in emulsion.The DIFS method allowed the fabrication of three-dimensional(3D)hollow polymer encapsulations with precisely controlled size and thickness over a wide range from micron to millimeter within just 1 s.Magnetic nanoparticles and luminescent materials were further introduced into 3D hollow polymer encapsulations via facile blending method.Moreover,encapsulated paraffin phase change materials with good thermal stability were also obtained using the DIFS method.Therefore,this work provides new insights into the design and preparation of functionalized encapsulation materials.

Aggregation-induced demulsification triggered by the hydrophilic fabric for the separation of highly emulsified oil droplets from water

A functional fabric with hierarchical structure consisting of basalt fibre fabric as a substrate and polyvinyl alcohol as a coating was developed,aiming at providing a low cost and high-performance way to separate highly emulsified oil in water.The coating functioned as a hydrophilic gate for the penetration of water in the emulsion,whereas the micro-channels formed in the fabric offered capillary force for the continuous flow of water.The synergy of these two materials led to the increase on the oil concentration in the liquid,which in turn enhanced the collision of emulsified oil droplets to aggregate into large ones in the emulsion and resulted separation from the water.Based on these findings,an aggregation-induced demulsification process was proposed to explain the above phenomenon,and the mechanism was confirmed by studying the distribution of oil droplets in emulsion with a controlled separation degree.

膜接触破乳——用于油包水乳液分离的超疏水ZIF-8@rGO膜

水-油界面不平衡是实现油水乳液破乳的关键。传统膜通常是依赖较高的跨膜压力破坏界面平衡而实现破乳。本文提出了可自然、快速地破坏水-油界面平衡的“接触破乳”的概念,开发了一种对有机组分具有高通量的新型破乳分离膜。具体制备过程分为两步,首先通过真空辅助抽滤法在聚四氟乙烯(PTFE)基底上组装ZIF-8@rGO微球(ZGS)层,再采用聚二甲基硅氧烷(PDMS)交联溶液中进行固定化处理。由于ZGS表面为微纳米阶层结构,所制备的ZIF-8@rGO@PDMS/PTFE(ZGPP)膜表面展现出超疏水性特性,当表面活性剂稳定的油包水乳液接触到膜表面时,微纳结构的超疏水膜表面会引起水-油界面不平衡。ZGPP膜对油包水乳液具有良好的分离破乳性能,在0.15 bar(15 kPa)的低跨膜压力下,分离效率可以达到99.57%,通量可达到2254 L·m^(-2)·h^(-1),且对于表面活性剂稳定的纳米级甲苯-水乳剂(平均液滴尺寸为57 nm)的体系也可以实现破乳分离。“接触破乳”概念的提出有望为开发新一代油包水乳液分离的破乳膜提供新的思路。

New Method for the Deep Dehydration and Desalination of Crude Oil

The present work focused on the environmentally friendly deep desalination of crude oil using ethylene glycol as the extraction solvent and quartz sand as the demulsifier.The effect of droplet size distribution in the emulsion on the dehydration results and desalination efficiency was investigated.Experimental results showed that the desalination efficiencies of Sarir and Basra crude oils were 93.3%and 90.0%,respectively.Furthermore,the desalination efficiency of Basra crude oil using ethylene glycol could be enhanced up to 96.7%by adding 30 g/L quartz sand with a particle size of 15μm.Finally,94%of the ethylene glycol and 86%of the quartz sand could be recovered from the emulsion.This process offers an alternative method to the deep desalination of crude oil.

A NOVEL METHOD OF BREAKING WATER-IN-OIL EMULSIONS BY USING MICROPOROUS MEMBRANE

A novel method for breaking emulsions with microporous membranes is presented.A membrane would act as a coalescer if its pore size is smaller than the emulsion droplets and if the dispersed phase has great affinity to the membrane.It was observed that a hydrophilic membrane is able to break water in oil emulsions with high separation efficiency.Effects of the membrane pore size,membrane thickness,transmembrane pressure and emulsion composition on demulsification performance were investigated.It was found that the membrane pore size and transmembrane pressure affect demulsification performance remarkably while other factors have slight or almost no effect.

Synthesis and characterization of lower generation broom molecules

Dendritic molecules with dodecyl groups as the hyperbranchs were synthesized in methanol by Michael addition with dodecylamine and methyl acrylate as raw materials. This new-type dendritic molecules were called vividly ＂broom molecules＂ in this report. The surface tension of the aqueous solution of broom molecule terminated amino group was measured by using the dropvolume method. The demulsification performance of the broom molecules for the oil/water （O/W） simulated crude oil emulsion was examined. The experimental results revealed that, as a new-type of surfactants, the broom molecules terminated amino groups showed demulsification for the O/W simulated crude oil emulsion. 2007 Jun Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All fights reserved.

Electrostatic Enhancement of Coalescence of Oil Droplets(in Nanometer Scale) in Water Emulsion

Oil droplets in nanometer scale which are dispersed in water cannot be separated easily. An attractive technique is carried out by electrical phenomena to demulsify oil in water emulsion. In this research, non-uniform electric field or dielectrophoresis （DEP） is applied to remove sunflower oil （which is dispersed in the water）. Effectsof temperature, time and voltage （using AC-electric field） were considered to get the highest DEP-force （Fdi） and the best results. The oil particles sizes with average of approximately 76 nm have been shown using a ZetaSizer Nano ZS, Model ZEN 1600 （Malvem Instrument Ltd.）. The maximum separation efficiency of 85% is obtained at the optimum temperature of 38 ℃ and voltage of 3000 V.

Pretreatment of super viscous oil wastewater and its application in refinery

Wastewater from super viscous oil processing cannot be effectively treated by conventional wastewater treatment plants in refineries because of its high concentration of various organic pollutants. In order to resolve this problem, a number of investigations were conducted in our work to understand the physicochemical properties, sedimentation, demulsification and pretreatment of such super viscous oil refinery wastewater. The results showed that the key issues for pretreatment of this wastewater were： （1） Optimized process parameters were used in the sedimentation and demulsification processes for oil removal to effectively recover oil and remove scum from wastewater; （2） A suitable flocculation process was selected to minimize oil, suspended solids （SS） and chemical oxygen demand （CODcr）. A pretreatment process including three continuous steps： oil removal by sedimentation, oil removal by demulsification, and flotation separation, was proposed and applied in Liaohe Petrochemical Company, PetroChina and the oil content in effluents was less than 200 mg/L and CODcr less than 2,500 mg/L, which completely met the requirement for influent of the conventional wastewater treatment plant, and the recovered super viscous oil reached 5,873 tons in the initial year in Liaohe Petrochemical Company, PetroChina.

RATE MODEL FOR PHASE SEPARATION OF WATER-IN-OIL EMULSION IN LIQUID SURFACTANT MEMBRANE PROCESS AT HIGH A.C.VOLTAGE

A new mechanism of electric demulsification was proposed and the coalescence behavior of fine waterdrops in oil under electric field was discussed in detail On this basis,a mathematical description for phaseseparation of emulsion in electric field has been derived and proved to be in good agreement with experimentaldata.Conditions influenced the electric coalescence was examined in a batch pulsed A.C.electric demulsifier.

Optimization and evaluation of reduced graphene oxide hydrogel composite as a demulsifier for heavy crude oil-in-water emulsion

The rising production of produced water from oilfields had been proven to bring detrimental environmental effects.In this study,an efficient,recyclable,and environmental-friendly reduced graphene oxide immobilizedκ-Carrageenan hydrogel composite(κCaGO)was fabricated as an alternative sorbent for crude oil-in-water demulsification.Polyethyleneimine(PEI)was employed to form a stable hydrogel composite.The conditions for the immobilization of graphene oxide(GO)on PEI-modifiedκ-Carrageenan(κC)beads were optimized appropriately.An immobilization yield of 77%was attained at 2%PEI,2 h immobilization activation time,and pH 6.5.Moreover,the synthesizedκCaGO is capable of demulsification with an average demulsification efficiency of 70%.It was found that the demulsification efficiency increases with salinity andκCaGO dosage,and it deteriorates under alkaline condition.These phenomena can be attributed to the interfacial interactions betweenκCaGO and the emulsion.Furthermore,theκCaGO can be recycled to use for up to six cycles without significant leaching and degradation.As such,the synthesizedκCaGO could be further developed as a potential sorbent substitute for the separation of crude oil from produced water.

Research on High Temperature and High Density White Oil Based Drilling Fluid and Its Application in Well 201H7-6

As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory.Research shows that the drilling fluid system has good rheological property,low filtration loss,strong anti-debris pollution capability and good plugging performance at high temperature and high density.The system has been successfully applied in the 201H7-6 well.Application results show that the drilling fluid rheology,high temperature and high pressure fluid loss and demulsification voltage meet the field requirements.The drilling fluid performance is stable in drilling an 1800 m horizontal section,and no stuck or shale swelling and wellbore collapsing are induced.It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region.It also sets several new records including the deepest well,the shortest drilling cycle,and the fastest drilling speed in that region,which provides valuable experience for the future drilling activities.