Water Separation Efficiency Research Articles

Effective oil-water mixture separation and photocatalytic dye decontamination through nickel-dimethylglyoxime microtubes coated superhydrophobic and superoleophilic films.

Oils and solvable organic pollutants in wastewater demand separations of the components along with efficient photocatalysis in water treatment. Herein, we report on a practical purification strategy by using the multifunctional nickel-dimethylglyoxime [Ni(DMG)2] microtubes to separate the liquid mixture and degrade organic pollutants. The self-assembled [Ni(DMG)2] tubes was synthesized by a facile co-precipitation method. The static contact angle of the film prepared by mixing [Ni(DMG)2] powder (1 : 2 wt%) into polydimethylsilicone (PDMS) to water can reach 161.3°, which can still remain superhydrophobic but oil-friendly under corrosion conditions. PDMS imparts good mechanical properties and serves as both the adhesive and hydrophobic material. PFOTS methanol solution contains a large number of low surface energy groups, which can reduce the surface free energy of [Ni(DMG)2] rough structure. The superhydrophobic rough surface prepared by hollow micron tubular [Ni(DMG)2] samples must have both low surface energy substance and hollow micron tubular morphology. Due to the unique wettability, oil and water were efficiently separated from the oil–water mixture through the films. The coated film itself is photocatalytic in degrading quinoline blue, rhodamine B, methyl orange and methylene blue. By using the film's multifunctionality, a practical wastewater treatment was realized via water–oil separation, followed by fast photocatalytic degradation of solvable dyes.

Demulsification of a Nigerian crude emulsion using ethoxylated-resoles and their xylene modified blends

Demulsification is a method used to reduce or disrupt the water - crude oil emulsion system without uttering the initial composition of the crude oil. This process is done by the introduction of chemicals called demulsifiers, which break the emulsion into aqueous and organic phases. In this study, the demulsifier formulated was the base-catalyzed phenol-formaldehyde resin known as the resoles, with the ratios of phenol to formaldehyde, varied between 1.0:1.2 and 1.0:2.0. The different samples of resoles where then ethoxylated to make them more hydrophilic using different weights (10, 15 & 20 g) of polyethylene glycol (PEG). Screening of the ethoxylated demulsifiers was done using the established bottle test procedure, at 70 °C, the concentration of 50 ppm, and 20 minutes of residence or separation time, in order to select the most effective demulsifier, based on the amount of water removed from the emulsion. The best chemical-demulsifier produced was the ethoxylated resole, which was then blended with xylene at varying percentages (0, 20, 40, 50, and 80 % weight/weight) and was further screened, using the bottle test method. From the analysis, it was obtained that the most effective ethoxylate-xylene demulsifier blend was sample DR3, and made of formaldehyde to phenol ratio of 1.8:1, 20 g of PEG 400 blended with 20 % xylene. The demulsifier gave a water separation efficiency of 85.7 %, compared with the commercial demulsifier, which yielded 72.7 %. The result indicates the practical significance of solvent modified demulsifiers for separating crude oil emulsions in the petroleum industries.

Separation Efficiency of Oil and Water from Oilfield Produced Water Using Cyclonic Flotation

Separation Efficiency of Oil and Water from Oilfield Produced Water Using Cyclonic Flotation

A novel super hydrophobic cotton yarn inspired by plant polyphenol for oil/water separation in sea water

The tannic acid/iron modified cotton yarn (TA/Fe@CY) as inspired by plant polyphenol was prepared as a stable and highly efficient material in oil/water separation with a simple and environmentally friendly preparation method. Owing to the rough structures of the surface, TA/Fe@CY showed super hydrophobicity with a water contact angle of greater than 150º using water droplets of different pH (from 1 to 10). In addition, the TA/Fe@CY showed high oil separation efficiency from the simulated seawater. TA/Fe@CY also exhibited high separation efficiency for six kinds of oil phases. This paper provides a simple preparation method with low-cost materials for efficient oil/water separation, especially for oil separation from seawater. • Simple preparation of a novel cotton yarn via complexation of tannic acid and iron. • Superhydrophobicity and good self-cleaning property. • Impressive durability with acid and alkali resistance. • Good oil–water separation efficiency in artificial seawater.

Rapid fabrication of textured membrane with super-wettability using simple spray-coating of Pd-doped WO3 nanoparticles for efficient oil-water separation

In this work, a membrane based, water passing, and gravity driven oil-water separation system using a separating membrane, with superhydrophilic-underwater superoleophobic surface wettability is presented. The surface with this unique wettability was realized by spray coating, locally synthesized palladium-doped tungsten oxide nanoparticles on the stainless steel mesh membranes. When oil water mixture comes in contact with the coated surface, the oil-water-solid system enters into Cassie wettability state, due to the micro-nano-hierarchical surface roughness. In the Cassie state, the water partially comes in contact with the air filled pits repels the oil in the oil water mixture, and this leads the surface to become under water superoleophobic. When the coated membrane of the uniquely engineered wettability is used in the oil water separating system, the water in the oil water mixture instantly passed through the membrane, while retaining the oil content on the top, which led to the oil water separation efficiency as high as 99.99 %. In addition to the improved separation efficiency, the fouling up of the membrane is almost completely eliminated, as the oil practically does not come in contact with the membrane surface, and this ensures the durability of the membrane for multiple uses. The reclaimed water could be contaminated with oil borne bacteria, which needs to be removed, and as palladium doped WO3 is a proven visible light active photo-catalyst, the coating of this particular material can pave a way to develop a multi-functional system, that can simultaneously carry out oil-water separation, and demineralization of organic pollutants from the filtered water, with visible light irradiation. The morphological and structural characterizations of the surface along with the wettability studies were carried out to elucidate the high separation efficiency of the coated membrane.

Strongly Hydrophobic and Superoleophilic PMMA Based Nanocoated Cotton Fabrics

Oil–water separation is among the critical issues worldwide due to recent massive oil spills. Moreover, domestic and industrial water pollution due to oil discharge affects marine and aquatic life. Cotton is the most predominant fiber globally because of its use as a principal and popular clothing material. Cotton is also the leading raw material for technical and functional textile applications. In this study, the fabric was cured with poly (methyl methacrylate) (PMMA) nanoparticles to develop hydrophobic and oleophilic cotton fabrics. The dehydrating agents, N,N′-dicyclohexylcarbodiimide (DCC) and dimethyl aminopyridine (DMAP), were used to catalyze the esterification. The results proved that the excellent hydrophobicity of modified cotton fabric provides a water contact angle higher than 140°. In addition, Fourier transforms infrared (FTIR) spectroscopy, as well as X-ray photoelectron spectroscopy (XPS) analysis, confirmed the fabric surface modification. Surface morphological analysis by scanning electron microscope (SEM) revealed the uniform rough surface structure of the modified fabric with nano-coating. The modified fabric resulted in the high separation efficiency of oil and water, suggesting this strategy to be suitable for advanced oil–water separation.

Sol–Gel SiO2 on electrospun polyacrylonitrile nanofiber for efficient oil-in-water emulsion separation

A membrane for efficient oil-in-water emulsion separation requires a surface with hydrophilic/underwater oleophobic properties. In this study, a simple and facile sol–gel strategy was proposed for preparing oil-in-water emulsion separation membrane with hydrophilic/underwater oleophobic surface by growing amorphous SiO2 sheets on an electrospun polyacrylonitrile nanofiber membrane (PAN NFM). The composite membranes (PAN@SiO2 NFMs) showed excellent properties in mechanical strength, hierarchical microporous structure, hydrophilicity and underwater oleophobicity, as well as remarkable performance in water flux, separation efficiency and cyclic stability. Under a low pressure of 1 kPa driven by the self-weight of emulsion, the PAN@SiO2 NFM demonstrated a large flux of 3994.3 ± 356.0 L m−2 h−1 and a high separation efficiency of 99.50%. In ten successive cycle tests, fluxes of the PAN@SiO2 NFM remained above 3000 L m−2 h−1, while the residual TOC in filtrate was stable at around 30 mg L−1, indicating the PAN@SiO2 NFM has excellent cyclic stability. It is also demonstrated that the PAN@SiO2 NFM is suitable for the separation of various kinds of emulsions, such as toluene, n-heptane, paraffin liquid, n-hexane and xylene. Hence, the prepared PAN@SiO2 NFM is a promising hydrophilic/underwater oleophobic membrane for efficient emulsion separation.

Dynamic demulsification of oil-in-water emulsions with electrocoalescence: Diameter distribution of oil droplets

The oil-in-water (O/W) emulsions, especially oily wastewater from EOR oilfield, generally contain small oil droplets in the continuous water phase, which is difficult to be removed with conventional oil separation process such as precipitation, flotation. The electrostatic coalescence is a promising pretreatment step to induce the oil droplets coalescence and promote the oil separation efficiency of conventional methods. In order to explore the feasibility of electrostatic demulsification for O/W emulsions, the influence of operating parameters including electric voltage, pulsatile frequency, water content of emulsions and hydraulic retention time (HRT) on oil diameter distribution of the emulsions were studied using dynamic demulsification experiment. The volume percentage of oil droplets with a diameter exceeding 40 μm (denoted as DG40) was adopted as the main indicator of demulsification results, it increased from 0 (the original emulsions) to 65.62% (the treated emulsions) at the optimal operation parameters including water content of emulsions 90 vol%, electric voltage 150 V, pulsatile frequency 1000 Hz, duty cycle ratio 0.5, hydraulic retention time (HRT) 60 s. Furthermore, the water separation efficiency for emulsions reached 82.5% at 11 min of the dynamic experiment duration. The results of this study showed that applying pulsatile electric field could be a feasible and effective technology for emulsified oil droplets coalescence in O/W emulsions.

Facile fabrication of robust superhydrophobic/superoleophlic Cu coated stainless steel mesh for highly efficient oil/water separation

A mechanically durable and chemically stable Cu coated stainless steel mesh is successfully prepared adopting a simple electrodeposition method. The novel copper film is featured with characteristics of dense stacking structure accumulated by micrometer stone-like grain, through which a suitable rougher surface is therefore formed, exhibiting excellent performance in mechanical stability, chemical endurance, self-cleaning and oil–water separation efficiency. The influences of the electrodeposition current and time on microstructural evolution, as well as the wettability were discussed. The superhydrophobic and superhyoleophilic coating possesses a water contact angle (WCA) of 160 ± 2°, a sliding angle (SA) of 2.2 ± 0.1° and oil contact angle (OCA) of 0° under the deposition condition of 0.18 A (0.033 A/cm2) for 150 s. The robust films maintain its superhydrophobicity not only in acid and alkali environments, but also after wear test under a pressure of 6.5 kPa with a length of 100 cm. In addition, the proposed film can withstand 2.35 kPa of water intrusion pressure. It exhibit high efficient separation for a mixture of oils or organic solvents with water and could achieve 98.3% separation efficiency in a short time of 9.2 s. The proposed design has great potential and prosperous future in practical industrial applications for mass production and efficient oil–water separation.

Modeling of oil–water separation efficiency in three-phase separators: Effect of emulsion rheology and droplet size distribution

The multi-fluid Eulerian multiphase model coupled with the inhomogeneous population balance model is applied to predict the gas, oil, and water separation behavior and emulsion destabilization in a high-pressure horizontal three-phase separator. The population balance model is applied to predict the evolving droplet size distribution due to droplet coalescence in the crude oil emulsion. The effect of water fraction on the emulsion viscosity was incorporated to predict the existence of the dense packed layer or zone (DPZ) – a high water-fraction emulsion layer formed at the interface between the oil and water phases. The novel emulsion viscosity model incorporates a dependence on the local droplet size. Parameter estimation for the droplet coalescence kernel in the population balance equation is determined from experimental measurements of emulsion separation kinetics. A proportional integral derivative (PID) controller logic is used to maintain the gas/oil and oil/water interface levels by automatically adjusting the oil and water outlet pressure, respectively. The pilot separator experimental measurements include inlet and outlet flowrates and density, and electrical capacitance measurement of the vertical water concentration profile. The CFD model determines the flow patterns, phase distributions and the dispersed water droplet size distribution in the emulsion in the separator. The model results are in good agreement with the data for the separation efficiency from the water flow rate in and out of the separator, the phase distributions and the DPZ at different flow rates and water fractions. This study demonstrates the importance in multiphase separator design and troubleshooting of including the influence of water fraction on emulsion viscosity and the droplet size distribution with droplet coalescence phenomena. The methodology presented has significant advantages over previously published methods and improves on the value and potential impact toward research and industry practice.

Superhydrophobic–superoleophilic copper–graphite/styrene–butadiene–styrene based cotton filter for efficient separation of oil derivatives from aqueous mixtures

A superhydrophobic/superoleophilic cotton fabric composed of copper–graphite/styrene–butadiene–styrene (Cu–G/SBS) nanocomposites on the cellulose fibers has been fabricated and used as a filter for separation of gas condensates and oily solvents from aqueous mixture. First, hierarchical flower-like Cu–G nanocomposites were prepared by controlling the reduction reaction parameters such as type of reducing agent, surfactant, reaction time and weight ratio of copper to graphite. Thereafter, the coating composition of Cu–G and SBS mixtures were applied on the surface of cotton fabric by a facile dip-coating approach. Contact angle analysis of modified cotton fabric by Cu–G–SBS composites exhibited water contact angle and oil contact angle about 152° and 0°, respectively. When the superhydrophobic/superoleophilic cotton fabric was employed as a filter to separate oily solvent from water and high separation efficiency above 94% with good recyclability and stability was obtained. The result suggests that as-fabricated cotton fabric filter can be used for efficient oil/water separation in industrial applications.

Evaluation of a naturally derived waste brown oil extract for demulsification of crude oil emulsion

Conventional methods of eliminating water from crude oil such as the chemical injection have both economic and environmental impacts; thus, this study proposed an economic and environmentally friendly demulsifier. The bottle test method was used to study the performance of the natural extract and commercial demulsifier on a crude oil sample. The GC-MS profile of the extract was in agreement with previous reports on composition of oil extracted from rice bran using hexane, ultrasound assisted extraction and conventional solvent extraction with ethanol. Varying degrees of saturated and unsaturated fatty acids as well as retention times as observed, was a function of total time of scanning, according to NIST08 library of mass spectra. The performance of the demulsifier was expressed in terms of percentage of water separated from 100 ml samples of the oil samples. For both the demulsifiers, the performance increased with increase in volume of the demulsifier, separation time and operating temperature. The extracted demulsifier performed better than the chemical demulsifier under all the experimental conditions adopted in this study. Based on the parametric evaluation, it was observed the results from software corroborated the results obtained from experiments in terms of the observations of the combined effect of temperature and volume which showed the most significant influence on demulsification of the emulsified crude. The highest efficiency of the bio-demulsifier was obtained with a volume of 5 mL of the extract, at a temperature of 70°C and separation time of 60 min. A water separation efficiency of 85.6% was obtained as compared to the chemical demulsifier, which gave an efficiency of 80.2%.

Design and preparation of mixed special wettability fabrics based on backed weave for separation of light oil/water/heavy oil mixtures

In recent years, the frequent emission of oily wastewater and marine oil spills has resulted in water bodies containing large amounts of light oil/water/heavy oil mixtures. The increasing pollution of the water prompts us to develop new materials that can separate oil and water effectively. In this work, a mixed special wettability fabric based on the backed weave organization is prepared by using different yarns with special infiltration properties. The mixed special wettability fabric can separate the light oil/water/heavy oil three-phase mixtures successfully in one step, due to the effect of gravity-driven and capillary force-driven. Under the optimal process with the reed number of the fabric 84#, the separation efficiency of water can reach 98.36%, and the average separation flux is 0.447 L/m2 s. In addition, the mixed special wettability fabric shows a good recycling, as well as structural stability, which is good for the application in practical oil–water separation.

Hydrophobic and Anti-Fouling Performance of Surface on Parabolic Morphology.

The hydrophobicity and anti-fouling properties of materials have important application value in industrial and agricultural production and people’s daily life. To study the relationship between the unit width L0 of the parabolic hydrophobic material and the hydrophobicity and anti-fouling properties, the rough surface structure of the parabolic with different widths was prepared by grinding with different SiC sandpapers, and further, to obtain hydrophobic materials through chemical oxidation and chemical etching, and modification with stearic acid (SA). The morphology, surface wetting and anti-fouling properties of the modified materials were characterized by SEM and contact angle measurement. The oil–water separation performance and self-cleaning performance of the materials were explored. The surface of the modified copper sheet forms a rough structure similar to a paraboloid. When ground with 1500 grit SiC sandpaper, it is more conducive to increase the hydrophobicity of the copper sheet surface and increase the contact angle of water droplets on the copper surface. Additionally, the self-cleaning and anti-fouling experiments showed that as L0 decreases, copper sheets were less able to stick to foreign things such as soil, and the better the self-cleaning and anti-fouling performance was. Based on the oil–water separation experiment of copper mesh, the lower L0 has a higher oil–water separation efficiency. The results showed that material with parabolic morphology has great self-cleaning, anti-fouling, and oil–water separation performance. The smaller the L0 was, the larger the contact angle and the better hydrophobic performance and self-cleaning performance were.

Oil-water separation through an ultrahydrophobic filter paper developed by sol-gel dip-coating technique

Eco-friendly oil–water separation substrates are mostly recommended in the present context of the world. In the present work, biodegradable and more economical ultrahydrophobic composite material was synthesized by sol–gel method using silica nanoparticles (SiO2) and poly (methyl methacrylate-co-ethyl acrylate) polymer (PMMA) with 1H,1H,2H,2H Perfluorooctyltrichlorosilane (PFOTS) coupler, and coated on 40-grade cellulose filter paper with a dip-coating method. As-prepared surfaces achieved static contact angle more than 175° and sliding angle 3.8°. The microstructure and chemical composition of ultrahydrophobic filter paper were characterized by scanning electric microscopy (SEM), X-ray spectroscopy (EDX), and Flourier transformation infrared spectroscopy (FTIR), respectively. The coated filter paper accomplished 98% oil–water separation efficiency by filtering different oils. Besides, the SiO2 nanoparticles were enhanced the thermal and UV aging resistance. The coated surfaces also showed excellent chemical inertness, and mechanical durability tested. This research work can be employed yet for domestic and industrial applications at a large scale for oil–water separation and self-cleaning.

Blends of Chalcone Benzoxazine and Bio-benzoxazines Coated Cotton Fabrics for Oil–Water Separation and Bio-silica Reinforced Nanocomposites for Low-k Applications

In the present work, chalcone benzoxazine (Chal-Bz) was co-polymerized with two bio-based benzoxazines namely cardanol (CrAb) and eugenol (EuAb) benzoxazine and coated over cotton fabric. The Chal-Bz/CrAb and Chal-Bz/EuAb blends coated cotton fabrics show water contact angle values of 163° and 156° respectively and their oil–water separation efficiency were observed found to be 97 and 96% respectively. In addition, the glycidoxypropyltrimethoxysilane (GPTMS) functionalized bio-silica in varying weight percentages (1, 3, 5, 7 and 10 wt%) was also reinforced with two co-polymerized blended matrices to obtain respective composites. The developed composites were studied for their dielectric, thermal and morphological behaviours. The values of dielectric constant of 10 wt% bio-silica reinforced Chal-Bz/CrAb and Chal-Bz/EuAb composites were found to be 2.1 and 2.3, respectively. Similarly the values of contact angle of 10 wt% bio-silica reinforced chal-Bz/CrAb and Chal-Bz/EuAb composites were 137° and 116°, respectively. Data obtained from different studies suggest that these bio-silica reinforced benzoxazine composites can be used in the form of coatings, adhesives, sealants and encapsulants for high performance micro-electronics insulation applications under adverse environmental conditions. Thermal assisted polymerization of chalcone based benzoxazine (Chal-Bz) with bio based benzoxazines cardanol-aniline based benzoxazine (CrAb) and eugenol-aniline based benzoxazine (EuAb)) for low k and oil–water separation application.

Analysis of Diethylene Glycol and Decylamine as Demulsifiers for Treatment of Water-In-Oil Emulsions: Case Study of the Niger Delta, Nigeria

Crude oil is made up of different hydrocarbon compounds. At different depths in the same reservoir, the properties of the crude oil differ from one another. During production of crude oil, emulsion is usually formed due interaction of water with emulsifying agents such as wax, as phaltenes, resins etc. present in crude oil. Water in oil emulsion (w/o) poses serious problems during production and pipeline transportation of crude oil. To separate water from crude oil, demulsifier is required. This research work seeks to evaluate two chemical demulsifiers (diethylene glycol and decylamine) on crude oil sample from the Niger Delta to ascertain the most effective in water separation. Demulsifier concentration used were 80% and 20% water. Water-in- oil emulsion was formulated in the ratio of 360ml:40ml of crude oil and distilled water respectively in the laboratory. The demulsification process was carried out at a temperature of 158 O F. Demulsifier doses of 0.5, 1, 1.5, and 2mls were carried out at centrifugal speed of 300rpm, 600rpm, 900 rpm and separation time (10, 20, 40, 60,100, 150 sec). Volumes of water separated were recorded and water separation efficiencies were calculated. Results have shown that faster rate of water separation and performance efficiency can be achieved when diethylene glycol is used as demulsifier on crude oil from the Niger Delta region of Nigeria.

Microfluidics Chip for Directional Solvent Extraction Desalination of Seawater

Directional solvent extraction is one of the promising membrane-less seawater desalination method. This technique was not extensively investigated due the poor mixing and separation performances of its bench-scale system. It is believed that, overcoming these drawbacks is possible now with the rapid development of microfluidics technology that enabled high-precession micro mixing and separation. This work presents microfluidics chip for extracting and separating salt from seawater. The chip was designed with two sections for extraction and separation. In both sections, the liquids were separated using capillary channels perpendicular to the main stream. The main channels were designed to be 400 µm in width and 100 µm in height. Two streams inlets were introduced through a Y-junction containing octanoic acid as the organic phase and saltwater as the aqueous phase. The desalination performance was investigated at four different temperatures and five different solvent flow rates. Water product salinity was recorded to be as low as 0.056% (w/w) at 60 °C and 40 mL/h. A maximum water yield of 5.2% was achieved at 65 °C and 40 mL/h with a very low solvent residual (70 ppm). The chip mass transfer efficiency was recorded to be as high as 68% under similar conditions. The fabricated microfluidic desalination system showed a significant improvement in terms of water yield and separation efficiency over the conventional macroscale. The high performance of this microsystem resulted from its ability to achieve a high mixing efficiency and separate phases selectively and that will provide a good platform in the near future to develop small desalination kits for personal use.

Breaking water-in-oil emulsion of Northern Iraq’s crude oil using commercial polymers and surfactants

Water (W) and oil (O) normally mix during production and while passing through valves and pumps to form a persistent water-in-oil (W/O) emulsion, which is a serious restriction in oil production and transporting and refining processes. The objective of this work is to treat emulsions of two crude oil samples labeled KD1 and DGH2 using commercial polymers and surfactants which are also known as demulsifiers. Hydrophile–lipophile balance (HLB) in the demulsifier structure has demonstrated a great effect on breaking W/O emulsion. Emulsion breakers with low HLB value showed better reduction in the dynamic IFT, high diffusivity at the W/O interface, and accelerated coalescence of water droplets. Concomitantly, high emulsion temperatures were found to reduce the interfacial film viscosity and accelerate water droplets coalescence. A maximum water separation efficiency (WSE) of 97% was achieved in the case of KD1 and 88% for DGH2, and using a (1:1) polymer blend demulsifier further increased WSE to 99% after 100 min.

Superhydrophobic cotton nonwoven fabrics through atmospheric plasma treatment for applications in self-cleaning and oil–water separation

In this study, a superhydrophobic cotton nonwoven fabric for oil–water separation was prepared by graft polymerization of siloxane under atmospheric pressure plasma in the medium of Air, N2 or O2. The effects of different process conditions on the contact angle, surface morphology, stability of the hydrophobic coating and the growth of nano-particles were investigated. This modified cotton nonwoven was tested for self-cleaning and oil–water separation efficiency. The surface characteristics of the prepared cotton nonwoven were systematically analyzed using scanning electron microscopy, Energy Dispersive X-ray Spectroscopy, and Fourier transform infrared spectroscopy. The water contact angle of treated nonwoven was up to 155°, and the precursor and jet movement speed have great influences on the surface morphologies and stability of the coating. Separation efficiency for oil–water mixture is higher than 97% and can be repeated for at least 10 times. Moreover, the superhydrophobic nonwoven treatment showed excellent stability toward strong acid and alkaline conditions, the resulting fabrics may be used under harsh environmental conditions.