In this work, the Demulsification of water-in-crude oil emulsions by dielectrophoresis via applying a non-uniform electric field in a labscale cylindrical cell was studied. The stability of emulsions was assessed through monitoring the size distribution of water droplets at 0, 3, 6, and 24 hours after the preparation of emulsion. The effect of operating parameters including the temperature, demulsifier concentration, water salinity, and time on the Demulsification of water was investigated. Sodium dodecyl sulfate and sodium chloride were used as demulsifier and salt respectively. The experiments were designed by the response surface methodology (RSM) based on the central composite design (CCD). The operating parameters including the voltage, temperature, demulsifier concentration, salinity of water, and separation time were optimized. The contours and 3-D response surfaces of the water separation were acquired. A quadratic polynomial model, which was statistically highly significant (R 2 =0. 9950, n=32), was provided by the RSM to predict the amount of the separated water. Comparison among the experimental and RSMoptimized values indicates a good agreement. The optimum amount of the water separation was obtained at the voltage of 15 kV, temperature of 60 ° C, demulsifier concentration of 123 ppm, salinity of water of 12260 ppm, and separation time of 12. 4 minutes. Under such conditions, the separation of water reached 98 %. The results obviously show that the electric field can be used as an appropriate means for the breakage of W/O emulsions.

Water in crude oil emulsions in the upstream oil industry causes serious problems such as corrosion and precipitation. Therefore, it is of crucial importance to demulsify and separate water at the production site. Demulsifiers’,performance is evaluated by its Demulsification efficiency, cost, and biocompatibility. Restrictive environmental regulations have resulted in an ongoing effort to identify and characterize new demulsifiers which offer biodegradability while maintaining Demulsification efficiency. In this study, biocompatible and biodegradable cellulosic polymers with trade names Walocel, Cellulose Acetate, Methocel-K3, and Methocel-E5 were used as demulsifiers. Demulsifiers’,performance was evaluated by bottle test using crude oil from the Sarvestan oil field. The initial tests revealed that Walocel and Methocel-E5 have better performance as compared with Cellulose acetate and Methocel-K3. It was found that increasing temperature up to 80 ⁰, C and increasing demulsifier concentration up to 3000 ppm results in faster and more efficient Demulsification. 90% separation of water at 80 ⁰, C and a demulsifier concentration of 3000 ppm was achieved within 2 hours by Methocel-E5 while the same separation took 4 hours for Walocel. After 12 hours of Demulsification at 80 ⁰, C and a demulsifier concentration of 3000 ppm, Walocel and MEthocel-E5 could demulsify and separate 99% and 98% of the initial water respectively

The crude oil contains various contaminants including water, gas and sediments which should be removed in desalination unit. In addition, the wastewater from desalination unit should be refined to remove the oil droplets. In this work, a mathematical model was presented for Demulsification process of crude oil emulsions from wastewater of desalination plant. A nonlinear hyperbolic integral differential equation was obtained by population balance method. The population balance integral equation terms were simplified using fixed pivot method and a system of partial differential equation (PDE) were obtained. The partial equations were converted into systems of ordinary differential equations (ODE) using the method of line. The ODEs were solved by the application of MATLAB Software. The profile of volumetric distribution of oil droplets, mean droplet diameter (D4, 3), and oil separation rate along the height of the system at different times were reported. The accuracy of the model was examined by comparing with experimental data of water dispersion in oil system obtained from literature. Then, the model was applied to predict the oil in water systems and the effects of viscosity and density crude oil on separation of dispersed phase and mean droplet diameter (D4, 3) were investigated. Finally, adjustable coefficients in the equations were estimated. The results showed that, by reducing the density of crude oil the settling velocity increases. Furthermore, the decreasing in crude oil viscosity will lead to increase the frequency collision droplets and oil separation.

Dispersed phase droplets recovery from an emulsion is widely used in various processes such as treating host liquids and collecting dispersed droplets. This article investigates the effect of ultrasonic waves on the Demulsification of the oil-in-water system. Then a mathematical model was proposed to predict the number and size of dispersed phase droplets. The population balance integral equation terms were simplified using the Fixed Pivot method and the resulting ODE set was solved by applying MATLAB Software. Using the ultrasonic collision frequency effect, the oil droplets volumetric distribution profile in 1 and 3 minutes was studied. In addition, the average droplet diameter D4,3 and the total volume of dispersed phase at 1 min. and 3 min. were reported and the model prediction was compared with experimental data. The average droplet diameter showed that under the ultrasonic waves effect, the average diameter of the drops increased by more than 50% in 3 minutes. Also, the total volume of dispersed phase results indicates that the total volume of oil droplets (due to the lack of phase separation) remains constant for 3 minutes. This result proves the correctness of the newly developed mathematical model.

A theoretical model is developed to consider the effect of demulsifier agent on Demulsification of water-in-crude oil emulsion. A thermodynamic approach is considered to correlate the critical micelle concentration of a demulsifier to the collision frequency function in population balance equation (PBE). Based on the proposed correlation, the collision frequency function is modified to account the effect of demulsifier agent on water droplets coalescence. The water separation capability of a selected group of demulsifiers is investigated via the conventional bottle test method to obtain the adjustable parameter of the developed equation so that the absolute relative error of predicted Demulsification efficiency and experimental data are considered as objective. Comparison between the model simulated results and the experimental data showed that the proposed model could appropriately reproduce the experimental data at different agent concentrations.

TiO2 nanocomposites on carbonaceous compounds, such as carboxyl-functionalized, multi-walled carbon nanotubes (MWCNT-COOH), and graphene oxide (GO) were synthesized by the sol-gel method. The samples were coded as TiO2 (T), TiO2-MWCNT-COOH (TM), and TiO2-GO (TG). The effect of the addition of carbonaceous compounds on the enhancement of Demulsification efficiency of TiO2 nanocomposites ‎in crude oil (W/O) emulsions was then investigated. FT-IR, Raman, and morphological analyses such as FE-SEM, EDXS, XRD, HR-TEM, DRS, BET surface area, and TGA were used to determine the properties and structures of the nanoparticles prepared. In addition, the Demulsification efficiency of three nanoparticles was studied under various concentrations, settling times, and temperature conditions by bottle test. According to the screening results, TG was selected as the best sample. The response surface method with a central composite design (CCD) was used to optimize the Demulsification activity of TiO2 nanocomposites with graphene oxide (TG). Thus, the impacts of temperature, demulsifier concentration, and time were studied by the RSM-CCD method. Ultimately, the results indicated ~100% Demulsification efficiency under optimal conditions at concentration, temperature, and time of 75 ppm, 65oC, and 120 min., respectively.

The main purpose of this research is experimental and theoretical study on demulsifying components effect on Demulsification rate of water-in-oil emulsions. In other words، some surfactants is considered and their function as a demulsifier in breaking crude oil emulsions has been investigated by bottle test. To develop a theoretical model to take into account the effect of demulsifier agent on Demulsification rate of water-in-oil emulsion. Considering similarity between gas adsorption، and agent adsorption on the water-oil interface، a Langmuir isotherm based model is developed to correlate interfacial tension of water and oil phases to demulsifier concentration. Based on the proposed correlation، the collision frequency function in population balance equation is modified to account the effect of demulsifier agent on water droplets coalescence. The proposed model consists of some adjustable parameters that need to be fitted with experimental data. Therefore، a group of surface-active compounds are supplied and their Demulsification capability is investigated through bottle test method. The experimental Demulsification results are compared with population balance simulation results and it is apperared that the developed model could appropriately reproduce experimental data at different agent concentrations.

Crude oil is released into the water sources during exploration, extraction or displacement operations due to the partial dissolution, and it can remain as a layer on the surface of the water or become emulsive. Crude oil emulsion is very stable due to the presence of asphaltene and cannot be removed by the common methods. In this research, iron oxide nanoparticles were coated with oleic acid (OA), stearic acid (SA), sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP) and polyoxyethylene (POE), by using the same method. After synthesizing iron oxide nanoparticles and coating their surface with fatty acids and surfactants, we have tried to break the crude oil emulsion in water and remove the crude oil from the environment by adsorption via these nanoparticles. Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), vibration sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Zeta potential devices were used to identify nanoparticles and their characteristics. Demulsification of crude oil in water (O/W) with nanoparticles coated with fatty acids and surfactants was studied. UV-Vis spectrophotometery was used to determine the amount of crude oil adsorption by nanoparticles. From the results, the nanoparticles coated with the fatty acids with smaller chains could more absorb the crude oil. The highest adsorption (98.03 %) was recorded for iron oxide nanoparticles coated with polyoxyethylene (Fe3O4@POE) and the lowest percentage (46.69 %) is related to the nanoparticles coated with palmitic acid in an alkaline medium. Alkalinization of the medium while coating the nanoparticles with fatty acid has increased only the efficiency in the case of oleic acid while led to a significant decrease in the efficiency for palmitic and stearic acids compared to the neutral state.