The Paraffin Crystallization in Emulsified Waxy Crude Oil by Dissipative Particle Dynamics

With the advancement of oilfield extraction technology,since oil-water emulsions in waxy crude oil are prone to be deposited on the pipe wall,increasing the difficulty of crude oil extraction.In this paper,the mesoscopic dissipative particle dynamics method is used to study themechanism of the crystallization and deposition adsorbed on thewall.The results show that in the absence of water molecules,the paraffin molecules near the substrate are deposited on themetallic surface with a horizontalmorphology,while the paraffin molecules close to the fluid side are arranged in a vertical column morphology.In the emulsified system,more water molecules will be absorbed on the metallic substrate than paraffin molecules,which obstructed the direct interaction between paraffin molecules and solid surface.Therefore,the addition of watermolecules hinders the crystallization of wax near the substrate.Perversely,on the fluid side,water molecules promote the formation of paraffin crystallization.The research in this paper reveals the crystallization mechanism of paraffin wax in oil-water emulsions in the pipeline from the microscopic scale,which provides theoretical support for improving the recovery of wax-containing crude oil and enhancing the transport efficiency.

Corn cob modified by lauric acid and ethanediol for emulsified oil adsorption

Corn cob is a naturally renewable material with developed micropore and hydrophobic characteristics, which enables it to show good oil adsorption capacity. In order to improve oil adsorption capacity, corn cob was modified with lauric acid and ethanediol. The structure of raw and modified corn cob was investigated using Fourier transform infrared(FTIR) spectroscopy, scanning electron microscopy(SEM), Brunauer-Emmett-Teller(BET) method, thermogravimetric analysis(TGA) and Ze Ta potential analyzer. The effects of p H level, adsorption time, adsorbent dosage, and initial oil concentration on oil absorbency of corn cob were studied. The results indicate that the modification significantly improved the lipophilicity of corn cob, making the modified corn cob with much better adsorption capacity on oil absorbency. Compared with raw corn cob, the maximum saturated adsorption capacity of modified corn cob is 16.52 mg/g at p H 5, and the increasing percentage is found to be 141%, which indicates that the modification causes a better adsorption capacity for oil removal. In addition, due to high oil adsorption capacity, affordable price and low secondary pollution, the modified corn cob could be considered promising alternative for the traditional oil adsorbent to clean up the emulsified oily water.

Experimental research on oil fi lm thickness and its microwave scattering during emulsifi cation

Synthetic Aperture Radar(SAR) plays a major role in identifying oil spills on the sea surface.However,obtaining information of oil spill thickness(volume) is still a challenge.Emulsification is an important process affecting the thickness and normalized radar cross section(NRCS) of oil film.Experiments of crude oil emulsification with C-band fully-polarized scatterometer were conducted combining airborne hyperspectral imaging spectrometer and 3 D laser scanner observation data,to provide experimental parameters and method to support accurate remote sensing monitoring on marine oil spill.It is further proved that through quantitative homogeneous emulsified oil spill experiments,to a certain extent,the NRCS of oil film increased during the emulsification process of crude oil.The backscattering mechanism of crude oil emulsification was explored using a semi-empirical model(SEM);the change of oil film NRCS was modulated by its dielectric constant and surface roughness,in which the dielectric constant showed a dominant effect.The relationship between thickness and NRCS of oil film was studied under two experimental conditions.The differences of NRCS between oil film and adjacent seawater(Δσ~0) and the damping ratio(DR) were found to have a linear relationship with oil thickness,which were best in the vertical polarization mode(VV) at 45° incident angle during the quantitative crude oil homogeneous emulsification process.In the natural emulsification process of continuous oil spill in which oil film was mixed with both crude oil and emulsified oil,an empirical equation of oil film thickness is preliminarily established.The Δσ~0,DR,and the empirical equation of oil film thickness were applied to the marine continuous oil spill incident on a 19-3 oil platform with spaceborne SAR image and successfully explained the distribution of the relative thickness of the oil film.

Kinetics of nitrobenzene degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by emulsified vegetable oil

Widespread contamination by nitrobenzene（NB） in sediments and groundwater requires better understanding of the biogeochemical removal process of the pollutant. NB degradation, coupled with dissimilatory iron reduction, is one of the most efficient pollutant removal methods. However, research on NB degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by electron donors is still experimental. A model for remediation in an actual polluted site does not currently exist.Therefore, in this study, the dynamics was derived from the Michaelis–Menten model（when the mass ratio of emulsified vegetable oil and NB reached the critical value 91：1）. The effect of SO4^（2-）, NO3^-, Ca^（2＋）/Mg^（2＋）, and the grain size of aquifer media on the dynamics were studied, and the NB degradation dynamic model was then modified based on the most significant factors. Utilizing the model, the remediation time could be calculated in a contaminated site.

EXPERIMENTAL STUDY ON ABSORPTION OF OIL BY SEDIMENT IN WATER

The absorption behaviour of emulsified oil by sediment (include loess) is studied by experiment. The absorption equation and the relations of absorption capacity with sediment concentration, grain size, salt concentration and temperature are analyzed. The absorbing reaction kinetics process is also studied. The absorption of emulsified oil by sediment in rivers is agreed with the Langmuir-Freundlich absorption equation. Experimental data shows that the larger the equilibrium oil concentration and the salt concentration , the more the absorption capacity. The absorption capacity increases immensely with grain size and temperature reduction.