Demulsification by increasing the gravitational force acting upon the dispersed phase owing to the adsorption/absorption of the magnetite particles

Using a New Fe3O4@CPAM Magnetic Flocculant and Microwave to Demulsify Heavy Oil-in-Water Emulsions

In this study, cationic polyacrylamide (CPAM)-coated magnetic nanoparticles (MNPs) Fe3O4@CPAM were synthesized for treating heavy O/W emulsions. This Fe3O4@CPAM was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM) techniques, and its synergistic performances with microwaves were evaluated in detail with respect to the microwave radiation power, radiation time, and magnetic nanoparticle concentration. On this basis, the distribution of oil droplets and the wettability and chargeability of magnetic nanoparticles were measured without or with microwave radiation using biomicroscopy, contact angle measurement instrument, and a ζ-potential analyzer, thus revealing the synergistic demulsification mechanism between microwave and magnetic nanoparticles. The results showed that excessively high or low microwave radiation parameters had an inhibitory effect on the magnetic nanoparticle demulsification, and microwave promoted the magnetic nanoparticle demulsification only when the radiation parameters were in the optimal range. In addition, the water separation rate showed an increasing and then decreasing trend with the increase of magnetic nanoparticles concentration, with or without microwave action. As an example, the water separation rate of the emulsion for 1 h was 21.34% when the Fe3O4 concentration was 175 mg/L without microwave action, while it increased to 55.56% with microwave action. In contrast, when the concentration of Fe3O4@CPAM was 175 mg/L, the water separation rate was 42.86% without microwave radiation, while it was further increased to 77.38% under microwave radiation. These results indicate that magnetic nanoparticles and their complexes significantly affect the water separation process under different conditions. There is a more obvious coupling synergistic effect between Fe3O4@CPAM and microwave. This was due to the lower absolute potential of Fe3O4@CPAM and its higher hydrophobicity.

Universal Rapid Demulsification by Vacuum Suction Using Superamphiphilic and Underliquid Superamphiphobic Polyurethane/Diatomite Composites

A process for universal rapid demulsification by vacuum suction using an as-prepared superamphiphilic and underliquid superamphiphobic polyurethane (PU)/diatomite composite has been developed and is used to demulsify kerosene-in-water and water-in-kerosene emulsions with and without a surfactant. The results show that the demulsification rate of all the emulsions exceeds 98.5% in long-term operation, with a stable demulsification speed exceeding 0.303 L/m² min. When a superhydrophobic channel for separation is added, the oil/water separation efficiency exceeds 99.0%, and the final products are qualified oil and water. This attractive universal demulsification capability of PU/diatomite originates from its underliquid superamphiphobicity, which attracts a continuous phase to form a stable liquid film and thus repels dispersed phase droplets, which have a similar interaction with the surface but are much less abundant. The vacuum forces emulsion droplets into the microstructure of the PU/diatomite cake, where they are compressed, coalesce, and finally demulsified. This observed mechanism suggests a promising strategy to avoid the negative effects of oil fouling in demulsification and achieve large-scale universal continuous rapid demulsification.

Nanoscale silica-coated graphene oxide and its demulsifying performance in water-in-oil and oil-in-water emulsions

In current work, GO@SiO₂ nanocomposite was prepared by coating nanoscale silica onto graphene oxide (GO). GO@SiO₂ was characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (IF-IR). Additionally, the demulsifying performance of GO@SiO₂ was investigated by bottle test. The results showed that GO@SiO₂ had a good demulsifying performance in both oil-in-water (O/W) and water-in-oil (W/O) emulsions. When the concentration of GO@SiO₂ was 200 ppm in the O/W emulsion, the optimal light transmittance of aqueous phase (LTA) and corresponding oil removal rate (ORR) at room temperature could reach 86.9% and 99.48%, respectively. Also, GO@SiO₂ had an excellent salt tolerance under acidic condition. Furthermore, GO@SiO₂ also could demulsify the W/O emulsion, and the efficiency at 70 °C could reach 80.5% when the concentration was 400 ppm.