11/2/2023 0 Comments Demulsification examples![]() 3c and Movie S1), at the particle concentration of 5 wt% and at the exiting current of 12 A. 3a), a complete demulsification is triggered within 2–3 min by alternating magnetic field (Fig. S2) are more easily wetted by the water phase and their contact with the oil phase is reduced, resulting in the curve of interface and the formation of spherical oil droplets 6, 8, 18.įull size image Rapid demulsification triggered by controllable magnetic fieldsĪfter the introduction of an asymmetrical and non-uniform magnetic field simulated by ANSYS Electronics 18.1 (Fig. The formed O/W emulsions are stable attributed to the fact that the hydrophilic particles (Fig. 2i and S1d), indicating a good emulsion stability. 2h and S1c), and the droplet appearance keeps changeless from 35 to 85 days (Figs. 2g and S1b), taking the emulsion with 5 wt% CIPs as an example interestingly, small oil droplets tend to coalesce to big ones from 15 to 35 days (Figs. 2f and S1a), the oil droplet size increases largely after 15 days (Figs. Compared with the freshly prepared emulsions (Figs. The obtained emulsion volume ( V e) increases and the extra water volume ( V w) underneath the emulsion decreases with time or at higher particle concentration (Fig. Because the particles can diffuse to the interfacial region, remain there, and form rigid structures, stabilizing the thin films 6, 16, 17. The Pickering emulsions stabilized by 2, 5, and 10 wt% CIPs, respectively, are of O/W emulsion type, showing high conductivity values of the emulsion phase (Table S1) and with a certain distributiuon and composition (Tables S2 and S3). Our results are expected to provide a scientific basis for a rapid, high-efficient, reproducible, and environmentally friendly separation technology. The effects of the particle concentration and magnetic property, and the magnetic field strength and time-domain characteristic, on the responsive demulsification performance were explored. It was found that the emulsions, showing a long-term stable state, were successfully triggered to a fast and high-efficient demulsification in the presence of an asymmetrical and alternating magnetic field. With this in mind, we imposed a controllable magnetic field on a series of Pickering emulsions stabilized by paramagnetic particles. However, the research and technology on switchable emulsions are rarely reported 6, 8, except a complete phase separation triggered by the aid of both magnetic field and stirrer, owning to the missing materials and understanding of the responsive demulsification mechanisms. Without introducing ‘‘chemical’’ demulsifiers to the emulsion systems, the environmental and secondary pollution, as well as the negative impact on downstream production processes, can be completely avoided. Therefore, enormous efforts have been devoted to the development of stimuli responsive emulsions, especially for the ones being responsive to ‘‘physical’’ triggers such as magnetic field 6, 7, 8, 9, temperature 10, 11, 12, or light 13, 14, 15. In significant application fields including oil recovery, synthesis of novel materials, and pharmaceutical industry, there is a great need of a facile, efficient, and green strategy to fabricate emulsions with long-term stability and rapid demulsification response on demand 1, 2, 3, 4, 5. This facile strategy to produce stable Pickering emulsions with a magnetic-response opens a promising avenue for various practical applications including oil recovery, wastewater treatment, and sludge removal. The alternating asymmetrical magnetic field endows oil-in-water droplets ‘‘big’’ N and S poles on the outer particle layers, and attracts the solid particles to the bottom of the vial after the coalescence and the deformation of the droplets, bringing the prevention of re-emulsion and the cyclic utilization. Here we fabricated microscale Pickering emulsions, by the use of paramagnetic particles, which possess excellent stability for several months and more interestingly perform complete demulsification under controllable magnetic fields in several minutes. However, the irreversible adsorption of particles as emulsion stabilizers endows the Pickering emulsions with kinetically stable property, resulting in a huge challenge to break the stability. Pickering emulsions with on–off properties provide significant advantages over simple solid-stabilized emulsions for the development of novel materials, such as oil-displacing agents for enhanced oil recovery and templates for the fabrication of porous materials.
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