| Amphiphilic nanoparticles can form a variety of nano-assembly by self-assembly in liquid-liquid interface, such as nanomembranes, micro-vesicles, hybrid nano-devices, as well as to stabilize Pickering emulsion. It has been a hot topic to the complementary combination of the tradition field of colloid and interface chemistry with emerging nanoscience research in recent years, showing a great advantage in terms of preparation of new materials and treatment of environmental issues. Nowdays the key point of this field has been focused on the design and preparation of the new solid particle stabilizer and development of the novel stimuli-responsive Pickering emulsion system. In recent years, room temperature ionic liquids is a green solvent as a substitute for conventional organic solvents in the field of extraction, synthesis, and catalytic. The corresponding based-ionic liquid microextraction, micro-catalytic, and organic microreactor have been exploited. However, the bottleneck of the real application for these above-mentioned micro-systems was difficult to obtain their simply and easy controllability and effective recycle for expensive ionic liquids. Currently, the stimuli-responsive Pickering emulsions based on ionic liquids were rarely reported. The magnetic responsive Pickering emulsions containing ionic liquid, especially, were much less reported by comparison. As for reported works, all systems involoved the magnetic ionic liquid, but it is gerenally accepted that some common used ionic liquids are diamagnetic. From a practical perspective, it is a lot of limitations to the already reported based-ionic liquid magnetic responsive Pickering emulsions. Therefore, it is significant important of the development of a magnetically-responsive Pickering emuslions based on frequently-used ionic liquid stabilized with the magnetic amphiphilic nanoparticles, which can be simple and easy to control the movement of ionic liquid droplets by the external magnetic field.On the basis of progress of self-assembly of amphiphilic nanoparticles on the interface, the Pickering emulsion formed by amphiphilic nanoparticles and magnetic responsive Pickering emulsions based on ionic liquids, the thesis focused on the design and preparation of a series of amphiphilic magnetically responsive nanoparticles, investigating their emulsifying ability for the ionic liquid. The removal of Gr2O72- from the water can be realized by the corresponding above-prepared ionic liquid emulsions acted as extraction systems. At the same time, the amphiphilic magnetic nanoparticle was developed to be acted as the effective demulsifier for the common ionic liquid-based stable emulsion, making the obviouse separation of ionic liquid-water phase. Specifically, the major work was done in the following two aspects:In the first part of the thesis, the organic-inorganic amphiphilic Fe3O4 nanoparticle was designed and prepared by using PEO group as the hydrophilic part, and cholesterol group as hydrophobic part, which is denoted as MN-CHOL. Its emulsifying capacity of some common hydrophobic ionic liquid was investigated. It is demonstrated that MN-CHOL showed excellent emulsifying ability for three different ionic liquids, that is [BMIM][PF6], [BMIM][TF2N] and [BMP][TF2N], forming stable magnetically responsive Pickering emulsions. Meanwhile, combined with the measurements of interfacial tension and contact angle, the three-phase contact angles of MN-CHOL at different ionic liquid-water interface were determined. The results proved that the [BMIM][PF6]/water system was IL/W with the best stability, which is in good agreement with observation for the emulsification tests. Furthermore, taking the [BMIM][PF6]/water systems as example, the marginal effect of pH value of aqueous phase on the stability and type of emulsion was found. By contrast, the droplet size of the emulsions was confirmed to become large and their stability was found to be gradually decrease by the increasion of the NaCl concentration based the water phase and the oil-water ratio, and the reduction of the concentration of MN-CHOL. More importantly, it was found that [BMIM][PF6] droplets stabilized by MN-CHOL showed the excellent stability, the repeatedly movement of droplets by the external magnetic field did not cause the demulsification of droplets. In addition, to take [BMIM][PF6]/water as the extraction system is able to realize to the removal of Cr2O72-from the aqueous phase, this lays a solid foundation for the purficiation of water containing heavy metal ions.In the second part of the thesis, a series of organic-inorganic hybrid amphiphilic Fe3O4 nanoparticles were prepared by using PEO as the hydrophilic part, and cholesterol group, alkyl chain, PPO fragment as the hydrophobic part, respectively, which are denoted as MN-CHOL, MN-PALM and MN-PPO, respectively. And then the three different stable ionic liquid-based emulsion with Tween 20 acted as surfactant were prepared by choosing [BMIM][PF6], [HMIM][PF6] and [OMIM][PF6] as oil phase, respectively. Using as-synthesized amphiphilic MNPs as demulsifiers, we investigated their demulsification performance for above-mentioned three emulsions. MN-PPO containing PEO/PPO fragment was found that it is the effective magnetic demulsifier for ionic liquid-based emulsions. Therefor, taking [HMIM][PF6]/water/Tween 20 as an example, the demulsification performance of MN-PPO was investigated, such as demulsifier dosage, demulsification time, and recycling stability, and so on. The optimal demulsification efficiency of MN-PPO is up to 66% when the dosage of demulsifier is 10 mg/mL and the demulsification time is 45 min. the recycles of demulsifier enabled its decreasing demulsification efficiency, which is decreased to 41% after six cycles. Obviously, it is to be found that demulsification efficiency is not high and the stability of demulsifier need to be improved, and the related work is still going on. Nevertheless, this work would lay the foundation for the control and separation of the ionic liquid-based multiphase systems. |
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