Construction Of Pickering Emulsion-based Flow Liquid-liquid Extraction And Flow Photo-catalytic Systems

Fractional extraction and continuous extraction are two types of liquid-liquid extraction processes,continuous extraction has higher separation efficiency,better repeatability,less emulsification and more labour-saving than fractional extraction.Similarly,flow chemistry,which is based on the continuous flow mode of chemical reaction technology and pumping materials,has more obvious advantages over the traditional container technology,and its emergence provides a new high-yield and fast means for chemical research and development.However,the current research focuses and implementation methods of the two extraction processes mainly depend on the development or integration of micro-chemical equipments manufactured by precision machining technology.In this paper,the concept of"column flow liquid-liquid extraction"was proposed for the first time,the"column flow liquid-liquid extraction"and"column flow chemistry"systems were constructed by utilizing the column flow method with"liquid granulated"micro-nano composites as column filler,the new"column flow liquid-liquid extraction"method was based on the strictly oil-water two-phase partition and large-sized emulsion droplets of the Pickering emulsion,moreover,the well-designed Pickering droplets can be used as stable column fillers under external phase flow conditions.Further,through a subtle combination of the Pickering emulsion,gel and nanocatalysts,a hydrogel sphere wrapped with Pickering emulsion droplets and Ti O₂ nanoparticles was prepared,hydrogel spheres and water were adopted as column filler and mobile phase respectively,a photocatalytic flow system with liquid-liquid extraction enrichment effect and photocatalysis function was constructed,the synergistic effects of the dual functions made the removal rate of2-naphthol from water reach 100%.The results of this study indicated that the"column flow liquid-liquid extraction"separation method based on the Pickering emulsion was feasible;the construction of highly efficient and multi-functional flow photo-catalytic system can be achieved by a rational combination or assembly of the Pickering emulsion with photocatalysts.The main contents of this paper are as follows:1.Construction of the flow liquid-liquid extraction separation system based on the Pickering emulsion.The ionic liquid-in-water Pickering emulsion droplets stabilized by graphene oxide were used as column filler,the mobile phase was water,a stable flow liquid-liquid extraction separation system,which adopted the Pickering emulsion as column filler,was successfully constructed,the separation efficiencies of common dyes（Rhodamine B and methyl orange）and organic pollutants（tetranitro-aniline,catechol and resorcinol）from water by the system were tested,the results showed that Pickering emulsion column with multiple"emulsion droplet micro-extraction reactors"can simply separate dye or organic compounds.It was proved that our innovative design of"column flow liquid-liquid extraction"separation method based on Pickering emulsion was feasible,which may develop into a new approach of flow liquid-liquid extraction separation with good stability and separation effect.2.Study on the functionalization and flow photocatalytic performance of hydrogel spheres embedded by Pickering emulsion droplets.We adopted a simple and effective gelation strategy to fabricate Pickering emulsion-gel spheres,inside which Ti O₂ and ionic liquid-emulsion droplets emulsified by graphene oxide were embedded.The solid-liquid hierarchical material containing"liquid particles"was assembled by emulsion,catalytic materials and gel,had dual functions of extraction and photocatalytic degradation of pollutants from water.The internal structure and composition of the gel sphere with a diameter of about 3 mm were characterized by various characterization methods.The properties of gel spheres and their adsorption/photocatalytic properties under static and flowing conditions were investigated at the same time,the photocatalysis mechanism was discussed in detail.The results of UV spectrum and GC-MS analysis showed that gel spheres had excellent photocatalytic properties for Rhodamine B and 2-naphthol.Especially in Pickering emulsion-based flow photocatalysis system,as demonstrated by good maintaining of almost 100%remove ability of hard-photodegradable 2-naphthol under the synergistic effects of extraction enrichment,photo-catalysis and flow mode,that will induce a potential application of the flow photocatalytic system.3.Extraction and separation of proteins by ionic liquid-based Pickering emulsion flow system.The Pickering emulsion-based liquid-liquid extraction system mentioned before was applied to separate and enrich proteins,and a novel separation and purification method of protein was developed.The charged behavior of proteins can be regulated by simply adjusting the p H value of the mobile phase in the Pickering emulsion-column to be higher or lower than its isoelectric point（p I）,thus,it was possible to separate and enrich various proteins or even proteins in human whole blood.The experimental results showed that when the p H of mobile phase was around7,acidic albumin in human serum flowed out from the emulsion column first;when the p H of mobile phase was around 9,the hemoglobin was eluted.SDS-PAGE electrophoresis and CD spectra suggested that there was no significant change existed in proteins,proteins remainedα-helical conformation after the extraction and separation.The pure protein samples can be obtained from the Pickering emulsion packed column and the column provides a new way for protein separation and purification.