Construction Of Liquid Compartment Microreactors Based On Ionic Liquid Gel Microspheres

Ionic liquids（ILs）as a new type of green solvent with low saturated vapor pressure,excellent solubility and designable anion-cation pairs.It can be used as medium,catalysts or additives in the process of chemical reactions,which effectively enhance the system thermal stability,improve the reaction efficiency and selectivity.However,the high viscosity,poor fluidity,and broad liquid range of ILs hinder the diffusion of dispersoids when employed as dispersants.Moreover,their separation and recovery from the reaction system pose significant challenges when used as catalysts,thereby limiting the further application of ionic liquids in catalysis.Encapsulating ILs within a liquid compartment microreactor is an effective strategy to compensate for these shortcomings.Ionic liquid gel microspheres possess micron or nanometer dimensions,and their network structure effectively immobilizes the ILs through diverse physical and chemical interactions.These ionic liquid gel microspheres not only facilitate the extraction and enrichment of reaction substrates but also interact with catalysts,thereby enhancing the loading of active sites.Based on this,the ionic liquid gel microspheres IL@PGMA were synthesized using polyglycidyl methacrylate（PGMA）as the network and hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate（[Bmim][PF₆]）as the liquid dispersion medium.Subsequently,various catalytically active components were loaded onto the microspheres using distinct loading methods,facilitating the construction of liquid compartment microreactors for exploring their catalytic performance.The specific research contents are outlined as follows:1.Preparation of phosphotungstate-functionalized ionic liquid gel microspheres PW/IL@PGMA,and their application in the oxidative degradation process of tetracycline.The imidazole-based phosphotungstate（[Bmim][PW]）was synthesized by ion-exchange method,while PW/IL@PGMA,consisting of the[Bmim][PF₆]and the active component[Bmim][PW],was synthesized via one-step synergistic polymerization process.The successful synthesis of PW/IL@PGMA was confirmed with various analytical techniques,including Infrared spectroscopy（FTIR）,Zeta potential analysis,X-ray photoelectron spectroscopy（XPS）,and thermogravimetric analysis（TGA）.The morphology and size distribution of PW/IL@PGMA were determined using Scanning electron microscopy（SEM）.The results demonstrated that PW/IL@PGMA exhibited spherical morphology with good monodispersity and an average particle size of approximately 1μm.PW/IL@PGMA exhibits efficient enrichment of tetracycline in water,achieving adsorption and extraction equilibrium within 10 minutes.Additionally,PW/IL@PGMA was used as the liquid compartment microreactors for catalyzing the oxidation degradation of tetracycline in the presence of H₂O₂.The results clearly demonstrated the significant superiority of the catalytic system over H₂O₂.When p H=6,initial tetracycline concentration is 20 mg·m L^-1,amount of PW/IL@PGMA is 50 mg,and H₂O₂ concentration is 45 m M,the highest removal rate of tetracycline reached 88.3%at 180 minutes.PW/IL@PGMA can be easily separated from the system through simple filtration.Moreover,even after five cycles of degradation experiments,the comprehensive removal rate remained at 87.2%,which demonstrated the excellent recoverability and stability of PW/IL@PGMA microshpeses.2.Preparation of acid-base bifunctional composite microspheres ASNPs-p-Ts OH/IL@PGMA,and their application in one-pot tandem reactions.Firstly,P-Toluene sulfonic acid（p-Ts OH）was impregnated into IL@PGMA,resulting in the formation of sulfonic acid-functionalized ionic liquid gel microspheres p-Ts OH/IL@PGMA.The structural composition,morphology,and size distribution of prepared particles were characterized using FTIR,Zeta potential,XPS,SEM,and dynamic light scattering（DLS）.It was confirmed that p-Ts OH was successfully impregnated onto IL@PGMA,and the morphology of p-Ts OH/IL@PGMA remained unaltered after the functional group loading.The influence of impregnation conditions on p-Ts OH loading was investigated using UV-Vis spectrophotometry.The results revealed that when ethanol as the impregnation medium,initial p-Ts OH concentration is 5 mg·m L^-1,the maximum loading of p-Ts OH reached 179 mg·g^-1 after 20 hours.Subsequently,the as-prepared amino-functionalized silica nanoparticles（ASNPs）were covalently combined with p-Ts OH/IL@PGMA.The amino group（-NH₂）of ASNPs underwent a reaction with the epoxy group on the surface of the gel microspheres,resulting in the formation of acid-base bifunctional composite microspheres ASNPs-p-Ts OH/IL@PGMA through the formation of an amide bond.FTIR and TGA results confirmed the successful synthesis of ASNPs-p-Ts OH/IL@PGMA.SEM results revealed the uniform distribution of ASNPs on the surface of p-Ts OH/IL@PGMA,forming raspberry-like composite microspheres with an particle size of 1.6μm.The acid-base catalyzed one-pot Deacetalization-Knoevenagel condensation tandem reaction was employed as model reaction,and the reaction progress was monitored by Gas chromatography（GC）and Nuclear magnetic resonance（NMR）spectroscopy.These results confirmed the suitability of ASNPs-p-Ts OH/IL@PGMA as liquid compartment microreactors.After optimization of the reaction conditions,when reaction temperature is 60°C,amount of ASNPs-p-Ts OH/IL@PGMA is 100 mg,and the molar ratio of benzaldehyde dimethyl acetal to malononitrile is 1:3,which achieved highest conversion rate of 84.3%and product recovery rate of 81.2%after 4 hours.The composite microspheres exhibit excellent recoverability and stability.Through extraction experiments,it was determined that the ILs in the composite microspheres were capable of extracting and enriching the reaction substrate under identical conditions.