Construction Of 5-HMF Integrated System Based On IL/DES-ATPS Catalytic Conversion And Extraction

The utilization of food biomass sugar by-products is currently focused on the study of efficient catalytic conversion to 5-hydroxymethylfurfural（5-HMF）.The catalytic reaction and extraction separation are carried out in stages,which increase the cost and complexity of the operation,making it difficult to carry out large Scale utilization.The development of an integrated platform with economic benefits,integrated production and extraction separation is still a crucial requirement,and the construction of a new aqueous two phase system（ATPS）is an important means to solve this problem.Therefore,this study constructed ATPS based on ionic liquid（IL）/deep eutectic solvents（DES）.The new ATPS has the advantages of the traditional dual-aqueous phase,with qualities such as easy to operate,easy to expand the application,spontaneous completion,etc.The characteristic solves the problem that the traditional double aqueous phase is difficult to be widely used due to its high viscosity.The new ATPS has wide application prospects,and is widely used in various researches such as sugar and protein.In this paper,the ionic liquid aqueous two phase system（IL-ATPS）was first constructed,and the application of the system to the extraction and separation of fructose and 5-HMF was studied;on the basis of this study,a synthetic IL substitute DES was synthesized,and its properties and low deep eutectic solvents aqueous two phase system（DES-ATPS）was used to extract 5-HMF.The effects of single factors on the extraction and separation of 5-HMF,the application range and extraction mechanism of the system were studied.Finally,the system was upgraded to a switchable（pH-driven）production-separation integrated system,and an integrated system based on the catalytic conversion of apple peel and the extraction and separation of 5-HMF based on the DES-ATPS was obtained.（1）An IL-ATPS based on two inorganic salts,K₃C₆H₅O₇ and NaH₂PO₄,was constructed with a composition of 30wt%[C₄mim][CF₃SO₃]+35wt%K₃C₆H₅O₇ and30wt%[C₄mim][CF₃SO₃]+40wt%NaH₂PO₄.IL-ATPS was used to extract 5-HMF and fructose,and a phase diagram composed of nine inorganic salts and[C₄mim][CF₃SO₃]was constructed.The 5-HMF and fructose extraction rates were95.73±0.26%and 97.27±0.41%,97.26±0.10%and 95.51±0.06%,respectively.The different process parameters,namely the temperature and time of the separation system were studied,and the process was optimized.The constructed system can complete extraction and separation at room temperature for 30 minutes.（2）DES were synthesized and characterized by nuclear magnetic resonance,Fourier infrared spectroscopy,thermogravimetry,rheology,etc.,to study the synthesis effect of DES and analyze their physical and chemical properties.The results disclosed that:NMR analysis showed that the five types of DES were found to have corresponding peak shapes,indicating they were physical hydrogen bonding rather than chemical changes;infrared analysis showed that all five DES formed hydrogen at3300 cm^-1.Bond width peaks prove successful synthesis;Rheological characterization results show that temperature has a great influence on the viscosity of DES,and the viscosity decreases with increasing temperature;thermogravimetric analysis shows that all five DES are uniform at room temperature.The results show that when the composition of the system is 30wt%ChCl-Betaine+45wt%K₂HPO₄,the optimal extraction system has high extraction efficiency,and the extraction as well as separation of 5-HMF and fructose can be completed within 60 minutes.At the same time,the required conditions are simple and the temperature in the application of this system has no significant effect,with the system having a wide range of applications.The concentration range of 5-HMF is 1¹00 mg/mL and the concentration range of fructose is 150²50 mg/mL;both have good separation effect.5-HMF extraction rate can reach more than 99%,and the fructose extraction rate can reach more than 85%.After dynamic light scattering analysis,it was found that the DES and 5-HMF were mixed to form more stable small particles,which proved that 5-HMF was easy to be enriched in the DES phase,so that 5-HMF and fructose were extracted and separated.（3）An integrated platform for the production and separation of pH-driven reversible DES-ATPS was studied,and the conclusions were as follows:It was found that the higher the proportion of ethanol and n-propanol,the stronger the hydrophobicity and the larger the range of the two-phase system formed.The[N₄₄₄₄]Cl:ethanol（1:2）and[N₄₄₄₄]Cl:n-propanol has excellent extraction effect on the the system 30wt%[N₄₄₄₄]Cl:ethanol（1:2）+35wt%C₆H₅K₃O₇:for 5-HMF extraction rate,98.53%,for fructose extraction rate,96.89%,and only takes 20min Complete extraction is complete.The system 30wt%[N₄₄₄₄]Cl:n-propanol（1:2）+40wt%C₆H₅K₃O₇ has an extraction rate of 98.59%for 5-HMF and 98.52%for fructose,and it takes only 20 minutes to complete the extraction.The system is capable of mutual conversion between single-phase and dual-phase under the driving of pH value,and no other impurities are introduced between single-phase and dual-phase conversion.The ability to reversibly transform is extremely important in the separation process.The integrated platform is constructed to perform catalytic reactions in a single-phase（acid system）,adjust the pH and switch to a two-phase（alkaline system）to separate5-HMF from the raw materials,and then adjust the pH to switch to a single-phase（acid system）.The raw materials are reused and the production effect is good.The fructose conversion rate can reach 87.21%,the 5-HMF yield can reach 46.76%,and the 5-HMF selectivity can reach 53.88%,0.1 g apple peel can catalyze 15.43 mg5-HMF.It has economic benefits,comprehensiveness and sustainability.