5-[(Formyloxy)methyl]furfural (FMF), an analogue of 5-(hydroxymethyl)furfural (HMF) is becoming more attractive due to its superior stability and hydrophobicity, which make it easier to refineand store. In the present study, FMF was produced from fructose by one-pot approach in pure formic acid media or by a two-step approach via HMF in choline chloride (ChCl)/fructose deep eutectic solvents (DES) system. A favorable FMF yield of 63.22% was reached by two-step approach. In addition, the effects of reaction parameters, such as temperature and acidity, on preparation of FMF from fructose were systematically investigated. The dehydration of fructose into HMF was confirmed as the rate-controlling step in the consecutive reaction. Ultimately, the separation and purification procedures of FMF were put forward. The FMF with a purity of 98.8% was obtained finally. Meanwhile, the FMF purified by saturated sodium bicarbonate solution showed an excelled storage stability.
Improving the content of polar crystal phase and the hydrophilicity of PVDF membranes are proved the efficient ways to improve the enduringly anti-fouling ability of PVDF membranes. But synergistic manipulating the polymorphic structure and hydrophilicity of PVDF membranes is rarely reported so far. In this paper, the in-situ esterification reaction between styrene-maleic anhydride (SMA) and meglumine (MG) during nonsolvent induced phase separation (NIPS) process is found to simultaneously manipulate the polymorphic structure and hydrophilicity of PVDF membranes. The water contact angle of membranes is largely reduced from 95.8° to 31.2° with the increase in the MG adding amounts, proving that the hydrophilicity of PVDF membranes is notably improved. Moreover, the β-phase content is improved as the MG adding amounts increase due to the enhanced interactions between the –OH groups and the –CF 2 groups of PVDF through hydrogen bonds. As a result, a highly hydrophilic PVDF membrane with >90 % β-phase content is obtained. The durable antifouling testing reveals that the PVDF blend membranes possess lower flow decline ratio and higher flux recovery ratio compared with the virgin PVDF membranes, thus exhibiting better antifouling ability. The synergistic manipulation of hydrophilicity and crystalline phase of PVDF membranes might offer a paradigm shift in the design of high-performance separation membranes.
Zhiwen Ma,Tao Lu,Yali Pan,Yupeng Yuan,Yingqiang Sun
Ionic liquids (ILs) catalyzed in-situ transesterification (IST) of microalgae is a promising strategy to improve biodiesel yield through enhancing cellulose solubility and catalyzing transesterification. Effect of anions of ILs on biodiesel has been widely investigated previously. However, how do cations of ILs affect IST of microalgae is still unclear. On this basis, ILs composed of alkyl-imidazolium cations with different length, 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF 4 ]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF 4 ]), and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim][BF 4 ]) catalyzed IST of microalgae are experimentally and theoretically investigated. The results indicate that increasing alkyl chains of cations weakens interactions of ILs-cellulose, and reduces acidities of ILs, subsequently leads to decrease of cellulose extraction yield and biodiesel yield. Although cellulose extraction yield and biodiesel yield are affected by reaction temperature, dosage of methanol, and MILs: Algae, however, H-bonding interactions of ILs-cellulose and acidities of ILs are still dominate parameters affecting cellulose extraction yield and biodiesel yield, respectively, leading to their unchanged sort under variable reaction conditions as following: [Emim][BF 4 ] > [Bmim][BF 4 ] > [Hmim][BF 4 ]. This work reveals that short alkyl chain of cation is favorable to both cellulose extraction and biodiesel yield, providing theoretical guides for screen and design of benign ILs to further improve biodiesel of in-situ transesterification of microalgae.
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