【作者】 高静；

【导师】 陈砺；

【作者基本信息】 华南理工大学 ， 化学工艺， 2014， 博士

【摘要】 极性非质子溶剂作为共溶剂能够降低离子液体的黏度，利于溶质的分散和溶解。含极性非质子溶剂的离子液体预处理木质纤维素已成为生物炼制研究领域的重要课题。为了降低离子液体带来的高成本和避免离子液体的潜在毒性所引发的环境污染，实现含极性非质子溶剂的离子液体的回收利用对推动离子液体的工业化进程具有深远意义。课题以离子液体/极性非质子溶剂预处理木质纤维素为研究背景，考察了离子液体的结构、预处理时间、预处理温度、木质纤维素粒径大小等因素对处理后样品的组分、结构、厌氧发酵沼气产量和酶水解产糖量的影响。与未经任何预处理的木质纤维素原料相比，经过1-丁基-3-甲基咪唑氯盐（[C4mim]Cl）和二甲基亚砜（DMSO）混合溶剂（5:1）在120℃下预处理2h的水葫芦、稻秆、芒果叶和杉树枝样品的比表面积增加，木质素去除率分别为49.2%、38.2%、23.7%和48.0%，结晶度分别下降了10.5%、6.60%、2.81%和8.57%，厌氧发酵四周后甲烷累计产量分别提高了97.6%、70.4%、65.4%和65.9%。采用1-乙基-3-甲基咪唑丙氨酸盐（[C2mim]Ala）和DMSO混合溶剂（5:1）在120℃下分别预处理水葫芦、稻壳和稻秆2h，能够除去48.5%、47.4%和31.3%的木质素，结晶度分别降低5.1%、5.6%和6.3%，处理后的样品比表面积增加，在50℃下水解48h后产糖率分别提高了232.5%、135.0%和139.5%。构建了含极性非质子溶剂的离子液体—盐四元双水相体系，离子液体回收率达到90%以上。通过考察极性非质子溶剂和离子液体的溶剂化效应参数、盐的水合吉布斯自由能、极性非质子溶剂迁移热力学参数，并结合双水相相图、系线长度、极性非质子溶剂的分配系数、离子液体的回收率以及体系的物理化学性质，明确了离子液体、盐、极性非质子溶剂和温度对离子液体-盐双水相体系的影响机理。研究表明：（1）极性非质子溶剂倾向于迁移到离子液体富集相中，能够相对的调节离子液体的疏水性质，提高亲水性离子液体（如[C4mim]Cl等）与无机盐形成双水相体系的能力，而不利于疏水性离子液体（如1-丁基-3-甲基咪唑四氟硼酸盐，[C4mim]BF4等）与有机盐形成双水相；（2）溶剂化效应参数中的氢键碱性（β值）在0.38~0.60范围内的疏水性离子液体具有与有机盐形成双水相的潜力，而亲水性离子液体的β值越小，回收率越高；（3）当咪唑基离子液体的阳离子侧链烷基由C2增加到C6时，离子液体形成双水相的能力逐渐增加至最大，而阳离子侧链烷基为C8的离子液体形成双水相的能力较弱；（4）“盐析效应”的强弱规律符合无机盐阴离子的Hofmeister序列，并随着有机盐阴离子的化合价和水合吉布斯自由能绝对值的增加而增大；（5）低温有利于双水相体系的形成；（6）两相间的密度差值越大，离子液体富集相表面张力越大，离子液体的回收率越高。毒理学研究表明离子液体对水生生物具有一定的潜在危害，排入水体可能会引发环境问题。本文采用等离子体电解技术对离子液体进行降解后处理。结果表明，当等离子体电解电压为600V、时间为2h、初始浓度为1.0~4.0g/100mL时，离子液体受到大量高能粒子的轰击和氧化后彻底分解为无机物小分子。更多还原

【Abstract】 Dipolar aprotic solvents (DASs) were used as co-solvents to reduce the viscosityof ionic liquids (ILs), and improve the dispersion and dissolubility of solute in the ILs.Therefore, ILs/DASs pretreatment of lignocellulosic biomass has been widely used inbiorefineries. Because of the cost for producing or purchasing the expensive ILs andthe potential environmental pollution, ILs recycling is of great significance to thepromotion of industrialization process for ILs.In this study, lignocellulosic biomass was pretreated by ILs/DASs. Effects of theIL structure, pretreatment time, pretreatment temperature and particle size onlignocellulosic composition, structural change, biogas production and sugar yieldswere evaluated. Moreover, IL-based aqueous biphasic systems (ABSs) in the presenceof DAS were formed to recycle and reuse the ILs along with the DASs. After thepretreatment of water hyacinth, rice straw, mango leaves and spruce with chloride([C4mim]Cl)/dimethyl sulfoxide (DMSO) under120℃for2h, the surface area ofregenerated samples was increased, the extracted lignin contents were49.2%,38.2%,23.7%and48.0%, crystallinity (CrI) values were decreased by10.5%,6.60%,2.81%and8.57%, and accumulated CH4productions were increased by97.6%,70.4%,65.4and65.9%, respectively. Moreover, after the pretreatment of water hyacinth, rice huskand rice straw with1-N-ethyl-3-methyimidazolium alaninate ([C2mim]Ala)/DMSOunder120℃for2h, the lignin could be remove by48.5%,47.4%and31.3%, CrIvalues were decreased by5.1%,5.6%and6.3%, and sugar yields were increased by232.5%,135.0%and139.5%, respectively, as compared with unpretreated samples. Inaddition, the ILs and DASs used in the study were recovered and reused by formingABSs with salt, and the recovery rates were all over90%.To evaluate the effects of ILs, salts, DASs and temperatures on the ABSscomposed with ILs and salts in the presence of DAS, the solvation parameters of ILsand DASs, the hydration Gibbs free energy of salt anions, and the standard molarthermodynamic functions of the transfer for DASs were investigated, and phase diagrams, tie-line lengths, partition coefficients of DAS, IL recovery efficiencies (RIL)and physicochemical properties were also studied. The results were summarized asfollows:(1) DAS preferentially dissolves in the IL-rich phase, adding DASs is able toaffect the hydrophobicity of ILs, and a large range of DASs are able to produce theABSs composed of hydrophilic ILs ([C4mim]Cl, etc) and inorganic salts, while theability of hydrophobic ILs (1-N-butyl-3-methyimidazolium tetrafluoroborate,[C4mim]BF4, etc) to form ABSs with organic salts was decreased with the increasingconcentration of DASs;(2) The hydrophobic IL with hydrogen bond basicity (β)ranging between0.38and0.60can form ABS with organic salts, and the lower βvalues of hydrophilic ILs results in greater RIL;(3) Increasing the length of thealiphatic chain from C2to C6alkyl chains increases the ability of ILs to form ABS,but the ability to form ABS for the ILs with longer cation side chain decreases;(4)Salting-out effect is in accordance with Hofmeister Series, and is increased with thevalence and the ΔhydG value of the salt anions;(5) IL-based ABSs preferentially formsat lower temperatures;(6) The RILvalues increase with the density differencesbetween the two phases and the surface tension of the top phase.Toxicity studies on aquatic organisms suggest the potential environmental risk ofILs. To avoid the release of the ILs into the environment through wastewaters, a novelmethod of degrading ILs using plasma electrolysis (PE) was proposed. Resultsindicated that ILs with initial concentrations of1.0~4.0g/100mL readily decomposedto inorganic molecules by the oxidation and cleavage of active radicals under anapplied boltage of600V within2h.更多还原