本文選題：纖維素　切入點(diǎn)：離子液體　出處：《南京林業(yè)大學(xué)》2017年碩士論文

【摘要】：目前,隨著煤、石油等化石能源的日益枯竭以及環(huán)境污染問(wèn)題的日益加劇,對(duì)綠色可再生資源的開發(fā)研究越來(lái)越多。纖維素在自然界中儲(chǔ)量豐富、廉價(jià)易得、可再生,是一種可替代化石燃料的生物質(zhì)資源。天然纖維素中含有大量的分子內(nèi)和分子間的氫鍵,不溶于大多數(shù)常規(guī)溶劑,這成為擴(kuò)展纖維素應(yīng)用的最大障礙之一。而用于纖維素溶解的傳統(tǒng)溶劑體系具有穩(wěn)定性差、揮發(fā)性大、毒性大、污染環(huán)境等缺點(diǎn),因此,開發(fā)新的纖維素溶劑體系是高效、綠色利用纖維素資源的良好途徑。本研究先合成了6種對(duì)稱型季胺鹽離子液體和2種非對(duì)稱型季胺鹽離子液體,平均得率在85%左右。研究了陽(yáng)離子結(jié)構(gòu)、離子液體/助溶劑比例、溶解溫度及纖維素原料對(duì)離子液體/助溶劑混合體系溶解纖維素的影響。結(jié)果顯示,上述四個(gè)因素對(duì)纖維素的溶解均有重大影響:陽(yáng)離子結(jié)構(gòu)為非對(duì)稱型的對(duì)纖維素的溶解優(yōu)于對(duì)稱型的;離子液體比例過(guò)低或者過(guò)多都不易于纖維素的溶解;溶解溫度越高,纖維素原料聚合度越低,則溶解速率越快。合成的離子液體中四丁基醋酸銨(TBAA)溶解纖維素速率最快,四丁基醋酸銨(TBAA)/二甲基亞砜(DMSO)(WTBAA=0.15)混合體系在25 oC下溶解1 wt%濾紙僅需3.5 min。1-己基-三乙基醋酸銨(N2226CH3COO)溶解纖維素的量最多,N2226CH3COO/DMSO(WN2226CH3COO=0.35)混合體系在25 oC下最多可溶解11.37 wt%濾紙。此外,對(duì)比TBAA/DMSO與N2226CH3COO/DMSO這兩個(gè)溶劑體系,溶解相同量纖維素時(shí),后者得到的纖維素溶液黏度更低。本研究對(duì)離子液體TBAA/DMSO混合體系溶解纖維素機(jī)理進(jìn)行了探討。選用纖維二糖為纖維素模型物,微晶纖維素為纖維素原料,通過(guò)1H NMR、13C NMR、ATR-FTIR、電導(dǎo)率和黏度等方法對(duì)溶解過(guò)程進(jìn)行表征,我們推測(cè)在TBAA/DMSO混合體系中,TBAA存在著“離子對(duì)”和“離子對(duì)分離”兩種狀態(tài);當(dāng)WTBAA=0.25~0.15時(shí)屬于“離子對(duì)”狀態(tài),即醋酸根陰離子與四丁基銨陽(yáng)離子結(jié)合較緊密;而WTBAA=0.15~0.05時(shí)屬于“離子對(duì)分離”階段,此狀態(tài)有助于TBAA上的醋酸根陰離子與纖維素上的羥基作用形成強(qiáng)的氫鍵(陰離子)O···H-O(纖維素)。另外,DMSO在混合體系中不僅起到了降低體系黏度的作用,還與溶解的纖維素作用使其穩(wěn)定存在于溶液中,促進(jìn)纖維素的溶解。此外,我們對(duì)纖維素在TBAA/DMSO均相溶解體系中的無(wú)催化劑法丁二酸酐改性進(jìn)行了研究。探討了混合體系中TBAA含量、丁二酸酐比例,反應(yīng)時(shí)間和反應(yīng)溫度對(duì)纖維素改性的影響,并用FTIR、TGA、XRD,固體CP/MAS 13C NMR光譜(CP/MAS 13C NMR)和SEM對(duì)改性纖維素進(jìn)行了表征。結(jié)果表明通過(guò)對(duì)反應(yīng)條件的控制可制備得到取代度范圍在0.337~1.191之間的改性纖維素。改性纖維素可以用于重金屬離子Cu2+和Cd2+的吸附。我們研究了改性纖維素取代度、金屬溶液pH、吸附時(shí)間、吸附溫度對(duì)吸附效果的影響。前兩個(gè)因素對(duì)吸附效果影響最大,吸附溫度次之。改性纖維素在室溫下較短時(shí)間即可對(duì)Cu2+和Cd2+實(shí)現(xiàn)良好吸附。對(duì)Cu2+和Cd2+的最大吸附容量分別為51.92 mg/g和50.35 mg/g。
[Abstract]:At present, with the increasing depletion of coal, oil and other fossil energy and environmental pollution become increasingly serious, more and more research and development of green renewable resources. Cellulose in the nature reserves are abundant, cheap, renewable, is an alternative to fossil fuel raw material resources. Natural cellulose contains a large number of molecules and intermolecular hydrogen bonds, insoluble in most common solvents, it has become one of the biggest obstacle to expanding applications. For traditional cellulose dissolved cellulose solvent systems have poor stability, high volatile, high toxicity, environmental pollution and other shortcomings, therefore, the development of new cellulose solvent system is efficient, green with a good way of cellulose resources. This study first synthesized 6 kinds of symmetric quaternary ammonium ionic liquids and 2 asymmetric quaternary ammonium ionic liquid, the average yield is about 85%. The effects of cationic structure, The ionic liquid / solvent ratio, temperature and the effect of dissolved cellulose materials on ionic liquid / solvent mixture to dissolve cellulose. The results showed that the dissolution of these four factors have a significant impact on the cellulose cation structure is asymmetric type of cellulose dissolved in the ionic liquid symmetrical; dissolution ratio is too low or too many are not easy to dissolve cellulose; the higher the temperature is, the lower the degree of polymerization of cellulose material, then the dissolution rate more quickly. The ionic liquid in four Butyl Ammonium acetate (TBAA) dissolved cellulose rate, four Butyl Ammonium acetate (TBAA) / two dimethyl sulfoxide (DMSO) (WTBAA=0.15) only mixed the system was dissolved in 25 oC 1 wt% 3.5 min.1- three - ethyl hexyl Filterpaper ammonium acetate (N2226CH3COO) dissolved cellulose was highest in N2226CH3COO/DMSO (WN2226CH3COO=0.35) hybrid system under 25 oC the dissolved 11.37 wt% filter paper. In addition, compared with the TBAA/DMSO and N2226CH3COO/DMSO of the two solvent system, the same amount of dissolved cellulose, cellulose solution viscosity lower the latter. This study discusses the ionic liquid TBAA/DMSO mixed system selection mechanism. The dissolution of cellulose fiber two sugar as model cellulose, microcrystalline cellulose as cellulose raw materials, by 1H NMR, 13C NMR. ATR-FTIR, electrical conductivity and viscosity methods were used to characterize the dissolution process, we hypothesized that the TBAA/DMSO hybrid system, TBAA has "ion pair" and "ion of separation" two states; when WTBAA =0.25~0.15 belongs to the "ion pair", namely the acetate anion and four Butyl Ammonium Cation combination; WTBAA=0.15~0.05 when belong to the ion pair separation stage, the effect of hydroxy state contribute to TBAA on cellulose acetate anion and the formation of hydrogen bond (strong anion O) - H-O (cellulose). In addition, DMSO in the mixed system not only to reduce the viscosity of the system, and the stability and dissolution of cellulose in solution, promote the dissolution of cellulose. In addition, we in the TBAA/DMSO homogeneous dissolution system in cellulose fadin's two anhydride catalyst the modification was studied. To investigate the content of TBAA in the mixed system, Ding two anhydride ratio, reaction time and reaction temperature on the effect of modified cellulose, and FTIR, TGA, XRD, CP/MAS (CP/MAS 13C NMR spectra of solid 13C NMR) and SEM on the modified cellulose were characterized. The results showed that the prepared replace the modified cellulose in 0.337~1.191 concentration range by controlling the reaction conditions. Modified cellulose can be used for the adsorption of heavy metal ions Cu2+ and Cd2+. We study the degree of substitution of modified cellulose, metal solution pH, adsorption time, adsorption The influence of temperature on the adsorption effect. The first two factors have the greatest influence on the adsorption effect and the adsorption temperature is second. Modified cellulose can achieve good adsorption for Cu2+ and Cd2+ at room temperature for a short time. The maximum adsorption capacity for Cu2+ and Cd2+ is 51.92 mg/g and 50.35 mg/g., respectively.

【學(xué)位授予單位】：南京林業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O636.11

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相關(guān)期刊論文 前2條

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2 肖小華,劉淑娟,劉霞,蔣生祥;離子液體及其在分離分析中的應(yīng)用進(jìn)展[J];分析化學(xué);2005年04期

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本文編號(hào)：1717625