蔗渣纤维素疏水改性及纤维素基水凝胶的制备及应用

发布时间：2018-02-10 15:25

本文关键词： 蔗渣纤维素核壳结构乳液疏水改性纤维素基吸附剂竞争吸附吸附机理　出处：《广西大学》2017年硕士论文　论文类型：学位论文

【摘要】：21世纪随着社会经济的高速发展,世界正面临着环境、能源、材料等领域空前挑战。植物纤维素是一种廉价、量广、易降解、生物相容性好的天然高分子。但纤维素分子间和分子内氢键和纤维素表面基团过于单一,致使纤维素应用受限,尤其在复合材料和废水处理领域。目前控制工业废水中重金属排放法规越来越严厉,各种去除重金属离子方法被大量使用,如化学沉淀、离子交换、吸附、纳滤、超滤、反渗透、电化学、电渗析等方法。目前吸附是一种有效、经济的方法,由于简单、有效、易操作和可重复使用等优点而被广泛研究。为提高植物纤维素对重金属离子的吸附量,本文采用环氧氯丙烷、乙二胺、二硫化碳对纤维素进行改性。将改性后的纤维素衍生物与羧甲基纤维素钠(CMC-Na)溶于氢氧化钠/硫脲体系后,用环氧氯丙烷进行交联得到纤维素基水凝胶吸附剂。讨论了初始浓度、pH、离子强度、温度对吸附剂吸附性能的影响。单组分吸附曲线表明Pb2+、Cu2+、Zn2+满足Langmuir等温吸附模型且最大吸附量分别是558.9、446.2、363.3 mg·g-1,吸附过程满足拟二级吸附动力学且为自发放热过程。在双组分系统中采用Competitive Langmuir isotherm模型模拟数据,结果显示实验数据和模拟数据间的误差均小于20%,表明该模型可对双组份重金属离子吸附进行较准确的预测。FTIR、SEM-EDAX、ICP-OES表明该吸附机理包括配位、离子交换、静电吸附等作用。为解决纤维素与树脂复合材料相界面“不相容”的问题。本文采用以苯乙烯(St)和己酸烯丙酯(AH)为核层共聚单体,丙烯酸丁酯(BA)、甲基丙烯酸丁酯(BMA)、甲基丙烯酸二甲氨乙酯(DMAEMA)为壳层共聚单体,以十六烷基三甲基氯化铵(CTAC)为乳化剂,2,2-偶氮二(2-甲基丙基咪)二盐酸盐(AIBA)为引发剂,二甲基丙烯酸乙二醇酯(EDGMA)为交联剂制备出“硬核软壳”的核壳型阳离子乳液。透射电镜(TEM)、动态光散射多角度粒径、Zeta电位分析仪测试结果表明制备的乳液粒径分布较宽(PDI=0.314),平均粒径84.95nm,Zeta电位32.8mv。在吸附过程中乳胶粒子分布较宽致使出现两段吸附。第一段符合拟一级动力学吸附模型,第二段符合拟二级动力学吸附模型。活化能表明吸附过程先是物理吸附后是化学吸附。在高浓度下的活化能较高且吸附速率小于低浓度的吸附速率,表明了该过程受活化控制。在低浓度下活化能较小,吸附速率较大则为扩散控制。当额外补加乳化剂时,低浓度下吸附率由60%增大到90%以上。通过红外(FTIR)、扫描电镜(SEM)、热重(TGA)、比表面积仪(BET)、接触角表明乳胶粒被成功的吸附在纤维素表面。在303 K时纤维素对乳胶粒的饱和吸附量520 mg·g-1。改性纤维素的接触角随吸附量的增加随之增大。当吸附量为196 mg.g-1时纤维素的接触角为102°,表明疏水性纤维素制备成功。纤维素在吸附过程中以静电吸附为主,共价和非共价作用(例如氢键、离子交换、电荷转移、链的缠绕)为辅进行吸附。
[Abstract]:In 21th century, with the rapid development of social economy, the world is facing unprecedented challenges in the fields of environment, energy and materials. Natural polymers with good biocompatibility. However, intermolecular and intramolecular hydrogen bonds and cellulose surface groups are too single, limiting the use of cellulose. Especially in the field of composite materials and wastewater treatment. At present, the regulations for controlling the discharge of heavy metals in industrial wastewater are becoming more and more stringent, and various methods of removing heavy metal ions are widely used, such as chemical precipitation, ion exchange, adsorption, nanofiltration, ultrafiltration, etc. Reverse osmosis, electrochemistry, electrodialysis, etc. At present, adsorption is an effective and economical method, which has been widely studied because of its advantages of simplicity, efficiency, ease of operation and reusability. Cellulose was modified with epichlorohydrin, ethylenediamine and carbon disulfide. The modified cellulose derivatives and CMC-Na were dissolved in the system of sodium hydroxide / thiourea. Cellulose based hydrogel adsorbent was prepared by crosslinking epichlorohydrin. The single component adsorption curve showed that Pb2 Cu2Zn2 satisfies the Langmuir isotherm model and the maximum adsorption capacity is 558.9% 446.2U 363.3 mg 路g-1.The adsorption process satisfies the pseudo-second-order adsorption kinetics and is a self-releasing heat process. The Competitive Langmuir isotherm model is used to simulate the data in the two-component system. The results show that the error between the experimental data and the simulated data is less than 20, which indicates that the model can accurately predict the adsorption of heavy metal ions in two components. FTIRN SEM-EDAXX ICP-OES indicates that the adsorption mechanism includes coordination and ion exchange. In order to solve the problem of "incompatibility" between cellulose and resin composites, the core layer copolymerization of styrene (St) and allyl hexanoate (AH) was studied. Butyl acrylate (BMA), butyl methacrylate (BMAA), dimethylaminoethyl methacrylate (DMAEMA) as shell copolymerization monomer and cetyltrimethylammonium chloride (CTAC) as emulsifier AIBA) were used as initiators. The core-shell cationic emulsion of "hard core soft shell" was prepared by using ethylene glycol dimethacrylate (EDGMA) as crosslinking agent. The particle size distribution of the prepared emulsion was determined by dynamic light scattering multi-angle particle size analyzer. The average particle size was 84.95 nm / m ~ (-1) and Zeta potential was 32.8mv. during the adsorption process, a wide distribution of latex particles resulted in two stages of adsorption. The first stage was in accordance with the pseudo-first-order kinetic adsorption model. The second stage accords with the pseudo-second-order kinetic adsorption model. The activation energy indicates that the adsorption process is first physically adsorbed and then chemisorbed. At high concentration, the activation energy is higher and the adsorption rate is lower than that of the low concentration adsorption rate. The results show that the process is controlled by activation. The activation energy is small and the adsorption rate is controlled by diffusion at low concentration. The adsorption rate increased from 60% to more than 90% at low concentration. The adsorption rate was increased from 60% to 90% by FTIR, SEM, TGA, TGA, BET. The contact angle indicated that the latex particles were successfully adsorbed on the cellulose surface. At 303K, cellulose saturated the latex particles. The contact angle of modified cellulose increased with the increase of adsorption capacity. When the adsorption amount was 196 mg.g-1, the contact angle of cellulose was 102 掳, which indicated that hydrophobic cellulose was successfully prepared. Covalent and non-covalent interactions (e. G. Hydrogen bonds, ion exchange, charge transfer, chain entanglement) are supplemented by adsorption.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ427.26;O647.3

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