豆渣一锅法均相制备羧甲基纤维素的研究

Study on the Homogeneous Synthesis of Carboxymethyl Cellulose from Soybean Dregs in One Pot

本研究在均相条件下通过一锅法合成羧甲基纤维素(carboxymethyl cellulose,CMC)。豆渣(soybean dregs,SD)溶解在6%NaOH/4%尿素水溶液得到碱纤维素,一步完成纤维素的提纯和碱化,再以氯乙酸钠为醚化剂制备CMC。经正交实验确定制备CMC的优化反应条件,并对其特性进行分析。结果表明:在55℃下醚化3 h,68℃保温1 h,豆渣添加量6.8 g,氯乙酸钠和纤维素摩尔比为4∶1,NaOH的浓度为1.5%时,得到取代度为0.51的淡黄色中性CMC,其溶解度为83.88%;红外光谱分析发现在1608.12 cm^-1处出现的新吸收峰,表明有羧甲基基团成功引入;1H NMR中化学位移的改变证明有羧甲基取代纤维素链上的羟基;热重分析表明制备CMC有良好的热稳定性;扫描电镜显示CMC由表面平滑的大颗粒结构转变成表面凹凸不平的短棒状。

In this study,synthesized carboxymethyl cellulose by one pot in the homogenous condition was developed.Soybean dregs dissolved in 6%NaOH/4%urea aqueous solution to obtain alkali cellulose solution,and the cellulose was purified and alkalized in one step,then reacting with sodium monochloroacetic acid as etherifying agent to synthesis carboxymethyl cellulose.The orthogonal test was designed to determine the optimal reaction conditions for preparing carboxymethyl cellulose,and the characteristics of the product were analyzed.The results could be summarized as follows:when the etherification time at 55℃ for 3 h and kept at 68℃ for 1 h,the soybean dregs concentration was 6.8 g,the molar ratio of sodium monochloroacetic acid to cellulose was 4∶1,and the concentration of NaOH was 1.5%,and the pale yellow neutral product with the degree of substitution of 0.51 was obtained.The solubility of the product was 83.88%.The FTIR spectra showed a new and strong absorption band at 1608.12 cm^-1 which indicated that carboxymethyl group successfully pulled in.The change in chemical shift in 1H NMR indicated that hydroxy group was substituted by carboxymethyl group.The thermogravimetric analysis showed that CMC has a better thermal stability.Scanning electron microscopy demonstrated that the modified sample was transformed from a smooth large particle structure to a short rod surface.