改性纤维素纳米晶体对镉的吸附特性

发布时间：2018-03-11 15:48

  本文选题：纤维素纳米晶体　切入点：改性纤维素纳米晶体　出处：《沈阳农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文以腐殖酸及纤维素纳米晶体为原料,用不同级别的腐殖酸溶液对纤维素纳米晶体进行改性,获得十五种改性纤维素纳米晶体。同时,分别对腐殖酸、纤维素纳米晶体及改性纤维素纳米晶体对Cd~(2+)的吸附特征进行研究。主要得出的结果如下:(1)通过傅里叶红外光谱对腐殖酸及纤维素纳米晶体的结构进行分析,结果表明腐殖酸中含有的化学基团主要包括-OH,不饱和C-H,-NO2,C-O-C,C=C等;纤维素纳米晶体主要包括-OH,C-H,C-O等化学基团;经腐殖酸改性后得纳米纤维素晶体引入了 C-O-C及-COOH官能团。(2)通过腐殖酸、纤维素纳米晶体及腐殖酸改性后的纤维素纳米晶体对Cd~(2+)的等温吸附及吸附动力学特性研究,可知腐殖酸与纤维素纳米晶体对Cd~(2+)符合单分子层吸附模型;腐殖酸与纤维素纳米晶体对Cd~(2+)的吸附符合准二级动力学吸附模型,且模拟出的平衡吸附量与实验得出的平衡吸附量结果相近;改性后纤维素纳米晶体对Cd~(2+)的吸附用Langmuir方程与Freundlich方程拟合的效果都比较好。改性纤维素纳米晶体对Cd~(2+)的吸附作用包括化学吸附与物理吸附,其吸附原理不能单独使用改性纤维素纳米晶体的化学官能团结构进行解释,需要对其物理结构进行观察,做进一步分析。(3)通过对纤维素纳米晶体与改性纤维素纳米晶体的吸附效果的比较,可以看出改性后的纤维素纳米晶体对Cd~(2+)的吸附量有了提升,当Cd~(2+)的初始浓度相同时,改性后的纤维素纳米晶体吸附量较原纤维素纳米晶体增加范围为:0.3%～93.8%,且除了用混合腐殖酸改性后的剑麻纤维素纳米晶体及用分析纯腐殖酸改性后的棉花纤维素纳米晶体与原纤维素纳米晶体对Cd~(2+)的吸附量无显著差异外,其他的腐殖酸处理纤维素纳米晶体与原纤维素纳米晶体对Cd~(2+)的吸附量存在显著差异;经过高活性腐殖酸改性后的纤维素纳米晶体比其它腐殖酸改性的纤维素纳米晶体对Cd~(2+)的吸附量大。
[Abstract]:In this paper, 15 kinds of modified cellulose nanocrystals were obtained by modifying cellulose nanocrystals with humic acid and cellulose nanocrystals with different levels of humic acid solution. The adsorption characteristics of cellulose nanocrystals and modified cellulose nanocrystals to Cd~(2) were studied. The main results are as follows: 1) the structure of humic acid and cellulose nanocrystals was analyzed by Fourier transform infrared spectroscopy. The results showed that the chemical groups contained in humic acid mainly included -OH, unsaturated C-H _ (no _ 2O) C-O-C _ (C), cellulose nanocrystalline mainly consisted of -OHH _ (C) -H _ (C) C-O, and modified by humic acid, the C-O-C and -COOH functional groups were introduced into the nanocellulose crystal through humic acid, and the humic acid was introduced into the nanocellulose crystal by humic acid, and then the C-O-C and -COOH functional groups were introduced into the nano-cellulose crystal by humic acid. The isothermal adsorption and adsorption kinetics of cellulose nanocrystalline and cellulose nanocrystalline modified by humic acid for Cd~(2) were studied. The results show that the adsorption of Cd~(2 by humic acid and cellulose nanocrystalline conforms to the monolayer adsorption model. The adsorption of humic acid and cellulose nanocrystals for Cd~(2) was in accordance with the quasi-second-order kinetic adsorption model, and the simulated equilibrium adsorption capacity was similar to the experimental results. The adsorption of modified cellulose nanocrystals to Cd~(2) was well fitted by Langmuir equation and Freundlich equation. The adsorption of Cd~(2 on modified cellulose nanocrystals included chemisorption and physical adsorption. The adsorption principle can not be explained by the chemical functional group structure of modified cellulose nanocrystalline alone, and the physical structure of the modified cellulose nanocrystalline should be observed. By comparing the adsorption effect of cellulose nanocrystals with modified cellulose nanocrystals, we can see that the adsorption capacity of modified cellulose nanocrystals to Cd~(2) has been increased, when the initial concentration of Cd~(2) is the same, The adsorption capacity of modified cellulose nanocrystalline was increased by 0.33% or 93.8% compared with the original cellulose nanocrystalline. Besides the modified sisal cellulose nanocrystalline modified with mixed humic acid and cotton cellulose nanocrystalline modified with analytical pure humic acid, the modified cellulose nanocrystalline was modified with humic acid. There was no significant difference in adsorption amount of Cd~(2 between crystal and cellulose nanocrystalline. Other humic acid-treated cellulose nanocrystals had significant differences in adsorption capacity between cellulose nanocrystals and original cellulose nanocrystals. The adsorption capacity of cellulose nanocrystalline modified by high active humic acid to Cd~(2 was higher than that of other HA modified cellulose nanocrystals.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
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本文编号：1598845