Zou Ming, Zhang Haixin, Miyamoto Naoto, Kano Naoki, Okawa Hirokazu
Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181, Japan.
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181, Japan.
Polymers (Basel). 2022 Apr 5;14(7):1473. doi: 10.3390/polym14071473.
In this study, a method of removing an anionic surfactant sodium dodecyl sulfate (SDS) from an aqueous solution by cellulose modified with quaternary ammonium cation was discussed. Cellulose, as the adsorbent, was obtained from medical cotton balls, and the quaternary ammonium cation (synthesized from dodecyl dimethyl tertiary amine and epichlorohydrin) was grafted onto the sixth hydroxyl group of D-glucose in the cellulose by the Williamson reaction under alkaline conditions. The modified cellulose was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS); and the zeta potential of the material was also measured after confirmation of the synthesis of quaternary ammonium salts by nuclear magnetic resonance (NMR). From these analyses, a peak of the quaternary ammonium group was observed at 1637 cm; and it was found that the surface of the material exhibited a positive charge in pH 2-7. The optimal conditions for SDS adsorption by modified cellulose were pH of 7, contact time of 3 h, and temperature of 60 °C in this study. Typical adsorption isotherms (Langmuir and Freundlich) were determined for the adsorption process, and the maximal adsorption capacity was estimated as 32.5 mg g. The results of adsorption kinetics were more consistent with the pseudo-second-order equation, indicating that the adsorption process was mainly controlled by chemical adsorption. Furthermore, thermodynamic analysis indicated that the adsorption process of SDS on the modified cellulose was endothermic and spontaneous and that an increasing temperature was conducive to adsorption.
在本研究中，探讨了一种通过用季铵阳离子改性的纤维素从水溶液中去除阴离子表面活性剂十二烷基硫酸钠（SDS）的方法。作为吸附剂的纤维素由医用棉球获得，季铵阳离子（由十二烷基二甲基叔胺和环氧氯丙烷合成）在碱性条件下通过威廉姆森反应接枝到纤维素中D - 葡萄糖的第六个羟基上。通过傅里叶变换红外光谱（FT - IR）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）对改性纤维素进行了表征；在通过核磁共振（NMR）确认季铵盐合成后，还测量了该材料的zeta电位。通过这些分析，在1637 cm处观察到季铵基团的峰；并且发现在pH 2 - 7时材料表面带正电荷。本研究中改性纤维素吸附SDS的最佳条件为pH值7、接触时间3 h和温度60℃。测定了吸附过程的典型吸附等温线（朗缪尔等温线和弗伦德利希等温线），最大吸附容量估计为32.5 mg/g。吸附动力学结果与准二级方程更一致，表明吸附过程主要受化学吸附控制。此外，热力学分析表明SDS在改性纤维素上的吸附过程是吸热且自发的，温度升高有利于吸附。
