Anionic modified viscose fiber (AVF) was prepared by using viscose fiber (VF) as raw material, sodium hydroxide as catalyst and sodium chloroacetate as modification reagent. The COOH content of anionic viscose fiber was 109.25 mmol/kg. Anionic viscose fibers were modified with branched polyethylenimine (HPEI) at 140 °C hydrothermal environment using a high-pressure reaction kettle. Zwitterionic viscose fibers (AVF-g-HPEI) with different amino and carboxyl contents could be obtained by changing the ratio of the two modified reagents. Increasing HPEI dosage resulted in amide group content of zwitterionic viscose fibers ranging from 0 to 108.35 mmol/kg. The zwitterionic viscose fibers were characterized by IR, SEM and XPS. IR analysis showed that zwitterionic viscose fiber was successfully prepared. SEM analysis showed that the reaction mainly occurred on the surface of the fiber, and the fiber structure was not changed. XPS analysis demonstrated that with the HPEI dosage increasing nitrogen elements on the surface of zwitterionic viscose fiber increased significantly. Dye adsorption experiments indicated that (1) AVF-g-HPEI could selectively adsorb the anionic dye or the cationic dye (such as methyl orange and methylene blue) from the mixed solution after the pre-treatment with pH 4.5 or pH 10.5 solution, respectively, (2) the dyes adsorbed by zwitterionic viscose fiber could be desorbed in the aqueous solution of pH 4.5 or 10.5, respectively and (3) the desorption ratio of AVF-g-HPEI remained above 0.85 after eight cycles.

以粘胶纤维（VF）为原料，以氢氧化钠为催化剂，以氯乙酸钠为改性剂，制备了阴离子改性粘胶纤维（AVF）。阴离子粘胶纤维的COOH含量为109.25 mmol / kg。使用高压反应釜在140°C水热环境下用支链聚乙烯亚胺（HPEI）改性阴离子粘胶纤维。两性离子粘胶纤维（AVF- g通过改变两种修饰试剂的比例可以得到具有不同氨基和羧基含量的-HPEI）。HPEI剂量的增加导致两性离子粘胶纤维的酰胺基含量在0至108.35 mmol / kg之间。用IR，SEM和XPS对两性离子粘胶纤维进行了表征。红外分析表明，成功制备了两性离子粘胶纤维。SEM分析表明，反应主要发生在纤维表面，且纤维结构未发生变化。XPS分析表明，随着HPEI剂量的增加，两性离子粘胶纤维表面的氮元素显着增加。染料吸附实验表明（1）AVF- g-HPEI分别在用pH 4.5或pH 10.5溶液预处理后可以从混合溶液中选择性吸附阴离子染料或阳离子染料（例如甲基橙和亚甲基蓝），（2）两性离子粘胶纤维吸附的染料分别在pH 4.5或10.5的水溶液中解吸；（3）经过八个循环后，AVF- g -HPEI的解吸率保持在0.85以上。