羧基化改性纤维素凝胶球的制备和表征

以微晶纤维素为原料，利用NaOH/尿素体系对微晶纤维素进行溶解，得到再生纤维素溶液。采用滴定悬浮的方法制备纤维素水凝胶球，采用2，2，6，6-四甲基哌啶-1-氧基自由基（TEMPO）/NaBr/NaClO选择性氧化体系对纤维素水凝胶球进行氧化处理，获得羧基化改性纤维素水凝胶球，冷冻干燥得到羧基化改性纤维素气凝胶球。研究结果表明：羧基化改性纤维素水凝胶球的含水量为95.64%，吸附4h，亚甲基蓝的吸附量达到6.97mg/g。对羧基化改性纤维素气凝胶球进行傅里叶变换红外光谱（FT-IR）和扫描电子显微镜（SEM）表征分析，在1600cm^-1处出现了CO的伸缩振动峰，TEMPO的选择性氧化对样品起到羧基化改性作用，羧基化改性纤维素气凝胶增加了球形气凝胶的表面通透性，内部仍呈现网络结构，羧基化改性纤维素气凝胶球的密度为0.038g/cm³。

Preparation and Characterization of Carboxyl Modification Cellulose Gel Beads

Regenerated cellulose solution was obtained by NaOH/urea system using microcrystalline cellulose as raw materials.Cellulose hydrogel bead was prepared by titration suspension method.Carboxyl modified cellulose hydrogel bead was obtained by oxidation treatment of TEMPO/NaBr/NaClO selective oxidation system and carboxyl modified cellulose aerogel bead was obtained by freeze drying.The results showed that water content of carboxyl modified cellulose hydrogel bead was 95.64%.After adsorption for 4 hours, the adsorption capacity of methylene blue was 6.97mg/g.The characterization analysis results of Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy(SEM) of carboxyl modified cellulose aerogel bead showed that CO stretching vibration absorption peak was appeared at 1600cm^-1, and TEMPO selective oxidation played a carboxyl modification role in the samples.The surface permeability of spherical aerogel was increased by carboxyl modification and the interior still presented network structure.The density of carboxyl modified cellulose aerogel bead was 0.038g/cm³.