壳聚糖/纤维素气凝胶球的制备及其甲醛吸附性能

摘要

Cellulose aerogel beads(CAB) and chitosan/cellulose aerogel beads(CCAB) were prepared through droplet-suspension gelation processing,and then the acid treated CAB(CAB-A) and acid treated CCAB(CCAB-A) were obtained through acetic acid post-processing from CAB and CCAB.Morphologies,chemical states,element distributions and pore structures of the aerogel beads were characterized and analyzed by SEM,FT-IR,XPS and BET.Meanwhile,formaldehyde adsorption performances of the aerogel beads were measured by gaseous formaldehyde adsorption test.The results showed that the prepared aerogels had uniform spherical shape,and the average particle sizes of CAB, CAB-A,CCAB and CCAB-A were (2.67±0.01), (2.47±0.02), (2.79±0.05) and (3.34±0.05) mm, respectively.Chitosan molecules were introduced into the cellulose matrix and no significant chemical changes occurred during the preparation.In addition,chitosan molecules by acid treatment were renewably distributed and self-assembled in the network of cellulose gel, formed more intensive aerogel network structure,and provided abundant pore structure with the specific surface area and mesoporous volume of CCAB-A of 1 350.7 m2/g and 4.511 cm3/g,respectively.Thus the adsorbing capacity of the composite aerogel beads reached up to 1.99 mmol/g after adsorption for 1 h which was far greater than that by coconut shell activated carbon material with same dosage (0.39 mmol/g).The chemical combination of azomethine and schiff base was formed between primary amine and formaldehyde molecule in the aerogel beads.%采用液滴悬浮凝胶法分别制备纤维素气凝胶球(CAB)和壳聚糖/纤维素气凝胶球(CCAB),再经酸处理过程分别制得酸处理的CAB(CAB-A)和酸处理的CCAB(CCAB-A),并通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、X光电子能谱(XPS)和比表面积孔隙测定仪等检测手段对复合气凝胶球的形貌、化学态、表面元素分布以及孔隙结构进行了分析.同时,通过气态甲醛吸附试验对样品的甲醛吸附性能进行测定.结果表明:该法制备的壳聚糖/纤维素复合气凝胶具有均匀的球形形态,CAB、CAB-A、CCAB和CCAB-A的平均粒径分别为(2.67±0.01)、(2.47±0.02)、(2.79±0.05)和(3.34±0.05)mm.壳聚糖引入到纤维素基体中没有发生化学变化,并且通过酸处理使壳聚糖分子在纤维素凝胶网络中进行了重新分布和组装,形成更为密集的气凝胶网状结构,产生了更为丰富的孔隙结构,CCAB-A的比表面积和介孔体积分别为1 350.7 m2/g和4.511 cm3/g.气态甲醛吸附测试结果表明:CCAB-A复合气凝胶球吸附1 h的吸附量高达1.99 mmol/g,远远大于相同用量的椰壳活性炭材料的甲醛吸附量0.39 mmol/g,并且与甲醛分子之间形成了稳定的甲亚胺和席夫碱的化学结合.