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以甲壳素为原料,次氯酸钠为氧化剂,2,2,6,6-四氧基哌啶-1-氧化物自由基和溴化钠为催化剂,制备了氧化甲壳素。通过红外光谱、X射线衍射仪、碳核磁共振图谱和扫描电镜对其结构和形貌进行表征,研究了其对亚甲基蓝的吸附性能。结果表明,氧化改性不改变α-甲壳素晶型,使甲壳素重复结构单元C6位置的部分羟甲基被氧化成羧基,表面由粗糙致密变为光滑结构。氧化甲壳素对亚甲基蓝吸附能够使用Pseudo-Second-order模型和Langmuir等温吸附方程拟合的自发放热反应。相同条件下,氧化甲壳素对亚甲基蓝的吸附能力优于未改性甲壳素和活性炭。
Chitin was prepared by using chitin as raw material, sodium hypochlorite as oxidant, 2,2,6,6-tetraoxopiperidine-1-oxide free radical and sodium bromide as catalyst. Its structure and morphology were characterized by infrared spectroscopy, X-ray diffraction, carbon nuclear magnetic resonance spectroscopy and scanning electron microscopy. The adsorption properties of methylene blue were studied. The results show that the oxidative modification does not change the α-chitin crystal form, so that some of the hydroxymethyl groups in the chitin repeat structure unit C6 are oxidized to carboxyl groups, and the surface changes from rough to dense to a smooth structure. The oxidized chitin-to-methylene blue adsorption spontaneous exothermic reaction can be fitted using the Pseudo-Second-order model and the Langmuir isotherm equation. Under the same conditions, the adsorption capacity of oxidized chitin to methylene blue is better than that of unmodified chitin and activated carbon.