魔芋葡甘聚糖/聚氨基酸纳米纤维膜吸附Cr(Ⅲ)的机制

Effect of Konjac Glucomannan/Poly (amino acid) Nanofiber Film and Its Adsorption for Cr(Ⅲ)

为了研究魔芋葡甘聚糖/聚氨基酸纳米纤维膜对Cr(Ⅲ)的吸附作用,以期获得一种具有良好吸附效果的吸附材料,采用静电纺丝的方法制备不同相对密度的魔芋葡甘聚糖/聚氨基酸纳米纤维膜,并通过流变仪、扫描电镜、傅里叶变换红外光谱和差示扫描量热法表征纳米纤维膜的结构和性能,结合吸附实验和吸附热力学及吸附动力学研究其吸附行为。结果表明,魔芋葡甘聚糖/聚氨基酸纳米纤维膜呈无序多孔的纳米结构,数个纳米大小的纤维组成了典型的"多孔网络"的交联结构,网络骨架的孔隙率较高,纳米纤维膜中微纤丝粗细最均匀且结点较少,纳米纤维膜中魔芋葡甘聚糖和聚氨基酸之间存在明显的相互作用。当聚氨基酸添加量为40mL时(浓度为1.2%),Cr(Ⅲ)溶液的pH为6.0,吸附时间为5d,可达到254.2 mg/g的吸附最大量,吸附过程满足准二级动力学方程,吸附形式为Langmuir单层吸附,符合Langmuir等温吸附模型;通过NaOH解吸附后,循环5次之后仍然具有51%以上的效率。

The konjac glucomannan / poly （amino acid） nanofiber membranes were synthesized for Cr （Ⅲ） adsorptiorL To obtain good adsorption materials, electrospinning technology was applied to prepare different proportion of konjac glucomannan / poly （amino acid） nanofibers. The morphology and structure of nanofiber membranes were analyzed by rheometer, scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR） and differential scanning （DSC）. The absorption behavior was explored by applying experiment of thermodynamics and kinetics. The results reveal that there are obvious interactions between glucomannan and amino acid. The nano porous structure disorderd presents in konjac glucomannan / poly （amino acid） nanofiher membrane, to form a porous network with high porosity and node less miecofibers. The maximum adsorption of nanofiber membrane can reach 254. 2 rag/g, under conditions as follows： poly （amino acid ） concentration of 1.2%, Cr （Ⅲ） solution of pH 6, the adsorption time of 5 d. The adsorption process satisfies the quasi second order kinetics equation, while the adsorption form belongs to Langmuir monolayer adsorption and accords with the isothermal adsorption model. After desorption with NaOH and recycled 5 times, the adsorption efficiency of nanofiber membrane remains over 51%.