赖氨酸改性纳米纤维素的表征及其对亚甲基蓝的吸附行为研究

Characterization of Lysine Modified Nanocellulose and Its Adsorption Behavior for Methylene Blue

为了制备可生物降解的高效吸附材料,以竹浆纳米纤维素为原料,通过高碘酸钠氧化和Schiff碱反应,得到了赖氨酸改性的纳米纤维素,采用傅里叶红外光谱(FT-IR)、透射电子显微镜(TEM)和热重分析(TG)等表征手段证实了赖氨酸成功引入到纳米纤维素的表面。以亚甲基蓝(MB)为模型物,研究了其吸附性能。考察了吸附剂添加量和溶液pH值对平衡吸附量的影响。结果表明,与纳米纤维素(NFC)、醛基纳米纤维素(NFC-CHO)相比,赖氨酸改性纳米纤维素(NFC-g-Lysine)的吸附能力大幅提高,当NFC-g-Lysine添加量0.08%、pH值为9、MB浓度为200mg/L时,NFC-g-Lysine对MB的平衡吸附量达到178 mg/g,相比NFC(110 mg/g)提高了61%;NFC-g-Lysine等温吸附过程符合Freundlich模型;动力学数据表明NFC-g-Lysine对MB的吸附满足伪二级动力学方程。

In order to obtain efficient biodegradable adsorbent, lysine modified nanocellulose was prepared by periodate oxidation and Schiff base reaction using bamboo cellulose as raw material. It was confirmed that the successful introduction of lysine onto the surface of nanocellu- lose by means of FT-IR, TEM, TG methods. The adsorption property of lysine modified nanocellulose was evaluated using methylene blue （MB） as a model compound. The effects of pH and adsorbent dosage and initial dye concentration on equilibrium adsorption capacity of MB were studied. THe results showed that the equilibrium adsorption capacity of lysine modified nanocellulose was significantly increased com- pared with those of unmodified nanocellulose and aldehyde-based nanocellulose intermediates. The equilibrium adsorption capacity reached 178 mg/g, which was 61% higher than that of the unmodified nanocellulose （ 110 mg/g, ） at the adsorbent dosage 0. 08 wt%, pH value 9 and MB concentration of 200 mg/L. The isothermal adsorption process was in accordance with the Freundlich model. The kinetic data showed that the adsorption of MB onto the nanocellulose derivative could be expressed as the second-order kinetics equation.