水葫芦木质素的提取及其苯胺吸附性能

摘要

采用碱提法从生态入侵植物水葫芦中提取木质素,利用傅立叶红外光谱(FT-IR)和扫描电镜(SEM)等手段对所获得的木质素进行表征,研究了水葫芦木质素对水中苯胺的吸附性能,考察了溶液pH值、吸附时间、初始浓度等因素对水葫芦木质素吸附苯胺的影响.当NaOH溶液浓度0.1 moL/L,提取时间4h,温度100 ℃,料液比1∶20时,水葫芦木质素的收率最大为6.81％.红外图谱显示,在1 456～1 656cm-1处存在木质素的芳香环骨架振动吸收峰;扫描电镜显示,木质素呈大量细小的颗粒,木质素颗粒表面存在许多微小的孔状结构,有利于吸附作用的发生.在室温下,溶液pH 6.0,苯胺初始浓度为150 mg/L,吸附剂用量为5 mg,吸附时间120 min时,水葫芦木质素对苯胺的最大吸附容量为12.2 mg/g.苯胺吸附实验数据拟合符合准二级动力学模型以及Langmuir吸附等温模型.水葫芦木质素对苯胺的吸附以单分子层化学吸附为主,属于优惠吸附.相同吸附条件下,水葫芦木质素对湖泊水样中苯胺的吸附与实验模拟水样的吸附效果相近.水葫芦木质素可作为富集分离材料用于分析样品制备以及水中污染物的吸附.%Lignin was extracted from ecological invasive plant water hyacinth by alkali extraction.The extracted product was characterized by FT-IR and SEM methods.The effects of some factors such as pH value,adsorption time,initial concentration on the adsorption capacity of water hyacinth lignin for aniline were evaluated.When the concentration of NaOH solution was 0.1 mol/L,the extraction time was 4 h,temperature was 100 ℃,and the solid-liquid ratio was 1 ∶ 20,the yield of water hyacinth lignin was the maximum of 6.81％.The infrared spectrum showed the stretching vibrations of the C =C bonds in the aromatic skeleton at 1 456-1 656 cm-1 The results of the infrared spectrum indicated that the obtained product was lignin.The result of SEM showed that water hyacinth lignin composed of a large number of small amorphous particlcs,and thcre were many micro pores on the surface of lignin particles,which would be benefit to increase the adsorption capacity.The maximum adsorption capacity reached up to 12.2 mg/g at pH 6.0 with an initial concentration of aniline of 150 mg/L,an adsorbent dosage of 5 mg and an adsorption time of 120 min at room temperature.The adsorption data fited well with thc Pseudo-second-order kinetics model and the Langmuir isotherm model.The adsorption of aniline by water hyacinth lignin was mainly assigned to chemical adsorption of monolayer and favorable adsorption.Under the same adsorption conditions,the adsorption capacities of water hyacinth lignin for aniline in a lake water samples were similar to that in the simulated water samples.Water hyacinth lignin could be used as enrichment and seperation material for sample pretreatment and removing pollutant in wastewater.