磁性木质素制备及其对染料的吸附性能

Preparation of lignin/Fe3O4 based magnetic material and their performance in adsorption of dyes

纳米材料粒径小、比表面积大、表面能高,具有良好的吸附特性。以磁性纳米颗粒合成的材料作为吸附材料时,不仅表现出高吸附容量,且易于回收和循环使用。本研究以沉淀法合成的超顺磁性Fe3O4纳米颗粒为负载物质,以黑液木质素为载体,采用原位吸附法和氨丙基三乙氧基硅烷(APTES)交联法分别制备磁性木质素Fe3O4@木质素和Fe3O4@APTES@木质素。采用红外线光谱仪、X射线衍射仪、透射电子显微镜、扫描电镜和振动样品磁强计对磁性木质素进行分析表征,并考察这些磁性木质素对染料(亚甲基蓝、刚果红和甲基橙)的吸附性能。结果显示:通过原位吸附法和交联法均能使木质素负载在Fe3O4外层,形成的Fe3O4@木质素和Fe3O4@APTES@木质素具有核壳结构,饱和磁强度分别为51和22 emu/g,负载前后Fe3O4的晶型结构和木质素的分子结构均不受影响。与黑液木质素、Fe3O4@木质素相比,利用交联法得到的Fe3O4@APTES@木质素对染料吸附性能最好,在颗粒添加量1.5 g/L,吸附温度298 K,初始染料质量浓度100 mg/L条件下,亚甲基蓝、刚果红和甲基橙的最大吸附量分别达到140.2,181.4和71.2 mg/g,吸附后磁性木质素在外磁场作用下能够从体系中分离出来,回收过程简便。

Nanomaterial has the properties of small particle size,large specific surface area and high surface energy,which make it an excellent candidate as the adsorbent.Introducing magnetic ability to nano-adsorbentcan facilitate the recovery and recycling of the nano-adsorbent.Although lignin has be used as the adsorbent to adsorb the dyes of methylene blue,congo red and methyl orange,it is non-recyclable and has limit adsorption capacity.In this study,magnetic nano-adsorbent was prepared from super paramagnetic nanoparticles of Fe3O4 and lignin precipitated from black liquor by in situ adsorption method and aminopropyltriethoxysilane cross-linking method.The resulted magnetic lignin/Fe3O4 based materials were termed as Fe3O4@lignin and Fe3O4@APTES@lignin,respectively.The as-synthesized magnetic lignins Fe3O4@lignin and Fe3O4@APTES@lignin were characterized by Fourier transform infrared spectroscopy,X-ray diffraction,transmission electron microscopy,scanning electron microscopy and vibrating sample magnetometerto understand their chemical and physical properties.Meanwhile,the adsorption performance of magnetic lignins on methylene blue,congo red and methyl orange were investigated.The results showed that lignins could successfully load on the surface of the Fe3O4 particles through both in situ adsorption method and aminopropyltriethoxysilane cross-linking method.The synthesized Fe3O4@lignin and Fe3O4@APTES@lignin exhibited a core-shell structures with the saturation magnetic intensity of 51 and 22 emu/g,respectively.In addition,it is found that the crystal structure of Fe3O4 particles and molecular structure of lignin were not changed in the synthesized magnetic lignins.Under the adsorption conditions of 1.5 g/L particle addition,298 K,and dye concentration with 100 mg/L,Fe3O4@APTES@lignin showed the maximal adsorption capacity to adsorb methylene blue,congo red and methyl orange of 140.2,181.4,and 71.2 mg/g,respectively.After adsorption,the magnetic lignins could be easily separated and recovered by a magnet.