木质素/Fenton污泥基磁性活性炭对亚甲基蓝和苯酚吸附特性的研究

Study on Adsorption Behaviors of Methylene Blue and Phenol by Lignin/Fenton Sludge Based Magnetic Activated Carbon

关键词:  磁性活性炭  吸附  亚甲基蓝  苯酚  木质素

Key Words:magnetic activated carbon  adsorption  methylene blue  phenol  lignin

摘要:以桉木硫酸盐法蒸煮黑液木质素和Fenton污泥为原料，氢氧化钾为活化剂，采用一步法制备磁性活性炭（MAC），利用比表面积及孔径分析仪（BET）、振动样品磁强计（VSM）和X射线衍射仪（XRD）对MAC的物相结构进行表征，评价了MAC对亚甲基蓝和苯酚的吸附性能。结果表明，所制备的MAC具有较大的比表面积和良好的磁分离性能，其BET比表面积为1079 m²/g，饱和磁化强度为5.79 emu/g，XRD分析发现磁性来源于Fe₃O₄或γ-Fe₂O₃；当MAC用量为0.5 g/L，亚甲基蓝和苯酚的初始浓度分别为300 mg/L和200 mg/L时，MAC对亚甲基蓝和苯酚的平衡吸附量分别达到了288 mg/g和98 mg/g；MAC对亚甲基蓝和苯酚的吸附动力学特性均符合准二级动力学方程；Freundlich模型能更好地描述MAC对亚甲基蓝的等温吸附过程，而Langmuir模型在描述MAC对苯酚的等温吸附过程更佳；MAC经过5次再生仍能达到原平衡吸附量的90%以上。

Abstract:In this study, magnetic activated carbon (MAC) was prepared from black liquor lignin and Fenton sludge by KOH activation via a simple one-step method. The phase structures of MAC were characterized by Brunauer-Emmett-Teller(BET), vibrating sample magnetometer (VSM ) and X-ray diffraction (XRD), and the adsorption performance of MAC on methylene blue and phenol and its recycling performance were investigated. The results showed that the MAC had a large BET specific surface area (1079 m²/g) and a good magnetic separation ability (saturation magnetization intensity: 5.79 emu/g). When MAC dosage was 0.5 g/L, and the initial concentrations of methylene blue and phenol were 300 mg/L and 200 mg/L respectively, the MAC equilibrium adsorption capacity of methylene blue and phenol achieved 288 mg/g and ‌‍98 mg/g respectively. The processes of adsorbing methylene blue and phenol fitted pseudo-second order kinetic reaction. Freundlich model and Langmuir model were suitable for describing the adsorption isotherms of methylene blue and phenol respectively. The recycling performance experiment showed that the adsorption capacity of MAC still retained more than 90% of the original adsorption capacity after 5 times reuse.