柠檬渣活性炭制备及其亚甲基蓝吸附性能研究

Preparation of Activated Carbon from Lemon Pomace and Its Adsorption Performance of Methylene Blue

摘要: 本论文以风干柠檬皮为原材料，破碎后进行碳化，采用混合碱炭化–活化两步法制备山竹壳基活性炭，探索活性炭对亚甲基蓝的去除效果。在本研究中通过探究吸附过程中不同温度，不同pH以及不同亚甲基蓝质量浓度对于吸附性能的影响，探讨了其吸附动力学，吸附等温线以及热力学模型。并使用了扫描电子显微镜、X射线衍射仪、拉曼光谱、傅里叶红外光谱、XPS和Brunauer-Emmett-Teller (BET)理论作为测试方法表征。结果表明：最佳吸附条件为温度为30℃，pH为11，亚甲基蓝质量浓度为90 mg/L时，活性炭的吸附能力最好，对亚甲基蓝溶液的吸附率达90%以上。吸附机理分析得，制得活性炭对亚甲基蓝溶液的吸附过程符合Langmuir吸附模型，并且符合准一级动力学模型，为单层物理吸附。制得的活性炭孔容为0.699 cm/g，孔径为2.025 nm，比表面积为1325.678 m²/g。通过对活化前后的活性炭进行结构表征，得出活化后的活性炭的孔多是中孔，并且活化前后只是微观结构产生改变，如减少杂质，打开孔隙结构，整体的宏观结构并没有因为活化而改变。

Abstract: In this study, air-dried lemon peel was used as raw material, crushed and carbonized, and mangosteen shell-based activated carbon was prepared by a two-step method of mixed alkali carbonization-activation to explore the removal effect of activated carbon on methylene blue. In this study, the adsorption kinetics, adsorption isotherms and thermodynamic modeling were investigated by investigating the effects of different temperatures, pH and mass concentration of methylene blue on the adsorption performance during the adsorption process. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), Raman spectroscopy, Fourier infrared spectroscopy (FTIR), XPS and Brunauer-Emmett-Teller (BET) theory were used as test methods for the characterization. The results showed that the optimal adsorption conditions were temperature of 30°C, pH of 11, and mass concentration of methylene blue of 90 mg/L, the activated carbon had the best adsorption capacity, and the adsorption rate of methylene blue solution reached more than 90%. The adsorption mechanism was analyzed, and the adsorption process of the prepared activated carbon on methylene blue solution conformed to the Langmuir adsorption model, and conformed to the quasi-primary kinetic model, which was monolayer physical adsorption. The pore volume of the activated carbon was 0.699 cm/g, the pore size was 2.025 nm, and the specific surface area was 1325.678 m²/g. Structural characterization of the activated carbon before and after activation showed that the pores of the activated carbon were mostly mesoporous, and the activated carbon was only altered in microstructure before and after activation, e.g., reduction of impurities and opening of pore structure, and the overall macrostructure was not altered by the activation.