亚甲基蓝在碳纳米管上的吸附行为及其热力学研究

采用亚甲基蓝作为碱性染料，测定了亚甲基蓝初始浓度为10mg/L，吸附平衡8h，温度290、300、310K时在多壁碳纳米管上的吸附行为，并拟合了Langmiur、Freundlich和Sips吸附等温模型的吸附参数，发现吸附行为最符合Sips模型；亚甲基蓝溶液在碳纳米管上的吸附量在pH 3～7范围内随pH值增大而增大；热力学参数计算得到G为负值，表明吸附自发进行并以物理吸附为主；H为正值表明吸附为吸热过程；S为正值，表明吸附过程是熵增过程.

ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ONTO CARBON NANOTUBES AND ITS THERMODYNAMICS

Methylene blue(MB) was chosen as a model dye to investigate the adsorption behaviors of basic dye from aqueous solution onto carbon nanotubes(MWCNTs). Adsorption isotherm of MB onto the MWCNTs was determined at 290,300 and 310K respectively, by using 10mg/L as the initial concentration of MB. Adsorption equilibrium was attained within 8h. Adsorption equilibrium data were fitted to the Langmuir, Freundlich and Sips models and isotherm constants were determined.The equilibrium data were best represented by the Sips isotherm model. The adsorption amount increased gradually with the increase of pH from 3 to 7. Thermodynamic parameters like changes in the free energy of adsorption(G), enthalpy(H) and entropy(S) were calculated. The negative values of G indicates that the MB adsorption process is a spontaneous in nature and dominated by physical adsorption. The positive value of H andS show the endothermic nature of MWCNTs system and the increasing confusion degree of MWCNTs system,respectively.