等温滴定微量热法测定腐殖酸与不同含氧量碳纳米管的相互作用

摘要

The interaction between carbon nanotubes (CNTs) with various oxygen contents and humic acids (HA) was studied through batch adsorption experiments and the isothermal titration calorimetry (ITC) technique .The effects of CNTs surface chemistry and solution ionic strength were evaluated .Adsorption results show that the binding strength between CNTs and HA and equilibrium adsorption capacity of HA increase with the decrease in CNTs'oxygen content decreases and the increase in ionic strength ,implying that hydrophobic interaction could be one of the main interaction forces between CNTs and HA .ITC results indicate that interaction between CNTs and HA is exothermic and that a stable CNT‐HA complex could be formed .CNTs solutions become more ordered after binding with HA .The negative enthalpy and entropy changes obtained from the ITC analysis imply the existence of hydrogen bonds between CNTs and HA .This could provide a better understanding of interactions between humic substances and CNTs ,and thus the migration and fate of CNTs in natural environments .%利用批次吸附实验和等温滴定微量热技术（ITC）测定了碳纳米管（CNT）与腐殖酸（HA）相互作用的热力学参数，并研究了碳纳米管含氧量和离子强度的影响．批次吸附实验结果表明，碳纳米管与腐殖酸的结合强度和平衡吸附量随碳纳米管含氧量的增加而降低，随离子强度的增加而升高，证明了疏水作用力对二者的结合起了重要作用．ITC结果表明二者结合是放热反应，能形成稳定的CNT‐HA复合物，加入腐殖酸后，体系的有序度增加，而负的熵变和焓变表明二者之间形成了氢键．以上结果有助于理解和研究腐殖质对碳纳米管在自然水体中迁移特性的影响．