聚苯胺/凹凸棒石纳米复合材料对甲基橙的吸附性能

ADSORPTION OF METHYL ORANGE ON POLYANILINE/ATTAPULGITE NANOCOMPOSITES

通过原位聚合法制备了盐酸和对甲苯磺酸共掺杂聚苯胺/凹凸棒石纳米复合材料,用Fourier红外光谱和透射电镜对纳米复合材料进行了表征,并从热力学和动力学角度探讨了甲基橙在纳米复合材料上的吸附机理。结果表明:纳米复合材料兼具凹凸棒石的结构和聚苯胺的性质;当pH=5～7时,该纳米复合材料对甲基橙有优异的吸附能力,对甲基橙的吸附热力学符合Langmuir和Freundlich等温吸附方程,最大吸附量可达121.62mg/g,吸附焓变为4.73kJ/mol,吸附自由能变为–(29.79～22.93)kJ/mol,吸附熵变约为98J/(mol·K),是一个自发的吸热过程;纳米复合材料对甲基橙的吸附动力学符合准二级动力学方程,速率常数随着甲基橙溶液初始浓度的提高而下降。

Polyaniline/attapulgite nanocomposites codoped with hydrochloric acid（HCl） and p-Toluene sulphonic acid（TSA） were prepared by in situ polymerization method.The samples were characterized by Fourier transform infrared spectra（FTIR） and transmission electron microscopy（TEM）.The kinetics and thermodynamics of methyl orange adsorption on the nanocomposites were investigated.The results reveal that the nanocomposites which have the structure of attapulgite and the nature of the polyaniline.The nanocomposites have an excellent adsorption for methyl orange when the pH value is 5–7.The thermodynamics of methyl orange adsorption on the nanocomposites follows the isothermal adsorption equations of Langmuir and Freundlich.The adsorption could be an endothermal and spontaneous process at the maximum adsorption capacity of 121.62 mg/g,the adsorption enthalpy of 4.73 kJ/mol,the Gibbs free energy of –（29.79 to 22.93） kJ/mol,and the entropy of 98 J/（mol·K）.The kinetics of methyl orange adsorption on the nanocomposites follows the law of pseudo-second order kinetics.The rate constant decreases with increasing the initial concentration of methyl orange.