Study On The Dye Adsorption And Electrochemical Properties Of Carbon Nanotube/Polyaniline Composites

Polyaniline (PANI) exhibits good acid-doping/base-dedoping, reversible redox property, high environmental stability, and strong interactions with dyes in aqueous solution, revealing a great potential for the PANI to be utilized as absorbents in wastewater treatments. However, the dye adsorption efficiency of PANI is rather low due to the compact accumulations and low specific surface area, which greatly limits the application of PANI in wastewater retreatment. in this dissertation, our objective is to improve the dye Adsorption capacity of absorbents by introducing carbon nanotubes (CNTs) into PANI matrix and forming a multi-scale porous structure of the CNT/PANI composites.The CNT/PANI composites were prepared by static interfacial polymerization and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is found that these composites showed multi-scale porous structures, where the entangled CNTs played a role of porous frameworks and the PANI was fully coated on the surface of CNTs, greatly increasing the specific surface area and dye Adsorption capacity of the composites. The adsorption of dye like Malachite Green (MG) on the CNT/PANI composites was investigated in details. The MG adsorption capacity and efficiency were greatly enhanced by incorporating CNTs into PANI matrix, which is mainly attributed to the porous structure and high specific surface area of the composites. The CNT/PANI composites exhibited higher MG Adsorption capacity than the neat PANI, increasing by increasing by 15% at the initial MG concentration of 16mg/l. in addition, we found the Adsorption capacity strongly depended on the initial dye concentration, and the dye Adsorption amount of composites was proportional to the dye concentration of solution. Moreover, the adsorption kinetics and isotherm process were also theoretically analyzed. It is found that the adsorption kinetics and the isothermal process can be well explained by using the Pseudo-second-order model and the Langmuir model, respectively.Moreover, the electrochemical properties of the CNT/PANI composites synthesized by dynamic interfacial polymerization were also investigated, and the cyclic voltammetry and AC impedance of the composites were measured by using a three-electrode system. The results showed that the specific capacity of the composites arrived to 822.1F/g, much higher than that of the neat PANI (743.7F/g). Furthermore, the AC impedance of CNT/PANI composites was reduced, which is beneficial to accelerate the redox process of PANI for obtaining high super-capacitor characteristics.In a summary, the CNT/PANI composites fabricated by static interfacial polymerization show multi-scale pore structure and high dye adsorption capacity and efficient removals of dyes from wastewater. Meanwhile, the CNT/PANI composites synthesized by dynamic interfacial polymerization exhibit good electrochemical characteristics. Consequently, the CNT/PANI composites have great potentials to be utilized as high-efficiency absorbents in wastewater treatment and super-capacitor electrode materials.